This Week in The Journal

Connections between hippocampal (CA3) pyramidal neurons support memory storage.But estimated connectivity rates sufficient for memory storage vary depending on whether researchers use morphological or electrophysiological methods.In this issue, Layous et al. used a new technique to measure the connectivity between pyramidal neurons in CA3 rat slices: voltage imaging.While both voltage imaging and whole-cell patch-clamp electrophysiology involve recording from cells in brain slices, the benefit with voltage imaging is that cells remain intact during recordings.By detecting spontaneous spiking and subthreshold responses in neurons, Layous and colleagues discovered higher connectivity rates than their observations with whole-cell patch-clamping.This was especially notable given that there was a lower signal-to-noise ratio with the voltage imaging technique.The authors also discovered that AMPA receptors mediated these pyramidal neuron synapses and that they were distributed randomly across the neuron population.Their experiments further provided support for CA3 pyramidal neurons being a heterogeneous cell population.According