Synchrony between orientation-selective neurons is modulated during adaptation-induced plasticity in cat visual cortex

Abstract

BackgroundVisual neurons respond essentially to luminance variations occurring within their receptive fields. In primary visual cortex, each neuron is a filter for stimulus features such as orientation, motion direction and velocity, with the appropriate combination of features eliciting maximal firing rate. Temporal correlation of spike trains was proposed as a potential code for linking the neuronal responses evoked by various features of a same object. In the present study, synchrony strength was measured between cells following an adaptation protocol (prolonged exposure to a non-preferred stimulus) which induce plasticity of neurons' orientation preference.ResultsMulti-unit activity from area 17 of anesthetized adult cats was recorded. Single cells were sorted out and (1) orientation tuning curves were measured before and following 12 min adaptation and 60 min after adaptation (2) pairwise synchrony was measured by an index that was normalized in relation to the cells' firing rate. We first observed that the prolonged presentation of a non-preferred stimulus produces attractive (58%) and repulsive (42%) shifts of cell's tuning curves. It follows that the adaptation-induced plasticity leads to changes in preferred orientation difference, i.e. increase or decrease in tuning properties between neurons. We report here that, after adaptation, the neuron pairs that shared closer tuning properties display a significant increase of synchronization. Recovery from adaptation was accompanied by a return to the initial synchrony level.ConclusionWe conclude that synchrony reflects the similarity in neurons' response properties, and varies accordingly when these properties change.

Synergistic activity between primary visual neurons

“…This seems to be in line with investigations reporting that V1 (layer II/III) neurons receive a diversity of oriented inputs from surrounding neurons, however, there is an enhanced connectivity between neurons that share orientation preference (Monier et al, 2003;Jia et al, 2010;Ko et al, 2011). Recently, we have shown that cell-assemblies develop heightened functional connections to a suitable orientation, and may wax and wane contingent upon the presented orientation (Ghisovan et al, 2008;Duret et al, 2006;Bharmauria et al, 2012;Bretzner et al, 2001). Then the results of the present investigation suggest that the formation of an encoding assembly of excited neurons may rest on two global processes: firstly, to an appropriate stimulus, there is a development of functional connections leading to construction of a functional connectome particular to that stimulus; secondly, these connections allow enhanced responses leading to relevant and salient neural activities that participate in signaling a specific target.…”

“…However, recently, authors (Ainsworth et al, 2012) have suggested a bias toward a precise temporal code (stimulus-driven-synchrony) that is a reflection of the anatomical architecture and synaptic biophysical properties of neurons (Ratté et al, 2013;Ainsworth et al, 2012). Synchronized neural activity implying specific functional connectivity has already been associated to the generation of coherent percepts (Fujisawa et al, 2008;Barthó et al, 2004;Ghisovan et al, 2008;Duret et al, 2006;.…”

“…Cortical neurons propagate information about the experience (input) through the complex temporal relationships of their action potentials (Kohn and Smith, 2005;Alloway and Roy, 2002;Fujisawa et al, 2008;Barthó et al, 2004;Yoshimura et al, 2005;Samonds et al, 2006;Ghisovan et al, 2008). Neurons principally coordinate in local sub-networks termed 'cell-assemblies' to represent distinct cognitive entities (Ko et al, 2013;Ko et al, 2011;Perin et al, 2011;Kampa et al, 2011;Hebb,1949;Buzsaki, 2010).…”

Adaptation and Neuronal Network in Visual Cortex

“…This means the excitation is from reference cell to the target cell [79,81]. Figure 5c corresponds to the synchrony between two neurons, as the peak straddles zero [73,82]. This means there is a common excitatory input to both neurons most likely from other neuron or neurons.…”

Adaptation of cerebral oxygen metabolism and blood flow and modulation of neurovascular coupling with prolonged stimulation in human visual cortex

“…Adaptation may occur at different timescales (Bao & Engel, 2012; Patterson, Wissig, & Kohn, 2013). Intrinsic synaptic and neuronal mechanisms and extrinsic network interactions may be important for adaptation (Dhruv, Tailby, Sokol, & Lennie, 2011; Ghisovan, Nemri, Shumikhina, & Molotchnikoff, 2008; Sanchez-Vives, Nowak, & McCormick, 2000). …”