Abstract
Recently we hypothesized that the intention to initiate a voluntary movement at free will may be related to the dynamics of hemodynamic variables, which may be supported by the intertwining of networks for the timing of voluntary movements and the control of cardiovascular variables in the insula. In the present study voluntary movements of 3 healthy subjects were analyzed using fMRI scans at 1.83-s intervals along with the time course of slow hemodynamic changes in sensorimotor networks. For the analyses of BOLD time courses the Wavelet transform coherence (WTC) and calculation of phase-locking values were used. Analyzed was the frequency band between 0.07 and 0.13 Hz in the supplementary motor area (SMA) and insula, two widely separated regions co-active in motor behavior. BOLD signals displayed slow fluctuations, concentrated around 0.1 Hz whereby the intrinsic oscillations in the insula preceded those in the SMA by 0.5–1 s. These preliminary results suggest that slow hemodynamic changes in SMA and insula may condition the initiation of a voluntary movement at free will.
Highlights
How voluntary movements originate is a classic problem in Neuroscience
It is noteworthy to underline that the anterior insular cortex (AIC), the rostral-frontal insular cortex (Cauda et al, 2011), besides its putative role in the initiation of movement, i.e., the “when” component, has a major role in the integration of visceral sensory information arising from baroreceptors and chemoreceptors within the cardiovascular system and plays a role in the efferent control of baroreflex function (Verberne and Owens, 1998; Zhang et al, 1999; Craig, 2004)
In this relationship we refer to the findings of Monto et al (2008) that the slow ongoing intrinsic oscillations reflect excitability changes in cortical networks correlated with slow fluctuations in human psychophysical performance
Summary
How voluntary movements originate is a classic problem in Neuroscience. It is generally assumed that voluntary movements result from neuronal activity in premotor and motor cortical areas that precedes the conscious decision to move. Both ACC and AIC are co-active in so many behaviors and during cognition, pain and emotions (Yarkoni et al, 2011) Be as it may, it is noteworthy to underline that the AIC, the rostral-frontal insular cortex (Cauda et al, 2011), besides its putative role in the initiation of movement, i.e., the “when” component, has a major role in the integration of visceral sensory information arising from baroreceptors and chemoreceptors within the cardiovascular system and plays a role in the efferent control of baroreflex function (Verberne and Owens, 1998; Zhang et al, 1999; Craig, 2004). It appears that in the AIC different kinds of neuronal processes are intertwined: those associated with the initiation of voluntary movement, and those involved in the control of cardiovascular functions, the precise neuronal networks supporting these intertwining processes are not yet clearly defined
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