Postnatal development of XXXX hippocampal gamma rhythm in vivo.

@entity131 @entity11728 @entity70590 @entity1251 @entity35 @entity25
Network oscillations in the gamma-frequency band (20-100 Hz) may have a central role in the timing and coordination of neural activity in the adult brain, yet their appearance in the course of development has remained unexplored. Moreover, electroencephalogram (EEG)-based classification of the vigilance states [ @entity25 ( @entity25 ), quiet sleep (QS), or awake (W)] has been thought to be possible only after the second postnatal week. We now report the presence of spontaneous @entity131 in the area @entity1251 of freely moving @entity35 at postnatal days (P) 5-10. Initially, at P5, the @entity11728 were seen in time-frequency analyses of intrahippocampal EEG recordings as brief (<500 ms) bursts at 20-30 Hz. The early gamma rhythmicity was most pronounced during periods of @entity25 but was occasionally detected also during QS. Toward P10, the @entity11728 gained amplitude and extended also to higher (<or=60 Hz) frequencies. In parallel, the @entity11728 were progressively more and more confined to @entity25 . To further consolidate these findings, we compared amplitude spectra averaged within the behavioral categories. @entity25 was characterized by the appearances of gamma (20-30 Hz) and theta (3-5 Hz) peaks at @entity70590 , respectively. QS, on the other hand, had considerably smoother amplitude distributions between 1 and 100 Hz for P5-P10, with no peaks in gamma or theta bands. Hippocampal gamma rhythm thus seems to hallmark early @entity25 . Our data provide the first in vivo evidence for both the presence and the behavioral correlate of spontaneous @entity11728 in the newborn @entity35 .
