Dynamic cortical cooperation related to visual perception

We have continued testing the hypothesis of visual feature-binding by synchronization in/spl gamma/ monkey visual cortex. Current support for this hypothesis comes from recent results demonstrating local synchrony among rhythmic or stochastic /spl gamma/-activities (30-90Hz) - including their perceptual modulation - and decoupling of /spl gamma/-activity among neural groups representing figure and background. On the other hand, /spl gamma/-synchrony in primary visual cortex is restricted to few millimeters, which challenges the binding-by-synchronization hypothesis for larger cortical distances. But we found that this restriction is due to extended traveling /spl gamma/-waves, randomly altering their directions. Thus, across intermediate distances, phase continuity of these waves may still support coding of object continuity. Finally, across large distances we observed cortico-cortical interactions among low frequency signals and the envelopes of amplitude-modulated /spl gamma/-signals. We discuss potential mechanisms of near-, medium- and far-range cooperativity on the basis of spike-coding model networks. They include two types of inhibitory feedback loops generating local /spl gamma/-activities and low-frequency modulations, respectively. In conclusion, we propose that the binding-by-synchronization hypothesis, initially restricted to synchrony of oscillatory /spl gamma/-signals, be extended to more general forms of signal coupling, including near-range phase synchrony (coherence) between /spl gamma/-activities, medium-range phase continuity of /spl gamma/-waves, and far-range coupling involving low-frequency signals and envelopes of /spl gamma/-signals.

[1]  R. Eckhorn,et al.  Amplitude envelope correlation detects coupling among incoherent brain signals , 2000, Neuroreport.

[2]  R. Eckhorn,et al.  Coherent oscillations: A mechanism of feature linking in the visual cortex? , 1988, Biological Cybernetics.

[3]  R. Eckhorn,et al.  Functional coupling shows stronger stimulus dependency for fast oscillations than for low‐frequency components in striate cortex of awake monkey , 2000, The European journal of neuroscience.

[4]  W. Singer,et al.  Oscillatory Neuronal Responses in the Visual Cortex of the Awake Macaque Monkey , 1992, The European journal of neuroscience.

[5]  R. Parenti,et al.  Expression of connexin36 mRNA in adult rodent brain , 2000, Neuroreport.

[6]  Reinhard Eckhorn,et al.  Lateral spike conduction velocity in the visual cortex affects spatial range of synchronization and receptive field size without visual experience: a learning model with spiking neurons , 2000, Biological Cybernetics.

[7]  W. Singer,et al.  Oscillatory responses in cat visual cortex exhibit inter-columnar synchronization which reflects global stimulus properties , 1989, Nature.

[8]  V. Bringuier,et al.  Horizontal propagation of visual activity in the synaptic integration field of area 17 neurons. , 1999, Science.

[9]  R. Kempter,et al.  Hebbian learning and spiking neurons , 1999 .

[10]  R. Eckhorn.  Neural Mechanisms of Visual Feature Binding Investigated with Microelectrodes and Models , 1999 .

[11]  Ch. von der Malsburg,et al.  A neural cocktail-party processor , 1986, Biological Cybernetics.

[12]  C D Gilbert,et al.  Circuitry, architecture, and functional dynamics of visual cortex. , 1993, Cerebral cortex.

[13]  R. Eckhorn,et al.  Contour decouples gamma activity across texture representation in monkey striate cortex. , 2000, Cerebral cortex.

[14]  R. Eckhorn,et al.  Flexible cortical gamma-band correlations suggest neural principles of visual processing , 2001 .

[15]  Reinhard Eckhorn,et al.  Feature Linking via Synchronization among Distributed Assemblies: Simulations of Results from Cat Visual Cortex , 1990, Neural Computation.

[16]  R. Eckhorn,et al.  Stimulus-specific fast oscillations at zero phase between visual areas V1 and V2 of awake monkey. , 1994, Neuroreport.

[17]  R. Eckhorn,et al.  Task-related coupling from high- to low-frequency signals among visual cortical areas in human subdural recordings. , 2004, International journal of psychophysiology : official journal of the International Organization of Psychophysiology.

[18]  C. Gray.  The Temporal Correlation Hypothesis of Visual Feature Integration Still Alive and Well , 1999, Neuron.

[19]  T. Bullock,et al.  EEG coherence has structure in the millimeter domain: subdural and hippocampal recordings from epileptic patients. , 1995, Electroencephalography and clinical neurophysiology.

[20]  R. Eckhorn,et al.  Perception-related modulations of local field potential power and coherence in primary visual cortex of awake monkey during binocular rivalry. , 2004, Cerebral cortex.

[21]  Roman Bauer,et al.  Fast oscillations display sharper orientation tuning than slower components of the same recordings in striate cortex of the awake monkey , 2000, The European journal of neuroscience.

[22]  Roman Bauer,et al.  Perceptual grouping correlates with short synchronization in monkey prestriate cortex , 2002, Neuroreport.

[23]  D. Contreras,et al.  Synchronization of fast (30-40 Hz) spontaneous cortical rhythms during brain activation , 1996, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[24]  H. J. Reitboeck,et al.  A Multi-Electrode Matrix for Studies of Temporal Signal Correlations Within Neural Assemblies , 1983 .