Joseph Gall (Phrenology)
Strongly proposed that the brain (and not heart) was where all behaviors came from. Traits are separated to different parts of the brain, and lumps on the head indicate a preference for the trait corresponding to the area where the lump occurs.
Paul Broca
Frontal lobe is important for language.
Broca's Patient "Tan
Could only say the word "tan" but understood everything.
Broca's Aphasia
Damage to the frontal region results in patients who can understand language but cannot speak coherently.
Wernicke's Aphasia
Damage to the temporal love results in patients who can speak (yet their sentences don't make sense) but cannot understand language properly.
Phinneas Gage
Had a rod through his skull and behind the left eye. Personality changes due to frontal lobe damage. First indication that there was a segregation in the functions of the brain.
Frontal Lobe
Executive function, decision-making, impulse control, and motor control.
Occipital Lobe
Eyesight; visual system.
Temporal Lobe
Auditory processing, learning, and memory.
Parietal Lobe
Perception. Directs movement.
Cerebellum
Balance; coordination.
Corpus Collosum
A large bundle of nerve fibers that connect corresponding parts of one side of the brain with those of the other.
Natural Selection
The gradual process by which biological traits become either more or less common in a population as a function of the effect of inherited traits on the differential reproductive success of organisms interacting their environment. Behaviors are advantageou
Fixed Action Pattern
A sequence of unlearned, innate behaviors that is unchangeable. Once initiated, it is usually carried to completion.
Trigger Stimulus
The stimulus that triggers the fixed action pattern.
Heritability
The percentage of the variation in a characteristic that can be attributed to genetic factors.
Motor Cortex
In front of the central gyrus (separates frontal lobe from parietal lobe).
Sylvian Fissure
Divides frontal/parietal lobes from temporal lobe.
4 Neuron Zones
1) Input zone
2) Integration zone
3) Conduction zone
4) Output zone
Input Zone (1/4)
(Dendrites.) Receives information from other cells.
Integration Zone (2/4)
(Cell Body/Soma.) Region where inputs are combined and transformed.
Conduction Zone (3/4)
(Axon.) Leads away from the cell body and transmits the electrical impulse.
Output Zone (4/4)
(Axon terminals.) Communicate activity to other cells.
Neuron Doctrine
After Golgi's silver stain, Ramon y Cajal proposed that the web-like figures were neurons.
3 Synaptic Components
1) Presynaptic membrane
2) Postsynaptic membrane
3) Synaptic cleft
Presynaptic Membrane (1/3)
On the axon terminal of the presynaptic neuron.
Postsynaptic Membrane (2/3)
On the dendrite of the cell body of the postsynaptic neuron.
Synaptic Cleft (3/3)
A gap that separates the membranes.
4 Glial Cell Types
Astrocytes
Microglia
Schwann cells
Oligodendrocytes
Astrocytes (1/4)
Star-shaped cells with many processes that receive neuronal input and monitor activity. Localized in the CNS.
Microglia (2/4)
Small cells that remove debris from injured cells. Localized in the CNS.
Schwann Cells (3/4)
Provide myelination to PNS cells.
Oligodendrocytes (4/4)
Provide myelination to CNS cells.
Myelination
The process in which glial cells wrap axons with a fatty sheath (myelin) to insulate and speed up conduction.
Multiple Sclerosis
A demyelinating disease.
Central Nervous System
Consists of the brain and spinal cord.
Peripheral Nervous System
All the nerve fibers radiating out beyond the brain and spinal cord, as well as the neurons outside the brain and spinal cord.
3 Autonomic Nervous System (PNS) Divions
1) Sympathetic nervous system
2) Parasympathetic nervous system
3) Enteric nervous system
Sympathetic Nervous System (1/3)
Fight or flight response.
Parasympathetic Nervous System (2/3)
Active in relaxed, non-dangerous situations.
Enteric Nervous System (3/3)
Regulates digestion.
Afferent Information
Sensory information coming into the CNS.
Efferent Information
Information leaving the CNS.
Gyrus
A ridged or raised portion of the convoluted brain surface.
Sulcus
A furrow of the convoluted brain surface.
Meninges
1) Skull
2) Dura mater
3) Arachnoid membrane
[Subarachnoid space --> filled with CSF]
4) Pia mater
Ventricular System
A series of chambers filled with CSF.
Cerebrospinal Fluid (CSF)
2 Functions:
1) Acts as a shock absorber.
2) Provides an exchange medium between blood and brain.
White Matter
Mostly axons with white myelin sheaths.
Gray Matter
Mostly cell bodies and dendrites, which lack myelin.
Neocortical Layers
6 layers. Distinguished by type of neuron and pattern of dendrites or axons.
Cytoarchitectonic Map
Broadmann defined areas by organization and characteristics, e.g. touch (red), vision (purple), and hearing (orange).
Ion Permeability
Water molecules are polar. Negative Cl- attracts + poles of H2O molecules, and positive NA+ attracts - poles of H2O molecules. Cell membranes are made of lipids and are not permeable to ions. Thus, for ions to go through, they must go through specialized
Resting Membrane Potnetial
The difference in charge between the inside and outside of a neuron when no impulse is being carried across the axon. (-70 mV.)
K+
Is free to enter and leave the cell through K+ channels.
Na+
Na+ channels are usually closed to prevent the entry of Na+.
Na+/K+ Balance
3 Na+ : 2 K+
Graded Potentials
Changes in membrane potential that vary in size, as opposed to being all-or-none.
Hyperpolarization
Increase in electrical charge across a membrane (more negative). Usually due to the inward flow of Cl- ions or outward flow of K+ ions.
http://www.dna2life.com/sites/default/files/action-potential1.jpg
Depolarization
Decrease in electrical charge across a membrane (more positive). Usually due to the inward flow of NA+ ions.
http://www.ric.edu/faculty/jmontvilo/335graphics/action_potential/polarizations.JPG
Input Integration
Can be across time and space (i.e. synapses).
TIME: multiple inputs coming in at the same area at different times.
SPACE: multiple inputs coming into different areas on the dendrite.
7 Types of Synapses
1) Dendrodendritic
2) Axodendritic
3) Axoextracellular
4) Axosomatic
5) Axosynpatic
6) Axoaxonic
7) Axosecratory
Dendrodendritic Synapse (1/7)
Dendrites send messages to other dendrites.
Axodendritic Synapse (2/7)
The axon terminal of one neuron synapses on the dendritic spine of another.
Axoextracellular Synapse (3/7)
Axon terminal with no specific target. Secretes neurotransmitter to extracellular fluid.
Axosomatic Synapse (4/7)
The axon terminal of one neuron synapses on the cell body of another.
Axosynaptic Synapse (5/7)
The axon terminal of one neuron synapses on the axon terminal of another.
Axoaxonic Synapse (6/7)
The axon terminal of one neuron synapses on the axon of another.
Axosecratory Synapse (7/7)
The axon terminal ends on a tiny blood vessel. Secretes neurotransmitter directly into blood.
Chemical Synapse
The junction where messenger molecules (neurotransmitters) are released from one neuron to excited or inhibit the next neuron.
Neurotransmitter
A chemical released by a neuron onto a target with an excitatory or inhibitory effect. Outside the CNS, many of these chemicals circulate in the bloodstream as hormones (have distant target and different action than neurotransmitter).
Otto Loewi (1921)
Frog heart experiment. Role of the vagus nerve and the neurotransmitter acetylcholine (ACh) in slowing heart rate.
Acetylcholine (ACh)
First neurotransmitter discovered in the PNS and CNS. Activates skeletal muscles in the Somatic Nervous System. May excite or inhibit internal organs in the Autonomic Nervous System.
