Hippocampal "time cells": time versus path integration

Hippocampal "time cells": time versus path integration Kraus Robinson White Eichenbaum Hasselmo

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Hippocampal "time cells": time versus path integration 2013 Neuron 10.1016/j.neuron.2013.04.015 Kraus2013-hippocampal-time-cells-time-versus-path-inte Kraus2013-hippocampal-time-cells-time-versus-path-inte.txt, the project's staged copy 25214f25ccc37a0d8d067b6b0e6317914878b5cf not-redistributable neuroscience

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0 spans located by searching the stored text for the quote's exact words, allowing any whitespace between them hippocampal time cells - and whether their apparent temporal tuning is instead an integration of the distance the animal has travelled Quotation withheld because this record is not cleared for redistribution. whether time, distance and location can be disentangled at all in hippocampal firing, and which of them each neuron actually tracks Quotation withheld because this record is not cleared for redistribution. clamping behavior and location and randomising treadmill speed shows both time-coding and distance-coding cells, firing in the same theta cycles - so neither pure path integration nor pure network dynamics accounts for the sequences Quotation withheld because this record is not cleared for redistribution. existence Quotation withheld because this record is not cleared for redistribution. hippocampal time cells Quotation withheld because this record is not cleared for redistribution. electrophysiology electrophysiology Quotation withheld because this record is not cleared for redistribution. mechanisms Repeating sequences of transiently active hippocampal cells act as a time-based template onto which episodic memories are written and from which they are later read out, disambiguating memories that share a location Quotation withheld because this record is not cleared for redistribution. mechanisms Distance-coding cells must be reading self-motion (idiothetic) cues generated by the moving belt, so their firing is driven by sensed movement rather than purely by internal network dynamics duplicate of: mechanisms[3] Quotation withheld because this record is not cleared for redistribution. the spiking of each neuron is fit to a generalized linear model including treadmill time, treadmill distance, spatial position, treadmill speed and spike history as covariates, and each nested model removes one or more categories of covariates Quotation withheld because this record is not cleared for redistribution. and the distance cells must be reading treadmill speed or the self-motion cues it produces, which is what rules out pure internal network dynamics Quotation withheld because this record is not cleared for redistribution. while the existence of time-only cells rules out pure path integration, so the hippocampus is holding both dimensions at once Quotation withheld because this record is not cleared for redistribution. with distance encoded even though there are no visual cues of movement to read it from Quotation withheld because this record is not cleared for redistribution. due to the residual correlation between time elapsed and distance traveled, the paper cannot say with certainty whether neurons influenced by both were encoding both simultaneously or whether the hippocampus was shifting between types of representations what this limits: the mixed cells specifically: WE CANNOT SAY WITH CERTAINTY WHETHER THOSE NEURONS ... WERE ENCODING BOTH TIME AND DISTANCE SIMULTANEOUSLY OR WHETHER THE HIPPOCAMPUS WAS SHIFTING BETWEEN TYPES OF REPRESENTATIONS Quotation withheld because this record is not cleared for redistribution. The experimental design cannot fully dissociate time from distance during ongoing treadmill running. what this limits: the time-versus-distance dissociation the paper is built on: IT IS IMPOSSIBLE TO COMPLETELY SEPARATE TIME AND DISTANCE AS LONG AS THE RAT IS STILL RUNNING ON THE TREADMILL Quotation withheld because this record is not cleared for redistribution. the clamping of behavior and location was largely successful, although minor variations persisted, and were taken into account in subsequent analyses what this limits: every claim that location and behaviour were held constant: the clamping WAS LARGELY SUCCESSFUL, ALTHOUGH MINOR VARIATIONS PERSISTED, AND WERE TAKEN INTO ACCOUNT IN SUBSEQUENT ANALYSES Quotation withheld because this record is not cleared for redistribution. time and distance cannot be