All events, All years

Technologies for all-optical interrogation of neural circuits in behaving animalsTechnologies for all-optical interrogation of neural circuits in behaving animals

Lecture
Date:
Tuesday, May 25, 2021
Hour: 12:30
Location:
Dr. Adam Packer
|
Department of Physiology, Anatomy and Genetics University of Oxford, UK

Neural circuits display complex spatiotemporal patterns of activity on the millisecond timescale during behavior. Understanding how these activity patterns drive behavior is a fundamental problem in neuroscience, and remains a major challenge due to the complexity of their spatiotemporal dynamics. The ability to manipulate activity in genetically defined sets of neurons on the millisecond timescale using optogenetics has provided a powerful new tool for making causal links between neuronal activity and behavior. I will discuss novel approaches that combine simultaneous two-photon calcium imaging and two-photon targeted optogenetic photostimulation with the use of a spatial light modulator (SLM) to provide ‘all-optical’ readout and manipulation of the same neurons in vivo. This approach enables reading and writing of activity in neural circuits with single-cell resolution and single action potential precision during behavior. I will describe the power, limitations and future potential of this approach; and discuss how it can be used to address many important problems in neuroscience, including transforming our search for the neural code and the links between neural circuit activity and behavior. Zoom link to join- https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070

Neural mechanisms of aggression

Lecture
Date:
Tuesday, May 18, 2021
Hour: 15:00 - 16:00
Location:
Prof. Lin Dayu
|
Dept of Psychiatry, Neuroscience and Physiology New York University Grossman School of Medicine, USA

Aggression is an innate social behavior essential for competing for resources, securing mates, defending territory and protecting the safety of oneself and family. In the last decade, significant progress has been made towards an understanding of the neural circuit underlying aggression using a set of modern neuroscience tools. Here, I will talk about our recent progress in the study of aggression. Zoom link to join- https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070

Using Deep Nets to Understand Visual Recognition in Mind and Brain

Lecture
Date:
Tuesday, May 11, 2021
Hour: 15:00 - 16:00
Location:
Prof. Nancy Kanwisher
|
Dept of Neuroscience, Brain and Cognitive Sciences, McGovern Institute for Brain Research, MIT, USA

In this talk I will describe two ongoing lines of work from my lab that use deep nets to better understand visual recognition and its neural and computational basis in the brain, by testing precise computational models against fMRI data from the ventral visual pathway, and by providing clues into why face recognition works the way it does in the human mind and brain. Zoom link to join- https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070

Neuropixels probes - two stories about development and use

Lecture
Date:
Thursday, May 6, 2021
Hour: 12:30 - 13:30
Location:
Dr. Michael Okun
|
Department of Neuroscience, Psychology and Behaviour, University of Leicester, UK

The first part of the presentation will describe the Neuropixels 2.0 probe, focusing on its ability to stably record from the same neurons across days and weeks in chronically implanted mice. The second part will describe the effects of psychedelic and intrinsic brain state transitions on the firing rates of neuronal populations, as revealed by high count Neuropixels recordings. Zoom link: https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Prof. Ilan Lampl ilan.lampl@weizmann.ac.il tel: 3179

The Vagus Nerve and Physiology of Reward and Digestion

Lecture
Date:
Tuesday, May 4, 2021
Hour: 15:00
Location:
Prof. Ivan E de Araujo
|
Neuroscience Dept, Diabetes, Obesity and Metabolism Institute Icahn School of Medicine at Mount Sinai

The presentation will discuss recent evidence supporting a role for the gut-brain axis in controlling brain circuits involved in reward. It will be argued that sensory neurons of vagus nerve function as reward neurons. Via defined brainstem targets, vagal signals dopaminergic brain reward circuits in midbrain. The mapping of these circuits opens a window into how signals generated by internal body organs give rise to motivated and emotional behaviors. Zoom link to join- https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070

Neural correlates of future weight loss reveal a possible role for brain-gastric interactions

Lecture
Date:
Tuesday, April 27, 2021
Hour: 12:30 - 13:30
Location:
Prof. Galia Avidan
|
Dept of Psychology Ben Gurion University of the Negev