Gap Junction
Fused presynaptic and postsynaptic membrane that allows ions (electrical messages) to pass directly from one neuron to the next.
4 Steps in Synaptic Transmission
1) Synthesis
2) Release
3) Receptor Action
4) Inactivation
Synthesis (1/4)
Some neurotransmitters are transported from the cell nucleus to the terminal button. Others made from building blocks are imported into the terminal and are packaged into vesicles there.
Release (2/4)
In response to an action potential, the transmitter is released across the membrane by exocytosis.
Receptor Action (3/4)
The transmitter crosses the synaptic cleft and binds to a receptor.
Inactivation (4/4)
The transmitter is either taken back into the terminal or inactivated in the synaptic cleft.
4 Ways to Deal with Excess Neurotransmitter
1) Diffusion
2) Degradation
3) Reuptake
4) Glial cells
Diffusion (1/4)
Diffusion of neurotransmitter away from the synaptic cleft.
Degradation (2/4)
Degradation of neurotransmitter by enzymes in the synaptic cleft.
Reuptake (3/4)
Reuptake of neurotransmitter into the presynaptic neuron for subsequent reuse.
Glial Cells (4/4)
Neurotransmitter is taken up by neighboring glial cells.
Small-Molecule Transmitters
Class of quick-acting neurotransmitters. Synthesized from dietary nutrients and packaged ready for use in axon terminals.
EXAMPLES:
Amines: Acetylcholine (ACh), Dopamine (DA), Norepinephrine (NE), Epinephrine (EP), Serotonin (5-HT)
Amino Acids: Gultamate
Gulatamate
Usually excitatory.
GABA
Usually inhibitory.
Amine Neurotransmitters
Modulate overall brain state.
Peptide Transmitters
Act as hormones that respond to stress. Enable a mother to bond with her infant; regulate eating/drinking and pleasure/pain; and contribute to learning. Opiates such as morphine and heroin mimic the actions of natural brain peptides.
Transmitter Gases
Neither stored in synaptic vesicles nor released from them. Synthesized in the neuron as needed. Easily cross cell membrane.
EXAMPLE: Nitric Oxide (NO). Viagra enhances the effects of NO in the blood vessels in the penis.
Excitatory Postsynaptic Potential (EPSP)
A neurotransmitter may depolarize the postsynaptic membrane, causing excitatory action on the postsynaptic neuron.
Inhibitory Postsynaptic Potential (IPSP)
A neurotransmitter may hyperpolarize the postsynaptic membrane, causing inhibitory action on the postsynaptic neuron.
Ionic Receptos
Fast. Quickly change shape and open or close an ion channel when the transmitter molecule binds.
Metabotropic Receptor
Slow. When activated, they alter chemical reactions in the cell, using a system of secondary messengers, to open an ion channel. May also start chemical reactions to change gene expression.
Saltatory Conduction
The propagation of an action potential across a myelinated axon along successive nodes of Ranvier, increasing the conduction velocity of the action potential.
Refractory Period
The resting period between action potentials.
Descartes
The brain controls movement/perception. The mind controls decisions. The mind communicates with the brain through the pineal gland.
Drugs
Chemicals that have physiological effects.
Psychoactive Drugs
Antianxiety Agents & Sedative Hypnotics
Antipsychotic Agents
Antidepressants & Mood Stablilizers
Opioid Analgesics
Psychotropics
Antianxiety Agents & Sedative Hypnotics (Psychoactive)
At low doses, they appear to depress inhibitory parts of the brain, leading to disinhibition or relaxation and talkativeness. As the dose is increased, the neural functions become depressed, leading to uncoordinated movements and unconsciousness.
EXAMPLES
Antipsychotic Agents (Psychoactive)
Can calm psychotic patients, like ones diagnosed with schizophrenia.
EXAMPLES:
Haloperidol blocks D2 (Dopamine) receptors.
Antidepressants & Mood Stablizers (Psychoactive)
Most antidepressants increase serotonin or norepinephrine systems. Mood stabilizers mute the intensity of one pole of Bipolar Disorder, making the other pole less likely to occur (includes Lithium, which stimulates neuronal repair, and Valproate, which st
Opioid Analgesics (Psychoactive)
Analgesic (pain-killing) drugs that produce a dream-like state and can lead to sleep. Also known as narcotics. Different from depressants because there is NO reckless abandon, slurred speech, or staggering.
EXAMPLES:
Morphine
Codein
Methadone
Heroin
Psychotropics: Behavioral Stimulants (Psychoactive)
Produce wakefulness and a sense of energy and well-being. The most powerful one can lead to a manic state of excitement combined with paranoia and hallucinations.
EXAMPLES:
Cocaine
Amphetamines
Caffeine
Psychotropics: Hallucinogens (Psychoactive)
Produce altered perceptions, including unusual visual sensations and quite often changes in the perception of one's body.
EXAMPLES:
Mescaline
LSD
PCP
Nicotine (Psychoactive)
Thought of as a mild stimulant. Also has some relaxant properties.
Marijuana (Psychoactive)
Often thought of as a relaxant but it is different from all other categories. At high doses it can produce hallucinations.
Pharmokinetics
The study of factors that affect bioavailability.
Bioavailability
How much of a drug does remains in the blood, free to bind to targets.
5 Pharmokinetic Factors
1) Drug administration
2) Absorption & distribution
3) Binding
4) Inactivation
5) Excretion
Drug Administration (1/5)
Oral, intravenous, subcutaneous, intramuscular, inhalation, etc. The route of administration will effect when the drug will reach its target and how much of it will get there. All eventually reach the circulatory system.
Absorption & Distribution (2/5)
Membranes of oral cavity, gastrointestinal tract, peritoneum, skin, muscles, lungs, etc. The distribution of drugs is fairly generalized through the capillaries...areas with more blood will have more drug (heart, brain, kidneys, and liver).
Binding (3/5)
Target sites (neuron receptors).
Inactivation (4/5)
Liver.
Excretion (5/5)
Intestines (feces), kidneys (urine), lungs (water vapor), sweat glands (sweat), saliva, etc.
Blood-Brain Barrier
Consists of capillaries that are bound VERY tightly so many things cannot pass through. In addition, the capillaries are surrounded by glial cells that make it harder for things to go through. However, lipid-soluble substances can still go through, and th
Placenta Barrier
The placenta connects the fetus with the mother's uterine wall and brings nutrients and gases to the fetus as well as removing wastes. As with any other cell membrane, lipid-soluble substances will diffuse easily through the placenta while water-soluble o
Alcohol (Effect on Fetus)
Can cause Fetal Alcohol Syndrome: decreased birth weight, adverse cognitive outcomes, and poorer linguistic abilities/deficits in attention and memory.
Cocaine (Effect on Fetus)
Decreased neonatal head circumference, birth weight, prematurity, growth retardation, fetal loss, decreased adaptability to stress (including a disruption in the habituation response in infants), and impaired attention.
Marijuana
Decreased birth weight/length and deleterious cognitive and attention effects in some preschool and early school-age samples.
Nicotine
Physical, cognitive, and behavioral effects in offspring.
Heroin/Morphine
Neonatal Abstinence Syndrome (intrathecal morphine associated with fetal bradycardia).
Caffein
Low birth weight; small head circumference.
Drug Elimination
Drugs are eliminated from the body by several mechanism, among them metabolism and excretion of the drug and its metabolites.
Half-Life
The amount of time required to remove 50% of a drug from the blood.
Drug Biotransformation
Most drugs are altered by the body's enzymes somehow before they are excreted. These changes take place in organs like...
