Central Canal
A fluid filled channel in the center of the spinal cord
Ventricles
Four fluid-filled cavities within the brain containing cerebrospinal fluid
- Each hemisphere contains one of the two large lateral ventricles. Toward their posterior, they connect to the third ventricle, positioned at the midline, separating the left thalamus from the right one. The third ventricle connects to the fourth ventricle in the center of the medulla.
Cerebrospinal Fluid
A clear fluid similar to blood plasma found in the brain and the spinal cord:
- Provides "cushioning" for the brain (against mechanical shock) when the head moves
- Provides a reservoir of hormones and nutrition for the brain and spinal cord
- Helps support the weight of the brain
- Fills the ventricles, flowing from the lateral ventricles to the third and fourth ventricles. From the fourth ventricle, some of it flows into the central canal of the spinal cord, but more goes into the narrow spaces between the brain and the thin meninges, membranes that surround the brain and spinal cord.
- if the flow of it is obstructed, it accumulates within the ventricles or the subarachnoid space, increasing pressure on the brain
- Causes hydrocephalus in infants
Cerebral Cortex
The most prominent part of the mammalian brain and consists of the cellular layers on the outer surface of the brain
- comprised of grey matter and white matter (the cells are gray matter and their axons extending inward are white matter)
- divided into two halves
- joined by three bundles of axons called the corpus callosum and the anterior and posterior commissure
- more highly developed in humans than other species
Corpus Callosum and Anterior Commissure
Two bundles of axons
Laminae
Layers of cell bodies that are parallel to the surface of the cortex and separated from each other by layers of fibers
- Lamina V, which sends long axons to the spinal cord and other distant areas, is the thickest in the motor cortex, which has the greatest control of the muscles. Lamina IV, which receives axons from the various sensory nuclei of the thalamus, is prominent in the primary sensory areas (visual, auditory, and somatosensory) but absent from the motor cortex.
Columns
Cells perpendicular to the laminae
Meninges
Membranes that surround the brain the brain and spinal cord
- has pain receptors
The Cerebral Cortex
- Organization of it:
- contains up to six distinct laminae (layers) that are parallel to the surface of the cortex
- cells of the cortex are also divided into columns that lie perpendicular to the laminae
- divided into four lobes: occipital, parietal, temporal, and frontal
- various parts of this do not work independently of each other (All areas of the brain communicate with each other)
Occipital Lobe
- Located at the posterior end of the cortex
- Known as the striate cortex or the primary visual cortex
- The main target for visual information - highly responsible for visual input
- The posterior pole of this lobe is known as the: primary visual cortex or striate cortex
(because of its striped appearance in cross-section)
- destruction of any part of the striate cortex causes cortical blindness in the related part of the visual field
- lose the ability of vision in dreams
- you can still receive visual information even though you can't see
Parietal Lobe
- Lies between the occipital lobe and the central sulcus, one of the deepest grooves in the surface of the cortex
-Contains the postcentral gyrus (aka "primary somatosensory cortex") is the primary target for touch sensations, and information from muscle-stretch receptors and joint receptors
- Also responsible for processing and integrating information about eye, head and body positions from information sent from muscles and joints.
Central Sulcus
One of the deepest grooves in the surface of the cortex
Postcentral Gyrus
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Temporal Lobe
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Frontal Lobe
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Precentral Gyrus
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Prefrontal Cortex
The integration center for all sensory information and other areas of the cortex (most anterior portion of the frontal lobe)
- responsible for higher functions such as abstract thinking and planning
- responsible for our ability to remember recent events and information ("working memory")
- allows for regulation of impulsive behaviors
Binding Problem
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Research Methods
Main categories of research methods to study the brain include those that attempt to:
- Correlate brain anatomy with behavior
- Record brain activity during behavior
- Examine the effects of brain damage
- Examine the effects of stimulating particular parts of the brain
Research Methods pt. 2
Correlating brain activity with behavior can involve the identifying of peculiar behaviors and looking for abnormal brain structures or function
- These abnormal brain structures can be identifies using:
- Computerized Axial Tomography (CAT scan)
- Magnetic Resonance Imaging (MRI)
Phrenology
The process of relating skull anatomy to behavior
- One of the first ways ever used to study the brain
- Yielded few, if any accurate results
Affective Faculties (p. 115)
...
Intellectual Faculties (p. 115)
...
Computerized Axial Tomography (CAT scan)
- Involves the injection of a dye into the blood and a passage of x-rays through the head then a person's head is placed into a CT scanner
- Scanner is rotated slowly until a measurement has been taken at each angle and a computer constructs the images of the brain
Magnetic Resonance Imaging (MRI)
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Research Method pt. 3
Recording brain activity involves using a variety of noninvasive methods including:
- Electroencephalograph (EEG)
- Positron-emission tomography (PET)
Electroencephalograph (EEG)
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Evoked Potentials or Evoked Responses
The results of recording spontaneous brain activity or activity in response to a stimulus
- Determines of you're alive or dead
Magnetoencephalograph (MEG)
It measures the faint magnetic fields generated by brain activity. It identifies the approximate location of activity within about a centimeter
- Researches using an MEG can identify the times at which various brain areas respond and thereby trace a wave of brain activity from its point of origin to all the other areas that process it
Positron-emission tomography (PET)
- Records emission of radioactivity from injected radioactive chemicals to produce a high-resolution image
pg. 111
Regional Cerebral Blood Flow (rCBF)
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Functional Magnetic Resonance Imaging (fMRI)
- Uses oxygen consumption in the brain to provide a moving and detailed picture
- An fMRI is a modified version of MRI based on hemoglobin instead of water
- When a brain area becomes more active, an fMRI scan records the processes of when: blood vessels dilate to allow more blood flow to the area and as the brain area uses oxygen, the percentage of hemoglobin without oxygen increases.
