Skip to main content
. 2016 Nov 8;10:88. doi: 10.3389/fncir.2016.00088

FIGURE 6.

FIGURE 6

VC measurement errors and somatic potentials are different in the 4 modeled neuron types. (A) The somata of the model neurons were clamped either to –70 mV (dark red) or to 0 mV (dark blue) in the SS to show the breakdown of local clamped potential in different compartments. The breakdown is more severe when trying to clamp to 0 mV in all cell types, and it is much stronger in the electrotonically extensive pyramidal and CR cells than in the compact PV and CCK cells. (B) The breakdown of VC is considerably stronger in the HCS for all cell types. In the compact PV neuron the error is still relatively small. However, for the other cells the voltage converges over a short distance toward the equilibrium potential set by the local excitatory/inhibitory ratio (arrows). In the case of the relatively compact CCK cell the voltage converges toward a relatively negative potential because this cell receives the highest ratio of dendritic inhibition (see Figure 3). For PCs the convergence point is different for the oriens/radiatum dendrites and the lacunosum-moleculare dendrites, since the E/I ratio is different. (C) Comparison of somatically recovered EPSC and IPSC amplitudes at –70 and 0 mV (the results for charge are quite similar, and are therefore not demonstrated). As emphasized by the gray stripe covering PSC amplitudes below the 10 pA detection threshold, a significant portion of the synaptic inputs are not detectable due to the rapid loss of current as we move away from the soma. With the exception of PV cells, inputs further away than 100–150 μm are not detectable. (D) The distribution of somatically visible EPSP and IPSP amplitudes without somatic current injection (the somata sit at slightly depolarized membrane potentials where the interaction of excitatory and inhibitory bombardment clamps them). The gray stripe shows the PSP detectability threshold, which was set to 0.1 mV. Note that the scale is the same for the PC, PV, and CCK cells, but it is different for the CR cells that receive half a magnitude higher PSPs, due to the electrotonic organization of their dendrites.