Generation and propagation of network bursts in the basal ganglia exhibit dynamic changes during early postnatal development

The neonatal brain is characterised by intermittent bursts of oscillatory activity interspersed by relative silence. While these bursts of activity are well characterised for many cortical areas much less is known whether and how these propagate and interact with subcortical regions. Here, early network activity was recorded using silicon probes from the developing basal ganglia, including the motor/somatosensory cortex, dorsal striatum and intralaminar thalamus, during the first two postnatal weeks in mice. Using an unsupervised detection and classification method, two main classes of bursting activity were found, consisting of spindle bursts (SB) and nested gamma spindle bursts (NGB), which were characterised by oscillatory activity at respectively ∼10 Hz and ∼30 Hz. These bursts were reliably identified across all three brain structures but differed in their structural, spectral, and developmental characteristics. Coherence and cross-correlation analyses revealed that burst events often occur synchronously across different brain regions and were mostly of a similar type, especially between cortex and striatum, which also exhibited the strongest interactions as compared to other brain regions. Interestingly, the preferred frequency for these interactions suggested a developmental shift from initial lower frequencies to higher frequencies across development. Together, these results provide the first detailed description of early network activity within the developing basal ganglia and suggests that distinct brain regions drive and coordinate burst activity at different developmental stages.