Event Abstract Back to Event Layer specific neuronal activities in response to visual object images in the inferior temporal cortex revealed by current source density analysis Junji Ito1*, Hiroshi Tamura2, Gaute T. Einevoll3 and Sonja Gruen1, 4, 5 1 Forschugszentrum Juelich, Institute of Neuroscience and Medicine (INM-6), Germany 2 Osaka University, Graduate School of Frontier Biosciences, Japan 3 Norwegian University of Life Sciences, Department of Mathematical Sciences and Technology, Norway 4 RWTH Aachen University, Theoretical Systems Neurobiology, Germany 5 RIKEN, Brain Science Institute, Japan Neurons in the inferior temporal (IT) cortex show selective responses to specific sets of complex visual objects (Tanaka, 1996). They are structurally organized in columns, within which neurons have similar object selectivity (Tanaka, 2003). Anatomical studies revealed specific intra- and inter-laminar connectivity structures within a column (Fujita and Fujita,1996), suggesting that neurons in different layers are involved in different aspects of the visual information processing. Several studies tried to reveal spatio-temporal profiles of the information processing performed within a column and explored the layer dependent differences in the neuronal spiking responses (Shinomoto et al., 2005; Sato et al., 2009). However, no clear evidence of layer specificity has been reported so far. To tackle this issue, we recorded from areas TE and TEO of anesthetized macaque monkeys the multi-unit activities (MUA) as well as the local field potentials (LFP) using linear electrode arrays while the animals were visually stimulated using various types of simple and complex visual object images. The electrode array spans 1.55 mm with 32 electrode contacts separated by 50 um and was inserted into the cortex perpendicularly to the surface. From the LFP recordings we reconstructed the current source density (CSD) (Pettersen et al., 2006), which reflects the local current flows induced by synaptic inputs to the local neuronal population. We examined whether and how the responses to the visual stimuli in the CSD signal differ across layers. We identified a current sink at about 100 ms after stimulus onset at a depth of approximately 1.2 mm from the cortical surface, likely corresponding to layer IV and thus reflecting the afferent input to these areas. In 200-300 ms after stimulus onset subsequent current sinks occurred in upper positions, supposedly corresponding to synaptic activities in layers II and III. The location and timing of the sequential activations were consistent with the feed-forward connectivity known for columns in the primary visual cortex, but on a much slower timescale compared to previous studies using electric or full-field flash stimulation (Mitzdorf, 1985, Schroeder et al., 1998). We calculated the object selectivity based on the magnitude of the CSD sinks in a time dependent manner, using the F-value of ANOVA (i.e. the ratio between across-stimulus and across-trial response variabilities) as a measure. We found that the initial sink in layer IV showed a significant but only weak object selectivity, while the subsequent sinks in upper layers showed a much stronger object selectivity. These results suggest that object selectivity in IT develops dynamically by activity propagating across cortical layers within the columnar structure. References Fujita, I., & Fujita, T. (1996). Intrinsic Connections in the macaque inferior temporal cortex. The Journal of comparative neurology, 368(4), 467-86. Mitzdorf, U. (1985). Current source-density method and application in cat cerebral cortex: investigation of evoked potentials and EEG phenomena. Physiological reviews, 65(1), 37-100. Pettersen, K. H., Devor, A., Ulbert, I., Dale, A. M., & Einevoll, G. T. (2006). Current-source density estimation based on inversion of electrostatic forward solution: effects of finite extent of neuronal activity and conductivity discontinuities. Journal of neuroscience methods, 154(1-2), 116-33. Sato, T., Uchida, G., & Tanifuji, M. (2009). Cortical columnar organization is reconsidered in inferior temporal cortex. Cerebral Cortex, 19(8), 1870-88. Schroeder, C. E., Mehta, a D., & Givre, S. J. (1998). A spatiotemporal profile of visual system activation revealed by current source density analysis in the awake macaque. Cerebral Cortex, 8(7), 575-92. Shinomoto, S., Miyazaki, Y., Tamura, H., & Fujita, I. (2005). Regional and laminar differences in in vivo firing patterns of primate cortical neurons. Journal of neurophysiology, 94(1), 567-75. Tanaka, K. (1996). Inferotemporal cortex and object vision. Annual review of neuroscience, 19, 109-39. Tanaka, K. (2003). Columns for complex visual object features in the inferotemporal cortex: clustering of cells with similar but slightly different stimulus selectivities. Cerebral Cortex, 13(1), 90-9. Keywords: Current Source Density, inferior temporal cortex, Object Selectivity Conference: Bernstein Conference 2012, Munich, Germany, 12 Sep - 14 Sep, 2012. Presentation Type: Poster Topic: Sensory processing and perception Citation: Ito J, Tamura H, Einevoll GT and Gruen S (2012). Layer specific neuronal activities in response to visual object images in the inferior temporal cortex revealed by current source density analysis. Front. Comput. Neurosci. Conference Abstract: Bernstein Conference 2012. doi: 10.3389/conf.fncom.2012.55.00244 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 10 May 2012; Published Online: 12 Sep 2012. * Correspondence: Dr. Junji Ito, Forschugszentrum Juelich, Institute of Neuroscience and Medicine (INM-6), Juelich, 52428, Germany, j.ito@fz-juelich.de Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Junji Ito Hiroshi Tamura Gaute T Einevoll Sonja Gruen Google Junji Ito Hiroshi Tamura Gaute T Einevoll Sonja Gruen Google Scholar Junji Ito Hiroshi Tamura Gaute T Einevoll Sonja Gruen PubMed Junji Ito Hiroshi Tamura Gaute T Einevoll Sonja Gruen Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.