Liver (most important)
Stomach
Kidneys
Brain
Intestines
Blood plasma
Liver (Role in Drug Inactivation)
Plays a major role in drug biotransformation. Contains large amounts of enzymes that can metabolize a wide variety of compounds.
Ways Drugs Exert their Effects
By altering synaptic transmission. Can change the...
1) Levels of neurotransmitter made
2) Amount of neurotransmitter available in the synapse
3) Sensitivity of the receptors
4) Availability of the receptors (ex/ by blocking them)
Agonist
Substance that ENHANCES the function of a synapse.
Antagonist
Substance the BLOCKS/DECREASES the function of a synapse.
Receptor-Ligand Specificity
The more specificity at the ligand binding site, the better/stronger the interaction.
Steps of Drug Action
1) Serves as neurotransmitter (NT) precursor
2) Inhibits NT synthesis
3) Prevents storage of NT in vesicles
4) Stimulates release of NT
5) Inhibits release of NT
6) Stimulates postsynaptic receptors
7) Blocks postsynaptic receptors
8) Stimulates autorecep
Monoamine Oxidase (MAO) Inhibitors
Block the enzyme MAO from degrading neurotransmitters such as dopamine, noradrenaline, and serotonin.
Tricyclic Antidepressants
First-generation antidepressants with a chemical structure characterized by 3 rings that block serotonin reuptake and transporter proteins.
Second-Generation Antidepressants
Action is similar to 1st-generation antidepressants, but more selective in action on the serotonin reuptake transporter proteins. Also called Atypical Antidepressants.
Selective Serotonin Reuptake Inhibitors (SSRIs)
Block the reuptake of serotonin into the presynaptic terminal.
Alcohol and Depressant Drugs
Many of them act on the GABA ionotropic receptor, whcih is a GABA gated ion channel. When open, the channel allows Cl- to come into the cell, which makes it harder to fire an action potential. Because alcohol and depressant drugs do not act on the same si
Amphetamine and Cocaine
Increase dopaminergic signaling by overlapping mechanisms. They are AGONISTS that block the reuptake of dopamine. Amphetamine also promotes the release of dopamine.
Chlorpromazine
ANTAGONIST that occupies the dopamine site on the D2 receptor, preventing receptor activation.
Neuroplasticity
The nervous system's potential for physical or chemical change that enhances its adaptability to environmental change and its ability to compensate for injury.
Drug Tolerance
A diminished response to drug administration after repeated exposure to that drug. It is better to think of tolerance developing to the EFFECTS of a drug rather than to the drug itself.
Drug Tolerance: Potency Changes
Increasingly large doses of the drug become necessary to obtain the same effect.
Drug Tolerance: Efficacy Changes
It becomes impossible to achieve the same magnitude of effect.
Characteristics of Tolerance
- Reversible when drug use stops.
- Dependent on dose and frequency of drug use and drug-taking environment.
- May occur rapidly, or after long periods of chronic use, or never.
- Not all effects of a drug show the same amount of tolerance.
Metabolic (Dispositional) Tolerance
Changes in the body's ability to metabolize a drug. The repeated use of a drug reduces the amount of drug that is available to the user. This is due to enzyme induction in the liver, which increase the metabolic capacity. This will result in cross-toleran
Physiological (Pharmacodynamic or Cellular) Tolerance
The most dramatic form of tolerance. When changes in nerve cell function compensate for the continued presence of the drug. Up-Regulation or Down-Regulation of the receptors.
Behavioral (Learned) Tolerance
Tolerance that arises from learning or conditioning mechanisms. This is evidenced when tolerance can been seen in the same environment in which the drug was habituated but is not seen in other environments.
LEARNED TOLERANCE:
Tasks learned in the presence
Sensitization
The enhancement of particular drug effects following repeated administration of the same drug dose. NOT the mirror-image of tolerance. Only some drugs lead to sensitization and this might occur only for some of the effects of the drug. It has been shown t
Cross-Sensitization
Has been shown between drugs and between other conditions like stress (ex/stress increases the effect of these drugs). Can be conditioned to environments, which suggests a component of classical conditioning.
Sensitization to Amphetamines
Sensitization develops with periodic repeated injections.
Sensitization to Tranquilizers
Sensitization depends on the occurrence of the behavior; increased occurrence causes an increase in the time taken for a behavior to be compelted.
Pure Food and Drug Act (1906)
Regulated labeling of patent medicines and created the FDA.
Harrison Act (1914)
Regulated dispensing and use of opioid drugs and cocaine.
18th Amendment (1920)
Banned alcohol sales except for medicinal use (repealed in 1933).
Marijuana Tax Act (1937)
Banned non-medical use of cannabis (overturned in 1969).
Controlled Substances Act (1970)
Established schedules of controlled substances and created the DEA.
Craving
Strong urge to take a drug.
Remission
Drug-free period.
Relapse
Period in which drug use re-occurs.
Substance Abuse
A maladaptive pattern of substance use leading to clinically significant impairment or distress, as manifested by 1+ of the following occurring at any time in the same 12-month period:
-Failure to fulfill obligations.
-Physical hazard.
Legal problems.
-Co
Substance Dependence
A maladaptive pattern of substance use leading to clinically significant impairment or distress, as manifested by 1+ of the following occurring at any time in the same 12-month period:
-Tolerance.
-Withdrawal.
-Substance often taken in larger amounts or o
Physical Dependence Model
Attempts to stop taking the drug result in withdrawal syndrome (aka abstinence syndrome). This motivates the user to take the drug again.
Initial drug use
|
Repeated drug use
|
Physical dependence
|
Attempts at abstinence
|
Withdrawal symptoms
|
Relapse
O
Positive Reinforcement Model
The drug is SO positively rewarding that the person is motivated to take it again.
Incentive-Sensitization Theory
Addiction is acquired unconsciously and is the result of conditioned learning. Distinguishes between liking and wanting.
Initial drug use
|
Positive reinforcement
|
Repeated drug use
|
Sensitization of drug "wanting" but not drug "liking"
|
Attempts at ab
Wanting: Drug Craving
Increased with addiction.
NEURAL BASIS: mesolimbic dopamine pathway.
Liking: Pleasure Produced by Drug-Taking
Decreases with addiction.
NEURAL BASIS: activity of opioid neurons.
Neural Basis of Addiction
The decision to take a drug is made in the frontal cortex. The drug activates opioid systems related to pleasurable experiences. Wanting drugs springs from activity in the dopaminergic system. Voluntary control of drug taking gives way to unconscious proc
Dopamine Pathways
1) Mesolimbic
2) Nydrostriatal
Mesolimbic Dopamine Pathway
Reward pathway.
Ventral Tegmental Area (VTA) --> addiction.
Nydrostriatal Dopamine Pathway
Movement pathway.
Substantia Nigra --> Parkinson's.
Neurospsychology
The study of relations between brain function and behavior.
Corri-Block Mapping Test (Memory)
Short-term recall of spatial position.
Mirror Drawing Test (Memory)
Procedural memory.
Morris (1980) Swimming Test (Memory)
Place learning.
Brain Lesions
Used by Karl Lashey (1920s) to find location of memory in the brain.
ALABATION: removal or destruction of tissue.
Stereotaxic Apparatus
A surgical device that permits a researcher or a neurosurgeon to target a specific part of the brain for ablation.
Brain Stimulation
First used by Penfield to stimulate the cerebral cortex of humans during neurosurgery. Rats with electrodes in the lateral hypothalamus will eat whenever the stimulation is turned on.
