Neuropixels spike couplings in visual cortex of 58 mice followed slice wiring in class order, latency and reciprocity, but couplings onto fast-spiking cells needed 2.9 times the slice-based gain
Question: Do the cell-class wiring rules that paired recordings in slices measure also control spike transmission in the awake mouse cortex? Data: 58 Allen Visual Coding Neuropixels sessions (16,778 units in six visual areas; 141 PV, 93 SST and 20 VIP units identified by optotagging) and the Allen Synaptic Physiology slice data (mouse V1, 19,136 probed pairs). Method: We computed cross-correlograms (CCGs) for 1,078,696 ordered unit pairs on the same probe. We detected excitatory peaks at 1.0-3.5 ms and inhibitory troughs at 1.0-4.5 ms against a baseline from lags of 5 ms or more, with causality, zero-lag and local-flank tests. We chose the rule by Dale's-law consistency of each unit's outputs. Non-synaptic lag windows gave at most 0.12% false detections. We calibrated detection by injecting synthetic couplings into real CCGs, and we corrected inhibition for the refractory shadow of reverse couplings. Results: For pairs at most 100 um apart, regular-spiking (RS) to fast-spiking (FS) excitation was detected in 11.4%, RS to RS in 0.87% (higher in all 58 sessions), and FS to RS inhibition in 9.5%. Slice probabilities were E to PV 20.1%, E to E 5.2%, PV to E 23.4%. Peaks onto FS units came 0.39 ms earlier than onto RS units (slices: 0.51 ms). Median transmission strength was 2.1 times higher for RS to FS (slice PSP ratio 2.1). Across 16 class pairs, the in vivo fraction had Spearman 0.55 (p = 0.029) with slice probability. Reciprocal RS-FS couplings were 3.7 times more frequent than independence predicts after the shadow correction (slices: 2.1). A model with slice probability, slice PSP amplitudes and one PSP-to-spike gain fit RS to RS detection, but it predicted only 40% of RS to FS detections within 40 um; a fit per class needed 2.9 times more gain for synapses onto FS units. In vivo couplings also fell off faster with vertical distance than slice probability (0-40 vs 100-200 um: 5.8 vs 2.4 for RS to FS), and the layer pattern did not match the slices. Limitations: waveform classes are not cell types; CCGs find only strong couplings; common input with a fixed lag can pass the tests; horizontal soma offsets are unknown; slice data are from V1 only.
Neuropixels · cross-correlogram · monosynaptic coupling · synaptic connectivity · mouse visual cortex · fast-spiking interneurons · parvalbumin · Allen Synaptic Physiology · optotagging · structure-function · spike transmission · Dale's law
References
8- usesdoi:10.1038/s41586-020-03171-x
Source of the Allen Visual Coding Neuropixels spike data (58 sessions) that we analysed.
- usesdoi:10.1126/science.abj5861
Source of the Allen Synaptic Physiology slice data (connection probability, PSP amplitude, latency) used as the reference.
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CCF v3 annotation used to assign cortical layers to units.
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Partially hollow Gaussian baseline and Poisson tests for CCG peaks.
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Standard monosynaptic detection rule (baseline, causality criterion) that we used as the robustness rule.
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Earlier use of CCG couplings and Dale's law to classify cortical units in vivo.
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In vivo whole-cell pairs in barrel cortex found E to PV more frequent and stronger than E to SST; our CCG data agree in visual cortex.
- Paired recordings in mouse V1 found most excitatory but less than half of the inhibitory connections that MICrONS electron microscopy predicted for 17 matched cell classes sci:sha256:ce046109af65d9a43f99d098f26cd85017dc112137362e3deed08cf3846aea5f
Compares MICrONS EM connectivity with the same slice data; our study adds the slice to in vivo step of the same chain.
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1 publicationPublic catalog entries on Sciscape.
- usesIn awake mouse visual cortex (58 mice), spike transmission facilitated onto optotagged SST units and depressed onto PV and fast-spiking units after 6–60 ms intervals, as slice release models predict
We reuse its spike-time cache, unit and pair tables, optotag rule and coupling detection rule, and we extend its class-order test to short-term dynamics.