Mapping of a non-spatial dimension by the hippocampal

Mapping of a non-spatial dimension by the hippocampal–entorhinal circuit Aronov Nevers Tank

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Mapping of a non-spatial dimension by the hippocampal–entorhinal circuit 2017 Nature 10.1038/nature21692 Aronov2017-mapping-of-a-non-spatial-dimension-by-the-hi Aronov2017-mapping-of-a-non-spatial-dimension-by-the-hi.txt, the project's staged copy 4ec2bc8734cc67da7d0a0ab843209ce69b02d5b1 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 whether the firing patterns that gave place cells and grid cells their names are about physical space, or about any continuous task-relevant variable Quotation withheld because this record is not cleared for redistribution. whether the hippocampal and entorhinal circuit represents an arbitrary non-spatial continuous dimension with the same discrete firing fields it uses for location Quotation withheld because this record is not cleared for redistribution. the same neurons, including identified place cells and grid cells, tile a sound-frequency axis with discrete firing fields in a task containing no spatial dimension Quotation withheld because this record is not cleared for redistribution. existence Quotation withheld because this record is not cleared for redistribution. hippocampal-entorhinal coding of a non-spatial continuous dimension Quotation withheld because this record is not cleared for redistribution. electrophysiology electrophysiology Quotation withheld because this record is not cleared for redistribution. mechanisms Spatial firing arises because location happens to be a continuous task-relevant variable, not because physical space is privileged for this circuit Quotation withheld because this record is not cleared for redistribution. mechanisms Performing a task drives a sequence of firing fields that are elicited parametrically as behaviour progresses Quotation withheld because this record is not cleared for redistribution. mechanisms Overlap between neighbouring fields encodes the order and adjacency of behavioural states, supporting episodic linking and planning Quotation withheld because this record is not cleared for redistribution. traversal speed is randomised trial by trial so that sound frequency and elapsed time are uncoupled, which is what makes a frequency field distinguishable from a time field Quotation withheld because this record is not cleared for redistribution. a model tested the strength of alignment of the neural activity to various task events, and each field was found to align best either to particular sound frequencies or to the press or the release of the joystick Quotation withheld because this record is not cleared for redistribution. the proposed general mechanism is that task performance activates a progression of firing fields, so that neighbouring and overlapping fields represent the order and adjacency of behavioural states Quotation withheld because this record is not cleared for redistribution. and the absence of field broadening across the trial is attributed to an informative sensory variable being continuously available, unlike in a delay task where the code can drift Quotation withheld because this record is not cleared for redistribution. Too few fields per grid cell in the sound task to test whether its firing corresponds to a one-dimensional slice through a hexagonal grid lattice. what this limits: the hexagonal-lattice interpretation only: THE SMALL NUMBER OF FIELDS PRODUCED BY GRID CELLS in the sound task makes the 1-dimensional-slice reading untestable here Quotation withheld because this record is not cleared for redistribution. The task itself did not require the animals to represent the whole acoustic dimension, so the functional necessity of the representation is not established. what this limits: every functional claim about the acoustic representation: IN THE SMT, RATS DID NOT ACTUALLY NEED TO REPRESENT THE STRUCTURE OF THE ENTIRE ACOUSTIC SPACE - the representation is not necessary for the behaviour Quotation withheld because this record is not cleared for redistribution. Grid-cell yield depended on arena size, fewer being detected in the smaller environment. what this limits: any comparison of grid-cell yield between environments: Quotation withheld THAN IN THE LARGER ONE Quotation withheld because this record is not cleared for redistribution. The three alignment classes (press-, release-, frequency-aligned) were not cleanly separable, with some fields loading on more than one task parameter. what this limits: the three-way classification of firing fields: THE THREE CLUSTERS WERE NOT PERFECTLY SEPARATED ... SOME FIRING FIELDS HAD SIGNIFICANTLY NON-ZERO REGRESSION COEFFICIENTS FOR MORE THAN ONE TASK PARAMETER: 14% IN CA1 - the classes overlap, and by how much is measured Quotation withheld because this record is not cleared for redistribution. the hexagonal-lattice reading of the grid cell results could not be tested, because grid cells produced too few fields in this task what this limits: the same scope as limitations[0] - too few fields to test the lattice reading Quotation withheld because this record is not