Differences in the Electrophysiological Properties of Mouse Somatosensory Layer 2/3 Neurons and Slice Stem from Intrinsic Sources Rather than a Network-Generated High Conductance State.

Synaptic activity can potentially alter the integration properties of neurons. Using recordings in awake mice, we targeted somatosensory layer 2/3 pyramidal neurons and compared neuronal properties with those from slices. Pyramidal cells had lower resistance and gain values, as well as broader spikes and increased spike frequency adaptation compared to the same cells in slices. Increasing conductance in neurons using dynamic clamp to levels observed , however, did not lessen the differences between and slice conditions. Further, local application of tetrodotoxin (TTX) blocked synaptic-mediated membrane voltage fluctuations but had little impact on pyramidal cell membrane input resistance and time constant values. Differences in electrophysiological properties of layer 2/3 neurons in mouse somatosensory cortex, therefore, stem from intrinsic sources separate from synaptic-mediated membrane voltage fluctuations.