Towards a systematization of brain oscillatory activity in actions

Abstract

Information processing in the brain is governed by oscillatory activity. Activity oscillations in specific frequency bands (theta, alpha, beta and gamma) have been associated with various cognitive functions. A drawback of this is that the plethora of findings led to considerable uncertainty as to the functional relevance of activity in different frequency bands and their interrelation. Here, we use a novel cognitive-science theoretical framework to better understand and conceptually harmonize neurophysiological research on human action control. We outline how this validated starting point can systematize and probably reframe the functional relevance of oscillatory activity relevant for action control and beyond.

Fig. 1. Principles of the BRAC-framework.

a Characteristics of commonly used experimental tasks to examine action control. Most tasks reveal a sequential structure (a trial n-1 to trial n structure), i.e., two consecutive displays are presented – the prime display followed by the probe display. Behavioral performance as well as neurophysiological processes underlying action control are typically examined at the probe. Crucially, BRAC states that binding/integration takes place at the prime and that upon feature repetition at the probe retrieval reinstates the prime-event file. b Schematical illustration of the BRAC framework delineating how event-files are managed. The event-file is at the core of the framework, which assumes two central processes: (i) the binding of stimulus (S), response (R) and effect features (E) into the event-file. (ii) a retrieval process of a previously bound event-file whenever one of the S, R or E features is re-encountered. This reflects the retrieval of an episodic memory trace. Importantly, binding and retrieval processes work independently from each other and are both subject to top-down or bottom-up modulatory effects.

Fig. 2. Oscillatory activity systematized using BRAC.

Oscillatory activity in the theta, alpha, beta and gamma frequency band mapped on the mechanistic structure of the BRAC framework. Alpha band activity is likely to be central for top-down (i.e., attentional weighting/instruction-based processes) and bottom-up (i.e., experience-based processes/perception) modulatory effects on binding and retrieval processes. Theta band activity is thus directly modulated by alpha band activity, because theta band activity is supposed to reflect binding and retrieval processes impinging on event-files Gamma band activity is also part of this dynamics, especially as far as the encoding/retrieval of locally bound stimulus features underlying a coherent perception are concerned. Beta band activity is thought to be essential for constituting the event-file structure and is thus subject to theta/gamma band activity effects underlying binding and retrieval processes.