Location-dependent differences between somatic and dendritic IPSPs

Recent experimental evidence suggests that inhibitory synapses are associated with different actions depending upon their location (Miles et al., Neuron 16 (1996) 815-823). We investigated that question of whether this effect is due to different subspecies of GABA(A) receptors giving rise to distinct responses (Pearce, Neuron 10 (1993) 189-20) or cable filtering by the dendritic tree. The effects of electrotonic filtering on GABA(A) receptor mediated IPSPs were studied in hippocampal pyramidal cells. We implemented two models with different morphologies where these differences could be explained by electrotonic filtering alone. Our parameter search resulted in realistic passive cell models where the dependence of electrotonic attenuation on morphological distance agreed with that seen in reconstructed cells.