Lifestyle dietary interventions are an essential practice in treating obesity, hence neural factors that may assist in predicting individual treatment success are of great significance. Here, in a prospective, open-label, three arms study, we examined the correlation between brain resting-state functional connectivity measured at baseline and weight loss following 6 months of lifestyle intervention in 92 overweight participants. We report a robust subnetwork composed mainly of sensory and motor cortical regions, whose edges correlated with future weight loss. This effect was found regardless of intervention group. Importantly, this main finding was further corroborated using a stringent connectivity-based prediction model assessed with cross-validation thus attesting to its robustness. The engagement of senso-motor regions in this subnetwork is consistent with the over-sensitivity to food cues theory of weight regulation. Finally, we tested an additional hypothesis regarding the role of brain-gastric interaction in this subnetwork, considering recent findings of a cortical network synchronized with gastric activity. Accordingly, we found a significant spatial overlap with the subnetwork reported in the present study. Moreover, power in the gastric basal electric frequency within our reported subnetwork negatively correlated with future weight loss. This finding was specific to the weight loss related subnetwork and to the gastric basal frequency. These findings should be further corroborated by combining direct recordings of gastric activity in future studies. Taken together, these intriguing results may have important implications for our understanding of the etiology of obesity and the mechanism of response to dietary intervention as well as to interoceptive perception. Zoom link to join: https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070

New insights on continuous attractor neural networks

Lecture
Date:
Tuesday, April 20, 2021
Hour: 12:30
Location:
Prof. Yoram Burak
|
Racah Institute of Physics and Edmond and Lily Safra Center for Brain Sciences The Hebrew University of Jerusalem

One of the most fundamental concepts in theoretical neuroscience is that of an attractor neural network, in which recurrent synaptic connectivity constraints the joint activity of neurons into a highly restricted repertoire of population activity patterns. In continuous attractor networks, these activity patterns span a continuous, low-dimensional manifold. I will survey two recent works from my group that are related to this concept. The first work is concerned with fixational eye drifts, a form of eye motion that occurs between saccades and is characterized by smooth, yet random, diffusive-like motion. This motion is tiny compared to saccadic eye motion, yet it is highly consequential for high-acuity vision. Even though fixational drift has been identified at least as early as the 19th century, its mechanistic origins have remained completely unknown. We hypothesize that the main drive for fixational drifts arises in diffusive motion along a line-attractor memory network - the oculomotor network, which is responsible for maintaining a fixed activation of the ocular muscles between saccades. I will present evidence in support of this hypothesis, coming from electrophysiology in monkeys and from theoretical modeling. The second work is concerned with the ability of a single recurrent neural network to express activity patterns that span multiple yet distinct continuous manifolds, a question that has been of interest in the context of spatial coding, across multiple environments, in area CA3 of the hippocampus. Zoom link to join- https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070

Uncovering the Boundaries of Olfactory Perception

Lecture
Date:
Monday, April 19, 2021
Hour: 15:00 - 16:00
Location:
Aharon Ravia (PhD Thesis Defense)
|
Prof. Noam Sobel Lab, Dept of Neurobiology Prof. David Harel Lab, Dept of Computer Science and Applied Mathematics WIS

The question of how to measure a smell has troubled scientists for over a century. It was none other than Alexander Graham Bell that raised the challenge: "we have very many different kinds of smells, all the way from the odor of violets and roses up to asafoetida. But until you can measure their likenesses and differences you can have no science of odor”. Such a measure of smell can be naturally derived from a model of olfactory perceptual quality space, and several such models have recently been put forth. These typically rely on finding mathematical rules that link odorant structure to aspects of odor perception. Here, I collected 49,788 perceptual odor estimates from 199 participants, and built such a model, finalizing a physicochemical measure of smell. This measure, expressed in radians, predicts real-world odorant pairwise perceptual similarity from odorant structure alone. Using this measure, I met Bell's challenge by accurately predicting the perceptual similarity of rose, violet and asafoetida, from their physicochemical structure. Next, based on thousands of comparisons, I identified a cutoff in this measure, below 0.05 radians, where discrimination between pairs of mixtures becomes highly challenging. To assess the usefulness of this measure, I investigated whether it can be used to create olfactory metamers, namely non-overlapping molecular compositions that share a common percept. Characterizing the link between physical structure and ensuing perception in vision and audition, and the creation of perceptual entities such as metamers, was important towards understanding their underlying dimensionality, brain mechanisms, and towards their ultimate digitization. I suggest that olfactory metamers can similarly aid these goals in olfaction. Zoom link to join: https://weizmann.zoom.us/j/93360836031?pwd=dDZEdTQ1QUkxUVVONVErVm9CcUJWQT09 Meeting ID: 933 6083 6031 Password: 591230

Dissecting the functional organization of sensory neurons in gut-brain communication

Lecture
Date:
Tuesday, April 13, 2021
Hour: 12:30
Location:
Dr. Henning Fenselau
|
Max Planck Institute for Metabolism Research, Cologne, Germany

