Psyc 4640 1st Edition Lecture 7 Current Lecture Cerebral cortex the outermost part of forebrain 80 of brain by volume Consists of a left and right hemisphere Covers all other forebrain structures Convoluted not smooth surface with sulci and gyri o Sulci sulcus grooves o Gyri gyrus bumps Each hemisphere is designed to receive sensory info from and send motor info to the contralateral side of the body A lot of crossing over of info at the pons Has grey matter on outer surface and large axons covered in myelin extend inward Two hemispheres communicate via two large axon bundles o The larger of the two is the corpus callosum o Anterior commissure Contains up to 6 distinct cell layers called laminae that are parallel to its surface You don t find all 6 in every part of the cortex o EX Lamina 5 sends very long axons to spinal cord Much more prominent in motor cortex areas o EX Lamina 4 is very prominent in sensory areas and absent in motor cortex o The cells in these layers are arranged in columns Columns are perpendicular to lamina and extend through several laminal layers If one cell in column responds to a particular stimulus every cell in that column responds to that same stimulus EX If only one cell responds to a flash of light at 45 degree angle every single cell in that same column responds only to a flash of light at 45 degree angle Based on lamina and columns there are more than 50 distinct areas in cerebral cortex Cut it down into 4 lobes Each lobe is responsible for more than indicated Occipital lobe in the back Visual lobe Main target for axons from thalamus that receive input from visual pathways The most posterior portion is known as the primary visual cortex striated cortex o Damage to PVC causes cortical blindness common on TV rare in life Eye architecture fine o Individuals with this kind of blindness have no visual imagery Not normal blindness Don t dream o You aren t born with it Result of injury Parietal lobe between occipital lobe and central sulcus Body information center what s happening to it and where your body is in space Postcentral gyrus primary target for touch sensations and other skin and muscle info o Also known as somatosensory cortex Results of damage is different depending on area o Left hemi damage isn t as severe as right hemi damage Relate visual and spatial info o EX Cannot read maps o EX Cannot recognize pen move from one space to another Registers as different pen Temporal lobe main target for info from ears and vestibular system sense of balance Vestibular organs are in inner ear Inner ear infection makes you woozy and unstable Very impt area left for understanding spoken language Facial recognition Pretty complex tasks Complex visual tasks Part of visual pathways in temporal lobe Tumors in temporal lobe can lead to wild pronounced visual hallucinations o Tumors in occipital usually make you see flashes of light Emotional and motivational behaviors Damage to temporal lobe might lead to Kl ver Bucy Syndrome characterized by complete lack of fear o EX Primates have innate fear of fire and snakes Will try to eat a lit match or play with snakes Are they scared or just not know what it is anymore o Incredibly rare condition in humans Individuals with schizophrenia who are actively hallucinating have high activity in temporal lobe on MRI They are seeing something it s registering in their brain as real Frontal lobe contains motor cortex Precentral gyrus part of motor cortex Specialized for very fine motor movement Most interior portion is the prefrontal cortex Receives sensory info from all sensory systems Only part of cortex to do so o A lot of dendritic spines o Integration of a lot of info o Important for internal representations Match to simple tasks Working memory o Object permanence if you can t see it it doesn t exist EX Infants when playing peekaboo actually think you re gone if they can t see you Do not have object permanence Development of PFC explains this See massive growth here between 7 12 mo of age Doesn t stop solidifying until late adolescence early adulthood o Impulse control o Knowing outcomes of potential behaviors o Prefrontal lobotomy Believed to make psychiatric patients more docile Destroy cortex with equivalent of knitting needle Widely misused Natural lobotomy Phineas Gage Railroad spike chin through skull Jerk Binding problem large scale integration problem really asks question how all parts of brain work together for you to see any object that you see o EX If a squirrel ran through the room how do you know it s a squirrel How does your brain put it together to recognize what a squirrel is o Hypothesis certain areas fire in sync at the same time Inferior parietal cortex includes basal ganglia organizes in sync firing Activity of neurons firing in sync and all that info is put together here Based on what is seen in people with brain damage If there is damage in this area the person cannot put color shape and motion together o Brain always tries to put info together so that you could see something that makes sense It binds things together sometimes that shouldn t go together EX We know some things don t match Foreign films with subtitles EX We all have a blind spot Brain fills it in for us EX Seeing a face in smoke or the Virgin Mary on a potato chip Evolutionarily very beneficial for us to do that u EX Walking in the woods seeing something curl up on the group We see a snake if it is we live if not oh well Methods of studying the brain several ways to study both structure and or function Many studies involving animals We know structure of all brains of all research animals Some indiv differences Animal brain atlases Often create lesions to see if this brings about a particular behavior Use stereotaxis instrument for each specific animals o Bregma point on skull where coronal suture is intersected perpendicularly by the coronal suture o Use numbers on ruler to see which part of the brain you want to test o Has an electrode Turn it on and generates current Destroys brain tissue o Can t do this in people Every single time you do an experiment need to include sham control group Only diff between experimental group and sham is at the very end when you turn the current on Anesthetize animal Shave scalp Cut open Drill hole in skull for needle insertion Go to atlas and find hypothalamus number wise Go to that point like a coordinate Needle lowered into hypothalamus Turn on current It will lesion hypothalamus localized to specific