cleared for redistribution. the rats did not actually need to represent the whole acoustic space to solve the task, since responding to one frequency would have sufficed what this limits: the same scope as limitations[1] - one frequency would suffice to solve the task Quotation withheld because this record is not cleared for redistribution. fewer grid cells were detected in the smaller environment than the larger one, so all grid comparisons had to be verified on the subset recorded in the larger environment what this limits: the same scope as limitations[2] - grid comparisons are confounded with arena size Quotation withheld because this record is not cleared for redistribution. a tightening of firing fields in the vicinity of joystick presses and releases may be due to a higher density of available sensory cues, or alternatively may result from the stronger salience of these events what this limits: the field-narrowing result near press and release: it may reflect A HIGHER DENSITY of sampling at those moments rather than a property of the fields Quotation withheld because this record is not cleared for redistribution. and a head-direction confound had to be excluded by a separate analysis, since head direction cells overlap the modulated population what this limits: the attribution of the modulation to the sound dimension: HEAD DIRECTION (HD) CELLS OVERLAP WITH SMT-MODULATED NEURONS, and a separate analysis was needed to exclude them Quotation withheld because this record is not cleared for redistribution. place cells, grid cells, border cells and head direction cells, carried into a task with no spatial dimension Quotation withheld because this record is not cleared for redistribution. the spatial information measure, applied unchanged to time bins instead of spatial bins Quotation withheld because this record is not cleared for redistribution. the perceptually uniform logarithmic frequency axis, used as the continuous dimension to be traversed Quotation withheld because this record is not cleared for redistribution. the claim that continuous non-spatial dimensions are mapped by this circuit, brought down to single units Quotation withheld because this record is not cleared for redistribution. modifications to the apparatus - a nosepoke aligned with the joystick handle - introduced in the second version eliminates: the possible SPATIAL CONFOUND of rats moving their heads while deflecting the joystick. It matters because the paper's claim is that these cells map a NON-SPATIAL dimension, so an uncontrolled head movement would make the result the very thing the paper denies · outcome (stated by the tagger, no quotation): held Quotation withheld because this record is not cleared for redistribution. grid cell grid cell Quotation withheld because this record is not cleared for redistribution. mechanism mechanism Quotation withheld because this record is not cleared for redistribution. information information Quotation withheld because this record is not cleared for redistribution. environment environment Quotation withheld because this record is not cleared for redistribution. SMT → linear track AN ANALOGY, BOUNDED BY ITS AUTHORS: the sound-manipulation task evolves along a continuous axis (sound frequency) and is therefore ANALOGOUS to spatial navigation on a linear track, SHARING SOME KEY FEATURES of neural representation - discrete firing fields tiling the task, multiple fields in MEC cells, clustering at salient features, and context-dependence. 'Some key features' is the authors' own bound and it is the part an equivalence edge deletes. Quotation withheld because this record is not cleared for redistribution. A CELL TYPE IS NAMED AFTER THE TASK IT WAS DISCOVERED IN: the well-known spatial patterns may be a consequence of the continuous nature of the task variable, rather than a primacy of physical space for this network Quotation withheld because this record is not cleared for redistribution. and the same neurons produce the same discrete fields on an axis of sound frequency, so spatial and non-spatial representations come from one population Quotation withheld because this record is not cleared for redistribution. MEMBERSHIP OF A NAMED CLASS BARELY PREDICTS THE SAME CELL IN ANOTHER TASK: the amount of task modulation had a very weak correlation with placeness and gridness, r2 about 0.005, which is read as nearly independent activity patterns Quotation withheld because this record is not cleared for redistribution. THE DEFINITION OF THE TYPE IS A THRESHOLD ON THIS DATASET'S OWN SHUFFLES: grid cells are cells whose grid score exceeds the 95th percentile of the shuffled samples, which in this dataset was 0.46 Quotation withheld because this record is not cleared for redistribution. and place cells are cells whose spatial information exceeds 99% of their own shuffled values, so both categories are defined relative to the recording rather than absolutely Quotation withheld because this record is not cleared for redistribution. AND THE COUNT OF A CELL TYPE DEPENDS ON THE ARENA: fewer grid cells were detected in the smaller environment than the larger one, so every grid comparison was re-verified on the subset recorded