NEUROBIOLOGICAL BASIS OF
BEHAVIOR
I.
NEURON
Neuron – nerve cell
- Basic unit of the nervous system
- Responsible for adopting the transmission of
information from a stimulus to a response
- Mostly found in the brain
- Transmit nerve impulses to and from the brain
at up to 200 mph
Neural impulse – electrical signal generated when
the neuron is active
Glial cells – supportive cell in the central nervous
system
- Surround neurons and provide support for and
insulation between them
Nerves – bundles of axons
- Often located in the peripheral nervous system
- Transmit information to various parts of the
body
 Types of Neurons
1. Sensory neuron (afferent neuron) – carry
information from the senses to the spinal cord
2. Interneuron – makes connections to other
neurons
3. Motor neuron (efferent neuron) – carries
signals from the brain or spinal cord to reacting
organs/muscles and glands
 Basic Parts of the Neuron
1. Cell body (soma) – provides the energy for
transmitting information in the neuron
2. Dendrites – branchlike fibers in the cell body
that receive signals from other neurons,
muscles, or sense organs
3. Axon – single threadlike structure that carries
signals away from the cell body to the
neighboring neurons, organs, or muscles
4. Myelin sheath – insulating sheath wrapped
around the axon; protects the axon from
interference from signals in other neurons;
increases the velocity at which signals travel in
the axon
5. Terminal bulbs (end bulbs) – tiny bulbs
located at the end of the axon’s branches;
contains neurotransmitters
6. Synapse – infinitely small space between an
end bulb and a muscle, body organ, or cell
body
- When end bulbs are stimulated,
neurotransmitters are released into the
synapse

-
Neurotransmitters
Chemicals substances released by a
neuron through the synapse and used for
communication between neurons
A) Types
1. Excitatory – turns on the neuron;
makes the neuron active and allows
nerve impulses to travel
2. Inhibitory – turns off the neuron;
places the neuron at a resting state

-
Reflex
Unlearned, involuntary response to a
stimulus
II.
NERVOUS SYSTEM
 Divisions of the Nervous System
A. Central Nervous System – contains the
brain and spinal cord
B. Peripheral Nervous System - contains
the nerves connecting the brain and spinal
cord to the sensory organs, muscles, and
glands
B.1. Somatic Nervous System – voluntary
system that includes the sensory receptors
and the motor nerves
B.2. Autonomic Nervous System –
maintains the normal activities of the glands
and the visceral organs, such as heart rate,
digestion, and respiration; usually functions
involuntarily or without conscious effort
B.2.1. Sympathetic Nervous System
– increases physiological arousal and
prepares the body for actions;
functions during stressful situations
B.2.2. Parasympathetic Nervous
System – decreases physiological
arousal and returns the body to a
calmer state

Autonomic Nervous System
Fight-flight response – state of increased
physiological arousal caused by activation of
the sympathetic nervous system; helps the
body cope with and survive threatening
situations
Homeostasis – state of internal balance;
sympathetic and parasympathetic nervous
systems work together to keep the body’s level
of arousal in balance for optimum functioning
III.
THE BRAIN
 Parts of the Brain
A. Forebrain – largest part of the brain
A1. Hemispheres:
1. Left Hemisphere – verbal,
mathematical, and analytic thinking
2. Right Hemisphere – spatial,
holistic, and creative thinking
A2. Parts of the Forebrain:
1. Cerebral Cortex – wrinkled
surface of the cerebrum
2. Cerebellum - center of thinking
and language; controls voluntary
actions
3. Corpus Callosum - serves as a
bridge between the two
hemispheres
B. Midbrain – has a reward or pleasure
center; has areas for visual and auditory
reflexes
1. Reticular activating system
(RAS) – Involved in stereotypical
behavior, such as attention,
walking, sleep, and arousal;
arouses the forebrain so that it is
ready to process information from
the senses
C. Hindbrain – consists of the pons, the
medulla, and the cerebellum
1. Pons – interconnects messages
between the spinal cord and the
brain; regulates sleep
2. Medulla – regulates vital bodily
processes, such as respiration,
heart rate, blood pressure, and
some reflexes
3. Cerebellum – controls bodily
balance and maintains smooth,
coordinated motor movements

Cerebral Cortex
A) Lobes of the Cerebral Cortex
1. Frontal Lobe – involved in interpreting
emotions and experiences, maintaining
a healthy personality, performing
voluntary movements, paying attention,
making decisions, and carrying out
plans
2. Parietal Lobe – processes sensory
information from body parts, such as
touch, pain, heat, visual perception
3. Occipital Lobe – processes visual
information
4. Temporal Lobe – involved in hearing,
speaking coherently, and understanding
oral and written language

Limbic System
- Group of structures that make up the core
of the forebrain; involved in regulating many
motivational behaviors, organizing
emotional behaviors, and storing memories
A) Parts
1. Hypothalamus – regulates motivational
behaviors (eating, drinking, sexual
behavior), emotional behaviors, and
the secretion of hormones
- Controls the autonomic
nervous system and much of
the endocrine system
2. Amygdala – evaluates the emotional
significance of stimuli and facial
expressions
3. Thalamus – receives sensory
information, processes it, and relays it
to areas of the cortex
4. Hippocampus – saves many kinds of
fleeting memories as long-term
memories

Endocrine System
- Body system made up of numerous glands
that secrete various hormones