Subcortical origin of spontaneous spindle bursts and gamma oscillations. (a) Schematic illustration of the experimental setup for simultaneous multichannel recordings of sensory evoked and spontaneous activity in both the thalamus and barrel cortex of a newborn rat. A 4-shank 32-channel electrode is located in the ventral posteromedial nucleus (VPM) of the thalamus (blue) and a 4-shank 16-channel electrode in the cortex (black). (b) Simultaneous 40 s recording of spontaneously occurring activity in the barrel cortex and VPM thalamus of a P1 rat. Upper trace represents the cortical FP recording; cortical (black bars) and thalamic MUA (blue bars) are presented below (A). The 3 spontaneous events i–iii marked in (A) are shown at higher resolution with corresponding spectrograms (B). Cross-correlogram of the spontaneous multiunit activity recorded simultaneously in the thalamus and barrel cortex (C). Yellow lines represent results from the shuffled dataset (for details see ). (c) Inactivation of the sensory periphery by injection of 2% lidocaine into the whisker pad (left) causes a significant reduction in the relative occurrence of spindle bursts and gamma oscillations recorded in the contralateral barrel cortex of 6 newborn rats (filled bars), whereas both activity patterns in the ipsilateral cortex are not affected (open bars). Data are expressed as box plots, and asterisks mark significant differences and . Reproduced with permission from  (a, b) and from  (c).