Sensory neurons relay gut-derived signals to the brain, and thereby contribute to systemic energy and glucose homeostasis regulation. However, the relevant sensory neuronal populations innervating the gut along with the pertaining underlying functional neurocircuits remain poorly understood. Advances in this field have been impeded by the challenges associated with targeting distinct sensory neurons of vagal and spinal origin in a cell-type-specific manner, thereby making the accurate determination of their function highly difficult. We employ a combinatorial set of modern molecular systems neuroscience tools and novel mouse genetic approaches to elucidate the role of molecularly defined sensory neurons in feeding behavior and glucose metabolism, and map their downstream neurocircuits in the brain. The overarching goal of our studies is to gain greater insights into the integral components of sensory neurons as gut-to-brain connectors in controlling metabolism. Zoom link to join- https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070

Cellular and circuit basis of distinct memory formation in the hippocampus

Lecture
Date:
Tuesday, April 6, 2021
Hour: 12:30
Location:
Dr. Christoph Schmidt-Hieber
|
Department of Neuroscience, Institut Pasteur, Paris

Formation and retrieval of distinct memories are complementary processes that put conflicting requirements on neuronal computations in the hippocampus, especially when memories closely resemble each other. How this challenge is resolved in hippocampal circuits to guide memory-based decisions is unclear. To address this question, our group uses in vivo 2-photon calcium imaging and whole-cell recordings from hippocampal subregions in head-fixed mice trained to distinguish between novel and familiar virtual-reality environments. We find that granule cells consistently show a small transient depolarization of their membrane potential upon transition to a novel environment. This synaptic novelty signal is sensitive to local application of atropine, indicating that it depends on metabotropic acetylcholine receptors. A computational model suggests that the observed transient synaptic response to novel environments leads to a bias in the granule cell population activity, which can in turn drive the downstream attractor networks to a new state, thereby favoring the switch from generalization to discrimination when faced with novelty. Such a novelty-driven cholinergic switch may enable flexible encoding of new memories while preserving stable retrieval of familiar ones. zoom link to join-https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070

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All events, All years

Neural mechanisms of aggression

Lecture
Date:
Tuesday, May 18, 2021
Hour: 15:00 - 16:00
Location:
Prof. Lin Dayu
|
Dept of Psychiatry, Neuroscience and Physiology New York University Grossman School of Medicine, USA

Aggression is an innate social behavior essential for competing for resources, securing mates, defending territory and protecting the safety of oneself and family. In the last decade, significant progress has been made towards an understanding of the neural circuit underlying aggression using a set of modern neuroscience tools. Here, I will talk about our recent progress in the study of aggression. Zoom link to join- https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070

Using Deep Nets to Understand Visual Recognition in Mind and Brain

Lecture
Date:
Tuesday, May 11, 2021
Hour: 15:00 - 16:00
Location:
Prof. Nancy Kanwisher
|
Dept of Neuroscience, Brain and Cognitive Sciences, McGovern Institute for Brain Research, MIT, USA

In this talk I will describe two ongoing lines of work from my lab that use deep nets to better understand visual recognition and its neural and computational basis in the brain, by testing precise computational models against fMRI data from the ventral visual pathway, and by providing clues into why face recognition works the way it does in the human mind and brain. Zoom link to join- https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070

Neuropixels probes - two stories about development and use

Lecture
Date:
Thursday, May 6, 2021
Hour: 12:30 - 13:30
Location:
Dr. Michael Okun
|
Department of Neuroscience, Psychology and Behaviour, University of Leicester, UK

The first part of the presentation will describe the Neuropixels 2.0 probe, focusing on its ability to stably record from the same neurons across days and weeks in chronically implanted mice. The second part will describe the effects of psychedelic and intrinsic brain state transitions on the firing rates of neuronal populations, as revealed by high count Neuropixels recordings. Zoom link: https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Prof. Ilan Lampl ilan.lampl@weizmann.ac.il tel: 3179

The Vagus Nerve and Physiology of Reward and Digestion

Lecture
Date:
Tuesday, May 4, 2021
Hour: 15:00
Location:
Prof. Ivan E de Araujo
|
Neuroscience Dept, Diabetes, Obesity and Metabolism Institute Icahn School of Medicine at Mount Sinai

The presentation will discuss recent evidence supporting a role for the gut-brain axis in controlling brain circuits involved in reward. It will be argued that sensory neurons of vagus nerve function as reward neurons. Via defined brainstem targets, vagal signals dopaminergic brain reward circuits in midbrain. The mapping of these circuits opens a window into how signals generated by internal body organs give rise to motivated and emotional behaviors. Zoom link to join- https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070

Neural correlates of future weight loss reveal a possible role for brain-gastric interactions

