Figure 3. Patchwork-type spontaneous activity in the neonatal barrel cortex L4.
In the neonatal barrel cortex, L4 excitatory neurons in the same barrel tend to fire together, even when whiskers are not touched or moved. This spontaneous activity is delivered to the cortex by TCAs. In the second postnatal week, the patchwork pattern of activity diminishes and L4 neurons even in the same barrel fire asynchronously.