in the larger environment Quotation withheld because this record is not cleared for redistribution. AN EXCLUSION CRITERION THAT DOES NOT EXIST OUTSIDE THE TASK IT WAS BUILT FOR: sharp-wave ripples are normally removed by rejecting low-velocity time points, and with no velocity in this task they had to be detected directly in the field potential Quotation withheld because this record is not cleared for redistribution. with the negative disclosure attached: excluding those spikes did not qualitatively change any result, it only raised the in-field to background ratio Quotation withheld because this record is not cleared for redistribution. THE SPATIAL CONFOUND IS DESIGNED OUT RATHER THAN CORRECTED FOR: rats moved their heads while deflecting the joystick in the first apparatus, so a nosepoke was added in the second Quotation withheld because this record is not cleared for redistribution. THETA DID NOT TRACK SPEED HERE, UNLIKE IN NAVIGATION, which is read as the navigation relationship being dependent on locomotion-related signals Quotation withheld because this record is not cleared for redistribution. THE CONTROL IS DECOMPOSED RATHER THAN RUN ONCE: passive playback alone engaged almost no cells, passive playback with a reward engaged a fifth of them with wider fields, so context matters and agency is not strictly required Quotation withheld because this record is not cleared for redistribution. and a frequency field is called analogous to a place field, naming the new thing after the old one in the same sentence that shows the old name was too narrow 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: a sound manipulation task in which a joystick drives frequency along a logarithmic axis at a randomly varied speed, so that frequency is uncoupled from elapsed time, with the same cells recorded again during random foraging 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: discrete firing fields that tile a continuous behavioural variable, and the overlap of that population with the known spatial cell types a second reading DIFFERING from the recorded value. Recorded: hippocampal-entorhinal coding of a non-spatial continuous dimension — 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. builds-on → the cognitive-map framework (refs 7-10) holding that spatial coding is one case of a general mechanism for continuous task-relevant variables, including recent human fMRI work on cognitive spaces Quotation withheld because this record is not cleared for redistribution. generalises → the cognitive map account, from locations to any continuous task-relevant variable Quotation withheld because this record is not cleared for redistribution. reinterprets → spatial firing itself, as a consequence of the continuity of the task variable rather than of space Quotation withheld because this record is not cleared for redistribution. extends → the non-spatial modulation literature, from discrete stimuli and time points to a continuously traversed dimension Quotation withheld because this record is not cleared for redistribution. distinguishes-from → time cells, whose fields broaden across a delay where these did not differs in: THE AXIS IS WHETHER THE FIELDS BROADEN ACROSS A DELAY, AND THE EXPLANATION IS GIVEN. 'Quotation withheld.' The broadening is not denied of time cells - it is attributed to the ABSENCE of an external reference, which this task supplies. Quotation withheld because this record is not cleared for redistribution. qualifies → the reported relationship between theta frequency and running speed, which did not appear when speed was not locomotion differs in: THE AXIS IS THE DOMAIN. 'Quotation withheld; this may imply that the relationship between theta and speed during navigation is' [specific to navigation]. The qualification is that an established correlation is domain-bound - and the evidence for it is a NULL (slope not significantly different from 0, p = 0.70), so the row also carries the polarity gap: see an internal file. Quotation withheld because this record is not cleared for redistribution. builds-on → the grid module literature, with wide-spacing modules producing wide fields in this task too Quotation withheld because this record is not cleared for redistribution. confirms → the previously reported dependence of grid cell detection on environment size Quotation withheld because this record is not cleared for redistribution. location —is-a→ continuous location continuous strength of the relation: 1 · note: location is given as an EXAMPLE of a continuous task variable, which is the whole demotion Audit 2026-09-28: DOUBTFUL - read against its span and kept, but the span names location as a continuous task variable; is-a is loose. Quotation withheld because this record is not cleared for redistribution. border cell —part-of→ SMT border cell SMT strength of the relation: 1 Audit 2026-09-28: DOUBTFUL - read against its full span and kept, but border cells were SMT-MODULATED; part-of a task is loose. Quotation withheld because this record is not cleared for redistribution. place cell —part-of→ SMT place cell SMT strength of the relation: 1 · note: a quarter of the place cells and a third of the grid