fully separated while the animal is still running, so the decoupling is partial by construction what this limits: the same scope as limitations[1], with the consequence for the figures: THE EFFECTS OF VARYING SPEED BECOMES MORE PRONOUNCED AS TIME ELAPSES, so the alignment is easier to see at the end of the run than the beginning Quotation withheld because this record is not cleared for redistribution. and the residual correlation means the paper cannot say whether the mixed cells encode both at once or switch between representations - the theta result is what makes the first reading likely what this limits: the same scope as limitations[0] - simultaneous coding and switching cannot be told apart here Quotation withheld because this record is not cleared for redistribution. the clamping of behaviour and location was only largely successful; minor variations persisted and had to be modeled rather than removed what this limits: the same scope as limitations[2], with the numbers: 75% OF THE TIME SPENT ON THE TREADMILL COULD BE ACCOUNTED FOR BY AN AREA WITH A RADIUS OF APPROXIMATELY 3.3 cm Quotation withheld because this record is not cleared for redistribution. and the cell classes are relative to this task - the same neurons carry ordinary place fields elsewhere on the maze what this limits: the cell-class labels, which belong to the task segment and not to the cell: NEURONS IDENTIFIED AS RESPONDING MORE ACCURATELY TO TIME OR ... DISTANCE ... OFTEN EXPRESSED STANDARD PLACE FIELDS IN OTHER REGIONS OF THE MAZE WHEN THE TREADMILL WAS OFF Quotation withheld because this record is not cleared for redistribution. Muller's random-foraging strategy of clamping behavior and randomising an irrelevant variable, reused with speed in place of direction Quotation withheld because this record is not cleared for redistribution. nested-model deviance testing, used to ask what each covariate class adds rather than whether a fit is good Quotation withheld because this record is not cleared for redistribution. the requirement that episodic memory be temporally organised, which is what makes a time-based template worth looking for Quotation withheld because this record is not cleared for redistribution. a commercial treadmill, set into a maze specifically to hold place constant while motion continues Quotation withheld because this record is not cleared for redistribution. a generalised linear model using ONLY spatial covariates, fitted to firing during treadmill running where distance and time are dissociated eliminates: that time-cell firing on the treadmill is really place coding - that the apparent timing signal is explained by where the animal is · outcome (stated by the tagger, no quotation): held Quotation withheld because this record is not cleared for redistribution. residual variation in location during treadmill running was checked against the transient firing eliminates: that the transient firing at specific moments is driven by small residual differences in the animal's position rather than by elapsed time · outcome (stated by the tagger, no quotation): held Quotation withheld because this record is not cleared for redistribution. elapsed time → distance THE TWO CANNOT BE SEPARATED IN THIS STUDY - the DESIGN form of the negative relation / No edge type can express it: all eight assert that a relation HOLDS. Recorded here because a confounding statement BOUNDS WHAT THE PAPER'S OWN RESULTS CAN MEAN, and it lives in a methods paragraph where nothing downstream will find it. The confound is between the two things the paper's own title sets against each other, and it is the paper that ANSWERS Eichenbaum2014's question - so a reader joining the two needs this sentence and would never see it. Quotation withheld because this record is not cleared for redistribution. TWO VARIABLES CONFOUNDED IN EVERY EARLIER STUDY OF THE PHENOMENON: when animals stayed in a constant location, ELAPSED TIME WAS CONFOUNDED WITH THE DISTANCE TRAVELLED - the number of steps taken - so the whole time-cell result was open to a path-integration reading Quotation withheld because this record is not cleared for redistribution. with the design answer stated as a verb - CLAMP behavior and location, and vary the treadmill speed so that time and distance come apart Quotation withheld because this record is not cleared for redistribution. AND THE DECOUPLING IS DECLARED INCOMPLETE: it is IMPOSSIBLE to completely separate time and distance as long as the rat is still running - the effect of speed grows as the run proceeds Quotation withheld