Self-Stimulation
Given the opportunity, rats will press a level to obtain the current. The stimulation affects a neural circuit involving both eating and pleasure.
Transcranial Magnetic Stimulation
A procedure in which a magnetic coil is place over the skull to stimulate the underlying brain. Used either to induce behavior or to disrupt ongoing behavior.
Computerized Axial Tomography (CAT) Scans
Uses X-rays. The emitter is on an arc that moves around the patient. Creates a 2-D, detailed image of the brain (but it is static). Can detect tumors, strokes, foreign objects, etc.
Magnetic Resonance Imaging (MRI)
Uses magnetic fields instead of X-rays. Great detail of the brain structure. Safer than CAT scans, but much more expensive. Better view of soft tissues. Used to study brain anatomy.
Electroencephalogram (EEG)
Records electrical activity produced by various brain regions. Brain potentials indicate sleep states and provide data in seizure disorders.
Magnetoencephalogram (MEG)
Similar to EEG but measures faint magnetic fields generated by brain activity instead.
Grand Mal Seizure
Abnormal Activity throughout the brain. Characteristic movements; seizures followed by confusion and sleep.
Petit Mal Seizure
Brain waves show patterns of seizure activity for 5-15 seconds (can be many times a day). No unusual muscle activity (just stopping and staring). Events during seizure are not remembered.
Complex Partial Seizure
Does not involve the whole brain.
Event-Related Potential (ERP)
While looking at the response to a stimulus in a single trial is hard, averaging several trails aligned to the onset of the stimulus yields a much easier to interpret data set.
Positron Emission Tomography (PET)
Records emission of radioactivity from injected radioactive chemicals to produce a high-resolution image. Time-limited, as the half-life of the radioactive chemical is in the order of seconds.
Functional MRI (fMRI)
The Blood-Oxygen Level Dependent (BOLD) signal is measured. It is an indirect measure of neural activity. Based on the fact that oxygenated and deoxygenated blood have different magnetic properties. Thus, areas that have increased cellular activity will r
Diffusion Tensor Imaging (DTI)
Allows us to map the projections between brain areas (the axons): density and integrity. Based on the diffusion of water molecules.
Sensation
The registration of physical stimuli from the environment by the sensory organs.
Perception
Subjective interpretation of sensations by the brain. Our visual experience is NOT an objective reproduction of what is "out there," but rather, a subjective construction of reality that is manufactured by the brain.
Retina
Light sensitive surface at the back of the eye consisting of neurons and photoreceptor cells. Translates light into action potentials. Discriminates wavelengths (colors). Works in a wide range of light intensities.
Iris
Opens and closes to allow more or less light in.
Pupil
The hole in the iris.
Lens
Focuses light; bends to accommodate near and far objects.
Sclera
Forms the eyeball--the "white of the eye.
Cornea
Clear outer; protective covering.
Steps of Light Focusing
1) The cornea and iris focus light rays to project a backward, inverted image on the fovea.
2) In the retina, light energy initiates neural activity; the fovea is the region of sharpest vision and has the densest distribution of photoreceptors specialized
Myopia
Nearsightedness. Inability to bring distant objects into clear focus. Focal point of light falls short of the retina.
People with myopia cannot bring distant objects into clear focus, because the focal point of light falls short of the retina. Most common
Hyperopia
Farsightedness. Inability to focus on near objects. Focal point of light falls beyond the retina.
People with hyperopia cannot focus on nearby objects because the focal point of light falls beyond the retina. Eyeball may be too short or the lens may be to
Presbyopia
Common form of hyperopia seen in older adults.
Fovea
Region at the center of the retina that is specialized for high acuity.
Blind Spot
Region of the retina (optic disc) where axons forming the optic nerve leave the eye and where blood vessels enter and leave. This region has no photoreceptors.
Rods
More numerous than cones. Sensitive to dim light. Used mainly for night vision. One type of pigment only.
Cones
Highly responsive to bright light. Specialized for color and high visual acuity. Located in the fovea only. 3 types of pigments.
Retinitis Pigmentosa
The photoreceptors die slowly. The first ones to die are rods. Caused by a variety of mutations --> "tunnel vision.
Macular Degeneration
Membrane under the macula becomes thin (dry AMD) or thick (wet AMD). Receptors in the macula start to die. Wet AMD progresses faster and involves new blood vessels and bleeding.
Glaucoma
The optic nerve is damaged, leading to progressive, irreversible loss of vision. Often, but not always, associated with increased pressure of the eye. Two forms: open Angle (slow, 90%) and closed Angle (sharp, painful, auras, 10%).
Trichromatic Theory of Vision
The perception of color depends on the activation of 3 types of opsins in different combinations. Each cone has only 1 type of opsin (also called conopsins).
Color Blindness
The detection of color depends on the expression of the 3 conopsins. Mutations in either one of them would lead to lack of perception of a specific color. Most common: red-green colorblindness --> most common in men.
Synaesthesia
A condition in which stimulation of one sensory system results in unusual experiences in a second, unstimulated system. Consistent, and it is now believed to be due to increased wining between brain areas involved in processing different types of sensory
Receptive Field
The area of the visual world for which a neuron can detect its activity changes if there is light or not in that area. Has complex response properties. The receptive fields of many retinal ganglion cells combine to form the receptive field of a single LGN
Striate Cortex
Controls orientation. Neurons with similar response properties cluster together in groups/layers.
Blindsight
People who state they are "not able to see" can still tell you attributes of the stimuli if prompted to do so. Believed to be caused by a lesion in the Primary Visual Cortex (V1) in the Occipital Lobe. The eye, however, is healthy, and so are other cortic
Ventral Stream
Occipital --> Temporal. Involved in object recognition ("What Pathway"). Neurons in the temporal lobe form columns that respond to categories of shapes.
Dorsal Stream
Occipital --> Parietal. Involved in the guidance of actions and recognizing where objects are in space ("Where Pathway" and "How Pathway").
Prospagnosia
Inability to distinguish between different faces, sometimes not even one's own.
Capgras Delusion
Inability to make an emotional connection with an individual face.
EXAMPLE:
My boyfriend has been taken over by aliens.
Retination
There is a map of the world on your cortex.
Visual Pathway
Optic Nerve
|
Optic Chiasm
|
Optic Tract
|
Visual Radiation
|
Visual Cortex
Frequency and Pitch Perception
The rate at which sound waves vibrate is measured as cycles per second (Hz).
Low frequency = low pitch.
High frequency = high pitch.
Amplitude and Perception of Loudness
Intensity of sound is usually measured in decibels (dB).
Low amplitude = soft sound.
High amplitude = loud sound.
Complexity and Timbre (Perception of Sound Quality)
Unlike the pure tone of a tuning fork, most sounds are a mixture of frequencies. A sound's complexity determines its timbre, allowing us to distinguish, for example, a trombone from a violin playing the same note.
Simple = pure tone.
Complex = mix of freq
3 Types of Ossicles
1) Malleus
2) Incus
3) Stapes (also Oval Window)
Tempanic Membrane
Eardrum.
Inner Hair Cells
Responsible for sound detection in the cochlea.
Basilar Membrane
Has a tonotopic map, which is how we know what we are listening to.
Tonotopic Representation
Maintained throughout the auditory pathways and into the primary auditory cortex.
3 Types of Deafness
1) Conduction Deafness
2) Sensorineural Deafness
3) Central Deafness
Conduction Deafness (1/3)
Disorders of the outer or middle ear that prevent sounds from reaching the cochlea.
