Entrainment of Neuronal Oscillations as a Mechanism of Attentional Selection

Abstract

Whereas gamma-band neuronal oscillations clearly appear integral to visual attention, the role of lower-frequency oscillations is still being debated. Mounting evidence indicates that a key functional property of these oscillations is the rhythmic shifting of excitability in local neuronal ensembles. Here, we show that when attended stimuli are in a rhythmic stream, delta-band oscillations in the primary visual cortex entrain to the rhythm of the stream, resulting in increased response gain for task-relevant events and decreased reaction times. Because of hierarchical cross-frequency coupling, delta phase also determines momentary power in higher-frequency activity. These instrumental functions of low-frequency oscillations support a conceptual framework that integrates numerous earlier findings.

Encoding of event timing in the phase of neural oscillations

“…In all lag-adaptation blocks, AV stimuli were presented at a rate of 1 Hz ± 100 ms. The temporal jitter was introduced to prevent full neural response time-locking and enable the dissociation of the oscillatory component from the evoked response (Lakatos et al, 2008). In both (A) and (C): one participant's superimposed single trial data (black) with the visual evoked response (red) at the end of A200V in visual cortex (A) and in auditory cortex (C).…”

“…In cortex, low-frequency neural oscillations are known to regulate the excitability of neural ensembles such that specific phases of lowfrequency neural oscillations are associated with periods of high and low neuronal excitability (Buzsáki, 2010;Lakatos et al, 2008;Schroeder and Lakatos, 2009): the phase of low-frequency neural oscillations modulates the power of high-frequency neural oscillatory responses, a mechanism known as phase-power or cross-frequency coupling (Canolty et al, 2006). Neural synchronizations in higher frequency ranges (e.g.…”

“…gamma range, N 40 Hz) provide a reliable index of feature binding within and across sensory modalities (Arnal et al, 2011;Engel et al, 1991;Roelfsema et al, 1997;Senkowski et al, 2008;Tallon-Baudry and Bertrand, 1999). In multisensory integration, low-frequency neural oscillations (delta, 1-2 Hz) play a crucial role in the temporal selection (Besle et al, 2011;Fiebelkorn et al, 2013;Gomez-Ramirez et al, 2011;Lakatos et al, 2008;Schroeder and Lakatos, 2009) and in the integration of AV information (Fiebelkorn et al, 2011;Kösem and van Wassenhove, 2012;Luo et al, 2010).…”

“…It is well known that distinct phases of low-frequency neural oscillations are associated with periods of high and low neural excitability (Buzsáki, 2010;Lakatos et al, 2008). These fluctuations have been shown to impose temporal constraints on the "what" of perception by modulating the perceptual detection threshold of various stimuli (Busch et al, 2009;Fiebelkorn et al, 2013;Henry and Obleser, 2012;Monto et al, 2008;Neuling et al, 2012).…”

“…Here, we hypothesize that the brain could use oscillatory entrainment to establish a temporal reference frame and we thus ask whether the phase of entrained neural oscillations actually encodes the "when" of perception. Specifically, the preferred phase of oscillatory entrainment is known to be context-dependent (Besle et al, 2011;Gomez-Ramirez et al, 2011;Lakatos et al, 2008;Rees et al, 1986), suggesting that neural entrainment may not be a passive neural response. Additionally, preferential phases of entrained neural oscillations are subject-specific (Besle et al, 2011), making this neural index particularly well-suited for investigating the highly subjective and variable nature of time perception.…”