Dynamics and plasticity of information processing in the cerebral cortex

In the cerebral cortex information processing strongly relies on the connectivity between different areas. So far, investigations have concentrated on the role of feed-forward connections linking lower areas to higher order centers. However, there is also a dense network of feed-back connections which transmit signals back to the primary sensory areas. We have investigated the role of these connections using optical and electrophysiological recording techniques in combination with reversible deactivation methods and showed that feed-back connections exert a strong influence over the neuronal processes in early sensory areas. Moreover, we investigated how use-dependent cortical plasticity is related to different states of cortical processing and found that only in states of high frequency oscillatory activity, which are related to wakefulness and attention, an enhancement of the representations of repetitively experienced stimuli can be induced.