Representational drift in primary olfactory cortex

Schoonover, Carl E.; Ohashi, Sarah N; Axel, Richard; Fink, Andrew J. P.

doi:10.1038/s41586-021-03628-7

Cited by 229 publications

(232 citation statements)

References 72 publications

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“…Finally, in the control experiments for the DREADD suppression of SLs, we noticed that PYR responses seemed to change more with time and/or stimulus presentation than SL responses. This result is consistent with an activity-dependent sculpting of recurrent connectivity so that PYR responses evolve while SL responses continue to faithfully represent the stimulus ( Jacobson et al, 2018 ; Bolding et al, 2020 ; Pashkovski et al, 2020 ; Schoonover et al, 2021 ).…”

Section: Discussionsupporting

confidence: 85%

Parallel processing by distinct classes of principal neurons in the olfactory cortex

Nagappan

Franks

2021

eLife

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Understanding how distinct neuron types in a neural circuit process and propagate information is essential for understanding what the circuit does and how it does it. The olfactory (piriform, PCx) cortex contains two main types of principal neurons, semilunar (SL) and superficial pyramidal (PYR) cells. SLs and PYRs have distinct morphologies, local connectivity, biophysical properties, and downstream projection targets. Odor processing in PCx is thought to occur in two sequential stages. First, SLs receive and integrate olfactory bulb input and then PYRs receive, transform, and transmit SL input. To test this model, we recorded from populations of optogenetically identified SLs and PYRs in awake, head-fixed mice. Notably, silencing SLs did not alter PYR odor responses, and SLs and PYRs exhibited differences in odor tuning properties and response discriminability that were consistent with their distinct embeddings within a sensory-associative cortex. Our results therefore suggest that SLs and PYRs form parallel channels for differentially processing odor information in and through PCx.

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Section: Discussionsupporting

confidence: 85%

Parallel processing by distinct classes of principal neurons in the olfactory cortex

Nagappan

Franks

2021

eLife

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“…Finally, in the control experiments for the DREADD suppression of SLs, we noticed that PYR responses changed more with time and/or stimulus presentation than SL responses. This result is consistent with an activity-dependent sculpting of recurrent connectivity so that PYR responses evolve while SL responses continue to faithfully represent the stimulus (Bolding et al, 2020; Jacobson et al, 2018; Pashkovski et al, 2020; Schoonover et al, 2021).…”

Section: Discussionsupporting

confidence: 85%

Parallel processing by distinct classes of principal neurons in the olfactory cortex

Nagappan

Franks

2021

Preprint

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Understanding the specific roles that different neuron types play within a neural circuit is essential for understanding what that circuit does and how it does it. The primary olfactory (piriform, PCx) cortex contains two main types of principal neurons: semilunar (SL) and pyramidal (PYR). SLs and PYRs have different morphologies, connectivity, biophysical properties, and downstream projections, predicting distinct roles in cortical odor processing. The prevailing model is that odor processing in PCx occurs in two stages, where SLs are the primary recipients of olfactory bulb (OB) input, and PYRs receive and transform information from SLs. Here we recorded from optogenetically-identified SLs and PYRs in awake, head-fixed mice. We found differences in SL and PYR odor-evoked activity that reflect their different connectivity profiles. But SL responses did not precede PYR responses and suppressing SL activity had little effect on PYR odor responses. These results suggest that SLs and PYRs form parallel odor processing channels.

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“…The representation encoding of odors and space in piriform illustrates that abstract cognitive variables can be prominently encoded by sensory regions outside of the canonical circuits for spatial cognition. It is likely that the posterior piriform cortex may serve as an odor-driven learning system 71 more akin to the hippocampus than to canonical primary sensory cortices, possessing computational and circuit properties of both sensory and learning systems. We posit that our work provides a new avenue of inquiry on the fundamental question of how sensory information is combined with cognitive maps in the brain to guide flexible behaviors.…”

Section: Discussionmentioning

confidence: 99%

Spatial maps in piriform cortex during olfactory navigation

Poo

Agarwal

Bonacchi

et al. 2020

Preprint

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Animals rely on chemical signals to forage for food, shelter, and mates. Such behaviors call for odor cues to be linked to locations within their environment . Nonetheless, where and how this happens in the brain is not known. Here, we show that spatial and olfactory information converge in posterior piriform cortex (pPCx), an olfactory region with strong associative circuity.Ensembles of pPCx neurons recorded in rats performing an odor-cued spatial navigation task were robustly selective for both odor identity and spatial location, forming an "odor-place map".Spatially-selective pPCx neurons displayed joint selectivity for odors, stability across behavioral contexts and functional coupling to the hippocampal theta rhythm. These results implicate the pPCx as a strong candidate region to associate spatial and olfactory information in support of navigational behavior. Main Text:Navigation requires the flexible integration of sensory information with a cognitive map of the environment ( 1 ) . The hippocampal formation and the primary olfactory (piriform) cortex (PCx) are believed to be dedicated to spatial navigation and olfactory discrimination, respectively ( 2 -8 ) . PCx neurons receive direct sensory input from olfactory bulb (OB) projection neurons ( 9 , 10 ) , but also contain dense recurrent olfactory circuitry and receive long-range corticocortical input from regions including the frontal cortex and temporal lobe ( 11 , 12 ) , including the hippocampus and the lateral entorhinal cortex (LEC) ( 12 -15 ) . C omputational modeling suggests that PCx neural architecture is well-suited to perform associative functions ( 16 -18 ) , which is supported by evidence for odor recognition and memory in PCx ( 19 -22 ) .While these properties of PCx make it a strong candidate to associate odor and spatial information, there is yet no physiological evidence for spatial representations here. To investigate, we developed a novel odor-cued spatial task that challenged rats to use spatial information along with odor identity to navigate to a specific location for reward. We recorded from the posterior PCx (pPCx) and area CA1 of the hippocampus in rats performing this task.We focused on pPCx due to the relative preponderance of associative circuits and connectivity to higher-order regions that have been found there ( 12 , 21 -24 ) . Our behavioral arena consisted of an elevated plus-maze with a 1 square meter footprint that was positioned in a room with visual landmarks ( Fig. 1A and supplementary video ). At the end of each arm was a port, each of which could deliver either an odor stimulus or a water reward.Trials began when an LED was activated at one of the four ports. If the rat inserted its snout into the lighted port, it received one of four odors chosen at random. Each odor could be presented at any one of the four possible initiation ports and, no matter where it was presented, it indicated a fixed reward location (e.g. odor 1 the north, odor 2 to the south, etc.) ( Fig. 1A, B ).After sampling the odor, the animal cou...

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Representational drift in primary olfactory cortex

Cited by 229 publications

References 72 publications

Parallel processing by distinct classes of principal neurons in the olfactory cortex

Parallel processing by distinct classes of principal neurons in the olfactory cortex

Parallel processing by distinct classes of principal neurons in the olfactory cortex

Spatial maps in piriform cortex during olfactory navigation

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