because this record is not cleared for redistribution. WITH THE CONSEQUENCE FOR THE FIGURES ADMITTED: the most visually distinct examples typically fire AT THE END of the treadmill run, because that is where the method has power - the examples shown are selected by where the design can see Quotation withheld because this record is not cleared for redistribution. and the residual correlation is carried into the conclusion - the paper CANNOT SAY WITH CERTAINTY whether mixed cells encode both dimensions or switch between them Quotation withheld because this record is not cleared for redistribution. THE CLAMP IS REPORTED AS PARTIAL, NOT AS ACHIEVED: clamping was LARGELY SUCCESSFUL, although minor variations persisted and were taken into account in the analyses Quotation withheld because this record is not cleared for redistribution. A FIRING-RATE THRESHOLD DEFINES A CELL CLASS: units averaging more than 8 Hz over the session were considered putative interneurons and EXCLUDED - the category is a number, applied before any analysis Quotation withheld because this record is not cleared for redistribution. TWO METHODS WITH DIFFERENT ASSUMPTIONS, MADE TO AGREE ON PURPOSE: a nonparametric spatial look-up table and a five-parameter GLM, correlating at r = 0.49 - so the conclusion DOES NOT DEPEND UPON THE ASSUMPTIONS MADE BY EITHER MODEL Quotation withheld because this record is not cleared for redistribution. and the location account is tested by construction rather than asserted - if position sufficed, the predicted and observed temporal tuning curves would match; if the rat were stationary the prediction would be FLAT Quotation withheld because this record is not cleared for redistribution. with the outcome that nearly all neurons DID show spatial tuning, and location was still NOT SUFFICIENT to explain the firing Quotation withheld because this record is not cleared for redistribution. THE POPULATION SPLITS AT BOTH EXTREMES: 42 neurons informative for distance but not time, 30 for time but not distance, 284 for both and 44 for neither Quotation withheld because this record is not cleared for redistribution. and the two extremes fire IN THE SAME THETA CYCLE, which is what argues for simultaneous representation rather than switching between them Quotation withheld because this record is not cleared for redistribution. THE CATEGORY IS RELATIVE TO THE TASK, NOT INTRINSIC TO THE CELL: neurons identified as time cells or distance cells on the treadmill OFTEN EXPRESSED STANDARD PLACE FIELDS elsewhere on the maze Quotation withheld because this record is not cleared for redistribution. AND THE FIELD ALREADY KNEW THIS ABOUT DIRECTION: where direction was irrelevant to the task, firing was NOT influenced by direction; where it becomes meaningful, it is - hippocampal activity reflects the regularities THAT CHARACTERIZE THE TASK AT HAND Quotation withheld because this record is not cleared for redistribution. with the precedent named - Muller's 1987 random foraging task used the same move, CLAMPING behavior and randomising direction to see what signal would emerge Quotation withheld because this record is not cleared for redistribution. TWO RIVAL ACCOUNTS ELIMINATED BY TWO SUBPOPULATIONS: distance cells rule out firing driven ENTIRELY by internal network dynamics, and time-only cells rule out pure path integration Quotation withheld because this record is not cleared for redistribution. and the same neurons carry place fields elsewhere, so space dominates when the task makes location matter - the representation follows what the experiment makes relevant Quotation withheld because this record is not cleared for redistribution. claim_type: existence a second reading reaching the same value. Recorded: existence — note: a second reading reaching the same value from a different sentence. Not applied - a person decides. Quotation withheld because this record is not cleared for redistribution. method: the same firing fit twice under different assumptions - a nonparametric spatial look-up table and a parametric nested-model GLM - so the conclusion does not rest on either a second reading DIFFERING from the recorded value. Recorded: electrophysiology — note: a second reading, verbatim-verified, disagreeing with the value on the record. Not applied - a person decides. Quotation withheld because this record is not cleared for redistribution. phenomenon: sequences of transient hippocampal firing during a delay in which behaviour and place are held constant a second reading DIFFERING from the recorded value. Recorded: hippocampal