RAPIDODORADAPTATION · Rapid adaptation to varying odor concentration
FP7 — People (Marie Curie Actions)
- Duration
- 2013-03-01 → 2017-02-28
- EU contribution
- €100,000
- Participants
- 1
- Scheme
- MC-CIG
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Results in brief
Rapid adaptation to varying odor concentration
Navigation using olfactory cues entails processing of three distinct types of information: odor identity, odor concentration, and time of cue sampling. The last two components govern the odor source localization process. Localization of the odor source relies on sampling and comparing odor concentration. This may be done in the spatial domain, by bilateral sampling and comparing between two nostrils, or temporal domain, by sequential sampling and comparison of concentrations sampled at consecutive times. While the role of the spatial strategy in olfactory navigation has been studied in various species, mechanism of temporal sampling and its contribution to odor localization remain obscure. Scientific results in order to adequately address the question of temporal sampling in olfactory bulb, we developed an odor delivery setup that allows switching and stabilization of different odor concentrations between consecutive sniff cycles. To study the neural basis of temporal sampling in mouse olfactory bulb, we monitored activity of mitral/tufted (M/T) cells in response to an olfactory stimulus, which flickered between four odor concentrations, in both anesthetized and awake animals. M/T responses to the flickering task revealed two distinct M/T populations: a) concentration tracking cells – providing information on actual odor concentration, and b) gradient detection cells – providing information on the concentration change. What is the mechanism underlying the ability of M/T cells to detect the change of concentration, and not the actual concentration? Odors activate numerous glomeruli, and consequently a large fraction of relevant M/T cells. Therefore, gradient-type responses may be due to lateral/reciprocal connections. To examine the necessity of lateral/reciprocal connections, we minimized their contribution by optogenetic activation of a subset of M/T cells selectively belonging to the dorsal M72 glomerulus. We measured the difference of M/T cell responses to light pulses of different intensity, given in ascending or descending order. Light stimulation of this specific glomerulus revealed that the associated M/T cells’ responses to identical light stimuli depend on previous stimuli intensity. These responses resembled those seen in gradient detection cells, suggesting that the underlying mechanism might be intrinsic. In summary, our results indicate that M/T cells respond to specific concentration or to change of odor concentration. The coexistence of this two different M/T responses may reveal two different streams of information in the olfactory system, resembling “what” and “where” streams of the visual system.
Data: CORDIS, © European Union
Project objective
In day-to-day life during navigation, hunting, escaping from predator and social interactions, animals rely on sensory information in general and on olfactory cues in particular. A general feature common to all forms of sensory processing is adaptation, whereby in the presence of continuous stimulation, sensory receptors exhibit a marked reduction in responsiveness. Perceptual adaptation attenuates neural and perceptual responses to sustained or redundant stimulation as means of enhancing the detection of new, transient stimuli. Rapid olfactory adaptation allows an animal to continually assess changes in odor environment and concentration that are essential to follow odor plumes and trails. Current research aims to provide first insight on neural representation of complex, dynamic input by the mammalian olfactory system.Here I propose to combine precise control of odor stimulus, electrophysiology and behavioral readout in mice to ask: how olfactory system represents changes in odor concentration and how this representation depends on the statistics of the olfactory input? At the first stage responses of the olfactory system to simple switches in odor concentration will be studied. This will gain insight into the role of adaptation in the olfactory system. A second project will study how the olfactory system adapts to a time-varying stimulus with the final goal to form a quantitative description of temporal adaptation.The current research will provide the first physiological recordings in mammals in response to controllable time-varying stimulus. I will use behavioral readout to find which features of the neural code contribute to perception. Moreover, recording M/T cell activity in the context of behavioral tasks will strengthen the link between specific activity patterns and odor intensity perception. Finally, correlating specific features of the response to choice trial-by-trial will identify the features most relevant to the animals’ perceptual decision
Original text from CORDIS.
Participants
- UNIVERSITY OF HAIFA · HaifaCoordinatorIsrael
Links
Data: CORDIS, © European Union