The Event-Related Potential (ERP)

The Event-Related Potential (ERP) • We have an ERP waveform for every electrode

The Event-Related Potential (ERP) • We have an ERP waveform for every electrode • Sometimes that isn’t very useful

The Event-Related Potential (ERP) • We have an ERP waveform for every electrode • Sometimes that isn’t very useful • Sometimes we want to know the overall pattern of potentials across the head surface • isopotential map

The Event-Related Potential (ERP) • We have an ERP waveform for every electrode • Sometimes that isn’t very useful • Sometimes we want to know the overall pattern of potentials across the head surface • isopotential map Sometimes that isn’t very useful - we want to know the generator source in 3D

Brain Electrical Source Analysis • Given this pattern on the scalp, can you guess where the current generator was?

Brain Electrical Source Analysis • Given this pattern on the scalp, can you guess where the current generator was? Duracell

Brain Electrical Source Analysis • Source Analysis models neural activity as one or more equivalent current dipoles inside a head-shaped volume with some set of electrical characteristics

Brain Electrical Source Analysis Project “Forward Solution” This is most likely location of dipole Compare to actual data

Brain Electrical Source Analysis • EEG data can now be coregistered with high-resolution MRI image

Intracranial and “single” Unit • Single or multiple electrodes are inserted into the brain • “chronic” implant may be left in place for long periods

Intracranial and “single” Unit • Single electrodes may pick up action potentials from a single cell • An electrode may pick up thecombined activity from several nearby cells • spike-sorting attempts to isolate individual cells

Intracranial and “single” Unit • Simultaneous recording from many electrodes allows recording of multiple cells

Intracranial and “single” Unit • Output of unit recordings is often depicted as a “spike train” and measured in spikes/second Stimulus on Spikes

Intracranial and “single” Unit • Output of unit recordings is often depicted as a “spike train” and measured in spikes/second • Spike rate is almost never zero, even without sensory input • in visual cortex this gives rise to “cortical grey” Stimulus on Spikes

Intracranial and “single” Unit • By carefully associating changes in spike rate with sensory stimuli or cognitive task, one can map the functional circuitry of one or more brain regions • What are the advantages and limitations of this approach?

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

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

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

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

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

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

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

The Event-Related Potential (ERP)