TRANSIENT PHASE-LOCKING AND DYNAMIC CORRELATIONS - ARE THEY THE SAME THING

This work represents an attempt to bring together two important themes in neuronal dynamics. The first is the characterization of dynamic co rrelations in multiunit recordings of spike activity using joint-peri- stimulus time histograms (J-PSTHs) [Aertsen and Preissl, 1991: Non Lin ear Dynamics and Neural Networks]. The second is transient phase-locki ng at high (gamma) frequencies, either in terms of spiking in separabl e spike trains [e.g., Eckhorn et al., 1988: Biol Cybern 60:121-130, Gr ay and Singer, 1989 Proc Natl Acad Sci USA 86:1698-1702], or using con tinuous electrical or biomagnetic signals [e.g., Desmedt and Tomberg, 1994 Neurosci Lett 168:126-129]. In this paper we suggest that transie nt phase-locking is necessary for frequency-specific, dynamic event-re lated correlations. This point is demonstrated using the gamma-frequen cy (36 Hz) component of neuromagnetic signals measured in the prefront al and partial regions of a subject during self-paced movements. A J-P STH analysis revealed dynamic changes in prefronto-parietal correlatio ns in relation to movement onset. These frequency-specific dynamic cor relations were associated with changes in the degree of phase-locking, of the sort reported by Desmedt and Tomberg [1994 Neurosci Lett 168:1 26-129]. (C) 1997 Wiley-Liss, Inc.