Chapter 3: Biological Bases of Behavior

Neuroanatomy

Neuroanatomy

refers to the study of the parts and function of neurons.

Neurons

are individual nerve cells.

Dendrites

rootlike parts of the cell that stretch out from the cell body.

Cell body

(also called the soma)—contains the nucleus and other parts of the cell needed to sustain its life.

Axon

wirelike structure ending in the terminal buttons that extends from the cell body.

Myelin sheath

a fatty covering around the axon of some neurons that speeds neural impulses.

Terminal buttons

(also called end buttons, terminal branches of axons, and synaptic knobs)—the branched end of the axon that contain neurotransmitters.

Neurotransmitters

chemicals contained in terminal buttons that enable neurons to communicate.

Synapse

the space between the terminal buttons of one neuron and the dendrites of the next neuron.

excitatory

meaning that they excite the next cell into firing.

inhibitory

meaning that they inhibit the next cell from firing.

Afferent neurons

take information from the senses to the brain.

Interneurons

Once information reaches the brain or spinal cord, interneurons take the messages and send them elsewhere in the brain or on to efferent neurons.

Efferent neurons

take information from the brain to the rest of the body.

The Central Nervous System

The central nervous system (CNS) consists of our brain and spinal cord

spinal cord

all the nerves housed within bone (the skull and vertebrae).

The peripheral nervous system (PNS)

consists of all the other nerves in your body—that is, all the nerves not encased in bone.

somatic nervous system

controls our voluntary muscle movements.

autonomic nervous system

controls the automatic functions of our body—our heart, lungs, internal organs, glands, and so on.

sympathetic nervous system

mobilizes our body to respond to stress.

Parasympathetic Nervous System

carries messages to the stress response system that causes our body to slow down after a stress response.

Lesioning

is the removal or destruction of part of the brain.

electroencephalogram (EEG)

detects brain waves.

computerized axial tomography (CAT or CT)

scan is a sophisticated X-ray.

Magnetic resonance imaging (MRI)

is similar to a CAT scan in a way: both scans give you pictures of the brain.

Positron Emission Tomography

lets researchers see what areas of the brain are most active during certain tasks.

Functional MRI (fMRI)

is a new technology that combines elements of the MRI and PET scans.

Hindbrain

consists of structures in the top part of the spinal cord.

Medulla

is involved in the control of our blood pressure, heart rate, and breathing.

Pons

(located just above the medulla and toward the front) connects the hindbrain with the midbrain and forebrain.

Cerebellum

(located on the bottom rear of the brain) looks like a smaller version of our brain stuck onto the underside of our brain.

Midbrain

coordinates simple movements with sensory information.

reticular formation

One specific structure in the midbrain you should be familiar with is the

Forebrain

control what we think of as thought and reason.

Thalamus

located on top of the brain stem.

Hypothalamus

The hypothalamus controls several metabolic functions, including body temperature, sexual arousal (libido), hunger, thirst, and the endocrine system

Amygdala

Structures near the end of each hippocampal arm

Hippocampus

There are two arms surrounding the thalamus.

Cerebral Cortex

This layer covers the rest of the brain, including most of the structures we have described.

left hemisphere

gets sensory messages and controls the motor function of the right half of the body.

right hemisphere

gets sensory messages and controls the motor function of the left half of the body.

association area

Any area of the cerebral cortex that it is not associated with receiving sensory information or controlling muscle movements is labeled as an

Frontal Lobes

are large areas of the cerebral cortex located at the top front part of the brain behind the eyes.

prefrontal cortex

The anterior or front of the frontal lobe

Broca’s area

is in the frontal lobe and is responsible for controlling the muscles involved in producing speech.

Wernicke’s area

located in the temporal lobe.

motor cortex

A thin vertical strip at the back of the frontal lobe (farthest from the eyes)

Parietal Lobes

are located behind the frontal lobe but still on the top of the brain.

sensory cortex

which is located right behind the motor cortex in the frontal lobe.

Occipital Lobes

are at the very back of our brain, farthest from our eyes.

temporal lobes

process sound sensed by our ears.

Endocrine System

This is a system of glands that secrete hormones that affect many different biological processes in our bodies.

Adrenal Glands

produce adrenaline, which signals the rest of the body to prepare for fight or flight.

Ovaries and testes

produce our sex hormones, estrogen for female systems and testosterone for male systems.

monozygotic twins

(since they develop from one fertilized egg called a zygote) share all the same genetic material

Thomas Bouchard

found more than 100 identical twins who were given up for adoption and raised in different families.

Down syndrome

are born with an extra chromosome on the twenty-first pair.