Brainstem
The oldest part and central core of the brain, beginning where the spinal cord swells as it enters the skull; the brainstem is responsible for automatic survival functions.
Medulla Oblongata
The base of the brain stem; controls heartbeat and breathing.
Reticular formation
A nerve network in the brainstem that plays an important role in controlling arousal.
Thalamus
The brain's sensory switchboard, located on top of the brainstem; directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla.
Cerebellum
The "little brain" attached to the rear of the brainstem; its functions include processing sensory input and coordinating movement output and balance.
Limbic system
A doughnut shaped system of neural structures at the border of the brainstem and cerebral hemisphere; associated with emotions such as fear and aggression and drives for food and sex. Includes the hippocampus, amygdala and hypothalamus.
Amygdala
Two lima bean shaped neural clusters that are components of the limbic systems and are linked to emotions.
Cerebral cortex
The intricate fabric of interconnected neural cells that covers the cerebral hemispheres; the body's ultimate control and information processing center.
Frontal lobe
The portion of the cerebral cortex lying just behind the forehead; involved in speaking and muscle movements, and in making plans and judgement.
Parietal lobe
The portion of the cerebral cortex lying at the top of the head and toward the rear; receives sensory input for touch and body position.
Occipital lobe
The portion of the cerebral cortex lying at the back of the head; includes the visual areas, which receives visual information primarily from the opposite visual field.
Temporal lobe
The portion of the cerebral cortex lying roughly above the ears; includes the auditory areas, each of which receives auditory information primarily from the opposite ear.
Hypothalamus
A neural structure lying below the thalamus; it directs several maintenance activities (eating, drinking, body temperature), helps govern the endocrine system via the pituitary gland, and is linked to emotion.
Motor cortex
An area at the rear of the frontal lobes that controls voluntary movement.
Sensory cortex
The area at the front of the parietal lobes that registers and processes body touch and movement sensations.
Association areas
Areas of the cerebral cortex that are not involved in primary motor or sensory functions; rather, they are involved in higher mental functions such as learning, remembering, thinking, and speaking.
Broca's area
Controls language expression; an area in the frontal lobe, usually in the left hemisphere, that directs the muscle movements involved in speech.
Wernicke's area
Controls language reception; a brain area involved in language comprehension and expression; usually in the left temporal lobe.
Corpus callosum
The large band of neural fibers connecting the two brain hemispheres and carrying messages between them.
Threshold
The level of stimulation required to trigger a neural impulse.
Synapse
The junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. The tiny gap at this junction is called the synaptic gap or cleft.
Neurotransmitters
Chemical messengers that traverse between the synaptic gaps between neurons. When released by the sending neuron, neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether that neuron will
Acetylcholine (ACH)
A neurotransmitter that enables learning and memory, and also triggers muscle action; Alzheimer's.
Endorphins
Natural, opiate-like neurotransmitters linked to pain control and to pleasure.
Biological psychology
A branch of psychology concerned with the links between biology and behavior.
Neuron
A nerve cell; the basic building block of the nervous system.
Dendrite
The bushy, branchy extension of a neuron the receives messages and conducts impulses toward the cell body.
Axon
The extension of a neuron, ending in branching terminal fibers, through which messages pass to neurons, muscles, or glands.
Myelin
A layer of fatty tissue segmentally encasing the fibers of many neurons; enables vastly greater transmission speed of neural impulses as the impulse hops from one node to the next.
Action potential
A neural impulse; a brief electrical charge that travels down an axon. The action potential is generated by the movement of positively charged atoms in and out of channels in the axon's membrane.
Nervous system
The body's speedy, electrochemical communication network consisting of all the nerve cells of the peripheral and central nervous systems.
Central nervous system (CNS)
The brain and spinal cord.
Peripheral nervous system (PNS)
The sensory and motor neurons that connect the central nervous system to the rest of the body.
Nerves
The neural "cables" containing many axons. These bundled axons, which are part of the peripheral nervous system, connect the central nervous system with muscles, glands, and sense organs.
Sensory neurons
Neurons that carry incoming information from the sense receptors to the central nervous system.
Motor neurons
Neurons that carry outgoing information from the central nervous system to the muscles and glands.
Interneurons
Central nervous system neurons that internally communicate and intervene between the sensory inputs and motor outputs.
Somatic nervous system
The division of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart.) Its sympathetic division arouses; its parasympathetic division calms.
Sympathetic nervous system
The division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations.
Parasympathetic nervous system
The division of the autonomic nervous system that calms the body, conserving energy.
Reflex
A simple, automatic, inborn response to a sensory stimulus, such as the knee jerk response.
Neural networks
Interconnected neural cells. With experience, networks can learn, as feedback strengthens or inhibits connections that produce certain results. Computer simulations of neural networks show analogous learning.
Endocrine system
The body's "slow" chemical communication system; a set of glands that secrete hormones into the blood stream.
Hormones
Chemical messengers, mostly those manufactured by the endocrine glands, that are produced in one tissue and affect another.
Adrenal glands
A pair of endocrine glands just above the kidneys. The adrenal glands secrete the hormones epinephrine (adrenaline) and norepinephrine (noradrenaline), which help to arouse the body in times of stress.
Pituitary gland
The endocrine system's most influential gland. Under the influence of the hypothalamus, the pituitary gland regulates growth and controls other endocrine glands.
Lesion
Tissue destruction. A brain lesion is a naturally or experimentally caused destruction of brain tissue.
Electroencephalogram (EEG)
An amplified recording of the waves of electrical activity that sweep across the brain's surface. These waves are measured by electrodes placed on the scalp.
PET (position emission tomography) scan
A visual display of brain activity that detects where a radioactive form of glucose goes while the brain performs a given task.
MRI (magnetic resonance imaging)
A technique that uses magnetic fields and radio waves to produce computer-generated images that distinguish among different types of soft tissue; allows us to see structures within the brain.
fMRI (functional magnetic resonance imaging)
A technique for revealing blood flow and therefore brain activity by comparing successive MRI scans. MRI scans show brain anatomy; fMRI scans show brain function.
Glial cells (glia)
Cells in the nervous system that support, nourish, and protect neurons.
Aphasia
Impairment of language, usually caused by left hemisphere damage either to Broca's area (impairing speaking) or Wernicke's area (impairing understanding.)
Split brain
A condition in which the two hemispheres of the brain are isolated by cutting the connecting fibers (mainly those of the corpus callosum between them.)
Dopamine
A neurotransmitter that influences movement, learning, attention and emotion.
Seratonin
A neurotransmitter that affects mood, hunger, sleep, and arousal; linked to depression and treated by Prozac. (Blocks reuptake of seratonin, activating more seratonin in neural pathways, therefore elevating mood.)
GABA (gamma-aminobutyric acid)
A major inhibitory neurotransmitter; alcohol.
Phineas Gage
Man whose frontal lobes were massively damaged after a rod shot through his skull, entering his left cheek and exiting his left frontal lobe. His mental abilities and memories were intact after accident, although his personality and temperament was not.
Angular gyrus
Transforms visual representations into auditory codes, then interpreted by Wernicke's and Broca's areas in the process of recognizing and interpreting language.
Agonist
Such as some opiates, an agonist excites by mimicking particular neurotransmitters or by blocking their reuptake.
Antagonist
Such as curare, an antagonist inhibits a particular neurotransmitter's release or blocks its effect.