Major Brain Structures and Functions

Warning! The brain is not neatly organized into structures that correspond to specific behaviors Most behavior involves neural activity in many brain parts Here we are generalizing! The brain is not as simple as we will make it sound!

The Brainstem: Oldest part of the brain; Present in all mammals; Hidden underneath cerebrum

“netlike”; runs from the spinal cord to the thalamus; arousal; alerts higher parts of the brain; neurons with serotonin and norepinephrine are found here (help us respond based on state of arousal) daf Your brainstem is also your crossover point: most nerves to and from each side of the brain connect with the body’s opposite side Pons: “bridge” between cerebral cortex and medulla; involved in coordination of movement, sleep, arousal, facial expressions place where spinal cord begins to swell; life support center: breathing, heart rate, blood pressure

Thalamus and Cerebellum Thalamus: 2 egg shaped structures; sensory switchboard; receives info from senses and routes them to higher brain regions; “gateway” to the cortex; also involved in sleep (helps us tune out during deep sleep) baseball sized; “little brain”; judgment coordinates voluntary movement; balance; coordination Alcohol first impairs the cerebellum; Autism – abnormalities in the cerebellum are common (subtle deficits in language, cognition, perception)

Midbrain: In between brain stem and limbic system smallest “region”; acts as a relay station for auditory and visual information; control of body movement; degeneration of dopamine neurons here causes Parkinson’s; one of the areas where pain is registered

Limbic System: “border” between brain’s older and newer parts “below”; reward center: hunger, thirst, body temperature, sexual behavior; monitors blood chemistry; motivation; biological rhythms lima bean sized; “almond”; influence fear and aggression; processing of emotional memories part of endocrine system; master gland; works with hypothalamus to secrete certain hormones “sea horse: new memories; learning

Cerebrum: Two Large Hemispheres; 85% of the brain’s weight Cerebral Cortex: “bark”; thin layer of interconnected neural cells that cover the hemispheres; contains more than 300 trillion synapses The more complex the animal, the larger the cerebral cortex What’s underneath? Filled with the axons that connect the cortex to the brain’s other regions Divided into lobes based upon fissures or folds Brain’s two halves are connected by the corpus callosum (band of neural tissue that connects the two halves of the brain)

Corpus Callosum

What’s in the Cerebral Cortex? Specialized cortexes control sensory functions (movement, sight, hearing, touch, etc) Other areas are known as association areas Areas of the cerebral cortex that are not involved in primary motor or sensory functions Involved in higher mental functioning (learning, remembering, thinking, speaking, etc)

Association Areas

Frontal Lobes Executive control center: coordinates messages from all of the lobes Association Areas: judgment, planning, processing of new memories, personality Cortex: Prefrontal cortex – goal directed behavior, control of impulses, metacognition (thinking about thinking), attention

Motor Cortex In the back of the frontal lobe Arc –shaped from ear to ear (like a headband!) Controls voluntary movements Body areas that require precise control (fingers, mouth) take up more space in the motor cortex

Parietal Lobes Association Areas: mathematical and spatial reasoning (larger and unusually shaped in Einstein's brain) Cortex: Sensory Cortex – front of parietal lobe; registers and processes touch, taste, pain, skin temperature

(Somato)Sensory and Motor Cortex

Temporal Lobes Association Areas: balance, equilibrium; right side allows us to recognize faces Auditory cortex: processes auditory information

Occipital Lobes Visual Cortex: Processes visual information

Language

Brain (Neural) Plasticity The brain’s ability to modify itself after some types of damage Severed neurons do not usually regenerate Instead, the brain’s neural tissue can reorganize itself One brain area can take on functions not normally “assigned” to that area Brain’s are most plastic when we are young