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Dean Shmuel, Haggai Sharon, Nitzan Censor; Early visual cortex underlies modulation of reactivated perceptual learning. Journal of Vision 2018;18(10):761. doi: https://doi.org/10.1167/18.10.761.
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Human visual perception thresholds can improve through perceptual learning processes. We utilized the memory reactivation-reconsolidation framework, stemming from studies at the synaptic level, according to which consolidated memories become susceptible to modulations upon their reactivation. Accordingly, brief reactivation of an existing memory opens a limited time-window during which the memory can be updated, degraded or strengthened. We have recently shown that brief reactivations of encoded visual memories are sufficient to improve perceptual discrimination thresholds (Amar-Halpert et al., 2017). Here, we used non-invasive brain stimulation to reveal the neural mechanisms underlying modulation of reactivated visual perceptual learning. We tested whether inhibitory noninvasive repetitive transcranial magnetic stimulation (rTMS) over early visual cortex, following brief reactivation of consolidated visual memory, modulates perceptual learning. Subjects first encoded and consolidated the visual memory by performing four daily practice sessions of the texture discrimination task (Karni and Sagi, 1991). Observers decided whether an array of 3 diagonal bars embedded in an array of horizontal bars was horizontal or vertical. The stimulus was backward-masked, and target-to-mask asynchrony (SOA) was randomly changed within the session to obtain a psychometric curve, from which the SOA discrimination threshold was derived. In the fifth session, the memory was briefly reactivated, followed by inhibitory 1Hz rTMS stimulation over early visual cortex, which was individually localized using functional MRI. Post-stimulation perceptual thresholds were measured on the sixth session. The results show deterioration in subjects' acquired perceptual thresholds, following inhibitory rTMS to early visual cortex synchronized with memory reactivation. These results indicate that even previously consolidated human perceptual memories are susceptible to modulation following their brief reactivation, involving early visual cortical processing. In addition, the opportunity to non-invasively neuromodulate human perceptual learning utilizing the memory reactivation framework, may have important clinical implications.
Meeting abstract presented at VSS 2018
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