Resting BOLD fluctuations in the primary somatosensory cortex correlate with tactile acuity

Abstract

Sensory perception, including 2-point discrimination (2ptD), is tightly linked to cortical processing of tactile stimuli in primary somatosensory cortices. While the role of cortical activity in response to a tactile stimulus has been widely investigated, the role of baseline cortical activity is largely unknown. Using resting state fMRI we investigated the relationship between local BOLD fluctuations in the primary somatosensory cortex (the representational field of the hand) and 2ptD of the corresponding index finger (right and left). Cortical activity was measured using fractional amplitudes of the low frequency BOLD fluctuations (fALFF) and synchronicity using regional homogeneity (ReHo) of the S1 hand region during rest. 2ptD correlated with higher ReHo values in the representational areas of the contralateral S1 cortex (left hand: p = .028; right hand: p = .049). 2ptD additionally correlated with higher fALFF in the representational area of the left hand (p = .007) and showed a trend for a significant correlation in the representational area of the right hand (p = .051). Thus, higher BOLD amplitudes and synchronicity at rest, as measures of cortical activity and synchronicity, respectively, are related to better tactile discrimination abilities of the contralateral hand. Our findings extend the relationship seen between spontaneous BOLD fluctuations and sensory perception.

Alterations of resting‐state fMRI measurements in individuals with cervical dystonia

“…Namely, accurate sensorimotor functions require a precision of neural representation with surrounding nonspecific activities suppressed. A recent rfMRI study in healthy individuals has shown that higher local signal amplitude and synchronicity in the somatosensory cortex, measured with fALFF and ReHo respectively, are related to better tactile discrimination abilities [Haag et al, 2015]. Based on this report, the present observation of decreased ReHo in the postcentral gyrus may also reflect impaired surround inhibition in individuals with CD suggesting impaired ability of proper control of agonist and antagonist muscles involved in head movements.…”

Altered interhemispheric resting state functional connectivity during passive hyperthermia

“…The increased VMHC under heat stress probably reflects the thermal sensation of the body, as a recent animal study has revealed that stress increases connectivity within the somatosensory networks [37]. In addition, the primary somatosensory cortex activity correlates with sensory perception and task performance [38,39]. As we did not measure sensory perception and task performance in the current study, the correlation between VMHC of the primary somatosensory cortex activity and sensory perception or task performance under heat stress needs to be explored in future studies.…”

Abnormal Local Brain Activity Beyond the Pain Matrix in Postherpetic Neuralgia Patients: A Resting-State Functional MRI Study

“…Then spatial smoothing was performed on the standardized individual ReHo map with a Gaussian kernel of 4 mm full-width at half maximum (FWHM) (21). After the preprocessing, fALFF were computed as previously described (11,14). First, the resampled images were smoothed with a Gaussian kernel of 4 mm.…”

“…The spontaneous local brain activity can be quantitatively measured by regional homogeneity (ReHo) (9,10) and fractional amplitude of the low frequency fluctuations (fALFF) (11,12). Both of them are powerful and reliable indices in evaluating resting-state brain activity (13)(14)(15). ReHo was first proposed by Zang et al (9).…”