time cells — note: a second reading, verbatim-verified, disagreeing with the value on the record. Not applied - a person decides. Quotation withheld because this record is not cleared for redistribution. replicates → Pastalkova et al. (2008) Quotation withheld because this record is not cleared for redistribution. contradicts → Pastalkova et al. (2008) — the proposal that treadmill-period firing is driven purely by internal network dynamics without idiothetic or allothetic cues differs in: whether anything outside the network drives the firing: THE NEURONS MUST BE RESPONDING TO THE TREADMILL SPEED, OR SELF-MOTION CUES INFLUENCED BY THE TREADMILL SPEED, IN ORDER TO ENCODE DISTANCE - against being DRIVEN ENTIRELY BY NETWORK DYNAMICS WITHOUT THE INFLUENCE OF EITHER IDIOTHETIC OR ALLOTHETIC CUES Quotation withheld because this record is not cleared for redistribution. contradicts → path-integration accounts of hippocampal function (Etienne and Jeffery, 2004; McNaughton et al., 1996, 2006) differs in: which variable drives the cell: CELLS WHOSE ACTIVITY WAS SIGNIFICANTLY INFLUENCED BY ONLY TIME INDICATES THAT THESE NEURONS ARE ALSO NOT EXCLUSIVELY DRIVEN BY PATH INTEGRATION Quotation withheld because this record is not cleared for redistribution. contradicts → the reading of hippocampal time cells as pure path integration over distance travelled differs in: whether it is one variable or both: OUR RESULTS SHOW THAT THE HIPPOCAMPUS REPRESENTS BOTH THE DISTANCE TRAVELED AND TIME, where path integration predicts distance alone Quotation withheld because this record is not cleared for redistribution. contradicts → the account that delay-period sequences are driven entirely by internal network dynamics without idiothetic or allothetic cues differs in: the same parameter as item 1 - the presence of self-motion cues: THE NEURONS MUST BE RESPONDING TO THE TREADMILL SPEED, OR SELF-MOTION CUES INFLUENCED BY THE TREADMILL SPEED, IN ORDER TO ENCODE DISTANCE Quotation withheld because this record is not cleared for redistribution. critiques → earlier time-cell studies, in which elapsed time was confounded with distance travelled differs in: whether time and distance were separable at all in the earlier designs: Quotation withheld OR CAN MOVE ON A SMALL PLATFORM OR IN A CHAMBER, ALLOWING MOVEMENT TO PLAY A SUBSTANTIAL ROLE IN ACCOUNTING FOR VARIATIONS IN FIRING RATE Quotation withheld because this record is not cleared for redistribution. supports → the view that hippocampal firing reflects whichever regularities the task makes relevant, rather than a fixed variable Quotation withheld because this record is not cleared for redistribution. reconciles → time coding and distance coding, by showing both in the same theta cycles rather than as alternating regimes differs in: concurrent against switching representations: WHETHER TIME AND DISTANCE WERE BEING REPRESENTED CONCURRENTLY OR WHETHER THE HIPPOCAMPUS WAS SWITCHING BETWEEN SEPARATE REPRESENTATIONS OF TIME AND DISTANCE - decided by whether the extreme neurons were ACTIVE TOGETHER WITHIN THE SAME THETA CYCLES Quotation withheld because this record is not cleared for redistribution. predicts → that the mixed-selectivity majority encode time and distance conjunctively at all times Quotation withheld because this record is not cleared for redistribution. time cell —operationalised-as→ firing time cell firing strength of the relation: 1 · note: neurons that fire at particular moments during periods when BEHAVIOR AND LOCATION ARE RELATIVELY CONSTANT Audit 2026-09-28: DOUBTFUL - read against its span and kept, but the span defines time cells by when they fire; operationalised-as is loose. Quotation withheld because this record is not cleared for redistribution. GLM —contrasted-with→ tuning curve GLM tuning curve strength of the relation: 1 Quotation withheld because this record is not cleared for redistribution. network dynamics —distinct-from→ self-motion network dynamics self-motion strength of the relation: 1 · note: TWO RIVALS ELIMINATED BY TWO SUBPOPULATIONS - distance cells must be reading treadmill speed or the self-motion cues it produces, so the firing is NOT driven entirely by network dynamics Audit 2026-09-28: DOUBTFUL - read against its span and kept, but the span says neurons are not driven entirely by network dynamics without cues; distinct-from is loose. Quotation withheld because this record is not cleared for redistribution. path integration —distinct-from→ time path integration time strength of the relation: 1 · note: and the time-only cells rule