Midterm 1 Wednesday next week!
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Midterm 1
Wednesday next week!
Synthesize the Big Picture
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– Electrolytic Lesions
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
Lesion Studies
• Animal Lesion Techniques– Vascular Lesions
• endothelin-1• good model of human stroke• severe damage• not pinpoint accuracy
Lesion Studies
• Animal Lesion Techniques– Reversible Lesions
• cooling• Local anesthetic, other drugs• highly selective• can cool specific layers of cortex• can be reversed!
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)
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
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
Lesion Studies
• Human Lesions– Trauma
• Frontal lobes are particularly susceptible
• Some famous cases (e.g. Phineas Gage)
Lesion Studies
• Human Lesions– Surgery
• Often surgery done to treat epilepsy• Occasionally corpus callosum is severed
• Problem: patient wasn’t “normal” before the surgery
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
Lesion Studies
• Making sense of Lesion studies
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
Lesion Studies
• Designing Lesion Studies– “design tasks that diagnose the function of
specific operations”– First, use a control group
Performance(e.g. accuracy, speed, etc.)
Task (e.g. memory task, perception task, etc.)A
Lesion X
HealthyThis difference indicates deficit
Lesion Studies
• Designing Lesion Studies– “design tasks that diagnose the function of
specific operations”– First, use a control group
Performance(e.g. accuracy, speed, etc.)
Task (e.g. memory task, perception task, etc.)A
Lesion X
Healthy
BUT maybe this is just a general deficit or a consequence of having a ANY brain damage
Lesion Studies
• Designing Lesion Studies– “design tasks that diagnose the function of
specific operations”– Consider another lesion group
Performance(e.g. accuracy, speed, etc.)
Task (e.g. memory task, perception task, etc.)A
Lesion X
Healthy
Lesion Y
Lesion Studies
• Designing Lesion Studies– “design tasks that diagnose the function of
specific operations”– X marks the double dissociation
Performance(e.g. accuracy, speed, etc.)
Task (e.g. memory task, perception task, etc.)A
Lesion X
Healthy
Lesion Y
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
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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
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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 organizationL
Research Proposals Should be “Theory Driven”
• Most proposals are organized around a specific theory
• What is the difference between a theory and a question?
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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
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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
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These aren’t necessary for your project
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
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