Percept-related fluctuations of MT local field potentials

Single-cell recordings in the awake monkey during bistable visual perception have revealed a diversity of roles for individual neurons with regard to an experienced percept. We have recently shown that this perceptual modulation is not only neuron-specific but also stimulus-specific: MT neurons showing perceptual modulation to one stimulus often do not show significant modulation to closely related ambiguous patterns that differ only in the value of a single parameter (Maier et al., SFN 2003). In the present study, we explore how this stimulus-specificity for perceptual modulation might be reflected in the local field potential (LFP) during the perception of ambiguous 3-D rotation, as well as during binocular rivalry flash suppression. Following the presentation of several combinations of rivaling patterns, as well as 3-D rotation, to the same neurons, we analyzed percept-related changes in band-limited power (BLP) during these paradigms. LFP recorded in area MT of two monkeys was band-pass filtered into multiple frequency bands and subsequently rectified to compute power changes with high temporal resolution. While all stimuli evoked power changes throughout the entire spectrum (ranging from delta to gamma bands), perceptual modulation of BLP was often more pronounced at higher frequencies. This enables us to study whether percept-related changes in LFP power transfers across paradigms, or whether it is similarly specific as single unit activity. Findings will be discussed in context with other findings on percept-related activity modulation in early visual cortex