Viselkedési neurobiológia (pl. alvás, tudatosság, jobb- és balkezesség)
Sleep spindles are major oscillatory components of Non-Rapid Eye Movement (NREM) sleep,
reflecting hyperpolarization-rebound sequences of thalamocortical neurons. Reports
suggest a link between sleep spindles and several forms of high-frequency oscillations
which are considered as expressions of pathological off-line neural plasticity in
the central nervous system. Here we investigated the relationship between thalamic
sleep spindles and ripples in the anterior and mediodorsal nuclei (ANT and MD) of
epilepsy patients. Whole-night LFP from the ANT and MD were co-registered with scalp
EEG/polysomnography by using externalized leads in 15 epilepsy patients undergoing
a Deep Brain Stimulation protocol. Slow (~12 Hz) and fast (~14 Hz) sleep spindles
were present in the human ANT and MD and roughly, 20% of them were associated with
ripples. Ripple-associated thalamic sleep spindles were characterized by longer duration
and exceeded pure spindles in terms of spindle power as indicated by time-frequency
analysis. Furthermore, ripple amplitude was modulated by the phase of sleep spindles
within both thalamic nuclei. No signs of pathological processes were correlated with
measures of ripple and spindle association, furthermore, the density of ripple-associated
sleep spindles in the ANT showed a positive correlation with verbal comprehension.
Our findings indicate the involvement of the human thalamus in coalescent spindle-ripple
oscillations of NREM sleep.
