SLEEP PHYSIOLOGY AS AN APPROACH OF DIFFERENTIAL PSYCHOLOGY: SIGNIFICANCE OF INDIVIDUAL EEG PATTERNS

One of the well described aspects of the electrophysiology of sleep is related to the organization of neural systems in synchronized oscillations. Beside the general aspects of these oscillations there is increasing evidence for the existence of some individual-specific traits, which can be quantified by the individual topographic and spectral fingerprints of sleep-EEG. Individual fingerprints of human sleep-EEG are characterized by remarkable stability, bidirectional relationship with neural plasticity and definiteness by neural connectivity. Given the latter characteristic, these fingerprints could play an important role in research work aiming to reveal the neurobiological bases of psychological differences. Accumulating evidence supports the pertinence of this approach. Correlations of sleep-dependent slow wave activity with memory and executive functions were found, while sleep spindling was shown to have a complex relationship with cognitive performance. This relationship may shed light on the neurobiological bases of general mental ability or intelligence. Some preliminary data supporting the correlation between sleep-EEG and the affective traits of human subjects strengthen the differential psychological relevance of sleep-EEG activity. Given the fact that individual functional neuroanatomy is a major factor that shapes sleep-EEG oscillations, the latter reflect the actual state of synaptic infrastructure. However, by facilitating plastic processes neural oscillations also open the door to the efficient and adaptive reorganization of neural connectivity.