Biological Bases of Behavior: The Brain Unit 3B

2 “brains” “old brain” – or “reptilian brain”—instinct, survival new brain – our thinking brain (cerebrum) Old brain Medulla—heartbeat, breathing Pons—coordinates movements Reticular formation—relays info to brain parts, deals with arousal Thalamus—top of brainstem, sends info to various brain parts Cerebellum = “little brain” in back of head. Coordinates movements, figures, and textures. (think ballerina)

Brain (cont.) Limbic system—lies between 2 hemispheres of brain Hippocampus—memory (I’ll never forget the day a hippo was loose on campus) Amygdala—(bean) emotions (fear, anger) (Amy G. Dala is such a drama queen!) Hypothalamus (lima bean) = “below thalamus”—hunger, thirst, body temp., sex Cerebral cortex—large wrinkled part of brain, 85% of size Glial cells— “drones” that feed brain cells Neurogenesis—creating new brain cells. To get more… Sleep, exercise, low stress Plastisticity—brain’s ability to change/reorganize itself; young!

Language Aphasia – impaired use of language Broca’s area – handles speech (left, side front); damaged—can understand words, but can’t speak words Wernicke’s area – assembles words to make sense (left, above ear) Angular gyrus – vision & speaking…reading aloud (left, rear)

Phineas Gage Phineas was workin’ on the railroad, then… Lesson: the brain has areas of specialization

4 brain scans Old days, brain damage led to brain research. Today, brain scans do this. EEG (electroencephalogram) – electrical read out of activity PET (positron emission tomography) – shows active regions based on sugar glucose usage (brain fuel) MRI (magnetic resonance imagery) – gives pic of brain structure fMRI (functional MRI) – gives pic of brain structure AND function

Split brain Left and right hemispheres have specialties. Left – rationality, logic, speech, words Mr. Left – methodical math teacher carefully works through problems in a step-by-step manner Right – images, emotions, intuition, music Mrs. Right – unpredictable but fun art teacher who can instantly tell if you’re having a good or bad day L & R hemispheres connected by the corpus callosum (bundle of fibers) Sometimes, corpus callosum is severed (cut) due to seizures.

Split brain research Researchers isolate left visual-field items to right brain (pics), right visual-field items to left brain (words). (This is backwards.) How? The optic nerve does this from retina to brain. Two things were done… Pics were sent to left side (word side). Person could not picture it, but could say it. Words were sent to right side (pic side). Person could not say it, but could draw it. Don’t go overboard on this L/R brain stuff. We do NOT have a severed corpus callosum. See video.

Split brain misc. Sign language…left (words) or right (pics) brain? Left brain. Sign language is language, it just gets to the brain differently. 90% of people are right handed. 96% of them process language in left hemisphere. But… only 70% of left handed people do. So… L/R handedness seems genetic. More left handers have reading disabilities, allergies, migraines. But, seem better at music, math, and art. Everything biological is psychological.

Brain & Consciousness (awareness) Brain scans help a person in a coma “speak” to us Dual processing – our brains seem able to keep track of multiple things at once (I’m in psych class, other students, weather outside, assignment coming up?) Seems more for instinctive, “low-road”, unconscious things (brain does it on its own) Warning! Parallel processing says the opposite! We process one thing at a time, we don’t multitask well at all. (texting + driving = crash) Seems more for “high road” conscious things (trying to do 2 things simultaneously)