AT Psych Unit Two

Neurons

Individual cells in nervous system that receive, integrate, and transmit information

Soma

Neuron cell body, contains cell nucleus and much of chemical machinery common to most cells

Axon

Long, thin fiber, transmitting signals away from soma to other neurons, muscles, or glands

Myelin Sheath

Sometimes on axons. Speeds up transmission of signals, prevents axons from sprouting in new directions.

Terminal Buttons

At the end of axons. Small knobs secreting neurotransmitters. Messengers activating neighboring neurons.

Synapses

Where neurons interconnect—information transferred between neurons

Glia

Cells found throughout the nervous system providing support for neurons. Generally much smaller than neurons and supply neurons with nourishment, remove their waste products, provide insulation, and have complex role in human embryo’s development.

Resting Potential

Neuron’s stable, negative charge when cell is inactive

Action Potential

A change in the ion distribution leads to a shift in the neuron’s electrical charge traveling along the axon

Absolute Refractory Period

Minimum length of time after an action potential during which more can’t begin

All or None Law

Either neuron fires or doesn’t—action potentials are the same size regardless of stimuli.

Presynaptic Neuron

Neuron that sends the signal across the synaptic cleft

Postsynaptic Neuron

Receives signal sent across the synaptic cleft

Synaptic Cleft

Microscopic gap between terminal button of one neuron and the cell membrane of the other neuron. Signals must cross the gap.

Neurotransmitters

Chemicals transmitting information between neurons, mostly stored in sacs in terminal buttons called synaptic vesicles.

Synaptic Vesicles

Sacs in terminal buttons storing neurotransmitters.

Postsynaptic Potential

Voltage change at receptor site on postsynaptic cell membrane. Don’t follow the all-or-none law.

Excitatory PSP

Positive voltage shift, increased likelihood the postsynaptic neuron will fire action potentials.

Inhibitory PSP

Negative voltage shift, decreased likelihood the postsynaptic neuron will fire action potentials.

Acetylcholine

Neurotransmitter—only one between motor neurons and voluntary neurons. Contributes to arousal, attention, and memory. Inadequate supply in certain areas of the brain is associated with the memory loss in Alzheimer’s

Monoamines

Category of neurotransmitters encompassing dopamine, norepinephrine, and serotonin. Regulate much of everyday behavior.

Dopamine

Neurotransmitter. Used by neurons controlling voluntary movements. “Feel-good” hormone. Low levels are linked to Parkinson’s, restless leg syndrome, ADHD, and depression, and schizophrenia is associated with both high and low levels.

Serotonin

One of many neurotransmitters contributing to the regulation of sleep and arousal, also a “feel-good” neurotransmitter that deals with feelings of calmness. Low levels associated with anxiety, depression, and OCD.

GABA

Amino acid producing inhibitory PSPs, responsible for much of central nervous system inhibition.

Endorphins

Internally produced chemicals resembling opioids in structure and effects. Widely distributed in the body. Contribute to modulation of pain.

Multiple Sclerosis

Disruption to the myelin sheath leading to a lack of communication between neurons.

Computerized Tomography (CT)

Computer-enhanced X-ray of brain structure, combining readings from many angles.

Magnetic Resonance Imaging (MRI)

Uses magnetic fields, radio waves, computerized enhancement to map out brain structure. 3D pictures with high resolution.

Lesioning

Destroying a piece of the brain to study what happens when it’s disabled. Largely limited to animal research.

Positron Emission Tomography (PET)

Radioactive markers to map chemical activity in the brain over time.

Functional MRI (fMRI)

Monitors blood flow and oxygen consumption in the brain. Maps brain activity with great precision.

Cerebellum

Relatively large, folded, adjacent to back surface of brainstem. Deals with coordination of movement, critical to sense of equilibrium + physical balance, sensing limb position.

Medulla

Attaches to spinal cord. Controls essentials and mostly unconscious functions.

Pons

Bridge of fibers connecting the brainstem with the cerebellum. Several cell bodies involved with sleep and arousal.

Reticular Formation

At the central core of the brainstem. Contributes to modulation of muscle reflexes, breathing, pain perception. Has a role in regulating sleep and wakefulness.

