Projection-specific filtering of delta-theta input by layer 5 neurons in mouse secondary visual cortex
Delta- and theta-band oscillations are thought to coordinate cortical activity and to convey top-down signals, but how the different output neurons of a cortical area transform such rhythmic input is less well understood. Layer 5 contains two projection classes, extratelencephalic (ET) and intratelencephalic (IT) neurons, which carry different information to different targets. Here we asked…
Layer 5 neurons in the mouse secondary visual cortex (V2M) exhibit distinct processing of slow rhythmic input in the delta-theta range. These neurons are divided into two projection classes: extratelencephalic (ET) and intratelencephalic (IT) neurons. IT cells act as low-pass filters, strongly summing small inputs, while ET cells resonate at low frequencies, forming moderate-resonance (ET1, about 3 Hz) and high-resonance (ET2, about 5 Hz) subgroups.
With small inputs, IT cells exhibit strong summation, acting as low-pass filters. Conversely, ET cells exhibit resonance at low frequencies, with ET1 resonating at around 3 Hz and ET2 at around 5 Hz. With large inputs, ET cells amplify depolarization more than hyperpolarization, maintaining similar resonance frequencies.
When stimulated by a 4 Hz sinusoid at threshold, all classes of cells fire at a similar phase and maintain this phase across cycles. In awake mice, visual stimulation increases deep-layer local field potential (LFP) power across a band of frequencies from 1 to 6 Hz, encompassing the mean ET1 and ET2 resonance frequencies.
Thus, while the two output classes of layer 5 in V2M process slow rhythmic input differently, once firing, they show no detectable difference in spike timing.
Written by urgent.news from bioRxiv's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
