Methods of Cognitive Neuroscience

Download Methods of Cognitive Neuroscience

Post on 29-Mar-2015

219 views

Category:

Documents

5 download

Embed Size (px)

TRANSCRIPT

  • Slide 1

Methods of Cognitive Neuroscience Slide 2 Slide 3 Slide 4 Slide 5 Slide 6 Slide 7 Slide 8 Slide 9 Slide 10 Slide 11 Slide 12 Slide 13 Lesion Studies Logic of Lesion Studies: damaged area plays a role in accomplishing whatever task is deficient after the lesion Slide 14 Lesion Studies Types of Lesions Animal Human Slide 15 Slide 16 Lesion Studies Animal Lesion Techniques Aspiration Lesions Electrolytic Lesions Slide 17 Lesion Studies Animal Lesion Techniques Aspiration Lesions Electrolytic Lesions Problems: These can damage surrounding tissue - especially white matter tracts nearby (fibers of passage) Irreversible eventual degradation of connected areas Slide 18 Lesion Studies Animal Lesion Techniques Vascular Lesions endothelin-1 good model of human stroke severe damage not pinpoint accuracy Slide 19 Lesion Studies Animal Lesion Techniques Reversible Lesions cooling Local anesthetic, other drugs highly selective can cool specific layers of cortex can be reversed! Slide 20 Lesion Studies Animal Lesion Techniques Selective Pharmacological lesions damage or destroy entire pathways that have a specific sensitivity to a particular chemical e.g. MPTP model of Parkinsons Disease (frozen addicts) e.g. scapolomine - acetylcholine antagonist - temporary amnesia Can be selective for specific circuits but not for specific brain areas can be reversible in some cases (e.g. scopolamine, but not MPTP) Slide 21 Lesion Studies Animal Lesion Techniques Gene Knock-Out/Knock-In (Transgenics) can selectively block/enhance expression Viral vectors, electroporation animal develops differently Can have temporal/regional/molecular specificity Slide 22 Lesion Studies Human Lesions Ischemic Events Stroke and Hemorrhage: typically due to blood clot or hemorrhage size of lesion depends on where clot gets lodged amount of damage depends on how long clot remains lodged Slide 23 Lesion Studies Human Lesions Trauma Frontal lobes are particularly susceptible Some famous cases (e.g. Phineas Gage) Slide 24 Lesion Studies Human Lesions Surgery Often surgery done to treat epilepsy Occasionally corpus callosum is severed Problem: patient wasnt normal before the surgery Slide 25 Lesion Studies Human Lesions Transcranial Magnetic Stimulation Electromagnet Induces current in the brain very transient, very focal reversible lesion Believed to be safe sites that can be studied are limited by the geometry of the head Slide 26 Slide 27 Slide 28 Slide 29 Slide 30 Slide 31 Lesion Studies Making sense of Lesion studies Slide 32 Lesion Studies Logic of Lesion Studies: damaged area plays a role in accomplishing whatever task is deficient after the lesion Warning: This isnt the same as saying the lesioned area does the operation in question examples: normal behaviour may be altered to accommodate lesion e.g. sensory loss of one arm favors other arm lesion might cause upstream problem or general deficit e.g. attention problem looks like specific deficit if you only test one specific demanding task Slide 33 Lesion Studies Designing Lesion Studies design tasks that diagnose the function of specific operations First, use a control condition Performance Task A Lesion X Slide 34 Lesion Studies Designing Lesion Studies design tasks that diagnose the function of specific operations First, use a control condition Performance Task A Lesion X Healthy Slide 35 Lesion Studies Designing Lesion Studies design tasks that diagnose the function of specific operations First, use a control condition Performance Task A Lesion X Healthy This difference indicates deficit Slide 36 Lesion Studies Designing Lesion Studies design tasks that diagnose the function of specific operations But maybe this is a general deficit! - use 2nd task Performance Task A Lesion X Healthy This difference indicates deficit Slide 37 Lesion Studies Designing Lesion Studies design tasks that diagnose the function of specific operations But maybe this is a general deficit! - use 2nd task Performance Task A Lesion X Healthy B Slide 38 Lesion Studies Designing Lesion Studies design tasks that diagnose the function of specific operations But maybe this is a general deficit! - use 2nd task Performance Task A Lesion X Healthy B indicates that deficit is selective Slide 39 Lesion Studies Designing Lesion Studies design tasks that diagnose the function of specific operations This result is called a single dissociation Performance Task A Lesion X Healthy B indicates that deficit is selective Slide 40 Lesion Studies Designing Lesion Studies design tasks that diagnose the function of specific operations What if Task A is just harder than B? - add a 2nd group Performance Task A Lesion X Healthy B Lesion Y Slide 41 Lesion Studies Designing Lesion Studies design tasks that diagnose the function of specific operations This result is a double dissociation Performance Task A Lesion X Healthy B Lesion Y Interaction suggests two lesions have specific and independent deficits Slide 42 Slide 43 Slide 44 Slide 45 Slide 46