This is one of the core projects and interests of the lab: how do ascending inputs from the rest of the brain affect the operations of early olfactory circuitry?
In particular:
- How do neuromodulatory chemicals, released into the olfactory system, alter the functional circuitry of the system?
- How does contextual information (from ventral hippocampus, via anterior olfactory nucleus) transform odor representations?
- How does the olfactory system respond to dynamic environmental conditions and constraints?
The first two central structures of the olfactory system – the olfactory bulb (OB) and piriform cortex – both are innervated by a common basal forebrain cholinergic nucleus that projects almost exclusively to olfactory structures: the horizontal limb of the diagonal band of Broca (HDB). How, mechanistically speaking, does the cholinergic modulation of multiple classes of acetylcholine-sensitive neurons embedded within the circuitry of these two linked structures combine to generate coherent functional outcomes at a systems/behavioral level of analysis? Conversely, in what behavioral contexts is the HDB normally activated so as to release acetylcholine into the OB and piriform cortex? We are studying both of these problems using behavioral pharmacology, in vivo recordings, slice recordings on planar multielectrode arrays, and computational modeling.
Parallel projects in the lab are asking analogous questions of noradrenergic and serotonergic neuromodulation in olfactory bulb.
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- Cholinergic modulation of perceptual acuity
- Muscarinic cholinergic regulation of intrinsic learning
- Recordings from the HDB during awake/behaving task performance
- Noradrenergic regulation of signal-to-noise ratios, and of intrinsic learning
- Serotonergic effects in adult olfactory bulb
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In another set of projects, we are investigating the integration of spatial context information into the secondary olfactory representation, via the ventral hippocampus and the anterior olfactory nucleus.
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- Contextual transformation of odor representations in olfactory bulb and anterior olfactory nucleus
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Finally, neural systems are, as a rule, highly responsive to environmental parameters, situational constraints, and the state of the organism’s knowledge of the world. One could argue, in fact, that this environmental responsiveness is the central point of their existence. We use the olfactory system as a model for understanding the adaptive response of functioning neural circuits to experimentally controllable environmental and experiential factors, such as:
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- Stress
- Environmental and olfactory enrichment
- Hunger/satiation
- Task dependence; task parameters; behavioral demands; strategy shifts
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