Sensorineural Deafness (2/3)
Results when hair cells fail to respond to movement of the Basilar Membrane. Oxotoxic (ear-damaging) effects may be due to drugs, noise pollution, or loud sounds. Damage to hair cells can result in tinitus, a persistent ringing in the ears.
Central Deafness (3/3)
Hearing loss caused by damage to the auditory brain areas such as by stroke, tumors, or traumatic brain injury.
Word Deafness: Unable to recognize spoken sounds.
Cortical Deafness: Difficulty in recognizing all complex
sounds or speech.
Cochlear Implants
Used to treat deafness due to hair cell loss. Electrical currents stimulate the auditory nerve fibers in the cochlea.
Auditory Ventral Pathway
Decodes spectrally-complex sounds (auditory object recognitions, including the meaning of speech).
Dorsal Pathway
Integrates auditory and somatosensory information to control speech production.
Localizing Music in the Brain
Passively listening to noise bursts activates Heschl's gyrus (in A1). Listening to melodies activates A2. Making relative pitch judgments about 2 notes of each melody activates a right Frontal Lobe area.
Music Therapy
Music is used as a treatment for mood disorders such as depression. Best evidence of its effectiveness lies in studies of motor disorders such as stroke and Parkinson's disease. Listening to rhythm activates the motor and premotor cortex and can improve g
Somatic Sensation
Enables body to feel, ache, chill, touch, etc. Responsible for touch, pain, and proprioception (sensing own body).
Types and Layers of Skin
1) Hairy and glabrous (hairless)
2) Epidermis (outer) and dermis (inner)
Functions of Skin
1) Protective
2) Prevents evaporation of body fluids
3) Provides direct contact with the world
4 Types of Mechanoreceptors
Make up most of somatosensory receptors.
1) Pacinian Corpuscles
2) Meissner's Corpuscles
3) Merkel's Cells
4) Ruffini's Endings
Rapidly-Adapting Receptors
Body sensory receptor that responds briefly to the onset of a stimulus on the body.
[RA] Pacinian Corpuscles (1/4)
Vibration.
[RA] Meissner's Corpulse (2/4)
Lateral motion.
[SA] Merkel's Cells (3/4)
Edges and points.
[SA] Ruffini's Endings (4/4)
Skin stretch.
Dermatome
An area of skin that is mainly supplied by a singly spinal nerve. (SHINGLES.)
Sensory Transduction
Sensory stimulation alters permeability of cation channel...e.g. stretch of membrane due to pressure opens channel.
Two-Point Discrimination
Depends on:
-Receptive field density
-Receptive field size
-Computing power
Ascending Pathways
1) Dorsal Column (Medial Lemniscal Pathway)
2) Spinothalamic Pathway
Dorsal Column (Medial Lemniscal Pathway)
Primary Somatosensory Cortex (S1) --> very plastic, located by the thalamus.
-Touch
-Vibration
-Two-Point Discrimination
-Proprioception
Spinothalamic Pathway
-Pain
-Temperature
-Some touch
Pain
Feeling of sore, aching, throbbing, etc.
Nociception
Sensory process, provides signals that trigger pain.
Nociceptors
Transduction of pain. Mechanically-gated ion channels opened by:
-Strong mechanical stimulation
-Temperature extremes
-Oxygen deprivation
-Chemicals
Types of Nociceptors
1) Polymodal
2) Mechanical
3) Thermal
Referred Pain
Internal organs synapse onto the same spinal cord neurons as specific skin areas. Since the internal organs rarely send information, the brain interprets the activation of the spinal cord neurons as coming from the skin.
The axons that carry pain informat
Social Pain
New research has shown that social pain activates similar brain areas to those activated by physical pain, such as:
1) dACC--dorsal Anterior Cingulate Cortex
2) AI--Anterior Insula
Basic Tastes
-Sweetness (23-10,000)
-Saltiness (2000)
-Sourness (100)
-Bitterness (1.6-8)
-Umami
Taste Receptor Cells
NOT neurons --> chemical receptors that release a neurotransmitter that activates a neighboring neuron and excites it to fire an action potential that eventually reach the gustatory centers.
Taste Transduction
Pass directly to ion channels:
-Saltiness
-Sour
Bind to G-protein-coupled receptors:
-Bitter
-Sweet
-Umami
Ageusia
The loss of taste perception.
Gustation
Important to the control of feeding and digestion.
-Hypothalamus
-Basal telencephalon
Label-Line Model
One neuron for each taste. Taste identified by which neuron is active.
Across-Fiber Model
All neurons = all tastes. Taste identified by a pattern of activity across all neurons.
Traditional Smell
-To find food
-To discriminate odors/select food
-To detect danger
Pheromonal Smell
-Reproductive behavior
-Territorial boundaries
-Identification
-Aggression
-Not clear if humans have pheromones
Olfactory Epithelium
Olfactory receptor cells, supporting cells, and basal cells.
Odorants
Activate transduction processes in neurons. Each odorant is recognized by a combination of receptors --> Population Coding.
Olfactory Nerve
Made up of olfactory axons.
Cribriform Plate
A thin sheet of bone through which small clusters of axons penetrate, coursing to the olfactory bulb.
Anosmia
Inability to smell.
Central Olfactory Pathways
DOESN'T go through the thalamus. Odor has unrestricted access to the brain. The neocortex is reached by a pathway that synapses in the medial dorsal nucleus.
Pheromone
Hormone that is released by an individual and which will cause behavioral change or an endocrine change in another organism of the same species. Important for:
-Mate finding and selection
-Dominance
-Tracking/guiding
-Reproductive maturation
Lee-Boot
When female rats are housed together, their estrous cycles slow and stop.
Whitten Effect
If the group of female rats is exposed to odor of a male, they start cycling again in synchrony.
Vandenbergh Effect
Acceleration of onset of puberty in female rat when exposed to odor of male.
Bruce Effect
Failure of recent pregnancy of female rat when exposed to male who is not the father.
Coolidge Effect (Cows?)
Restorative effect of introducing a new female sex partner to a male rat that has apparently become "exhausted" by "sexual activity.
Major Histocompatability Complex (MHC)
1940: Discovered in mice in connection with skin grafting. Name refers to the region of several linked genes that control skin grafting. Connection to immune system.
MHC Genes
Human MHC molecules are called Human Leukocyte Antigens (HLA). Most polymorphic genes in genomes. Codominantly expressed. Categorized as Class I or Class II.
The T-Shirt Test
Males and females were typed for HLA-A, -B, and -DR. Males wore shirts for 2 consecutive nights. Women rated the smell of shirts on pleasantness, intensity, and memory association.
2 sample populations:
1) Oral contraceptive users
2) Non-oral contraceptiv
Forms of Neuroplasticity
Learning, memory formation, and experience-dependent modification of circuitry usually involve changes in the strength of synapses in response to biochemical signals. Can also require formation of new synapses for birth of new neurons.
Early Deprivation of Sensory Experience
Has the opposite effect of cognitively stimulating environments: atrophy of dendrites.
Early Deprivation of Social Experience
Has a profoundly negative effect or later intellectual and social behaviors.
Amblyopia
A condition in which vision in one eye is reduced as a result of disuse; usually caused by a failure of the 2 eyes to point in the same direction. Visual input from the "lazy eye" does not contribute to the tuning neural connections.
If fixed early in lif
Sensitive Period
A period during development in which an organism can be permanently altered by a particular experience or treatment. They vary across animal species, being somewhat proportional to lifespan. Within one organism, different sensory systems and properties ha
Monocular Deprivation
Depriving animals of light in one eye.
If done during the sensitive period, it results in loss of vision in the deprived eye. (The axons that carry information from the eye have shrunk.)
