Event Abstract Back to Event Stimulus repetition reduces stimulus encoding by small neuronal populations in macaque inferior temporal cortex Dzmitry A. Kaliukhovich1 and Rufin Vogels1* 1 KU Leuven, Neuroscience, Belgium Stimulus repetition reduces spiking responses in macaque inferior temporal (IT) cortex, i.e. repetition suppression or adaptation. Single cell recording studies in V1 and V4 reported that adaptation improves stimulus encoding. Thus far it is not known whether the same holds true in IT, in particular given the apparently greater adaptation strength in IT compared to earlier visual areas. Here, we examined the effect of stimulus repetition on the accuracy of small populations of IT neurons to classify familiar images of objects. We recorded multi-unit activity with a laminar electrode (16 sites spaced 100 µm) in the rostral ventral bank of the superior temporal sulcus in 2 rhesus monkeys (N = 32 penetrations) while they were performing a passive fixation task. We presented 2 stimuli (A and B) successively, each for 500 ms, with an ISI of 500 ms. Trials consisted either of a repetition (AA or BB) of the same stimulus or of their alternation (AB or BA). Stimulus-selective adaptation was present in 90% of stimulus x responsive site combinations (N = 468; see Kaliukhovich and Vogels, 2012 for details). Machine learning-based classifiers (Support Vector Machines (SVM) and correlation-based classifier) were employed to decode stimulus identity (A vs. B) from the neuronal population responses (spike counts in an interval of 60-310 ms after stimulus onset per trial and site) of each penetration. Classifiers were trained using half of the data and tested using the remaining half. The SVM classifier showed significantly lower classification for the test compared to the adapter stimulus (mean across penetrations: 80% vs. 74%, P < 0.000005) in repetition trials. However, classification for test stimuli in alternation trials and when only one of the stimuli was adapted (e.g. A following A vs. B following A) did not differ significantly from that of the adapter. The correlation-based classifier produced highly similar results. Shuffling trial order of a stimulus across sites within a penetration, i.e. eliminating noise correlations, and using the SVM classifier produced similar effects, except that classification was significantly larger by ~2% (P < 0.0005). These data suggest that stimulus-specific adaptation in IT does not improve coding of objects repeated in short stimulus sequences but instead may impair it. Acknowledgements This work was supported by Fonds voor Wetenschappelijk Onderzoek Vlaanderen (G.0644-08), Geconcerteerde Onderzoeksactie (GOA/10/019), Interuniversitaire Attractiepool (IUAP) and Programma Financiering (PF 10/008). For the computation of classifiers we used the infrastructure of the VSC – Flemish Supercomputer Center, funded by the Hercules Foundation and the Flemish Government – department EWI. References Kaliukhovich, D. A., & Vogels, R. (2012). Stimulus repetition affects both strength and synchrony of macaque inferior temporal cortical activity. Journal of Neurophysiology, 107, 3509-3527 Keywords: adaptation, inferior temporal cortex, stimulus discriminability, repetition suppression, macaque monkey Conference: Belgian Brain Council, Liège, Belgium, 27 Oct - 27 Oct, 2012. Presentation Type: Poster Presentation Topic: Higher Brain Functions in health and disease: cognition and memory Citation: Kaliukhovich DA and Vogels R (2012). Stimulus repetition reduces stimulus encoding by small neuronal populations in macaque inferior temporal cortex. Conference Abstract: Belgian Brain Council. doi: 10.3389/conf.fnhum.2012.210.00106 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: 21 Aug 2012; Published Online: 12 Sep 2012. * Correspondence: Dr. Rufin Vogels, KU Leuven, Neuroscience, Leuven, 3000, Belgium, rufin.vogels@kuleuven.be 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 Dzmitry A Kaliukhovich Rufin Vogels Google Dzmitry A Kaliukhovich Rufin Vogels Google Scholar Dzmitry A Kaliukhovich Rufin Vogels PubMed Dzmitry A Kaliukhovich Rufin Vogels 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.