Friedrich: Neuronal circuits and computations in the...
Apr
24
Thu 12:30 PM
When Thursday, April 24, 2008
Time
12:30 PM - 1:30 PM
Where Pancoe/ENH Abbott Auditorium
Contact Jo Atkinson
847 467 1573
Group Interdisciplinary Seminar in Nonlinear Science
Neurobiology & Physiology Seminar
Title: Neuronal circuits and computations in the olfactory bulb
Speaker: Rainer Friedrich, Ph.D., FMI-Friedrich Miescher Institute, Basel, Switzerland
Abstract: Odor information is first represented in the olfactory bulb (OB) by distributed glomerular activity patterns that contain nested spatial maps of primary and secondary molecular stimulus features. Neuronal circuits in the OB transform these input patterns into spatio-temporal patterns of output activity that are transmitted to higher brain regions by mitral cells. To understand the computations associated with this transformation and the function of chemotopic maps, we measured odor-evoked activity patterns across thousands of individual neurons in the intact brain of zebrafish using electrophysiology, temporally deconvolved 2-photon calcium imaging, and transgenic cell type markers. We found that the OB performs multiple computations including a decorrelation of initially overlapping activity patterns, a multiplexing of complementary information, and gain control. The chemotopic representation of primary molecular features is maintained in OB output activity patterns, while secondary chemotopic maps disappear during the initial phase of an odor response. This reorganization is caused by the local sparsening of MC activity within chemotopic foci and promotes the decorrelation of overlapping input patterns. Computational modelling provided elucidated the structural and functional features of neuronal circuits that are required for pattern decorrelation by local sparsening. These results provide insights into the basic computational functions of the OB.
Title: Neuronal circuits and computations in the olfactory bulb
Speaker: Rainer Friedrich, Ph.D., FMI-Friedrich Miescher Institute, Basel, Switzerland
Abstract: Odor information is first represented in the olfactory bulb (OB) by distributed glomerular activity patterns that contain nested spatial maps of primary and secondary molecular stimulus features. Neuronal circuits in the OB transform these input patterns into spatio-temporal patterns of output activity that are transmitted to higher brain regions by mitral cells. To understand the computations associated with this transformation and the function of chemotopic maps, we measured odor-evoked activity patterns across thousands of individual neurons in the intact brain of zebrafish using electrophysiology, temporally deconvolved 2-photon calcium imaging, and transgenic cell type markers. We found that the OB performs multiple computations including a decorrelation of initially overlapping activity patterns, a multiplexing of complementary information, and gain control. The chemotopic representation of primary molecular features is maintained in OB output activity patterns, while secondary chemotopic maps disappear during the initial phase of an odor response. This reorganization is caused by the local sparsening of MC activity within chemotopic foci and promotes the decorrelation of overlapping input patterns. Computational modelling provided elucidated the structural and functional features of neuronal circuits that are required for pattern decorrelation by local sparsening. These results provide insights into the basic computational functions of the OB.