out pure path integration, so the hippocampus represents BOTH dimensions simultaneously Audit 2026-09-28: DOUBTFUL - read against its span and kept, but the span says time-only cells are not exclusively driven by path integration; distinct-from is loose. Quotation withheld because this record is not cleared for redistribution. ANOVA ANOVA Quotation withheld because this record is not cleared for redistribution. correlation correlation Quotation withheld because this record is not cleared for redistribution. bootstrap bootstrap Quotation withheld because this record is not cleared for redistribution. confidence interval confidence interval Quotation withheld because this record is not cleared for redistribution. generalized linear model generalized linear model Quotation withheld because this record is not cleared for redistribution. likelihood ratio test likelihood ratio test Quotation withheld because this record is not cleared for redistribution. chi-squared chi-squared Quotation withheld because this record is not cleared for redistribution. maximum likelihood estimation maximum likelihood estimation Quotation withheld because this record is not cleared for redistribution. Poisson regression Poisson regression 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. two-factor ANOVA two-factor ANOVA Quotation withheld because this record is not cleared for redistribution. Pearson’s linear correlation coefficient Pearson’s linear correlation coefficient Quotation withheld because this record is not cleared for redistribution. deviance deviance Quotation withheld because this record is not cleared for redistribution. Firing of hippocampal neurons during treadmill running was driven by elapsed time and distance run, and could not be explained by the small residual variation in the rat's head position. Quotation withheld because this record is not cleared for redistribution. 42 neurons (11%) showed distance but not time as informative, and 30 neurons (8%) showed time but not distance as informative Quotation withheld because this record is not cleared for redistribution. neurons only responding significantly to time fired within the same theta cycle as neurons only responding significantly to distance, suggesting that the hippocampus is representing both time and distance simultaneously Quotation withheld because this record is not cleared for redistribution. Active neurons fired in a repeating sequence that tiled the whole treadmill run, so some subset of cells was firing at every moment. Quotation withheld because this record is not cleared for redistribution. Distance coding on a treadmill shows the hippocampus can integrate path length using self-motion alone, without the visual flow that normally accompanies travel. Quotation withheld because this record is not cleared for redistribution. Firing fields that peaked later in the run were also wider, so temporal precision degraded as the run progressed. Quotation withheld because this record is not cleared for redistribution. neurons identified as responding more accurately to time or more accurately to distance during treadmill running often expressed standard place fields in other regions of the maze when the treadmill was off Quotation withheld because this record is not cleared for redistribution. TWO VARIABLES CONFOUNDED IN EVERY EARLIER STUDY: elapsed time was confounded with the distance travelled, THE NUMBER OF STEPS TAKEN, leaving the time-cell result open to a path-integration reading Quotation withheld because this record is not cleared for redistribution. and path integration has been proposed as the PRIMARY FUNCTION of hippocampal networks, which is why the parameters had to be disentangled Quotation withheld because this record is not cleared for redistribution. the design stated as a verb - CLAMP behavior and location, and vary the treadmill speed to decouple distance from time Quotation withheld because this record is not cleared for redistribution. neurons fire at particular moments during periods when behavior and location are relatively constant, with the speed varied to distinguish time from distance Quotation withheld because this record is not cleared for redistribution. most neurons were strongly influenced by both time and distance, and some significantly by only one Quotation withheld because this record is not cleared for redistribution. AND THE DECOUPLING IS DECLARED INCOMPLETE: it is IMPOSSIBLE to completely separate time and distance while the rat is still running Quotation withheld because this record is not