Midterm 1

1. Midterm 1 Wednesday next week!

2. Synthesize the Big Picture

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 • Local anesthetic, other drugs • 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 (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) 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/Knock-In (Transgenics) • can selectively block/enhance expression • Viral vectors, electroporation • animal develops differently • Can have temporal/regional/molecular specificity

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

18. Lesion Studies • Making sense of Lesion studies

19. 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

20. Lesion Studies • Designing Lesion Studies • “design tasks that diagnose the function of specific operations” • First, use a control group Lesion X Healthy Performance (e.g. accuracy, speed, etc.) This difference indicates deficit A Task (e.g. memory task, perception task, etc.)

21. Lesion Studies • Designing Lesion Studies • “design tasks that diagnose the function of specific operations” • First, use a control group Lesion X BUT maybe this is just a general deficit or a consequence of having a ANY brain damage Healthy Performance (e.g. accuracy, speed, etc.) A Task (e.g. memory task, perception task, etc.)

22. Lesion Studies • Designing Lesion Studies • “design tasks that diagnose the function of specific operations” • Consider another lesion group Lesion X Lesion Y Performance (e.g. accuracy, speed, etc.) Healthy A Task (e.g. memory task, perception task, etc.)

23. Lesion Studies • Designing Lesion Studies • “design tasks that diagnose the function of specific operations” • X marks the double dissociation Lesion X Lesion Y Performance (e.g. accuracy, speed, etc.) Healthy A Task (e.g. memory task, perception task, etc.)

24. Your Research Proposal Project • A research proposal attempts to persuade the reader that: • The underlying question is highly important • The proposed methodology and experimental design is the best available approach • That you have the knowledge and talent to do the proposed research • That you have a research program worth funding L

25. Your Research Proposal Project • A research proposal is therefore similar to many other situations in which you will try to persuade someone of something • The skill is portable L

26. Your Research Proposal Project • As in other situations, your reader should be assumed to be unconvinced and thus unwilling to spend much time and energy entertaining your argument! • You must make your argument easy and fast • The key to that is organization L

27. Research Proposals Should be “Theory Driven” • Most proposals are organized around a specific theory • What is the difference between a theory and a question? L

28. The Parts of a Research Proposal • Background • Statement of the theory • Prediction(s) that follow from the theory • Experimental Method and Design • Timeline • Budget • References L

29. The Parts of a Research Proposal • Background • Statement of the theory • Prediction(s) that follow from the theory • Experimental Method and Design • Timeline • Budget • References These aren’t necessary for your project L

30. Assignment • Rules: • Must be human Cognitive Neuroscience • Experimental approach may involve animal research only if this is the best way to test your theory • Studying humans is preferable to studying animals when you have a specific theory about human cognition • One moves to animal research because it tells you something that human research cannot • If this applies to your theory, you will make this constraint explicit in your proposal L