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Mapping Prefrontal Cortex Inputs to the Olfactory Cortex

Estelle in 't Zandt

Authors:  Estelle E. in ‘t Zandt, Hillary L. Cansler, Daniel W. Wesson

Faculty Mentor: Daniel W. Wesson

College:  College of Medicine

Abstract

The brain is constantly bombarded by sensory information from the environment. To perform any cognitive task, selective attention is required to filter these stimuli and focus only on pertinent information. The medial prefrontal cortex (mPFC) is crucial for selective attention, but how this works in the olfactory system is unknown. Because odor information in the olfactory tubercle is modulated by attention, we mapped mPFC inputs to the OT to refine our understanding of this network’s potential role in olfactory attention. We injected rats (n=3) with two viruses encoding red or green fluorophores tagged to the synaptic protein synaptophysin into two subdivisions of the mPFC, the prelimbic (PrL) and infralimbic (IL) cortices. We examined the distribution of green- versus red-synaptophysin in the OT to determine which regions receive input from the PrL and/or the IL. Interestingly, we found that the medial OT receives more input from the PrL and IL than the lateral OT. Further analysis will examine mPFC inputs to another olfactory cortex, the piriform cortex, whose role in olfactory attention is unclear. These results highlight the potential significance of the medial OT for olfactory attention and will guide future work investigating the functional significance of this pathway.

Poster Pitch

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Poster

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15 Responses
  5. Madeline Olesky

    Hi Estelle, I really liked your presentation! Do you have any hypotheses on why these differences in connectivity exist?

  7. Estelle in 't Zandt

    Hi Maddie! The PrL and IL have different specific functions for selective attention (for example, the PrL is more involved in context-dependent attention). At the same time, different regions of the OT and PCX also have different functions. So if the IL is projecting more to the medial OT than other areas, it’s likely that the activity in the IL is what is specifically regulating attention-based encoding in the medial OT. All of this would have to be tested with physiological/behavioral studies though!

  8. Alex Angerhofer

    Interesting work, good job presenting it. It wasn’t clear to me what the injected virus particle do. Are they spreading along neurons? What are the pigments they encode?

  9. Marta L. Wayne

    Congratulations indeed! I can easily see why you were a winner. Great job on video and poster both.

  11. Estelle in 't Zandt

    Dr. Angerhofer – The virus encodes a protein called synaptophysin tagged to a fluorophore. Synaptophysin is expressed naturally in neurons and is involved in the release of synaptic vesicles. The difference is that the virally-encoded synaptophysin has an attached GFP or Ruby fluorophore which causes the red or green fluorescence seen in the images. When a virus infects a neuron’s cell body, it is expressed and the synaptophysin-fluorophore product is naturally transported to the synaptic terminal just as a non-tagged synaptophysin protein would be.

  13. Alara Guvenli

    Nice job Estelle, this is so interesting! Were you surprised by the results that themedial OT receives more inputs than the lateral OT dependent?

  14. Estelle in 't Zandt

    Hi Alara! We had previously injected retrograde viruses into the medial OT and seen many PrL and IL neurons labeled, so we knew medial OT received input from PrL and IL. Here, we learned that medial OT input was significantly denser than lateral OT input, which we didn’t know before! We were also surprised by the large contrast between the OT and PCX, since the PCX is a prominent component of the olfactory cortex in both size and function. These data really nicely show that the OT is perhaps much more important for olfactory attention than the PCX.