Prof. Greg Francis 5/23/08

Transcription

1 Brain parts The brain IIE 269: Cognitive Psychology Greg Francis Lecture 02 The source of cognition (consider transplant!) Weighs about 3 pounds Damage to some parts result in immediate death or disability Damage to other parts seems to have no effect! What s the deal with left and right brains? What brain parts are important to cognition? How do we discover the role of each brain part? The brain The brain cortex Hind-brain brain stem) Hind-brain (brain stem) Hypothalamus (appetite, thirst, temperature, hormones) Limbic Lobe (sexual behavior, emotional behavior, memory) Thalamus (sensory gateway, except smell) Cerebellum (muscle control, learning) crumpled newspaper page Grooves (fissures or sulci) separate regions crumpled newspaper page Grooves (fissures or sulci) separate regions Central Sulcus Central Sulcus 1

2 crumpled newspaper page crumpled newspaper page Grooves (fissures or sulci) separate regions Grooves (fissures or sulci) separate regions Central Sulcus Central Sulcus Contralateral processing Processing in the brain is done on the opposite side of your organs Control of your right arm is from the left side of your brain Information from your left field of view goes to the right side of your brain Contralateral processing Neural fibers from eye cross on way to cortex Contralateral processing Cut corpus collasum Brain hemispheres connected by a mass of neural fibers called the corpus collasum Behavior changes very little Subtle effects 2

3 If nut flashes on left screen subject cannot name it subject can pick up nut with left hand If nut flashes on right side subject can name it subject cannot pick up nut with left hand until he says nut out loud Brain sides Brain sides Results led to further study and common belief Left side: language, analytical, classification, Western rationalization Right side: art, music, recognition of faces and shapes, Eastern mysticism Vast oversimplification in a normal brain, both sides are involved in many tasks Results do support the idea that different parts of the brain are involved in different cognitive tasks (modularity hypothesis) Nobel Prize! In the experiment Brain asymmetry You saw a pair of chimeric faces and were asked to choose which one looked younger Chimeric faces The faces were made by taking a normal face and an artificially aged face Chimeric faces Take opposite halves of the faces Chimeric faces Put them together, and make the other face by flipping it Thus, both faces are mirror images, they contain the same information 3

4 If you stare at the middle of face, the information on the left goes to the right hemisphere which is supposed to be better able to deal with face information than the left hemisphere So the information on the left side of the face should dominate the face decision This face should look relatively young If you stare at the middle of face, the information on the left goes to the right hemisphere which is supposed to be better able to deal with face information than the left hemisphere So the information on the left side of the face should dominate the face decision This face should look relatively old So, we would expect people with brain asymmetries would usually choose as younger, the face that has the younger half on the left side Left handed people typically do not show as much brain asymmetry effects as right handed people Thus, we can look for differences between left and right handed people We expect right handed people to select the face with the younger image on the left more often than left handed people Here is the data average for the class 132 right handed people 17 left handed people Left handed Right handed Percentage of choices with younger face on left Here is data from everyone who has done the lab 6381 right handed people and 662 left handed people Not what we expected! Left handed Right handed Percentage of choices with younger face on left Anatomy The cortex contains large fissures that separate five major areas Limbic (already discussed) Occipital Parietal Temporal Frontal Each has distinct properties 4

5 Occipital lobe Parietal lobe Primary visual area (V1) Receives information from Sensations of pain, temperature, touch, pressure the eye Most investigated area of the brain Primary sensory area Parietal lobe Temporal lobe Primary sensory area sensitivity involves disproportionate areas of the brain, relative to size of body part Hearing speech (left) music (right) Memory and attention visual recognition Frontal lobe Brain structure Largest part of cortex Divide lobes into areas» layers planning e.g. Broadman prediction Area 1, Area 12, Area 200 motor area speech area Can partly identify function by looking at nerves coming in and out of area 5

6 Monkey cortex is similar to human cortex in general structure Broadman s areas Area specificity Seems to be separation of functional aspects e.g., for visual perception Motion binocular MST MT Recognition? Orientation binocular V2 IT V4 Color V1 Orientation Color binocular There is order and function even within an area The cortex is a sheet of neurons In its thickness are 6 layers of neurons numbered 1-6 sometimes include subdivisions (4a, 4b, 4cα, 4cβ, ) Brain layers Conclusions Lots of research in this area New brain regions are being mapped out daily with ever increasing resolution Cognitive neuroscience relies strongly on the modularity hypothesis Putting everything together is very difficult Brain scans EEG recordings MRI scans PET scans Functional MRI Next time How to study the brain without killing someone. 6