pg. 112
Research Methods pt. 4
Examining the effects of damage to the brain is done using laboratory animals includes:
- Lesion techniques
- Ablation techniques
Other research methods used to inhibit particular brain structures include:
- Gene Knockout Approach
- Transcranial Magnetic Stimulation
Lesion techniques
Purposely damaging parts of the brain
- To damage a structure in the interior of the brain, researchers use a stereotaxic instrument, a device for the precise placement of electrodes in the brain
Ablation techniques
Removal of specific parts of the brain
Gene Knockout Approach
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Transcranial Magnetic Stimulation
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Research Methods pt. 5
Brain stimulation techniques assume stimulation of certain areas should increase activity
- Researchers observe the corresponding change in behavior as a particular region is stimulated
Plasticity
- Refers to the idea that the brain is constantly changing throughout the lifetime
- Development of the brain is due to both experience and physical maturation
- Rapid development especially occurs early in life
- Prefrontal cortex develops rapidly between 7 and 12 months (allowing for object permanence)
Development of the Brain (pt. 1)
The human central nervous system begins to form when the embryo is approximately 2 weeks old
- The dorsal surface thickens forming a neural tube surrounding a fluid filled cavity
- The forward end enlarges and differentiates into the hindbrain, midbrain, and forebrain
- The rest of the neural tube becomes the spinal cord
- The fluid-filled cavity becomes the central canal of the spinal cord and the four ventricles of the brain
- The fluid is the cerebrospinal fluid
- At birth, the human brain weighs approximately 350 grams
- By the first year, the brain weighs approximately 1000 grams
- The adult brain weighs 1200-1400 grams
Development of the Brain (pt. 2)
The development of neurons in the brain involves the following four processes:
1. Proliferation
2. Differentiation
3. Myelination
4. Synaptogenesis
Proliferation
Refers to the production of new cells/neurons in the brain primarily occurring early in life
- Early in development, the cells lining the ventricles divide
- Some cells become stem cells that continue to divide
- Others remain where they are or become neurons or glia that migrate to other locations
Migration
Refers to the movement of the newly formed neurons and glia to their eventual locations
- It occurs in a variety of directions throughout the brain
- It occurs via cells following chemical paths in the brain of immunoglobins and chemokines
Differentiation
Refers to the forming of the axon and dendrite that gives the neuron its distinctive shape
- The axon grows first either during migration or once it as reached its target and is followed by the development of the dendrites
- Neurons differ int heir shape and chemical component depending on their location in the brain
Myelination
Refers to the process by which glia produce the fatty sheath that covers the axons of some neurons
- Myelin speeds up the transmission of neural impulses
- Myelination first occurs in the spinal cord and then in the hindbrain, midbrain, and forebrain
- Myelination occurs gradually for decades
Synaptogenesis
The final stage of neural development and refers tot he formation of the synapses between neurons
- Occurs throughout the life as neurons are constantly forming new connections and discarding old ones
- It slows significantly later in the lifetime
Development of the Brain (pt. 3)
Although it was originally believed that no new neurons were formed after early development, recent research suggests otherwise:
- Two examples:
1. Stem cells are undifferentiated cells found in the interior of the brain that generate "daughter cells" which can transform into glia or neurons
2. New olfactory receptors also continually replace dying ones
Animal research has also shown the development of new neurons occurring on other brain regions. - Example: songbirds have a steady replacement of new neurons in the singing are of the brain
Development of the Brain (pt. 4)
- Axons must travel great distances across the brain to form the correct connections
- Sperry's (1954) research with newts indicated that axons follow a chemical trail to reach their appropriate target
- Growing axons reach their target area by following a gradient of chemicals in which they are attracted by some chemicals and repelled by others
- When axons initially reach their targets, they form synapses with several cells
- Postsynaptic cells strengthen connection with some cells and eliminate connections with others
- The formation or elimination of these connections depends upon input from incoming of axons
Development of the Brain (pt. 5)
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Neurotropin
A chemical that promotes the survival and activity of neurons
- Axons that are not exposed to neutropins after making connections undergo apoptosis, a preprogrammed mechanism of cell death
- Therefore, the healthy adult nervous system contains no neurons that failed to make appropriate connections
Nerve Growth Factor (NGF)
A type of neurotrophin released by muscles that promotes the survival and growth of axons
- The brain's system of overproducing neurons and then applying apoptosis enables the exact matching of the number of incoming axons to the number of receiving cells
Development of the Brain (pt. 6)
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Fetal Alcohol Syndrome
A condition that children are born with if the mother drinks heavily during pregnancy
- The condition is marked by the following:
- Hyperactivity and impusiveness
- Difficulty maintaining attention
- Varying degrees of mental retardation
- Motor problems and heart defects
- Facial abnormalities
(pg. 131)
Development of the Brain (pt. 7)
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Development of the Brain (pt. 8)
The brain has the limited ability to reorganize itself in response to experience
- Axons and dendrites continue to modify their structure and connections throughout the lifetime
Dendrites continually grow new spines
-The gain and loss of spines indicates new connections and potentially new information processing
- Rats raised in an enriched environment develop a thicker cortex and increased dendritic branching
- Measurable expansion of neurons has also been shown in humans as a function of physical activity
- The thickness of the cerebral cortex declines in old age but much less in those that are physically active