Brain Structures and Functions

Welcome to the lecture, recapping previous topics and introducing new ones.
Review of yesterday's lecture is recommended, especially regarding the divisions of the nervous system and differences between animal and human brains.
Today's focus: hemispheric dominance, hindbrain structures, and potentially the forebrain.
Study session today: 4-5 PM in Building 201, Room 342.

Question: Briefly outline two differences between animal and human brains.
Difference 1: Animals often have larger olfactory bulbs due to a greater reliance on smell.
Difference 2: Human brains have more ridges and bumps (sulci and gyri) to increase surface area.

Animals like rats and rabbits rely heavily on olfaction (smell) as a primary sense, hence larger olfactory bulbs.
In humans, smell tracks are located underneath the frontal lobes.
Although vision is our primary sense, smell is still useful.

The brain consists of two hemispheres: left and right.
Anatomically similar but functionally different.
Left Hemisphere:
- Primarily responsible for language processing (understanding and production) in most people (90%+).
Right Hemisphere:
- Primarily responsible for spatial awareness.
- Processes information about the location of objects in space, including the position of one's limbs.
Activity: Close your eyes and visualize how you will get to your next destination after the lecture to activate right hemisphere.

Question regarding dyspraxia and affected brain areas: a complex question that requires a more in-depth answer (to be addressed in Stage 2).

Brain is divided into three major parts:
- Hindbrain (back of the brain).
- Midbrain (deep inside the brain, hidden from view).
- Forebrain.

Deals with arousal (consciousness and alertness).
Relays sensory information to other parts of the brain.
Role in breathing and respiration (automatic functions).
Important for sleep and dreaming.
Involved in shutting down muscles during sleep.
Locked-in syndrome:
- Caused by damage to the pons, often due to stroke or head injury.
- Results in the inability to move voluntary muscles (including blinking in some cases).
- Cognitive function remains intact.
Research in the 1960s involving cats demonstrated the pons' role in muscle shutdown during sleep.

Vital for life functions.
Regulates breathing and heart rate (automatic processes).
Controls reflexes such as vomiting, defecation, and swallowing.
Damage to the medulla can be fatal or cause difficulties with swallowing that requires assistance from a speech language therapist because of the risk of choking.
Active in simpler animals for movements like crawling or swimming.

Located at the back of the brain, appears cauliflower-like.
Heavily involved in balance and movement.
Works in conjunction with other brain areas to enable complex movements.
Monitors body position and movement, even before movements occur.
Moderates head movements to prevent dizziness.
Plays a role in learning new movements and movement skills.
Damage to the cerebellum:
- Affects balance, stance, and gait (walking).
- Causes difficulty with smooth, coordinated movements.
- Can be caused by injury or brain disease, or temporarily affected by alcohol.
- Impairs sequencing and timing of precise skilled movements (e.g., playing the piano).
Finger tap task: used to check for cerebellum damage by assessing the speed and coordination of finger movements.

Police officer example: illustrates the effects of intoxication on balance and coordination.

Located on top of the hindbrain structures, hidden from view by the cerebral cortex.
Deals with basic vision and audition (hearing).
Relays sensory information to other areas of the cerebral cortex.
Birds of prey:
- Have large midbrains due to the complex coordination required for hunting.
Floppy-eared animals (e.g., rabbits):
- Exhibit midbrain activity when hearing novel stimuli, orienting their ears to the sound.
Important for species survival activities such as mating and fighting, and decreases sensitivity to pain during these behaviors.
In humans, the midbrain became smaller over evolution as its functions were taken over by other areas of the cortex.

Technical definition: everything above the midbrain.
Primates, humans, and mammals have the largest forebrains.
Surrounds the midbrain and hangs over part of the hindbrain.
Cerebral cortex:
- The outer shell of the brain, with a wrinkled appearance.
- Most important for psychological functions, including language and thinking.
- Resembles squashed up sausages.