It has been suggested that the period of sleep onset is particularly suitable for
making evoked response studies in infants and children. However, it has been shown
in animals that sleep spindles which occur during this period interfere with the mediation
of afferent impulses to the cortex. We therefore investigated somatosensory and auditory
evoked responses in 12 babies aged 5–9 months whilst sleep spindles were present in
the EEG and compared them to those obtained when spindles were absent. No consistent
differences in shape, latency or amplitude of the evoked responses were found when
spindles were present and when they were absent. Three possible explanations for this
findings are discussend: 1. Primary sensory pathways are less important for cortical
evoked responses in young children than they are in adults. 2. Spindles produced in
thalamic centers besides the somasensory relay nuclei have obscured the effect of
an occlusion occuring in the relay nuclei during spindle generation. 3. EEG spindles
in early ontogenetic stages are produced in the cortex itself and are not dependent
on thalamo-cortical pathways.
Sleep - sleep spindles - somatosensory evoked responses - auditory evoked responses
