Poster B103, Sunday, March 25, 8:00-10:00 am, Exhibit Hall C
Local field potential recordings reveal enhanced feedback in the primate visual system for familiar compared to novel objects
Ryan E.B. Mruczek1, Amalia K. Davis1, David L. Sheinberg2; 1Worcester State University, 2Brown University
Repeated exposure to the same objects alters the selectivity of neurons in the inferior temporal cortex (IT) for those objects. Specifically, IT neurons respond to a smaller number of familiar objects (i.e., higher selectivity) and to a broader number of novel objects (i.e., lower selectivity). Previously, we reported differences in the shape of the local field potential (LFP) in anterior IT evoked by familiar and novel objects, starting approximately at 160-180 ms after stimulus onset (Anderson et al., 2008, Cerebral Cortex, 18:2540). Consistent with the selectivity changes noted above, classification of object identity based on the shape of the LFP was better for familiar objects. However, it is unclear how these experience-dependent changes alter intercortical communication within the visual system. Recent evidence has demonstrated that feedforward and feedback signals in primate visual cortex utilize different frequency channels: gamma-band oscillations mediate feedforward processing, whereas alpha-/beta-band oscillations mediate feedback processing (Bastos et al., 2015, Neuron, 85:390; van Kerkoerle et al., 2014, PNAS, 111:14332). Considering these advances, we reanalyzed our previous dataset (Anderson et al., 2008) to determine whether differences in LFPs evoked by familiar and novel stimuli reflect changes in feedforward or feedback processing. We most consistently observed increased power in the ~5-17 Hz alpha/beta range for familiar objects. We also observed, less consistently, decreased power in the ~65-100 Hz gamma range for familiar objects. These results support the hypothesis that long-term familiarity leads to stronger feedback connections within the visual system.
Topic Area: PERCEPTION & ACTION: Vision