Integration of bottom-up and top-down signals in visual recognition

Abstract

Event Abstract Back to Event Integration of bottom-up and top-down signals in visual recognition Julie Blumberg1*, Jonas Bruder1, Daniel Millman2 and Andreas Schulze-Bonhage1 1 University hospital Freiburg, Epilepsy center, Germany 2 Harvard Medical School, Children's Hospital, United States In a collaboration of Harvard Medical School and University hospital Freiburg we study visual perception and memory in the human brain with high spatial and temporal resolution. Subjects are epilepsy patients who are implanted with depth electrodes and/or intracranial surface electrodes to localize the seizure focus for potential surgical resection. In parallel with field potentials we record single neuron spiking activity using microwires inserted in depth electrodes. The goal of this collaborative effort is to understand the interaction and integration of bottom-up and top-down signals through the combination of neurophysiological recordings at high spatial and temporal resolution in the human brain, computational data analysis and modeling. The properties of hierarchical and feed-forward theories of visual recognition provide a quantitative framework to examine information processing in the feedforward path along the ventral stream to account for ultra-rapid complex object recognition. One of the main limitations of these models is that they do not take into account the massive backprojections that convey information from higher cortical areas back to the lower areas. In order to explain everyday visual perception, we need to incorporate a quantitative and computational description of top-down control of sensory processing derived from frontal and parietal cortex as well as medial temporal lobe memory structures. In our study we examine progressively more complex tasks that include both bottom-up and top-down components in order to shed light on the dynamical integration of feed-forward and feed-back signals in the human ventral visual cortex. One type of information that can be fed back is the temporal relationships among visual events in an episodic memory. In order to investigate memory function involved in object recognition, we have subjects perform tasks that involve the learning of image sequences while we record from temporal lobe structures including hippocampus. These tasks offer the potential to reveal functions of the hippocampus in the learning of temporal relationships, such as prospective/anticipatory coding of upcoming images and/or learning of associations among temporally-linked images. In particular, we test the involvement of the hippocampus in learning the temporal component of episodic memories, beyond simple association of the events which are members of the episode. Here, we dissociate the learning of which images are members of a particular sequence from learning of temporal order by asking patients to memorize sequences, then testing either their memory of the sequence members or memory of the temporal relationships among sequence members. Finally, replaying of the order of activation of place cells that together constitute a trajectory to a reward location during and after training occurs in the rodent hippocampus, and is believed to play a role in memory consolidation. We test whether such replay occurs in non-spatial cognitive domains in the human hippocampus. Acknowledgements This work was supported by the NSF/BMBF Award for US-German Collaboration in Computational Neuroscience (Award ID 1010109/01GQ1010). Keywords: single-unit recordings, Epilepsy, Visual Cortex, Feedback, ECoG Conference: Bernstein Conference 2012, Munich, Germany, 12 Sep - 14 Sep, 2012. Presentation Type: Poster Topic: Sensory processing and perception Citation: Blumberg J, Bruder J, Millman D and Schulze-Bonhage A (2012). Integration of bottom-up and top-down signals in visual recognition. Front. Comput. Neurosci. Conference Abstract: Bernstein Conference 2012. doi: 10.3389/conf.fncom.2012.55.00044 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: 13 Jul 2012; Published Online: 12 Sep 2012. * Correspondence: Mrs. Julie Blumberg, University hospital Freiburg, Epilepsy center, Freiburg, Germany, julie.blumberg@uniklinik-freiburg.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 Julie Blumberg Jonas Bruder Daniel Millman Andreas Schulze-Bonhage Google Julie Blumberg Jonas Bruder Daniel Millman Andreas Schulze-Bonhage Google Scholar Julie Blumberg Jonas Bruder Daniel Millman Andreas Schulze-Bonhage PubMed Julie Blumberg Jonas Bruder Daniel Millman Andreas Schulze-Bonhage 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.