cells were modulated in the sound task Audit 2026-09-28: DOUBTFUL - read against its full span and kept, but 25.1% of place cells were SMT-MODULATED; part-of a task is loose. Quotation withheld because this record is not cleared for redistribution. grid cell —part-of→ SMT grid cell SMT strength of the relation: 1 Audit 2026-09-28: DOUBTFUL - read against its full span and kept, but 34.3% of grid cells PARTICIPATED in the SMT; part-of a task is loose. Quotation withheld because this record is not cleared for redistribution. random foraging —contrasted-with→ SMT random foraging SMT strength of the relation: 1 · note: the same cells recorded in both, with a mixed representation in CA1 - some cells in one task only, some producing fields in both Audit 2026-09-28: DOUBTFUL - read against its full span and kept, but cells were recorded in both the random-foraging task and the SMT and some fired in both; contrasted-with is loose. Quotation withheld because this record is not cleared for redistribution. grid cell —operationalised-as→ grid score grid cell grid score strength of the relation: 1 · note: THE DEFINITION IS A THRESHOLD ON THIS DATASET'S OWN SHUFFLES: the 95th percentile of the shuffled samples, which here was 0.46 Quotation withheld because this record is not cleared for redistribution. grid score —operationalised-as→ percentile grid score percentile strength of the relation: 1 Audit 2026-09-28: DOUBTFUL - read against its span and kept, but the grid score is compared against shuffled percentiles; operationalised-as is loose. Quotation withheld because this record is not cleared for redistribution. place cell —operationalised-as→ spatial information place cell spatial information strength of the relation: 1 · note: and place cells are those whose information rate exceeds 99% of their own shuffled values Quotation withheld because this record is not cleared for redistribution. spatial information —operationalised-as→ location spatial information location strength of the relation: 1 · note: the same formula as the task-phase information, run over 1600 spatial bins instead of time bins Audit 2026-09-28: DOUBTFUL - read against its span and kept, but spatial information is defined via location; operationalised-as is loose. Quotation withheld because this record is not cleared for redistribution. SWR —part-of→ CA1 SWR CA1 strength of the relation: 1 Audit 2026-09-28: DOUBTFUL - read against its full span and kept, but some CA1 spikes occurred DURING sharp-wave ripple events; part-of is loose. Quotation withheld because this record is not cleared for redistribution. head direction —distinct-from→ SMT head direction SMT strength of the relation: 1 · note: and the residual head-direction confound was tested directly, since those cells overlap the modulated population Quotation withheld because this record is not cleared for redistribution. time cell —contrasted-with→ SMT time cell SMT strength of the relation: 1 Quotation withheld because this record is not cleared for redistribution. task —contrasted-with→ passive playback task passive playback strength of the relation: 1 · note: THE CONTROL SEPARATES THE STIMULUS FROM THE TASK: 1.7% of the same CA1 cells responded to the identical sweeps outside the task, against 31.1% inside it Quotation withheld because this record is not cleared for redistribution. reward —operationalised-as→ salience reward salience strength of the relation: 1 · note: and the control is then run a second time WITH a reward, recovering a fifth of the cells Audit 2026-09-28: DOUBTFUL - read against its span and kept, but the span says salience was increased by delivering a reward; the direction of operationalised-as is loose. Quotation withheld because this record is not cleared for redistribution. behavioral context —causes→ firing field behavioral context firing field strength of the relation: 1 · note: fields in the rewarded playback task were more than twice as wide, so context affected both how many cells were activated and how precise they were Quotation withheld because this record is not cleared for redistribution. frequency —causes→ release frequency release strength of the relation: 1 · note: releases were predicted by frequency alone with almost no added influence of elapsed time Audit 2026-09-28: DOUBTFUL - read against its span and kept, but the span says sound frequency influenced when rats released the joystick; the endpoint 'release' is terse. Quotation withheld because this record is not cleared for redistribution. frequency —distinct-from→ duration frequency duration strength of the relation: 1 · note: trial durations were three times more variable than release frequencies, which is how the strategy is identified Audit 2026-09-28: DOUBTFUL - read against its span and kept, but the span compares variability of durations and frequencies; distinct-from is loose. Quotation withheld because this record is not cleared for redistribution. octave —operationalised-as→ frequency octave frequency strength of the relation: 1 · note: and the unit is RELATIVE - octaves above a 2 kHz start, so the number does not join without its reference Audit 2026-09-28: DOUBTFUL - read against its span and