cleared for redistribution. with the consequence for the figures admitted - the most visually distinct examples typically fire AT THE END of the run, because that is where the effect of speed has grown Quotation withheld because this record is not cleared for redistribution. and the residual correlation is carried into the conclusion - the paper CANNOT SAY WITH CERTAINTY whether mixed cells encode both dimensions or switch between them Quotation withheld because this record is not cleared for redistribution. THE CLAMP IS REPORTED AS PARTIAL: largely successful, with minor variations persisting and taken into account rather than removed Quotation withheld because this record is not cleared for redistribution. the rats spent 74% of treadmill time inside an area visited in every time bin, and that area contained 82% of the tighter one Quotation withheld because this record is not cleared for redistribution. A FIRING-RATE THRESHOLD DEFINES A CELL CLASS: units averaging more than 8 Hz were considered putative interneurons and excluded before any analysis Quotation withheld because this record is not cleared for redistribution. significantly more neurons were active on the treadmill than expected if they were simply place cells with fields there Quotation withheld because this record is not cleared for redistribution. the location account is tested BY CONSTRUCTION - if position sufficed the predicted and observed curves would match, and a stationary rat would give a FLAT prediction Quotation withheld because this record is not cleared for redistribution. and nearly all neurons DID show spatial tuning, with location still NOT SUFFICIENT to explain the firing Quotation withheld because this record is not cleared for redistribution. 92% of treadmill-active neurons significantly changed firing rate across time bins Quotation withheld because this record is not cleared for redistribution. TWO METHODS WITH DIFFERENT ASSUMPTIONS MADE TO AGREE ON PURPOSE: the finding DOES NOT DEPEND UPON THE ASSUMPTIONS MADE BY EITHER MODEL Quotation withheld because this record is not cleared for redistribution. six nested models, each removing one or more CATEGORIES of covariate, so each deviance measures what that category was worth Quotation withheld because this record is not cleared for redistribution. THE POPULATION SPLITS AT BOTH EXTREMES: 42 neurons (11%) distance-but-not-time and 30 (8%) time-but-not-distance, with 284 (70%) informative for both Quotation withheld because this record is not cleared for redistribution. at the extremes some neurons EXCLUSIVELY signalled time and others EXCLUSIVELY distance Quotation withheld because this record is not cleared for redistribution. 62% were more tuned to time and 38% more tuned to distance, with 63% more influenced by time than by space Quotation withheld because this record is not cleared for redistribution. and the two extremes fire IN THE SAME THETA CYCLE, arguing for simultaneous representation rather than switching Quotation withheld because this record is not cleared for redistribution. NOT A PROPERTY OF THE CELL: neurons identified as responding more accurately to time or more accurately to distance during treadmill running OFTEN EXPRESSED STANDARD PLACE FIELDS in other regions of the maze when the treadmill was off Quotation withheld because this record is not cleared for redistribution. AND THE FIELD ALREADY KNEW THIS ABOUT DIRECTION: where direction was irrelevant firing ignored it, where it became meaningful it did not - activity reflects the regularities THAT CHARACTERIZE THE TASK AT HAND Quotation withheld because this record is not cleared for redistribution. with the precedent named - Muller 1987 clamped behaviour as foraging and randomized direction to see what signal would emerge Quotation withheld because this record is not cleared for redistribution. TWO RIVALS ELIMINATED BY TWO SUBPOPULATIONS: distance cells rule out firing driven ENTIRELY by network dynamics, since they must read treadmill speed or self-motion cues Quotation withheld because this record is not cleared for redistribution. and time-only cells rule out pure path integration, so both dimensions are represented at once Quotation withheld because this record is not cleared for redistribution. with distance integrated EVEN IN THE ABSENCE of the visual cues usually associated with movement through space Quotation withheld because this record is not cleared for redistribution. fields peaking later in the run were wider (r = 0.50) Quotation withheld because this record is not cleared for