Chapter 3: The Biological Basis of Behavior Module 8: The Brain

Lower-Level Brain Structures: BrainstemMedulla Oldest part of the brain Responsible for automatic survival functions Located where the spinal cord swells and the brain just begins –Rose or tail? The base of the brainstem Controls life- supporting functions like heartbeat and breathing Damage to this area can lead to death.

More lower-level brain structures: Reticular Formation A nerve network extending up and down the spinal cord into the brain Controls an organism’s level of alertness Damage to this area can cause a coma.

L.L.B.S. (cont.): Thalamus Sits atop the brainstem –Right in the middle! Like a switchboard –Directs messages to the sensory receiving areas in the cortex Thalamus is Greek for “inner chamber.”

L.L.B.S. (cont.): Cerebellum Latin for the “little brain” Located in the rear of the brain Helps with balance & coordination –Also, memories to play instrument or walk. Allows us to run or write If damaged, the person could perform basic movements but would lose fine coordination skills.

L.L.B.S.: The Limbic System Area around the thalamus –At the border of the brainstem and cerebral cortex –B/t older core regions and newly developed ones Helps regulate memory, aggression, fear, hunger, and thirst Includes the hypothalamus, hippocampus, and amygdala

Hypothalamus Located directly under the front of the thalamus Regulates eating, drinking, body temperature, and the fight or flight reactions to stress Plays a role in emotions, pleasure, and sexual function

Hippocampus Wraps around the back of the thalamus Plays a role in processing new memories for permanent storage Looks something like a seahorse –Hippo is Greek for “horse.”

Amygdala Two almond shaped structures Controls emotional responses such as fear and anger

The Cerebral Cortex Module 8: The Brain

Cerebral Cortex The wrinkled outer surface The body’s ultimate control and information processing center Covers the brain’s lower level structures –30 billion nerve cells can exist in a tissue layer 1/8 th of an inch thick.

Longitudinal Fissure Most dramatic feature of cortex. The crevice that divides the brain into two halves or hemispheres. The Corpus Callosum is the large band of neural fibers that connects the two halves and carries messages between them. This and other fissures in the brain create 4 major divisions in the brain called lobes.

Frontal Lobes The portion of the cerebral cortex lying just behind the forehead Is involved in making plans and judgments

Parietal Lobes Regions available for general processing, including mathematical reasoning Designated as the association lobes Behind the frontal lobes

Occipital Lobe The primary visual processing area Located in the back of the head

Temporal Lobes Includes the auditory cortex where sound information is processed Located roughly above the ears

Motor Cortex Area at the rear of the frontal lobes Controls voluntary movement Different parts of the cortex control different parts of the body. The motor cortex in the left hemisphere controls the right side of the body and visa versa.

Somatosensory Cortex Located in the front of the parietal lobes Registers and processes body senses Soma is Greek for “body.”

Hemispheric Differences Module 8: The Brain

Hemispheric Differences “Left-brained” and “right-brained” debunked Brain is divided into two hemispheres but works as a single entity. Both sides continually communicate via the corpus callosum, except in those with split brains.

Hemispheric Differences: Language and Spatial Abilities Module 8: The Brain

The Brain’s Left Hemisphere For most people, language functions are in the left hemisphere. For a small percentage of people, language functions are in the right hemisphere.

Broca’s Area Located in the frontal lobe and usually in the left hemisphere Responsible for the muscle movements of speech If damaged the person can form the ideas but cannot express them as speech

PET Scan of Broca’s Area

Wernicke’s Area Located in the temporal lobe Involved in language comprehension and expression; our ability to understand what is said to us Usually in the left temporal lobe

PET Scan of Wernicke’s Area

The Brain’s Right Hemisphere Houses the brain’s spatial abilities Our spatial ability allows us to perceive or organize things in a given space, judge distance, etc. Helps in making connections between words

Brain Plasticity The ability of the brain tissue to take on new functions Greatest in childhood Important if parts of the brain are damaged or destroyed