Assignment

1. Assignment • Rules: • Must be Human Cognitive Neuroscience • Experimental approach may involve animal research only if this is the best way to test your theory • Your mindset should be that studying humans is preferable to studying animals when you have a specific theory about Human cognition • One moves to animal research because of some insurmountable constraint on Human research • If this applies to your theory, you will make this constrain explicit in your proposal L

2. Methods of Cognitive Neuroscience

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

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

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

6. 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

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

8. Lesion Studies • Animal Lesion Techniques • Reversible Lesions • Cooling • highly selective • can cool specific layers of cortex • can be reversed!

9. 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)

10. Lesion Studies • Animal Lesion Techniques • Gene Knock-Out • can selectively block expression of specific receptor types • animal developes differently

11. 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

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

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

14. 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

15. Lesion Studies • Making sense of Lesion studies

16. Lesion Studies • Why are there only certain kinds of deficits associated with lesions? Why not every possible deficit?

17. 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