{"654189":{"#nid":"654189","#data":{"type":"event","title":"Learning and Forgetting in the Primary Olfactory Cortex","body":[{"value":"\u003Cp\u003E\u003Cstrong\u003EAndrew Fink, Ph.D. and Carl Schoonover, Ph.D.\u003C\/strong\u003E\u003Cbr \/\u003E\r\n\u003Cstrong\u003EDepartment of Neuroscience\u003Cbr \/\u003E\r\nColumbia University \/ Howard Hughes Medical Institute\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Ca href=\u0022https:\/\/bluejeans.com\/779689666\/5799\u0022\u003ELivestream via BlueJeans\u003C\/a\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EABSTRACT\u003C\/strong\u003E\u003Cbr \/\u003E\r\nWe have discovered that in the rodent primary olfactory cortex (piriform) the pattern of\u0026nbsp;neural activity evoked by a smell changes with the passage of time. These changes,\u0026nbsp;which unfold absent a task or learning paradigm, accumulate to such an extent that\u0026nbsp;after just a few weeks odor responses bear little resemblance to their original form. The\u0026nbsp;piriform has been traditionally hypothesized to establish the identity of odorants. Our\u0026nbsp;observations have forced us to radically reconsider the role of this vast brain region in\u0026nbsp;olfactory perception. We propose that the piriform operates instead as a flexible learning\u0026nbsp;system, a \u0026lsquo;scratch pad\u0026rsquo; that continually learns and continually overwrites itself. This\u0026nbsp;poses the problem of how transient memory traces can subsequently be stored over\u0026nbsp;long timescales.\u003Cbr \/\u003E\r\n\u003Cbr \/\u003E\r\nThese results also raise the question of what the piriform learns.\u0026nbsp;We have designed a\u0026nbsp;behavioral assay that provides a sensitive readout of whether mice expect a given\u0026nbsp;sensory event. Using this assay we have demonstrated that\u0026nbsp;mice learn the identity,\u0026nbsp;order and precise timing of elements in a sequence of neutral odorants, A--\u0026gt;B, without\u0026nbsp;reward or punishment.\u0026nbsp;Simultaneous recordings in\u0026nbsp;na\u0026iuml;ve\u0026nbsp;piriform\u0026nbsp;show strong and\u0026nbsp;distinct responses to both A and B.\u0026nbsp;These diminish with experience in a manner that\u0026nbsp;tracks these expectations: predictable cues, such as B in the A--\u0026gt;B sequence, evoke\u0026nbsp;hardly any response in experienced animals. This does not reflect simple adaptation.\u0026nbsp;When B is presented alone, it elicits robust activation. When B is omitted, and A is\u0026nbsp;presented alone, piriform exhibits vigorous activity at the precise moment when the\u0026nbsp;animal, expecting odor B, encounters nothing. Thus, when the external world conforms\u0026nbsp;to expectation, piriform is relatively quiescent, but any departure from the expected\u0026nbsp;results in vigorous activation. We hypothesize that the piriform learns to implement a\u0026nbsp;comparator that reports the difference between the world as it expects it and the world\u0026nbsp;as it is. The biological learning mechanisms that generate this predictive activity, a\u0026nbsp;feature more commonly encountered in higher order cortices, can be readily studied\u0026nbsp;and probed in a circuit only two synapses from the sensory periphery.\u003Cbr \/\u003E\r\n\u003Cbr \/\u003E\r\n\u003Cstrong\u003ESPEAKER BIOS\u003C\/strong\u003E\u003Cbr \/\u003E\r\nWe are postdoctoral fellows in Richard Axel\u0026rsquo;s laboratory at Columbia University, where\u0026nbsp;we carry out a shared research program. We seek to understand how organisms learn\u0026nbsp;continuously while also storing stable memories over their lifetimes. The rodent olfactory\u0026nbsp;system, an easily accessible, well-defined circuit whose input can be precisely\u0026nbsp;controlled, presents a relatively simple and tractable model to address these basic open\u0026nbsp;problems. We have established methods for long-term observation of\u0026nbsp;neurophysiological activity in the rodent primary olfactory cortex (piriform), and\u0026nbsp;developed naturalistic ethological behavioral paradigms to probe continuous learning.\u003Cbr \/\u003E\r\n\u003Cbr \/\u003E\r\nAs graduate students, Carl Schoonover (BA Philosophy, Harvard College) studied the\u0026nbsp;thalamocortical projection to primary somatosensory cortex under the supervision of Dr.\u0026nbsp;Randy Bruno, and Andrew Fink (BA Physics, Carleton College) studied spinal\u0026nbsp;presynaptic inhibition under the supervision of Dr. Thomas Jessell.\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EHost: Dr. Tim Cope\u003C\/p\u003E\r\n","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":"","field_summary_sentence":[{"value":"Biological Sciences Seminar by Drs. Andrew Fink and Carl Schoonover"}],"uid":"27964","created_gmt":"2022-01-09 17:57:05","changed_gmt":"2022-02-06 22:09:41","author":"Jasmine Martin","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2022-02-15T11:00:00-05:00","event_time_end":"2022-02-15T12:00:00-05:00","event_time_end_last":"2022-02-15T12:00:00-05:00","gmt_time_start":"2022-02-15 16:00:00","gmt_time_end":"2022-02-15 17:00:00","gmt_time_end_last":"2022-02-15 17:00:00","rrule":null,"timezone":"America\/New_York"},"extras":[],"groups":[{"id":"1275","name":"School of Biological Sciences"}],"categories":[],"keywords":[{"id":"189875","name":"Andrew Fink"},{"id":"189876","name":"Carl Schoonover"},{"id":"166882","name":"School of Biological Sciences"},{"id":"166892","name":"School of Biological Sciences Seminar"},{"id":"172234","name":"Timothy Cope"},{"id":"174814","name":"Tim Cope"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[{"id":"1795","name":"Seminar\/Lecture\/Colloquium"}],"invited_audience":[{"id":"78761","name":"Faculty\/Staff"},{"id":"177814","name":"Postdoc"},{"id":"174045","name":"Graduate students"},{"id":"78751","name":"Undergraduate students"}],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[],"email":[],"slides":[],"orientation":[],"userdata":""}}}