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Biological Psychology

The study of the links between biology and behavior.


The basic building block of the nervous system.

Sensory Neurons

These carry information from the sensory receptors to the central nervous system for processing.

Motor Neurons

These carry information and instructions for action from the central nervous system to muscles and glands.


The neurons of the central nervous system that link the sensory and motor neurons in the transmission of sensory inputs and motor outputs.


The bushy, branching extensions of a neuron that receive messages from other nerve cells and conduct impulses toward the cell body.


The extension of a neuron that sends impulses to other nerve cells or to muscles or glands.

Myelin Sheath

A layer of fatty tissue that segmentally covers many axons and helps speed neural impulses.

Action Potential

A neural impulse generated by the movement of positively charged atoms in and out of channels in the axon's membrane.


The level of stimulation that must be exceeded in order for the neuron to fire, or generate an electrical impulse.


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.


Chemicals that are released into synaptic gaps and so transmit neural messages from neuron to neuron.


The absorption of excess neurotransmitters by a sending neuron.


Natural, opiatelike neurotransmitters linked to pain control and to pleasure.

Nervous System

The speedy, electrochemical communication system, consisting of all the nerve cells in the peripheral and central nervous systems.

Central Nervous System (CNS)

This consists of the brain and spinal chord; it is located at the center, or internal core, of the body.

Peripheral Nervous System (PNS)

This includes the sensory and motor neurons that connect the central nervous system to the body's sense receptors, muscles, and glands; it is at the periphery of the body relative to the brain and spinal chord.


The bundles of neural axons, which are part of the PNS, that connect the central nervous system with muscles, glands, and sense organs.

Somatic Nervous System

The division of the peripheral nervous system that enables voluntary control of the skeletal muscles; also called the skeletal nervous system.

Autonomic Nervous System

The division of the peripheral nervous system that controls the glands and the muscles of internal organs and thereby controls internal functioning; it regulates the automatic behavior necessary for survival.

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 its energy.


A simple, automatic, inborn response to a sensory stimulus; it is governed by a very simple neural pathway.

Endocrine System

The body's "slower chemical communication system, consists of glands that secrete hormones into the bloodstream.


Chemical messengers, mostly those manufactured by the endocrine glands, that are produced in one tissue and circulate through the bloodstream to their target tissues, on which the have specific effects.

Adrenal Glands

These produce epinephrine and norepinephrine, hormones that prepare the body to deal with emergencies or stress.

Pituitary Gland

This is under the influence of the hypothalamus. They regulate growth and control other endocrine glands; sometimes called the "master gland."


The destruction of tissue.

Electroencephalogram (EEG)

An amplified recording of the waves of electrical activity of the brain.

PET (Positron Emission Tomography) Scan

Measures the levels of activity of different areas of the brain by tracing their consumption of radioactive form of glucose, the brain's fuel.

MRI (Magnetic Resonance Imaging)

This uses magnetic fields and radio waves to produce computer-generated images that show brain structures more clearly.

fMRI (Functional magnetic resonance imaging)

Scans taken less than a second apart are compared to reveal blood flow and, therefore, brain structure and function.


The oldest and innermost region of the brain, is an extension of the spinal cord and is the central core of the brain; its structures direct automatic survival functions.


Located in the brainstem, this controls breathing and heartbeat.

Reticular Formation

Located in the brainstem, this is a nerve network that plays an important role in controlling arousal.


Located atop the brainstem, this routes incoming messages to the appropriate cortical centers and transmits replies to the medulla and cerebellum.


This processes sensory input and coordinates movement output and balance.

Limbic System

A neural system associated with emotions such as fear and aggression and basic physiological drives; at the border of the brainstem and cerebral hemispheres.


A part of the limbic system and influences emotions of fear and aggression.


A part of the limbic system that regulates hunger, thirst, body temperature, and sexual behavior; helps govern the endocrine system via the pituitary gland; and contains the so-called reward centers of the brain.

Cerebral Cortex

A thin intricate covering of interconnected neural cells atop the cerebral hemispheres. The seat of information processing, the this is responsible for those complex functions that make us distinctively human.

Glial Cells

Provide nutrients and insulating myelin, and help remove excess ions and neurotransmitters.

Frontal Lobes

Just behind the forehead, these are involved in speaking and muscle movements and in making plans and judgments.

Parietal Lobes

Situated between the frontal and occipital lobes, and contain the sensory cortex.

Occipital Lobes

Located at the back and base of the brain, and contain the visual cortex, which receives information from the eyes.

Temporal Lobes

Located on the sides of the brain, and contain the auditory cortex, which receive information from the ears.

Motor Cortex

Located at the back of the frontal lobe, and controls voluntary movement.

Sensory Cortex

Located at the front of the parietal lobes, just behind the motor cortex, and registers and processes body touch and movement sensations.

Association Areas

Located throughout the cortex, and are involved in higher functions, such as learning, remembering, and abstract thinking.


The brain's capacity for modification, as evidenced by brain reorganization following damage (especially in children).


The formation of new neurons.

Corpus Callosum

the large band of neural fibers that links the right and left cerebral hemispheres. Without this band of nerve fivers, the two hemispheres could not interact.

Split Brain

A condition in which the major connections between two cerebral hemispheres (the corpus callosum) are severed.

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