Thesis supervisor: Prof. Dr. Volker Franz Co-Supervision: Iris Zerweck

Abstract

Rhythmic stimulus presentation is a concept used in multiple sensory modalities and widely used; in the EEG, rhythmic oscillations in the alpha range (7 - 14 Hz) are one of the most prominent patterns. Interindividual differences in these rhythms can be demonstrated, characterizing complex neural activity into an easily measurable marker. Individual resting state alpha frequencies (IAF) and their characteristics (power, phase, frequency) have been shown to correlate with complex cognitive functions, such as the attentional blink (MacLean, Arnell & Cote, 2012) or temporal visual perception (Ronconi, Busch & Melcher, 2018). By presenting rhythmic stimuli, oscillatory activity in the brain can be entrained and subsequentially influences stimulus processing (Mathewson et al., 2012). The present study aimed to examine to what extent IAF and visually entrained frequencies influence the processing of near-threshold (masked) stimuli. No effects of IAF or entrainment to different frequencies (8, 12, 30 Hz) could be found. This result demonstrates that the frequency of rhythmic brain activity itself did not prove to be a reliable indicator of the temporal resolution of the visual system in the discrimination task used here. The speed of visual processing as examined by briefly presented masked stimuli does not seem to be connected to the dominant alpha frequencies during resting states. Further examination of IAF and visual alpha oscillations is required to examine their connection to the speed of visual processing.