Project The sensorimotor µ-rhythm as cholinergically controlled pulsed inhibition

Basic data

Title:
The sensorimotor µ-rhythm as cholinergically controlled pulsed inhibition
Duration:
01/12/2017 to 30/11/2020
Abstract / short description:
The most pronounced neuronal oscillation observable in the electroencephalography (EEG) of the awake and healthy human brain is the 8-14 Hz alpha oscillation. In the sensorimotor cortex, serving as the model region in this project, it is called the mu-rhythm. Initially thought to simply reflect cortical idling, alpha/mu oscillations are nowadays believed to actively gate information flow in the brain. The influential Pulsed Inhibition Hypothesis assumes that the alpha/mu oscillation is asymmetric and composed of recurring bouts of inhibition, which become stronger with increasing amplitude, thereby rhythmically suppressing neural processing in task-irrelevant cortical regions. However, the proposed asymmetric and inhibitory nature of the oscillation has never been directly demonstrated. Moreover, alpha/mu oscillations must be under top-down control of attention, since the mere anticipation of an upcoming stimulus already modulates their amplitude. Yet, also the neuronal implementation of its top-down control is still unknown. It has been hypothesized that cortico-cortical projections from the prefrontal cortex modulate the local release of acetylcholine from ascending basal forebrain cholinergic neurons in the sensory cortices via axo-axonal synapses. Acetylcholine is known to regulate the de /synchronization of neuronal activity. Therefore, prefrontally mediated transient changes in the cholinergic modulation of local sensory alpha/mu oscillations and thus cortical excitability may represent the neural mechanism, underlying the attentional gating of perception as well as resulting stimulus-induced synaptic plasticity. I will test the hypotheses of pulsed inhibition and a prefrontally controlled cholinergic alpha modulation for the model case of the sensorimotor mu-rhythm. The combination of transcranial magnetic stimulation (TMS) of the primary motor cortex with concurrent EEG assessment of the sensorimotor mu-rhythm allows to noninvasively study cortical excitability and intra-cortical inhibition in an amplitude and phase-dependent manner in the human brain. The project is composed of two major parts. Firstly, I will use real-time EEG-triggered single- and paired-pulse TMS to study the neural mechanisms mediating fluctuations in phase and amplitude of the spontaneous sensorimotor mu-rhythm and their implication for the induction of synaptic plasticity. Secondly, I will employ (anti )cholinergic pharmacological interventions and a virtual lesion approach using repetitive TMS to uncover the neural mechanisms mediating top-down control of the mu-rhythm in the context of a tactile spatial attention task. Together the project is expected to provide fundamentally new insights into the neurophysiological underpinnings of the alpha/mu oscillations, their role in gating information processing and synaptic plasticity, and the prefrontal and cholinergic mechanisms of their attentional top-down control.
Keywords:
mu-rhythm
alpha oscillation
pulsed inhibiton
acetylcholine
EEG
electroencephalography, Elektroenzephalografie
EEG-triggered TMS

Involved staff

Managers

University Department of Neurology
Hospitals and clinical institutes, Faculty of Medicine

Contact persons

University Department of Neurology
Hospitals and clinical institutes, Faculty of Medicine

Local organizational units

Department of Neurology with Focus on Neurovascular Diseases
University Department of Neurology
Hospitals and clinical institutes, Faculty of Medicine

Funders

Bonn, Nordrhein-Westfalen, Germany
Help

will be deleted permanently. This cannot be undone.