Basic Research – Physiology & Pharmacology

Driven by anatomical data, prior literature, models, and thought experiments, we develop hypotheses about how neuromodulatory signaling interacts with local brain circuits. We test those models in behaving animals using electrophysiological and psychophysical measures as a readout of circuit activity, and task engagement and pharmacological manipulations to achieve causal control.

Current projects in the lab make use of:

Linear electrode arrays to record single- and multi-unit activity, and field potentials generated by neurons across the layers of cortex.
Pressure ejection and retrodialysis for drug delivery at different spatial and temporal scales.
Passive viewing to explore modifications to basic visual receptive field properties by neuromodulators.
Detection and discrimination tasks to ascertain the perceptual consequences of changes to receptive field tuning and other basic response properties of visual cortical neurons.

Control of local circuit computations

Control of communication between circuits

Regulatory control of neuromodulation

Neuromodulators modify processing by local circuits in ways that enable computational flexibility on fast timescales.

We study the means by which that flexibility is conferred by investigating modulator-induced changes in neural responses in the primary visual cortex, V1.

Questions we're currently working on in this domain include:

- In what ways does serotonin modify the gain of visual responses in the layers of V1 that receive ascending input from the thalamus?
- To what extent, and in what form, do gain changes induced by acetylcholine and serotonin acting at the input layer propagate through the V1 circuit?
- Under what circumstances do these gain changes modify perception?
- Are there differences in the ways that neuromodulators target the magnocellular and parvocellular visual pathways in V1?

Anatomical data show us that receptors for modulatory molecules are often expressed on the mid- and long-range axons that mediate communication between neural circuits. This localization affords neuromodulatory systems the capacity to regulate the balance of inputs (for example data from the eyes versus prior knowledge about the statistical properties of the visual world) that support circuit computations.

Understanding the ways activating modulatory receptors on long range axons alters the outcome of processing in the primary visual cortex is another key goal for the work in our lab.

Some of the questions we are interested in addressing include:

- When receptors for multiple modulators are activated on the same axons/ pathway, how are those modulatory signals integrated?
- (How) does activating modulatory receptors on feedforward pathways into V1 alter perception?
- Can understanding the functional effects of modulating of feedback axons into V1 teach us something about the role of feedback in vision more broadly?
- Is V1 special in the ways that input control is exerted on it by neuromodulators? Or are there general principles to be learned from this circuit?

While we often consider modulatory systems in insolation, in reality at any given moment multiple modulatory molecules are active in any circuit.

In addition to studying the ways that the cortical circuit integrates those signals we are also interested in the extent to which modulatory systems 'talk' to each other to achieve regulatory control of the net neuromodulation exerted upon a circuit.

Questions we're interested in this domain include:

- By what mechanisms to modulatory systems regulate themselves?
- By what mechanisms to modulatory systems regulate each other?
- Does local circuit activity regulate neuromodulator release?

Basic Research – Physiology & Pharmacology

Physiology and Pharmacology

Current Projects

Comparative Anatomy

Neurochemistry

Alzheimer's Disease