Thalamus

Relay station. All sensory information (except smell) must pass through this structure to get to the cerebral cortex. Composed of somas relaying sensory information to specific parts of the cortex. Seems to play active role in integrating information from various senses.

Hypothalamus

Regulates biological needs. Located near the base of the forebrain. Deals with fighting, feeding, fleeing, and mating.

Limbic System

Loosely connected network of structures on the border between the cerebral cortex and deeper subcortical areas that deals with emotions.

Hippocampus

Role in memory processes—creating new memories.

Amygdala

Structure with a role in learning fear responses and processing other emotional responses.

Cerebrum

Largest and most complex part of the brain. Includes areas responsible for learning, remembering, thinking, and consciousness.

Cerebral Cortex

Folded outer layer of the cerebrum.

Corpus Callosum

Thick band of fibers connecting brain hemispheres and enabling communication between the hemispheres.

Occipital Lobe

Most visual signals sent here, and visual processing begins here.

Parietal Lobe

Registers touch, involved in integrating visual input and monitoring the body’s position in space.

Temporal Lobe

Contains the primary auditory cortex for auditory processing. Damage to the area in the left hemisphere can cause difficulties in language/speech understanding.

Frontal Lobe

Contains the primary motor cortex, mirror neurons, and prefrontal cortex.

Mirror Neurons

Neurons firing/activated by seeing another performing the same action.

Primary Motor Cortex

Controls muscle movement. Amount of motor cortex dedicated to body part based on precision and diversity of movement.

Prefrontal Cortex

Affects decision making and self-control.

Neuroplasticity

The brain changes with time. Experience can sculpt features of brain structure.

Neurogenesis

Formation of new neurons.

Peripheral Nervous System

Nerves outside the brain and spinal cord. Includes nerves. Divided into somatic and autonomic nervous system.

Somatic Nervous System

Lets you feel the world and move around in it. Made of nerves connecting to voluntary skeletal muscles and sensory receptors.

Afferent Nerve Fibers

Axons carrying information to the central nervous system from the periphery of the body.

Efferent Nerve Fibers

Axons carrying information from the central nervous system to the periphery of the body.

Autonomic Nervous System

Made up of nerves connecting to the heart, blood vessels, smooth muscles, and glands. Controlled by the central nervous system. Controls automatic, involuntary, and visceral functions. Mediates much of physiological arousal occurring when people experience emotions. Divided into parasympathetic and sympathetic divisions.

Sympathetic Division

Mobilizes body’s resources for emergencies

Parasympathetic Divisions

Conserves the body’s resources.

Central Nervous System

Brain and spinal cord. Bathed in cerebrospinal fluid. Within skull and spinal column.

Cerebrospinal Fluid

Nourishes brain and provides protective cushion. Derived from carefully filtered blood. Substances in blood must cross blood-brain barrier to enter CSF.

Spinal Cord

Connects brain with the rest of the body through peripheral nervous system. Houses bundles of axons carrying the brain’s commands to peripheral nerves and vice versa.

Endocrine System

Second communication system consisting of glands secreting chemicals into the bloodstream to help control bodily functioning (hormones).

Hormones

Chemicals released by endocrine glands. Like neurotransmitters but slower and less specific. Tend to have intermittent releases.

Pituitary Gland

Releases variety of hormones fanning out within the body, stimulating actions in other endocrine glands.

Structural Neuroplasticity

Ability to physically change brain structure due to learning and experience.

Functional Neuroplasticity

Synaptic remodeling following brain disfunction or injury.

Dendrites

Dense branches of a neuron specialized to receive information.

Norepinephrine

Also known as noradrenaline. Part of sympathetic division. Increases alertness, arousal, and attention, and affects your sleep-wake cycle, mood, and memory. Low levels associated with depression, poor memory, lack of energy, and ADHD.

Electroencephalogram (EEG)

Test that measures electrical activity in the brain.

Epinephrine

Also known as adrenaline. Primary impact is as a hormone, but plays small role as a neurotransmitter. Helps you react quickly in cases of perceived danger (fight-or-flight response).