Lecture
Date:
Tuesday, April 27, 2021
Hour: 12:30 - 13:30
Location:
Prof. Galia Avidan
|
Dept of Psychology Ben Gurion University of the Negev

Lifestyle dietary interventions are an essential practice in treating obesity, hence neural factors that may assist in predicting individual treatment success are of great significance. Here, in a prospective, open-label, three arms study, we examined the correlation between brain resting-state functional connectivity measured at baseline and weight loss following 6 months of lifestyle intervention in 92 overweight participants. We report a robust subnetwork composed mainly of sensory and motor cortical regions, whose edges correlated with future weight loss. This effect was found regardless of intervention group. Importantly, this main finding was further corroborated using a stringent connectivity-based prediction model assessed with cross-validation thus attesting to its robustness. The engagement of senso-motor regions in this subnetwork is consistent with the over-sensitivity to food cues theory of weight regulation. Finally, we tested an additional hypothesis regarding the role of brain-gastric interaction in this subnetwork, considering recent findings of a cortical network synchronized with gastric activity. Accordingly, we found a significant spatial overlap with the subnetwork reported in the present study. Moreover, power in the gastric basal electric frequency within our reported subnetwork negatively correlated with future weight loss. This finding was specific to the weight loss related subnetwork and to the gastric basal frequency. These findings should be further corroborated by combining direct recordings of gastric activity in future studies. Taken together, these intriguing results may have important implications for our understanding of the etiology of obesity and the mechanism of response to dietary intervention as well as to interoceptive perception. Zoom link to join: https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070

New insights on continuous attractor neural networks

Lecture
Date:
Tuesday, April 20, 2021
Hour: 12:30
Location:
Prof. Yoram Burak
|
Racah Institute of Physics and Edmond and Lily Safra Center for Brain Sciences The Hebrew University of Jerusalem

One of the most fundamental concepts in theoretical neuroscience is that of an attractor neural network, in which recurrent synaptic connectivity constraints the joint activity of neurons into a highly restricted repertoire of population activity patterns. In continuous attractor networks, these activity patterns span a continuous, low-dimensional manifold. I will survey two recent works from my group that are related to this concept. The first work is concerned with fixational eye drifts, a form of eye motion that occurs between saccades and is characterized by smooth, yet random, diffusive-like motion. This motion is tiny compared to saccadic eye motion, yet it is highly consequential for high-acuity vision. Even though fixational drift has been identified at least as early as the 19th century, its mechanistic origins have remained completely unknown. We hypothesize that the main drive for fixational drifts arises in diffusive motion along a line-attractor memory network - the oculomotor network, which is responsible for maintaining a fixed activation of the ocular muscles between saccades. I will present evidence in support of this hypothesis, coming from electrophysiology in monkeys and from theoretical modeling. The second work is concerned with the ability of a single recurrent neural network to express activity patterns that span multiple yet distinct continuous manifolds, a question that has been of interest in the context of spatial coding, across multiple environments, in area CA3 of the hippocampus. Zoom link to join- https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070

Uncovering the Boundaries of Olfactory Perception

Lecture
Date:
Monday, April 19, 2021
Hour: 15:00 - 16:00
Location:
Aharon Ravia (PhD Thesis Defense)
|
Prof. Noam Sobel Lab, Dept of Neurobiology Prof. David Harel Lab, Dept of Computer Science and Applied Mathematics WIS

The question of how to measure a smell has troubled scientists for over a century. It was none other than Alexander Graham Bell that raised the challenge: "we have very many different kinds of smells, all the way from the odor of violets and roses up to asafoetida. But until you can measure their likenesses and differences you can have no science of odor”. Such a measure of smell can be naturally derived from a model of olfactory perceptual quality space, and several such models have recently been put forth. These typically rely on finding mathematical rules that link odorant structure to aspects of odor perception. Here, I collected 49,788 perceptual odor estimates from 199 participants, and built such a model, finalizing a physicochemical measure of smell. This measure, expressed in radians, predicts real-world odorant pairwise perceptual similarity from odorant structure alone. Using this measure, I met Bell's challenge by accurately predicting the perceptual similarity of rose, violet and asafoetida, from their physicochemical structure. Next, based on thousands of comparisons, I identified a cutoff in this measure, below 0.05 radians, where discrimination between pairs of mixtures becomes highly challenging. To assess the usefulness of this measure, I investigated whether it can be used to create olfactory metamers, namely non-overlapping molecular compositions that share a common percept. Characterizing the link between physical structure and ensuing perception in vision and audition, and the creation of perceptual entities such as metamers, was important towards understanding their underlying dimensionality, brain mechanisms, and towards their ultimate digitization. I suggest that olfactory metamers can similarly aid these goals in olfaction. Zoom link to join: https://weizmann.zoom.us/j/93360836031?pwd=dDZEdTQ1QUkxUVVONVErVm9CcUJWQT09 Meeting ID: 933 6083 6031 Password: 591230

