Neuronal assemblies typically synchronize within the gamma band (30-80 Hz) and are fundamental to... more Neuronal assemblies typically synchronize within the gamma band (30-80 Hz) and are fundamental to information processing. Despite numerous investigations, the exact mechanisms and origins of gamma oscillations are yet to be known. Here, through multiunit recordings in the primary visual cortex of cats we show that the strength of gamma power (20-40 Hz and 60-80 Hz) is significantly stronger between the functionally connected units than the unconnected units within an assembly. Furthermore, there is increased frequency coherence in the gamma range between the connected units than the unconnected units. Lastly, the higher gamma rhythms (60-80 Hz) are mostly linked to the fast-spiking neurons. These results led us to postulate that gamma activity is intrinsically generated between the connected units within cell-assemblies (microcircuits) in relation to the stimulus within an emergent '50 ms-temporal window-of-opportunity'. This article is protected by copyright. All rights res...
Cortical organization rests upon the fundamental principle that neurons sharing similar propertie... more Cortical organization rests upon the fundamental principle that neurons sharing similar properties are co-located. In the visual cortex, neurons are organized into orientation columns. In a column, most neurons respond optimally to the same axis of an oriented edge, that is, the preferred orientation. This orientation selectivity is believed to be absolute in adulthood. However, in a fully mature brain, it has been established that neurons change their selectivity following sensory experience or visual adaptation. Here, we show that after applying an adapter away from the tested cells, neurons whose receptive fields were located remotely from the adapted site also exhibit a novel selectivity in spite of the fact that they were not adapted. These results indicate a robust reconfiguration and remapping of the orientation domains with respect to each other thus removing the possibility of an orientation hole in the new hypercolumn. These data suggest that orientation columns transcend anatomy, and are almost strictly functionally dynamic.
Neuronal assemblies typically synchronize within the gamma band (30-80 Hz) and are fundamental to... more Neuronal assemblies typically synchronize within the gamma band (30-80 Hz) and are fundamental to information processing. Despite numerous investigations, the exact mechanisms and origins of gamma oscillations are yet to be known. Here, through multiunit recordings in the primary visual cortex of cats we show that the strength of gamma power (20-40 Hz and 60-80 Hz) is significantly stronger between the functionally connected units than the unconnected units within an assembly. Furthermore, there is increased frequency coherence in the gamma range between the connected units than the unconnected units. Lastly, the higher gamma rhythms (60-80 Hz) are mostly linked to the fast-spiking neurons. These results led us to postulate that gamma activity is intrinsically generated between the connected units within cell-assemblies (microcircuits) in relation to the stimulus within an emergent '50 ms-temporal window-of-opportunity'. This article is protected by copyright. All rights res...
Cortical organization rests upon the fundamental principle that neurons sharing similar propertie... more Cortical organization rests upon the fundamental principle that neurons sharing similar properties are co-located. In the visual cortex, neurons are organized into orientation columns. In a column, most neurons respond optimally to the same axis of an oriented edge, that is, the preferred orientation. This orientation selectivity is believed to be absolute in adulthood. However, in a fully mature brain, it has been established that neurons change their selectivity following sensory experience or visual adaptation. Here, we show that after applying an adapter away from the tested cells, neurons whose receptive fields were located remotely from the adapted site also exhibit a novel selectivity in spite of the fact that they were not adapted. These results indicate a robust reconfiguration and remapping of the orientation domains with respect to each other thus removing the possibility of an orientation hole in the new hypercolumn. These data suggest that orientation columns transcend anatomy, and are almost strictly functionally dynamic.
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