Brain areas & functions

diencephalon (interbrain)

sits atop brain stem, linking it to the cerebrum, and is enclosed by cerebral hemispheres

thalamus (in diencephalon, 3rd ventricle)

• a complex relay station for sensory  impulses passing upward to the sensory cortex (except smell)

• get crude recognition of whether      sensation we’re about to experience is pleasant or unpleasant; actual interpret. is done in sensory cortex

• regulates states of sleep and wakefulness

• plays a major role in regulating arousal, levels of awareness and activity

• damage to area can cause permanent coma 

hypothalamus (floor of diencephalon)

• important autonomic nervous system center b/c it plays a role in regulation of body temp., water balance and metabolism

• Hormone production

• deals with sleep/wake cycle

limbic system (hypothalamus, diencephalon)

emotional/ visceral, many parts in one

• deals with emotion, motivation, and emotions with memory

• influences formation of memory by   integrating emotional states with stored memories of physical sensations

amygdala (limbic system)

aggression, jealousy, and fear

hippocampus (limbic system)

formation of long-term memories

pituitary gland (ant. floor hypothalamus)

center for many drives (hunger, thirst, sex- pain and pleasure) and emotions (therefore an important part of limbic system)

mammillary bodies (floor of hypothalamus)

• reflex centers involved in olfaction; may be important for memory

epithalamus

roof of third ventricle

pineal gland (epithalamus)

secretes melatonin, which induces sleep

choroid plexus (epithalamus)

forms CSF, knots of capillaries within each ventricle

brain stem (diencephalon, epithalamus)

• provides pathways for ascending and descending tracts, has many small gray matter areas, which are part of cranial nerves and control vital activities (breathing, blood pressure…)

midbrain (mesensephalon, brain stem)

• extends from mammilary bodies to pons inferiorly; divided into three parts:

  • Cerebral aqueduct

  • Cerebral peduncles 

  • Corpora quadrigemina  

  • Process visual & auditory info

  • Generate involuntary motor responses

  • Maintains consciousness

pons (brain stem)

• rounded structure; protrudes just below midbrain – connects cerebellum to brain stem

  • Somatic & visceral motor control, especially important  in the control of breathing

medulla oblongata (brain stem)

• most inferior part of brain stem; merges into spinal cord inferiorly

  • regulate vital visceral activities (heart rate, blood pressure, breathing, swallowing, vomiting, etc.)

fourth ventricle (medulla oblongata)

•  lies posterior to pons and medulla and anterior to cerebellum

cerebellum

projects dorsally from under the occipital lobe; like cerebrum, it has two hemispheres, convoluted surface, outer cortex made of gray matter and inner region of white matter

• precise timing for skeletal muscle activity and coordination

• controls our balance and equilibrium

• monitors body position and amount of tension in various body parts and adjusts voluntary & involuntary motor activities accordingly

• Repetition and rote memorization

ventricles

• 4 internal cavities of the brain that contain cerebrospinal fluid

  • 1. Lateral ventricles (2)

  • 2. Third ventricle

  • 3. Fourth ventricle

broca’s area

 involved with ability to speak; found at base of precentral gyrus; located in only one hemisphere, usually left; damage to this area causes inability to say words properly- you know what you want to say, but you can’t vocalize the words

speech area

• located at junction of temporal, parietal, and occipital lobes; allows one to sound out words

cerebral cortex

• gray matter in outermost areas

corpus callosum

•  large tract; connects cerebral hemispheres

basal nuclei

• (formerly called the basal ganglia)- islands of gray matter buried deep within white matter; help regulate voluntary motor activities by modifying instructions sent to skeletal muscles by primary motor cortex; problem with basal nuclei 🡪 people cannot carry out voluntary movement normally; ex. Parkinson’s disease

corticospinal/ triangular tract

• major vol. motor tract; formed from motor axons; descends to cord, frontal lobe

anterior area

• involved with higher intellectual reasoning, socially acceptable behavior, and language comprehension (word meanings); also complex memories (frontal and temporal lobes), personality, frontal lobe

motor homunculus

•  body represented upside- down; crossed pathways; body areas with finest control (face, mouth, hands) = more brain area, frontal lobe

sensory homunculus

•  spatial map; body represented upside-down; crossed pathways (impulses from left side of body travel to right side of brain & vice versa); more sensitive the area (lips, fingertips), more brain area it takes up, parietal lobe

reticular formation

• extending entire length of brain stem; is a diffuse mass of gray matter; involved in motor control of visceral organs

reticular activating system RAS (reticular formation)

• center of arousal and motivation

  • plays a crucial role in consciousness, maintaining alertness, and the awake/sleep cycles

  • acts as a filter when asleep

  • damage can result in permanent unconsciousness (coma)

  • involved with circadian rhythm

  • general anesthesia and many psychotropic drugs (caffeine and nicotine, hallucinogenics, pain medications) work here (note: the RAS is not believed to generate consciousness, but plays an indirect role- ie. physiologically supports thalamus)