Changes in sleep spindle activity of subjects with chronic somatosensitive and sensorial deficits. Preliminary results

Abstract

We investigated the effects of the somatosensitive and sensory afferent inputs on the thalamic generators of sleep spindles (SS) in adult subjects affected by posterior funiculi lesions (five subjects), deafness (four subjects) or blindness (four subjects). The density, duration and frequency of SS, as well as the index of spindling, were analyzed during stage 2 NREM. The results show that the subjects with somatosensitive and sensorial lesions spent much more time on SS activity than the control group (eight subjects), and had a significantly increased density (< .0001), duration (< .0005) and index of spindling (< .0001). On the other hand, the frequency of spindling was little modified (< .05). Moreover, among the three groups of patients, those with somatosensitive deficits showed the greatest SS activity. In conclusion, our results suggest that the thalamic generators of SS are markedly modulated by peripheral inputs in man.

Nocturnal sleep spindle activity in blind subjects

“…Scrofani et al reported that four blind subjects resulted in increased sleep spindle activity relative to the control group. 3 This finding does not agree with the results of the present study. The blind subjects in this study showed a decrease in the total number and numbers/min of sleep spindle compared to the values found in sighted persons.…”

“…Thus, these results indicate that the absence of input from the sensory system might affect the synchronization system in the thalami‐cortical neurons, although we have no reasons to discuss the disagreement with Scrofani et al ’s results. 3 …”

“…Recently, Scrofani et al reported an increase in sleep spindle activity in subjects affected by posterior funiculi lesions, deafness or blindness compared to the control group. 3 This study also investigated sleep spindle activity during nocturnal sleep in five congenital blind subjects to determine the relationship between the sensory input and the synchronization system of electroencephalogram (EEG).…”

Structural brain correlates of human sleep oscillations

“…Indeed, focusing on audition as the prime exogenous route of sensory sleep interference, recent findings have demonstrated that inter-individual variability in sleep spindles over sensory cortex predicts the extent to which the sleep state is protected and hence conserved in response to experimental auditory stimulation (Dang-Vu et al, 2010a). Circumstances of acquired hearing loss have further been associated with decreases in auditory grey matter and congruent reductions in slow-frequency spindles (Landgrebe et al, 2009; Scrofani et al, 1996). These associations between slower sleep spindle frequency and grey matter volume in sensory areas may reflect the role of sleep spindles (of slower frequency) in the protection from sensory disruption (both extereoceptive, and intereoceptive) during sleep.…”

Evidence for an Association Between Hearing Impairment and Disrupted Sleep: Scoping Review

“…However, statistically significant within-group increases in EEG activity were reported for Stage 2 and REM sleep for the implanted participants when the device was turned off; the authors attributed this to neural plasticity induced by a lack of auditory input. Scrofani et al (1996) used EEG to investigate sleep spindles (SS; a distinctive, non-REM, thalamocortical EEG oscillation) activity in four deaf participants, as part of a larger study into pathological deafferentation of somatosensory and sensory inputs. The authors report statistically significant increases in SS activity, including increased SS frequency and duration in deaf participants compared with controls.…”