Chapter 3: Biological Bases of Behavior

**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.