Hippocampal CA1 and CA3 neural recording in the human brain: validation of depth electrode placement through high-resolution imaging and electrophysiology

Hippocampal CA1 and CA3 neural recording in the human brain: validation of depth electrode placement through high-resolution imaging and electrophysiology Wicks Witcher Couture Laxton Popli Whitlow Fetterhoff Dakos Roeder Deadwyler Hampson

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Hippocampal CA1 and CA3 neural recording in the human brain: validation of depth electrode placement through high-resolution imaging and electrophysiology 2020 Neurosurgical Focus 10.3171/2020.4.focus20164 wicks2020-hippocampal-ca1-and-ca3-neural-rec wicks2020-hippocampal-ca1-and-ca3-neural-rec.txt, the project's staged copy 6130d9bbbc3c3c694fb0c27e15248ebc8eae63fc open-access neuroscience

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0 spans located by searching the stored text for the quote's exact words, allowing any whitespace between them method Quotation withheld because this record is not cleared for redistribution. localization of single-neuron recordings in human hippocampal CA1 and CA3 Quotation withheld because this record is not cleared for redistribution. electrophysiology electrophysiology Quotation withheld because this record is not cleared for redistribution. mechanisms Monosynaptic Schaffer collateral transmission from CA3 to CA1 produces the 2-5 msec lagged firing correlation, while shared perforant path input to both subfields produces the 0-msec synchronous correlation. Quotation withheld because this record is not cleared for redistribution. Only the 2-5 msec feed-forward correlations can be taken as definitive evidence of CA3-to-CA1 synaptic connectivity; the synchronous and long-lag pairs are inferred to be correctly assigned rather than proven so. what this limits: the connectivity claim, separated from the suggestive part: ONLY THE 2- TO 5-MSEC FEED-FORWARD CORRELATIONS (20.3%) CAN BE DEFINITIVELY IDENTIFIED AS CA3-TO-CA1 SYNAPTIC CONNECTIVITY Quotation withheld because this record is not cleared for redistribution. The localization procedure used here is not a standardized stereotactic system, which the authors say would be needed for cross-centre standardization. what this limits: any comparison across surgical centres: LOCALIZATION USING STANDARDIZED TEMPORAL STEREOTACTIC SYSTEMS ... WOULD BE USEFUL FOR FUTURE ITERATIONS OR FOR STANDARDIZATION ACROSS SURGICAL CENTERS Quotation withheld because this record is not cleared for redistribution. A cell type is inferred from a firing-rate threshold and those cells are excluded from the sample. what this limits: any proportion reported over these neurons: cells with steady-state resting firing rates above 20 Hz were treated as clearly interneurons and were not recorded Quotation withheld because this record is not cleared for redistribution. The cell-type labels are confirmed by the connectivity pattern they are used to demonstrate. what this limits: the identification of these neurons as CA3 and CA1: cells were selected as candidates on waveform and firing-rate characteristics and then confirmed within the CA3-to-CA1 projection pathways via measures of functional connectivity Quotation withheld because this record is not cleared for redistribution. The human proportion is validated by its resemblance to published animal numbers. what this limits: the 26% feed-forward correlation reported here: the authors support it by noting that it favourably compares to reports of 20%-25% feedforward CA3-CA1 correlation in published animal studies Quotation withheld because this record is not cleared for redistribution. post-operative electrode placement verified by MRI eliminates: assigning CA1 and CA3 recordings to the wrong subfield, which is the entire distinction the paper rests on · outcome (stated by the tagger, no quotation): held Quotation withheld because this record is not cleared for redistribution. interneurons interneurons Quotation withheld because this record is not cleared for redistribution. principal neurons principal neurons Quotation withheld because this record is not cleared for redistribution. functional connectivity functional connectivity Quotation withheld because this record is not cleared for redistribution. inverse correlation inverse correlation Quotation withheld because this record is not cleared for redistribution. synaptic connectivity synaptic connectivity Quotation withheld because this record is not cleared for redistribution. feed-forward correlations feed-forward correlations Quotation withheld because this record is not cleared for redistribution. an interneuron, here - A FIRING RATE ABOVE 20 Hz: the classification is made in a parenthesis