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Top-down gain modulation and learning across cortical areas

English title Top-down gain modulation and learning across cortical areas
Applicant Senn Walter
Number 105966
Funding scheme Project funding (Div. I-III)
Research institution Institut für Physiologie Medizinische Fakultät Universität Bern
Institution of higher education University of Berne - BE
Main discipline Neurophysiology and Brain Research
Start/End 01.10.2004 - 30.09.2007
Approved amount 335'000.00
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All Disciplines (2)

Neurophysiology and Brain Research

Keywords (4)

dendritic gain modulation; perceptual learning; computational models; category learning

Lay Summary (English)

Lay summary
Previous work in our labs showed that pyramidal neurons in the neocortex increase their gain in response to synaptic inputs on the apical dendritic tree (Larkum et al., 2004). This dendritic mechanism is believed to implement a top-down induced gain modulation of the neuronal transfer function. A top-down gain modulation is often postulated to underly attentional modulation in the cortex. In this project we explored whether the same mechanism may also support learning processes. We were showing that top-down gain modulation explains properties in perceptual learning which so far have always been assigned to purely feedforward processing of sensory input (Schäfer et al., 2007). A top-down model of perceptual learning is also compatible with electrophysiological recordings which otherwise are difficult to be explained (see also Sch\"afer et al., 2008). We also studied the impact of top-down signals on cortical map formation during exposure to sensory stimuli. We show that top-down gain modulation can induce discrete category formation in a recurrently connected cortical sheet, and that the number of emerging categories can be modulated by the strength of the top-down signal (Kim et al., 2008). We further investigated synaptic plasticity algorithms based on reward feedback, and applied these to learning tasks involving multiple cortical layers (Vasilaki et al., 2007; Urbanczik and Senn, 2007; Vladimirski et al., 2008).
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants


Associated projects

Number Title Start Funding scheme
65234 Synaptic plasticity and response properties of cortical neurons: theory and experiments 01.10.2001 Project funding (Div. I-III)
118084 Learning via top-down signaling in the neocortex 01.10.2007 Interdisciplinary projects
133094 Dendritic pointers and time multiplexing as cortical binding mechanisms 01.05.2011 Project funding (Div. I-III)