Gamma oscillations in human visual cortex

Monday 18 September 2023, 12:30 pm
PhD student
B.M.J. Kausch-Blecken von Schmeling MSc.
prof. dr. P. Fries, prof. dr. D. Poeppel

Visual gamma oscillations are a network phenomenon generated by excitation-inhibition interactions in early visual cortex. They depend on stimulus drive and homogeneity, can be influenced by cognitive and stimulus-history factors, and have been proposed to underlie both the binding of visual information into objects, and selective neuronal communication. While tremendous progress has been achieved over the last thirty years, many questions on the mechanisms, prerequisites, and functions of gamma oscillations remain. 
Using MEG and psychophysical experiments in human participants, I have demonstrated that a) colored stimuli of equal L-M retinal cone contrast induce equally strong gamma oscillations, that b) gamma oscillations show gamma repetition suppression over few stimulus repetitions and gamma repetition enhancement over many repetitions, that gamma repetition enhancements are stimulus-specific, persist over many minutes and strengthen feedforward functional connectivity along the visual hierarchy, and that c) as predicted by the CTC hypothesis of gamma function, phase-leading stimuli are processed and perceived more intensely than phase-lagging stimuli. 
Thereby, this work advances the understanding of gamma oscillations in humans and integrates recent research into a comprehensive account of their stimulus dependencies and effects. 

Benjamin Kausch-Blecken von Schmeling was born as Benjamin Stauch on November 23, 1991 in Bremen, Germany. He studied Psychology at the Technische Universität Dresden, attaining his B.Sc. in 2015 with a bachelor thesis on the effects of glucocorticoid receptor gene methylation and childhood trauma on cortisol stress reactivity, written under the supervision of Prof. Nina Alexander. He continued his studies at Westfälische Wilhelms-Universität Münster, where he graduated in 2017 with a master thesis on the modulation of directed forgetting using rTMS stimulation of the dorsolateral prefrontal cortex, written in the lab of Prof. Simon Hanslmayr. Having discovered the fascinating research field of human oscillatory brain responses and their non-invasive measurement using MEG and EEG recordings in Simon Hanslmayr's lab, he applied for a PhD position in the lab of Prof. Pascal Fries through the International Max Planck Research School (IMPRS) for Neural Circuits Frankfurt, where he undertook his doctoral work.