Dissecting the functional organization of sensory neurons in gut-brain communication

Lecture
Date:
Tuesday, April 13, 2021
Hour: 12:30
Location:
Dr. Henning Fenselau
|
Max Planck Institute for Metabolism Research, Cologne, Germany

Sensory neurons relay gut-derived signals to the brain, and thereby contribute to systemic energy and glucose homeostasis regulation. However, the relevant sensory neuronal populations innervating the gut along with the pertaining underlying functional neurocircuits remain poorly understood. Advances in this field have been impeded by the challenges associated with targeting distinct sensory neurons of vagal and spinal origin in a cell-type-specific manner, thereby making the accurate determination of their function highly difficult. We employ a combinatorial set of modern molecular systems neuroscience tools and novel mouse genetic approaches to elucidate the role of molecularly defined sensory neurons in feeding behavior and glucose metabolism, and map their downstream neurocircuits in the brain. The overarching goal of our studies is to gain greater insights into the integral components of sensory neurons as gut-to-brain connectors in controlling metabolism. Zoom link to join- https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070

Cellular and circuit basis of distinct memory formation in the hippocampus

Lecture
Date:
Tuesday, April 6, 2021
Hour: 12:30
Location:
Dr. Christoph Schmidt-Hieber
|
Department of Neuroscience, Institut Pasteur, Paris

Formation and retrieval of distinct memories are complementary processes that put conflicting requirements on neuronal computations in the hippocampus, especially when memories closely resemble each other. How this challenge is resolved in hippocampal circuits to guide memory-based decisions is unclear. To address this question, our group uses in vivo 2-photon calcium imaging and whole-cell recordings from hippocampal subregions in head-fixed mice trained to distinguish between novel and familiar virtual-reality environments. We find that granule cells consistently show a small transient depolarization of their membrane potential upon transition to a novel environment. This synaptic novelty signal is sensitive to local application of atropine, indicating that it depends on metabotropic acetylcholine receptors. A computational model suggests that the observed transient synaptic response to novel environments leads to a bias in the granule cell population activity, which can in turn drive the downstream attractor networks to a new state, thereby favoring the switch from generalization to discrimination when faced with novelty. Such a novelty-driven cholinergic switch may enable flexible encoding of new memories while preserving stable retrieval of familiar ones. zoom link to join-https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070

Uncovering Olfactory Perception Boundaries

Lecture
Date:
Thursday, March 25, 2021
Hour: 15:00 - 16:00
Location:
Aharon Ravia (PhD Thesis Defense)
|
Prof. Noam Sobel Lab, Dept of Neurobiology Prof. David Harel Lab, Dept of Computer Science and Applied Mathematics

The question of how to measure a smell has troubled scientists for over a century. It was none other than Alexander Graham Bell that raised the challenge: "we have very many different kinds of smells, all the way from the odor of violets and roses up to asafoetida. But until you can measure their likenesses and differences you can have no science of odor”. Such a measure of smell can be naturally derived from a model of olfactory perceptual quality space, and several such models have recently been put forth. These typically rely on finding mathematical rules that link odorant structure to aspects of odor perception. Here, I collected 49,788 perceptual odor estimates from 199 participants, and built such a model, finalizing a physicochemical measure of smell. This measure, expressed in radians, predicts real-world odorant pairwise perceptual similarity from odorant structure alone. Using this measure, I met Bell's challenge by accurately predicting the perceptual similarity of rose, violet and asafoetida, from their physicochemical structure. Next, based on thousands of comparisons, I identified a cutoff in this measure, below 0.05 radians, where discrimination between pairs of mixtures becomes highly challenging. To assess the usefulness of this measure, I investigated whether it can be used to create olfactory metamers, namely non-overlapping molecular compositions that share a common percept. Characterizing the link between physical structure and ensuing perception in vision and audition, and the creation of perceptual entities such as metamers, was important towards understanding their underlying dimensionality, brain mechanisms, and towards their ultimate digitization. I suggest that olfactory metamers can similarly aid these goals in olfaction. Zoom link to join: https://weizmann.zoom.us/j/93360836031?pwd=dDZEdTQ1QUkxUVVONVErVm9CcUJWQT09 Meeting ID: 933 6083 6031 Password: 591230

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