Attention-dependent changes in network configuration: a basic neuronal mechanism enabling flexible and goal directed behavior

Eric Drebitz, Universität Bremen, AG Prof. Andreas Kreiter



For fast and effective behavior in a natural environment, the brain must restrict itself to the processing of relevant information for decision-making. It also needs to be able to switch its focus of processing flexibly in dependence of changes in the environment or a change of the motivational state, such as appetite or thirst. These requirements and restrictions imply a need for a mechanism, which selects and routes currently relevant information along the visual processing pathways, while it suppresses irrelevant information. Furthermore, this mechanism needs to be sufficiently fast and flexible in order to cope with changing demands on behavior. However, the timescale at which network functions need to change is too fast for changes of anatomical connections between neurons. Hence, it has been hypothesized that the selective processing of relevant information is based on fast changes of the correlation between neuronal activity patterns. This hypothesis is supported by the observation of attention-dependent modulations of the synchronization between neuronal populations encoding and processing the currently relevant information. However, so far there has been no demonstration of a causal relation between the modulation of synchronization and changes in selective signal transmission. Therefore, we applied weak signals by intracortical microsimulation within the visual system of macaque monkeys performing an attention task. We found that the impact of these additional signals, which were delivered to neurons in area V2, on downstream area V4 and on behavior strongly, depended on the phase of γ-oscillatory activity in V4. These findings strongly support the idea of temporal synchronization and desynchronization as a mechanism for selective information routing and processing.


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