Modeling unitary fields and the single-neuron contribution to local
field potentials in the hippocampus
Maria Telenczuk, Bartosz Telenczuk and Alain Destexhe
Journal of Physiology 598: 3957-3972, 2020.
Synaptic currents represent a major contribution to the local field
potential (LFP) in brain tissue, but the respective contribution
of excitatory and inhibitory synapses is not known. Here, we
provide estimates of this contribution by using computational
models of hippocampal pyramidal neurons, constrained by in vitro
recordings. We focus on the unitary LFP (uLFP) generated by single
neurons. We first reproduce experimental results for hippocampal basket cells, and in
particular how inhibitory uLFP are disrtributed within hippocampal
layers. Next, we calculate the uLFP generated by pyramidal neurons,
using morphologically-reconstructed CA3 pyramidal cells. The model
shows that the excitatory uLFP is of small amplitude, smaller than
inhibitory uLFPs. Indeed, when the two are simulated together,
inhibitory uLFPs mask excitatory uLFPs, which might create the
illusion that the inhibitory field is generated by pyramidal cells.
These results provide an explanation for the observation that
excitatory and inhibitory uLFPs are of the same polarity, in vivo
and in vitro. These results also show that somatic
inhibitory currents are large contributors of the LFP, which is
important information to interpret this signal. Finally, the
results of our model might form the basis of a simple method to
compute the LFP, which could be applied to point neurons for each
cell type, thus providing a simple biologically-grounded method to
calculate LFPs from neural networks.
A perspective commentary was written about this paper, by
Manisha Sinha and Rishikesh Narayanan in the same issue of The
Journal of Physiology (see PDF copy
of this commentary).
See also the Cover
picture, which was taken from the paper.
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