BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Talks.cam//talks.cam.ac.uk// X-WR-CALNAME:Talks.cam BEGIN:VEVENT SUMMARY:The stabilized supralinear network: A simple "\;balanced netwo rk"\; mechanism explaining nonlinear cortical integration - Ken Miller \, Columbia University DTSTART:20160316T110000Z DTEND:20160316T120000Z UID:TALK65027@talks.cam.ac.uk CONTACT:Guillaume Hennequin DESCRIPTION:Across multiple sensory cortical areas\, strong nonlinearities are seen in the summation of responses to multiple stimuli. Responses to two stimuli in a neuron's receptive field (the sensory region in which app ropriate stimuli can drive spike responses) typically sum sublinearly\, wi th the response to the two stimuli presented simultaneously typically clos er to the average than the sum of the responses to the two individual stim uli. However\, when stimuli are weak\, responses sum more linearly. Simila rly\, contextual stimuli\, outside the receptive field\, can suppress resp onses to strong stimuli in the receptive field\, but more weakly suppress or facilitate responses to weaker receptive field stimuli. I'll present a simple circuit mechanism that explains these and many other results. Indiv idual neurons have supralinear input/output functions\, leading the gain o f neuronal responses to increase with response level. This drives a transi tion from (i) a weak-input regime in which neurons are weakly coupled\, re sponses sum linearly or supralinearly\, and contextual stimuli can facilit ate\, to (ii) a stronger-input regime in which neurons are strongly couple d and stabilized by inhibition against excitatory instability\, responses sum sublinearly\, and contextual stimuli suppress. In this strongly-couple d regime\, recurrent input `conspires' to cancel or 'balance' external inp ut\, leaving a residual input that grows slowly (sublinearly) as a functio n of external input. I'll describe this mechanism and show how it can expl ain a variety of cortical behaviors\, including those described above as w ell as suppression of correlated neural variability by stimuli (joint work with G. Hennequin and M. Lengyel) and other behaviors as time permits. LOCATION:Cambridge University Engineering Department\, CBL\, BE-438 (http: //learning.eng.cam.ac.uk/Public/Directions) END:VEVENT END:VCALENDAR