Synchronized oscillatory activity in a frequency range of approximately 20-100Hz (the so-called ‘gammaband’ sometimes also referred to as ’40Hz activity’) is considered as a signature of the binding of the various features of a stimulus, which are processed in separate cortical areas. In particular, increased gammaband activity at approximately 200-400ms after stimulus onset is hypothesized to reflect the activation of cortical object representations. Numerous human EEG studies provided evidence for the representational hypothesis.

However, recently these findings were challenged by the work of Yuval-Greenberg et al. (2008) who stated that gammaband responses are an artefact caused by microsaccades. According to them microsaccades are accompanied by short spike potentials, which are the true source of activity in the gammaband frequency range.

In my talk I will explain how microsaccades might lead to patterns of activity, which might be erroneously interpreted as oscillatory activity of cortical origin. Furthermore, I will suggest some strategies how to deal with the artefactual influence of eye movements on gammaband responses. Furthermore, evidence will be presented that it would be overly pessimistic to conclude that all EEG gammaband activity has its source in microsaccades.