What is the perisomatic region of a neuron?
In cortical GABAergic cells with local axonal projections, the perisomatic region is defined as that part of the plasma membrane including the proximal dendrites, the cell body and the axon initial segment (Zabó et al., 2010).

Reference
- Zabó et al., Eur J Neurosci (2010); 31(12): 2234–46