1 / 46

Methods of Cognitive Neuroscience

Methods of Cognitive Neuroscience. Lesion Studies. Logic of Lesion Studies: damaged area plays a role in accomplishing whatever task is deficient after the lesion. Lesion Studies. Types of Lesions Animal Human. Lesion Studies. Animal Lesion Techniques Aspiration Lesions

asta
Télécharger la présentation

Methods of Cognitive Neuroscience

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Methods of Cognitive Neuroscience

  2. Lesion Studies • Logic of Lesion Studies: • damaged area plays a role in accomplishing whatever task is deficient after the lesion

  3. Lesion Studies • Types of Lesions • Animal • Human

  4. Lesion Studies • Animal Lesion Techniques • Aspiration Lesions • Electrolytic Lesions

  5. 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

  6. Lesion Studies • Animal Lesion Techniques • Vascular Lesions • endothelin-1 • good model of human stroke • severe damage • not pinpoint accuracy

  7. Lesion Studies • Animal Lesion Techniques • Reversible Lesions • cooling • Local anesthetic, other drugs • highly selective • can cool specific layers of cortex • can be reversed!

  8. 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 Parkinson’s 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)

  9. 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

  10. 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

  11. Lesion Studies • Human Lesions • Trauma • Frontal lobes are particularly susceptible • Some famous cases (e.g. Phineas Gage)

  12. Lesion Studies • Human Lesions • Surgery • Often surgery done to treat epilepsy • Occasionally corpus callosum is severed • Problem: patient wasn’t “normal” before the surgery

  13. 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

  14. Lesion Studies • Making sense of Lesion studies

  15. Lesion Studies • Logic of Lesion Studies: • damaged area plays a role in accomplishing whatever task is deficient after the lesion • Warning: • This isn’t 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

  16. Lesion Studies • Designing Lesion Studies • “design tasks that diagnose the function of specific operations” • First, use a control condition Lesion X Performance A Task

  17. Lesion Studies • Designing Lesion Studies • “design tasks that diagnose the function of specific operations” • First, use a control condition Lesion X Healthy Performance A Task

  18. Lesion Studies • Designing Lesion Studies • “design tasks that diagnose the function of specific operations” • First, use a control condition Lesion X Healthy Performance This difference indicates deficit A Task

  19. Lesion Studies • Designing Lesion Studies • “design tasks that diagnose the function of specific operations” • But maybe this is a general deficit! - use 2nd task Lesion X Healthy Performance This difference indicates deficit A Task

  20. Lesion Studies • Designing Lesion Studies • “design tasks that diagnose the function of specific operations” • But maybe this is a general deficit! - use 2nd task Lesion X Healthy Performance A B Task

  21. Lesion Studies • Designing Lesion Studies • “design tasks that diagnose the function of specific operations” • But maybe this is a general deficit! - use 2nd task Lesion X Healthy Performance indicates that deficit is selective A B Task

  22. Lesion Studies • Designing Lesion Studies • “design tasks that diagnose the function of specific operations” • This result is called a single dissociation Lesion X Healthy Performance indicates that deficit is selective A B Task

  23. 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 Lesion X Healthy Performance Lesion Y A B Task

  24. Lesion Studies • Designing Lesion Studies • “design tasks that diagnose the function of specific operations” • This result is a double dissociation Lesion X Healthy Performance Lesion Y Interaction suggests two lesions have specific and independent deficits A B Task

More Related