No changes are seen in the eyes themselves, just the brain.
Binocular Deprivation
Depriving animals of light in both eyes.
Can result in long-lasting blindness, but the distribution of ocular dominance is normal.
Cataracts
Clouded lenses result in very poor patterns of vision. If removed early in life, then normal vision is restored. If removed later, normal vision cannot be regained. Even 6 months of cataracts can affect the ability to perceive 9 years later in life.
Nocioception
IRRITATION. Perception of pain, temperature, and itch.
Hapsis
PRESSURE. Perceptual ability to discriminate objects on the basis of touch.
Proprioception
MOVEMENT. Perception of the position and movement of the body, limbs, and head.
Slowly-Adapting Receptor
Body sensory receptor that responds as long as a sensory stimulus is on the body.
Dorsal-Root Ganglia
Flanks each spinal cord segment. Contains neurons of many times. Location of cell bodies whose dendrites carry somatosensory information into the CNS.
Deafferentiation
Loss of incoming sensory input usually due to damage to sensory fibers; also loss of any afferent input to a structure.
Dorsal Spinothalamic Tract
Pathway that carries fine-touch and pressure fibers.
Dorsal-Column Axons
Synapse in the ventrolateral thalamus, the part of the thalamus that carries information about body senses to the somatosensory cortex.
Ventral Spinothalamic Tract
Pathway from the spinal cord to the thalamus that carries afferent information about pain and temperature (nocioceptive).
Unilateral Damage to the Spinal Cord
Causes loss of fine-touch and pressure sensation on the same side of the body below the cut. Also, causes of pain and temperature sensation on the opposite side of the body below the cut.
Monosynaptic Reflex
Reflex requiring one synapse between sensory input and movement.
Perceiving Pain
There may be as many as 8 different kinds of pain gibers. Some chemicals irritate surrounding tissue, stimulating it to release other chemicals to stimulate blood flow and to stimulate pain fibers themselves. These reactions contribute to pain, redness, a
Responding to Pain
Neuronal circuits in the spinal cord allow haptic-proprioceptive and nocioceptive pathways to interact. These interactions may be responsible for our puzzling and variable responses to pain.
Pain Gate
Hypothetical neural circuit in which activity in fine-touch and pressure pathways diminishes the activity in pain and temperature pathways.
Treating Pain
One of the most successful treatments for pain is the injection of small amounts of morphine under the dura mater.
Electrical Stimulation (For Pain)
(At a number of sites in the brainstem) Can reduce pain, perhaps by closing brainstem pain gates.
Periaqeductal Gray Matter (PAG)
Nuclei in the midbrain that surround the cerebral aqueduct joining the 3rd and 4th ventricles. PAG neurons contain circuits for series-typical behaviors (i.e. female sexual behavior) and play an important role in the modulation of pain. These neurons prod
Primary Somatosensory Cortex (S1)
Recieves projections from the thalamus. Begins the process of construction perceptions from somatosensory information. Located by the postcentral gyrus behind the central fissure in the parietal lobe.
Secondary Somatosensory Cortex (S2)
Refines perceptual constructions and sends information to the frontal cortex. Located in the parietal love behind the Primary Somatosensory Cortex.
Effects of Damage to the Somatosensory Cortex
Damage to the PSC impairs the ability to make even simple sensory discriminations and movements.
Apraxia
Inability to make voluntary movements in the absence of paralysis or other motor/sensory impairment, especially an inability to make proper use of an object.
Orbitofrontal Cortex (OFC)
Prefrontal cortex located behind the eye sockets that receives projections from the dorsomedial nucleus of the thalamus. Plays a central role in a variety of emotional and social behaviors as well as in eating.
Olfactory Receptor Cells
Project to the olfactory bulb, ending in ball-like tufts of dendrites called glomeruli.
Mitral Cells
Send their axons from the olfactory bulb to a broad range of forebrain areas.
Olfactory Targets
Examples: amygdala and pyriform cortex. No connections through the thalamus, the way other sensory systems besides olfaction do.
Gustatory Receptors
Gustatory stimuli interact with receptor tips (microvilli) to open ion channels, leading to changes in membrane potential.
Critical Period
Most cortical cells become binocular as the two eyes are stimulated by experience. When an eye is closed in development, it quickly loses its connection to the visual cortex. If deprived long enough, the animal will become blind in that eye. Similar depri
Population Coding
Involves reading out population activity of many different neurons along the pathway. (How taste, olfaction, and gustation sensations are processed.)
Learning
Lifelong adaption to environment. Acquisition of new information.
Memory
Retention of learned information.
Declarative Memory
Facts and events.
Nondeclarative Memory
Procedural memory--skills, habits.
Working Memory
Keeping a "memory trace" active to try to remember information that will be used very soon (like someone's phone number).
Short-Term Memory
Lasting less than 1 hour.
Long-Term Memory
Lasting hours, days, months, or years.
Lashley's Engram Search
Designed a maze task where rates had to follow the correct path to find a food reward. Learning and memory are measured as a decrease in the time it takes the rate to find the path to the food and decrease in wrong turns. Found that lesions before learnin
Hebb and the Cell Assembly (1949)
External events are represented by cortical cells. Cells reciprocally interconnected--the stimulus reverberates. Neurons that were active together would tend to strengthen the connections between them. If repeatedly activated, then the "memory" or "activi
Retrograde Amnesia
Inability to recall any personally experienced events. Associated with frontal lobe injuries or reduced blood flow to the frontal lobe (lobe that may allow us to mentally travel through our past).
Anterograde Amnesia
Inability to form new memories of events or experiences. Associated with damage to the temporal lobe/hippocampus.
Implicit Memory
Operant Conditioning: cerebellum and striatum. Fear Conditioning: amygdala. Classical Conditioning: systems involved in coding of sensory and motor aspects of the task.
Explicit Memory
Association areas of the frontal lobe. Temporal lobe.
Milner
Patient HM: had large areas of both temporal lobes removed as a treatment for epilepsy; couldn't form any new memories anymore.
Penfield
Experimental responses: stimulation of certain areas in the temporal lobe lead to coherent recollections of earlier memories.
Stages of Explicit Memory
Memory acquisition/encoding, memory consolidation, and memory retrieval.
EM Stage 1: Memory Acquisition/Encoding
The process in which new information is attended to and processed. The encoding is critical to how well something learnt will be remembered later.
EM Stage 2: Memory Consolidation
The process that makes this newly stored information and makes it more stable for long-term storage. This involves the expression of genes and protein synthesis.
EM Stage 3: Memory Retrieval
Process that permit the recall and use of stored information. A constructive process that involves multiple brain areas.
Eye-Blink Conditioning
Commonly used experimental technique in which subjects learn to pair a formerly neutral stimulus to a defensive eye-blinking response.
Memory Disruption
2 reasons:
1) Storage failure --> permanent amnesia
2) Retrieval failure --> temporary amnesia
Memory Consolidation Theory
Assumes that memory traces are vulnerable to disruption shortly after they are first established but, with time, the trace becomes stable and resistant to disrupting events.
Active Memory State
Short-term memory. Vulnerable to disruption.
Inactive Memory State
Long-term memory.
Ways for Memory Trace --> Active State
1) Novel experiences generate new active memory trace.
2) Retrieving existing long-term memory traces will return these traces to the short-term active sate.
Nader's Reconsolidation Theory (2000)
Anisomycin inhibits protein synthesis, so cells only have access to materials already present in them. It also disrupts the LTM retention of the reactivated fear memory but had no effect on the STM retention of the memory. Inactive memories are brought ba
Disruption of Memory
Disruption of memory reconsolidation is specific to the recalled memory.