redistribution. where maze locations mattered to task success, space strongly influenced the firing of even the same neurons Quotation withheld because this record is not cleared for redistribution. time cells time cells Quotation withheld because this record is not cleared for redistribution. path integration path integration Quotation withheld because this record is not cleared for redistribution. difference score difference score Quotation withheld because this record is not cleared for redistribution. clamp clamp Quotation withheld because this record is not cleared for redistribution. interneuron interneuron Quotation withheld because this record is not cleared for redistribution. deviance deviance Quotation withheld because this record is not cleared for redistribution. field width field width Quotation withheld because this record is not cleared for redistribution. treadmill speed treadmill speed Quotation withheld because this record is not cleared for redistribution. neuronal firing pattern neuronal firing pattern Quotation withheld because this record is not cleared for redistribution. distance traveled distance traveled Quotation withheld because this record is not cleared for redistribution. time time Quotation withheld because this record is not cleared for redistribution. distance distance Quotation withheld because this record is not cleared for redistribution. speed speed Quotation withheld because this record is not cleared for redistribution. field width field width Quotation withheld because this record is not cleared for redistribution. 927 — putative pyramidal cells recorded, drawn from 18 sessions in 6 rats Quotation withheld because this record is not cleared for redistribution. 92% (366/400) — share of treadmill-active neurons whose firing rate changed significantly across time bins in the two-factor ANOVA Quotation withheld because this record is not cleared for redistribution. 380/400 — neurons for which adding time plus distance covariates significantly improved the GLM fit over space alone Quotation withheld because this record is not cleared for redistribution. 314/400 (79%) and 326/400 (82%) — neurons for which distance, in addition to time and space, was informative, and neurons for which time, in addition to distance and space, was informative Quotation withheld because this record is not cleared for redistribution. 220/356 (62%) — neurons more strongly tuned to time than distance, the remaining 38% being more tuned to distance Quotation withheld because this record is not cleared for redistribution. 0.50 — Pearson correlation between a neuron's normalized peak firing time and its normalized firing field width Quotation withheld because this record is not cleared for redistribution. 35 to 49 cm/s — the range from which treadmill speed was randomly drawn on each trial Quotation withheld because this record is not cleared for redistribution. 3.3 cm — radius of the area containing 75% of the rat's head positions during treadmill running, the measure of how well location was clamped Quotation withheld because this record is not cleared for redistribution. 42 neurons (11%) ... 30 neurons (8%) — cells informative for distance but not time, and for time but not distance - the two small groups that eliminate one rival account each Quotation withheld because this record is not cleared for redistribution. 8 Hz — the session-average firing rate above which a unit was reclassified as an interneuron and dropped - a cell class defined by a threshold rather than by a property of the cell Quotation withheld because this record is not cleared for redistribution. 92% — of treadmill-active neurons significantly changing firing rate across time bins - the coarse result the rest of the paper has to survive Quotation withheld because this record is not cleared for redistribution. 0.49 — agreement between a nonparametric and a parametric estimate of the same thing, reported so that the conclusion cannot be attributed to either model's assumptions Quotation withheld because this record is not cleared for redistribution. 74% — of treadmill time spent inside the area visited in every time bin - the number that makes 'location was held constant' checkable rather than asserted Quotation withheld because this record is not cleared for redistribution.

The full text of this article is not redistributable, so it is not included here. The evidence sentences are withheld with it; the tag layer and its grounding status remain. The article itself is at https://doi.org/10.1016/j.neuron.2013.04.015.