Feature Linking via Synchronization among Distributed Assemblies: Simulations of Results from Cat Visual Cortex

Abstract

We recently discovered stimulus-specific interactions between cell assemblies in cat primary visual cortex that could constitute a global linking principle for feature associations in sensory and motor systems: stimulus-induced oscillatory activities (35-80 Hz) in remote cell assemblies of the same and of different visual cortex areas mutually synchronize, if common stimulus features drive the assemblies simultaneously. Based on our neurophysiological findings we simulated feature linking via synchronizations in networks of model neurons. The networks consisted of two one-dimensional layers of neurons, coupled in a forward direction via feeding connections and in lateral and backward directions via modulatory linking connections. The models' performance is demonstrated in examples of region linking with spatiotemporally varying inputs, where the rhythmic activities in response to an input, that initially are uncorrelated, become phase locked. We propose that synchronization is a general principle for the coding of associations in and among sensory systems and that at least two distinct types of synchronization do exist: stimulus-forced (event-locked) synchronizations support “crude instantaneous” associations and stimulus-induced (oscillatory) synchronizations support more complex iterative association processes. In order to bring neural linking mechanisms into correspondence with perceptual feature linking, we introduce the concept of the linking field (association field) of a local assembly of visual neurons. The linking field extends the concept of the invariant receptive field (RF) of single neurons to the flexible association of RFs in neural assemblies.

Nonrenewal spike train statistics: causes and functional consequences on neural coding

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Selective visual-spatial attention alters induced gamma band responses in the human EEG

“…One suggestion was ± based on theoretical considerations and ®ndings in intracortical recordings in animals ± that the object is coded in a Hebbian-like neuronal cell assembly which is distributed across different functional visual areas by means of synchronized bursts of action potentials in a frequency range above 20 Hz, i.e. the gamma band (Milner, 1974;Malsburg and Schneider, 1986;Eckhorn et al, 1990;Gray et al, 1990;Singer et al, 1990;Eckhorn et al, 1992;Singer and Gray, 1995). Contrary to the above mentioned VEPs, these synchronized oscillations are neither phase-nor time-locked to stimulus onset.…”

Processing of affective pictures modulates right-hemispheric gamma band EEG activity

“…By synchronizing their ®ring patterns, neurons in a cell assembly would produce EEG activity in the gamma band when the assembly is ignited (Eckhorn et al, 1990;Singer and Gray, 1995;Pulvermu Èller et al, 1997). In humans, non-invasive electro-(EEG) and magnetoencephalographic (MEG) recordings have provided evidence that cortical activity in the gamma band range (above 20 Hz) is modulated by (a) the features of a stimulus (Mu Èller et al, 1996;Tallon et al, 1995;Mu Èller et al, 1997;Tallon-Baudry et al, 1997b), by (b) visual spatial attention (Mu Èller, 1998;Gruber et al, 1999), and (c) may represent the perception of a Gestalt (Tallon-Baudry et al, 1997a,b;Keil et al, 1999).…”