Post-Traumatic Stress Disorder (PTSD)
A significant number of individuals who experience severe stress may continue to experience stress and anxiety through intrusive memories or dreams of these traumatic events. Clear genetic component.
SYMPTOMS:
Recurrent nightmares
Sleep disturbances
Numbi
Reconsolidation and PTSD
There are studies into the effectiveness of reconsolidation of traumatic memories in new contexts (such as a safe place). Initial evidence suggests that this treatment is promising. Drugs that interfere with reconsolidation have been tested in animals and
Traumatic Brain Injury
Occurs when an external force traumatically injures the brain. Leading cause of death and disability in persons under 45 years old, occurring more frequently than breast cancer, AIDs, MS, and spinal cord injury combined.
Common Mild TBI/Postconcussive Symptoms
-Headache
-Poor concentration
-Memory difficulty
-Irritability
-Fatigue
-Depression
-Anxiety
-Dizziness
-Light sensitivity
-Sound sensitivity
3 Ways to Recover from TBI
1) Learn new ways to solve problems
2) Reorganize the brain to do more with less
3) Generate new neurons to produce new circuits
(Not fully independent of one another)
Learning New Ways (1/3)
If someone loses a certain ability, such as being able to write with their right hand, they may be able to compensate by learning how to write with their left hand.
New-Circuit Solution (2/3)
In response to injury, the brain can form new corrections and do "more with less." The amount of recovery is increased significantly if the person also engages in some form of intervention.
Behavioral Therapy
Ex/ speech or physiotherapy.
Pharmacological Therapy
Ex/ nerve growth factor or amphetamine.
Nerve Growth Factor (NGF)
A "neurotrophic factor" that provides signals that neurons need to survive and that provide growth signals plays a key role in development.
NGF Experiment
Animals received a cortical stroke. Some were treated with NGF; others were not.
CONCLUSION:
NGF stimulates dendritic growth and increased spine density in both normal and injured brains. These neuronal changes are correlated with improved motor function
Lost-Neuron Replacement (3/3): Fetal Tissue Implantation
Limited success to date: more suited for situations where only a small number of cells are needed.
EXAMPLE: dopamine-producing cells in the substantia nigra for Parkinson's patients.
Lost-Neuron Replacement (3/3): Epidermal Growth Factor
Neurotrophic factor that stimulates the subventricular zone to generate cells that migrate into the striatum and eventually differentiate into neurons and glia. It is possible that, in the future, trophic factors may be useful in the treatment of brain in
Stem Cells (Stroke)
After cortical stroke (left), infusion of epidermal growth factor into the lateral ventricle of a rat induced neurogenesis in the subventricular zone. The stem cells migrate to the site of injury and filled in the damaged area (right).
Emotion
A class of subjective feelings created by stimuli that have high significance to an individual.
Stimuli that produce high arousal generally produce strong feelings. Are rapid and automatic. Emerged through natural selection to benefit survival and reprodu
Functions of Emotion
Emotions can move us to act, triggering motivated behavior. They help us to set goals, but emotional states can also be goals in themselves. Finally, they are important in many different areas, including rational decision making and purposeful behavior.
Components of Emotions
1) Characteristic physical sensations
2) Conscious feeling
Emotions v. Feelings
Emotions: Bodily states
Feelings: Conscious sensations
Mediated by different neuronal circuits.
Animal Emotions (Darwin)
Basic emotions are innate (inborn) and "hard-wired." Rapid fear; fight or flight. Fear, anger, disgust, surprise, sadness, and happiness.
Social Emotions (Damasio)
More complex. Not automatic, processed in the brain. More nuanced. Regret, longing, jealousy, etc.
The Feeling of What Happens by Antonio Damasio
Ways of Studying Emotions
-Studying negative emotions is relatively easy
-Most animals feel afraid and angry, and this is easy to assess
-However, positive emotions are much harder to study (happiness is hard to assess and surprise is not easy to do repeated trials with)
Folk Psychology Theory of Emotion
Automatic responses (like stomach churning) are caused by emotions.
Stimulus (Bang!)
|
Perception/Interpretation (Danger)
|
Particular emotion experienced (Fear)
|
Specific pattern of autonomic arousal (Heart races, etc.)
The James-Lange Theory of Emotion
States that the emotions we feel are caused by bodily changes; emotions differ because they are generated by different physiological responses.
Stimulus (Bang!)
|
Perception/Interpretation (Danger)
|
Specific pattern of autonomic arousal (Heart races, etc
Support for James-Lange Theory
Intensity of emotions in individuals with spinal cord damage depends upon the level at which the spinal cord is severed. However, many different situations can generate similar autonomic responses...how do we know what to feel?
Cannon-Band Theory of Emotion
States that the cerebral cortex simultaneously decides on the appropriate emotional experience and activates the autonomic nervous system to prepare the body for what is needed.
Stimulus (Bang!)
|
Perception/Interpretation (Danger)
| |
General autonomic P
Model for Emotional Facial Expressions Across Cultures
Subtle cultural differences suggest that cultures prescribe rules for facial expression and they control and enforce those rules by cultural conditioning.
...
Elicitors
(Actual or anticipated situations, recollections, etc.)
|
Facial affect program
(Happiness, sadness, embarrassment, surprise, contempt, fear, anger, and disgust)
|
Mediation by culture-specific display rules
(Exaggerate, minimize, counteract, an
Facial Feedback Hypothesis
Suggests that sensory feedback from out facial expressions can affect our mood (supporting the James-Lange Theory). Manipulation facial expressions can alter a person's mood. Impairment of facial expressions may affect social interaction.
Cosmetic Botox Treatment Reduces Anxiety and Depression
Patients were given cosmetic Botox injections in forehead (BTX group) or underwent a different cosmetic treatment not affecting their ability to move face muscles (control).
Reason for Crying
It has been proposed that crying in response to behavioral emotion might have been a mutation/accident, but that either it had no deleterious effect or maybe it had a positive effect (helping communication).
Chemosignal in Tears
In mice, tears serve as a chemosignal. A study thus hypothesized that human tears may similarly serve a chemosignaling function. The scientists found that merely sniffing negative-emotion-related odorless tears obtained from women donors induced reduction
Amygdala and Fear
Fear is an incredibly important emotion. The amygdala is involved in fear processing. It also responds to body expressions of fear.
Amygdala and Organization Role
The amygdala is the organizing center for the somatic expression of emotion. Electrical stimulation of the amygdala in humans lead to feelings of fear and apprehension. Damage to the amygdala in experimental animals leads to tameness.
Fear and Awareness
You don't need to be aware to feel fear. Presenting 2 stimuli, we can only be aware of 1 at a time. Fearful faces activate the amygdala whether they were reported as seen or not--thus, without conscious awareness.
Kluver-Bucy Syndrome
Removal of monkey amygdala leads to:
-Lose fear of/aggressiveness towards humans
-No facial expression
-Examine things regardless of danger: fire, broken glass
-Eat everything: meat, feces
-Mate with everything: other sex, same sex, inanimate objects
Same
Urbach-Wiethe Syndrome
Patients suffer damage in the amygdala due to accumulation of Ca2+ deposits.
-Fail to recognize expressions of fear in human faces
-Have normal memory, language, and intelligence
-Have normal sensory and motor systems
-Problems in decision-making
Damaged
Amygdala Ablation
Removes:
-Ability to undergo fear conditioning
-Ability to respond to scaring stimuli (such as tone after conditioning has take place)
-Ability to express innate fear reactions
Amygdala: EXPRESSION of emotions, NOT storage of emotional memories.