and acted on in the main clause, so a rate threshold becomes a cell type and then an exclusion, and every proportion in the paper is computed over what remained Quotation withheld because this record is not cleared for redistribution. a CA3 or CA1 principal neuron - CANDIDATE BY WAVEFORM, CONFIRMED BY CONNECTIVITY: the label is assigned from waveform and firing rate and then confirmed by the projection pattern it predicts, so the classification and the finding it supports rest on each other Quotation withheld because this record is not cleared for redistribution. the argument for the labels - AN EXPECTED SIGNATURE OF ERROR: misidentification is said to be expected to yield a higher percentage of inverse correlation, so the low inverse rate is offered as evidence the labels are right - sound only if misidentification could not also produce the observed pattern Quotation withheld because this record is not cleared for redistribution. extends → Ulbert et al., intraoperative layer-specific human hippocampal recordings with postoperative histology Quotation withheld because this record is not cleared for redistribution. feed-forward correlations —operationalised-as→ synaptic connectivity feed-forward correlations synaptic connectivity holds when: only for correlations in the 2- to 5-msec window · strength of the relation: 1 Audit 2026-09-28: DOUBTFUL - read against its full span and kept, but the span says the correlations can be IDENTIFIED as connectivity; operationalised-as is loose. Quotation withheld because this record is not cleared for redistribution. t-test t-test Quotation withheld because this record is not cleared for redistribution. cross-correlation cross-correlation Quotation withheld because this record is not cleared for redistribution. standard deviation standard deviation Quotation withheld because this record is not cleared for redistribution. p-value p-value Quotation withheld because this record is not cleared for redistribution. Nearly 80% of putative CA3-to-CA1 cell pairs showed positive cross-correlations compatible with a feed-forward connection, whereas only 2.6% showed inverse (feedback) correlation. Quotation withheld because this record is not cleared for redistribution. Feed-forward correlation was found in 1,071 of 4,070 CA3-CA1 pairs (26%), a rate close to the 20%-25% reported in animal studies, even after synchronous and long-latency correlations were excluded. Quotation withheld because this record is not cleared for redistribution. In non-epileptic patients the CA1 region lay at an average depth of 36.06 mm from the outer table of the skull on the left and 34.84 mm on the right. Quotation withheld because this record is not cleared for redistribution. Only the 2-5 msec feed-forward correlations (20.3%) are definitive CA3-to-CA1 synaptic connectivity, but positive correlations dominated (77.8%) and inverse correlations were rare, which the authors read as evidence that the cells were correctly assigned to CA3 and CA1. Quotation withheld because this record is not cleared for redistribution. Anterior hippocampal neurons fired mainly at the sample response, whereas posterior hippocampal neurons fired at elevated rates in the interval between the sample and the match responses. Quotation withheld because this record is not cleared for redistribution. About five times as many recorded hippocampal neurons fired below 5.0 Hz as fired above 5.0 Hz. Quotation withheld because this record is not cleared for redistribution. Delayed-Match-to-Sample Delayed-Match-to-Sample Quotation withheld because this record is not cleared for redistribution. cross-correlograms cross-correlograms Quotation withheld because this record is not cleared for redistribution. line noise line noise Quotation withheld because this record is not cleared for redistribution. 2.6% — proportion of CA3-CA1 cell pairs showing feedback (inverse) correlation, taken as the misidentification rate Quotation withheld because this record is not cleared for redistribution. 1071 (26%) of 4070 — number and share of cell pairs showing feed-forward CA3-to-CA1 correlation Quotation withheld because this record is not cleared for redistribution. 77.8% — share of CA3-CA1 pairs showing any positive (synchronous, short-lag or long-lag) correlation Quotation withheld because this record is not cleared for redistribution. 36.06 ± 2.88 mm — mean depth of left-hemisphere CA1 from the outer table of the skull in non-epileptic patients Quotation withheld because this record is not cleared for redistribution. 744 — number of neurons recorded across the 23 implanted patients (per Table 1) Quotation withheld because this record is not cleared for redistribution.

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