Independent Causal Contributions of Alpha- and Beta-Band Oscillations during Movement Selection

Abstract

To select a movement, specific neuronal populations controlling particular features of that movement need to be activated, whereas other populations are downregulated. The selective (dis)inhibition of cortical sensorimotor populations is governed by rhythmic neural activity in the alpha (8 -12 Hz) and beta (15-25 Hz) frequency range. However, it is unclear whether and how these rhythms contribute independently to motor behavior. Building on a recent dissociation of the sensorimotor alpha-and beta-band rhythms, we test the hypothesis that the beta-band rhythm governs the disinhibition of task-relevant neuronal populations, whereas the alpha-band rhythm suppresses neurons that may interfere with task performance. Cortical alpha-and beta-band rhythms were manipulated with transcranial alternating current stimulation (tACS) while human participants selected how to grasp an object. Stimulation was applied at either 10 or 20 Hz and was imposed on the sensorimotor cortex contralaterally or ipsilaterally to the grasping hand. In line with task-induced changes in endogenous spectral power, the effect of the tACS intervention depended on the frequency and site of stimulation. Whereas tACS stimulation generally increased movement selection times, 10 Hz stimulation led to relatively faster selection times when applied to the hemisphere ipsilateral to the grasping hand, compared with other stimulation conditions. These effects occurred selectively when multiple movements were considered. These observations functionally differentiate the causal contribution of alpha-and beta-band oscillations to movement selection. The findings suggest that sensorimotor beta-band rhythms disinhibit task-relevant populations, whereas alpha-band rhythms inhibit neuronal populations that could interfere with movement selection.

Transcranial Alternating Current Stimulation (tACS) Mechanisms and Protocols

“…A tACS-fMRI investigation revealed that the behavioral change was positively correlated with BOLD activity in primary motor cortex (M1) but it was negatively correlated with activity in dorsomedial prefrontal cortex, a region regarded as a locus of executive motor control (Moisa et al, 2016 ). Brinkman et al ( 2016 ) compared alpha and beta tACS to investigate movement selections. Enhanced movement acceleration and velocity were achieved with gamma band entrainment of the M1 (Moisa et al, 2016 ), and sensorimotor integration was promoted by beta band entrainment (Guerra et al, 2016 ).…”

Electrocorticographic dissociation of alpha and beta rhythmic activity in the human sensorimotor system

“…Second, we considered the slope of the power-spectral density function (1/f slope), a summary index of synaptic excitation/inhibition balance (Gao et al, 2017). Furthermore, rather than assuming that alpha-and beta-band rhythms are spatially stationary across the sensorimotor cortex (Brinkman et al, 2016(Brinkman et al, , 2014, we examined the spatiotemporal distribution of the two sensorimotor rhythms and their cortical effects through two complementary analyses. First, we considered the organization of spatially systematic phase relationships among rhythmic signals (traveling waves) across the sensorimotor cortex (Ermentrout and Kleinfeld, 2001;Muller et al, 2018).…”

Modulation of Somatosensory Alpha Rhythm by Transcranial Alternating Current Stimulation at Mu-Frequency

“…Non-invasive brain stimulation methods such as transcranial alternating current stimulation (tACS) may offer a possibility to modulate neuronal oscillatory activity (for a review, see Herrmann et al, 2013 ) and human brain function in different modalities such as vision (Kanai et al, 2008 ; Laczó et al, 2012 ; Brignani et al, 2013 ; Helfrich et al, 2014a , b ; Cabral-Calderin et al, 2015 ; Vossen et al, 2015 ; Kasten et al, 2016 ; Vosskuhl et al, 2016 ), motor function (Pogosyan et al, 2009 ; Feurra et al, 2011a ; Schutter and Hortensius, 2011 ; Joundi et al, 2012 ; Brittain et al, 2013 ; Wach et al, 2013 ; Krause et al, 2014 ; Brinkman et al, 2016 ; Lustenberger et al, 2016 ; Moisa et al, 2016 ), audition (Neuling et al, 2012 ; Riecke et al, 2015 ; Heimrath et al, 2016 ; Riecke, 2016 ; Rufener et al, 2016 ), somatosensation (Feurra et al, 2011b ; Gundlach et al, 2016 ), and higher cognitive functions such as decision making, risk taking behavior, creativity, fluid intelligence, mental rotation or self-aware dreaming (Sela et al, 2012 ; Herrmann et al, 2013 ; Voss et al, 2014 ; Lustenberger et al, 2015 ; Santarnecchi et al, 2016 ; Kasten and Herrmann, 2017 ). In addition there is preliminary evidence that alternating current stimulation might be effective to support recovery of function in patients with stroke (Fedorov et al, 2010 ; Naros and Gharabaghi, 2017 ) or optic neuropathy (Sabel et al, 2011 ; Schmidt et al, 2013 ).…”