Circadian Rhythm
Change in physiological functions according to brain clock. Daily.
Period
Time required to complete a cycle of activity.
Circannual Rhythm
Yearly (e.g. migratory cycle of birds).
Infradian Rhythm
Less than a year (e.g. human menstrual cycle).
Ultradian Rhythm
Less than a day (e.g. eating cycle).
Free-Running Rhythms
Rhythm of the body's own devising in the absence of all external cues. Without input from external cues, our bodies have their own rhythms with periods of 25-27 hours. Sleep-wake cycle shifts an hour or so every day. Animals expand and contract their slee
Zeitgeber
Environmental event that entrains biological rhythms; a "time-giver."
EXAMPLE:
Light resets the biological clock.
Entrainment
Determine or modify the period of a biorhythm.
Jet Lag
Fatigue and disorientation from rapid travel through time zones and exposure to a changed light-dark cycle.
Suprachiasmatic Nucleus (SCN)
Main pacemaker of circadian rhythms located just above the optic chiasm.
Retinohypothalamic Pathway
Neural route from a subset of core receptors in the retina to the SCN of the hypothalamus; allows light to entrain the rhythmic activity of the SCN. Other pacemakers exist in the retina and pineal gland, but the SCN is the main one.
M-Cells
Control morning activity and need light for entrainment.
E-Cells
Control evening activity and need darkness for entrainment.
Ralph and Colleagues SCN Experiment
After lesions to the SCN, eat and sleep a normal amount, but the rhythmic nature of these behaviors disappears. If SCN cells from embryos are transplanted into the lesioned animals, they will reestablish circadian rhythms.
Feedback Loop
Circadian rhythm involves a feedback loop in which proteins are first made and then combine. Combined protein, called a dimer for 2 proteins, inhibits the production of its component proteins. Dimer degrades and the process begins anew.
Model for Pacemaking
Light entrains the SCN pacemaker, which drives a number of "slave oscillators," each of which controls the rhythmic occurrence of 1 behavior (e.g. body temperature). SCN pacemaker may drive the slave oscillators via hormones, proteins, or neurotransmitter
Pineal Gland
Located in basal forebrain near thalamus. Secretes melatonin in response to activity of SCN of hypothalamus.
Brain Rhythms
1) Beta waves (14 Hz, activated cortex)
2) Alpha waves (8-13 Hz, quiet waking state)
3) Theta waves (4-7 Hz, some sleep states)
4) Delta waves (< 4 Hz, deep sleep)
Alpha Waves
Observed in wakeful individuals. Higher synchronization than B-waves. Relaxation, super learning. Increased serotonin production. Pre-sleep, meditation.
Beta Waves
Observed in wakeful individuals and in REM sleep. Concentration, arousal, alertness. Higher levels are associated with anxiety and fight or flight response.
Delta Waves
Dreamless sleep (deep sleep). High amounts of human growth hormone (HGH) release. Deep trance, with loss of body awareness.
Theta Waves
In early sleep (not too deep). Increased production of catecholamines. Deep meditation.
Functions of Brain Rhythms
There have been many different hypotheses:
1) Brain's way of disconnecting cortex from sensory input.
2) No direct function, by-products of strongly interconnected circuits.
3) Neural rhythms coordinate activity, synchronize oscillations, bind together (W
Epilepsy
Repeated seizures.
CAUSES: tumor, trauma, infection, vascular disease, many cases unknown.
Generalized Seizure
Entire cerebral cortex, complete behavior disruption, consciousness loss.
Partial Seizure
Circumscribed cortex area, abnormal sensation or aura.
Absence Seizure
< 30 seconds of generalized, 3 Hz EEG waves.
Behavioral Definition of Sleep
1) Reduced motor activity.
2) Decreased response to stimulation.
3) Stereotypic postures (eyes closed).
4) Relatively easy reversibility.
4 Stages of Sleep
1) Low voltage EEF at 15-25 Hz.
2) Burst of synusoidal waves (sleep spindles) and high voltage biphasic waves (K complexes).
3) High amplitude, low frequency (0.5-1) waves (caused Delta Waves).
4) Dominated by slow waves.
Total Sleep Deprivation in Rats
Results in:
-A decrease in body weight despite an increase in food intake.
-A failure to regulate core body temperature (body temperature drops as a result).
-The development of infections.
-And eventually: DEATH.
Freud's View on Dreams
Wish-fulfillment, conquer anxieties.
Hobson's View on Dreams
Activation-Synthesis Hypothesis.
Sleep and Memory Storage
Sleep plays a role in solidifying and organizing events in memory.
CONSOLIDATION:
Process of stabilizing a memory trace after learning.
RECONSOLIDATION:
The process of restabilizing a memory trace after the memory is revisited.
Place Cell
Hippocampal cell that fires when a rat is in a certain location in an environment.
Maquet Experiment on REM and Implicit Memory (2000)
Used PET imaging to record brain activity while human subjects performed a serial reaction-time task. PET imaging during subsequent sleep revealed that the same brain regions that were active during the task were also active during REM sleep.
Subjects wer
Attention
The process of selecting or focusing on one or more stimuli for enhanced processing and analysis.
Arousal
The global level of alertness in an individual. This would enhance processing and analysis of ALL stimuli, without preferences.
Overt Attention
Occurs when the focus coincides with the sensory orientation.
Covert Attention
The focus is independent of sensory orientation (for example, focusing in front of you but paying attention to a side stimuli).
Divided Attention Tasks
Subjects are asked to process two or more simultaneous stimuli. These tasks show that attention is a limited resource.
Attentional Spotlight
Shifts around the environment, highlighting stimuli for enhanced processing.
Early-Selection Models (Of Attention)
Say that higher-order cognitive processes can exclude non-attended stimuli before processing. However, some unattended stimuli are processed and may even capture attention (ex. calling your name).
Late-Selection Models (Of Attention)
Suggest the bottleneck occurs later, after some processing has occurred. The Stroop Test provides support for this model.
Stroop Task
Irrelevant information interferes with target stimuli at a semantic level. Accurate attention in this task must involve late attentional selection.
Attention and Neural Activity
When human subjects are instructed to attend to visual stimuli in the left visual field. There is an increase in the neural activity in the contralateral visual cortex.
When monkeys are presented with a bar at several orientations, the activity of individ
Neglect Syndrome (Parietal Lesions)
Failure to report, respond, or orient to novel or meaningful stimuli presented to the side opposite a brain lesion, when this failure cannot be attributed to either (primary) sensory or motor deficits. (Heilman, 1979)
2 Types of Neglect (Parietal Lesions)
1) Spatial
2) Personal
Spatial Neglect (1/2)
-Neglect the hemisphere contralateral to lesion.
-Usually associated with damage to the right parietal cortex.
-Variously termed: hemispatial neglect, visuospatial agnosia, hemispatial agnosia, visuospatial neglect, unilateral spatial neglect, and contral
Personal Neglect (2/2)
-Fail to dress or groom left side of body
-Run into doorways on left side
-Left paralyzed limb hangs over wheelchair arm
Right Hemisphere
Attention to the left and right sides of the body and extrapersonal space.
Left Hemisphere
Attention to the right side only (due to language in left hemisphere).
Evolution of Prefrontal Cortex
The PFC has expanded over mammalian and primate evolution. A greatly enlarged PFC is a distinctively human and primate feature.
Executive Control
Control processes are important for overcoming behaviors that would otherwise be carried out more or less automatically. Processes...
1) Inhibition: the suppression of an automatic behavior.
2) Task Switching: engaging in new behaviors.
3) Stimulating Beh