kept, but the span measures frequency in octaves; the direction of operationalised-as is reversed. Quotation withheld because this record is not cleared for redistribution. grid cell —part-of→ module grid cell module strength of the relation: 1 · note: and the module a cell belongs to predicts its field width in the SOUND task as well as in the arena Quotation withheld because this record is not cleared for redistribution. t-test t-test Quotation withheld because this record is not cleared for redistribution. coefficient of variation coefficient of variation Quotation withheld because this record is not cleared for redistribution. chi-squared test chi-squared test Quotation withheld because this record is not cleared for redistribution. Wilcoxon rank-sum test Wilcoxon rank-sum test Quotation withheld because this record is not cleared for redistribution. shuffle (permutation) test shuffle (permutation) test Quotation withheld because this record is not cleared for redistribution. mutual information mutual information Quotation withheld because this record is not cleared for redistribution. linear regression linear regression Quotation withheld because this record is not cleared for redistribution. bootstrap bootstrap Quotation withheld because this record is not cleared for redistribution. correlation correlation Quotation withheld because this record is not cleared for redistribution. mean squared error mean squared error Quotation withheld because this record is not cleared for redistribution. standard error of the mean standard error of the mean Quotation withheld because this record is not cleared for redistribution. principal component analysis principal component analysis Quotation withheld because this record is not cleared for redistribution. confidence interval confidence interval about this quote: This quote ends with the stray word 'The', the first word of the next sentence. It is not trimmed, because the quote without it occurs more than once in the paper's text and could not be tied to one place. The claim is carried by the sentence before 'The'. Quotation withheld because this record is not cleared for redistribution. coefficient of determination coefficient of determination Quotation withheld because this record is not cleared for redistribution. shuffle test shuffle test Quotation withheld because this record is not cleared for redistribution. mutual information rate mutual information rate Quotation withheld because this record is not cleared for redistribution. Wilcoxon rank-sum test Wilcoxon rank-sum test Quotation withheld because this record is not cleared for redistribution. coefficient of variation coefficient of variation Quotation withheld because this record is not cleared for redistribution. bootstrap bootstrap Quotation withheld because this record is not cleared for redistribution. linear regression linear regression Quotation withheld because this record is not cleared for redistribution. Rats solved the task by tracking sound frequency rather than elapsed time, releasing the joystick later when frequency advanced more slowly. Quotation withheld because this record is not cleared for redistribution. A large fraction of both CA1 and entorhinal cells were significantly task-modulated during the non-spatial sound task. Quotation withheld because this record is not cleared for redistribution. Task-modulated activity took the form of discrete firing fields resembling those seen during spatial navigation. Quotation withheld because this record is not cleared for redistribution. Most fields occurring during sound presentation were locked to sound frequency rather than to the motor events bounding the trial. Quotation withheld because this record is not cleared for redistribution. Almost no CA1 cells, including the task-modulated ones, responded to passive playback of the same sounds (1.7% against 31.1% during the task). Quotation withheld because this record is not cleared for redistribution. Adding a reward at the end of passive sweeps produced task-modulated activity, but in fewer cells than the task itself (20.2%). Quotation withheld because this record is not cleared for redistribution. Fields in the rewarded passive-playback task were about twice as wide as SMT fields, i.e. temporally less precise. Quotation withheld because this record is not cleared for redistribution. A quarter of identified place cells also carried the non-spatial sound representation. Quotation withheld because this record is not cleared for redistribution. Grid cells likewise participated in the non-spatial task. Quotation withheld because this record is not cleared for redistribution. How spatially tuned a neuron was barely predicted how strongly it was modulated in the sound task, indicating the two codes are near-independent within the same cells. Quotation withheld because this record is not cleared for redistribution. Grid module identity carried over to the sound task: modules with wider spatial fields produced wider sound fields. Quotation withheld because this record is not cleared for redistribution. the reconciling framework is stated in advance - spatial representation as one example of a general mechanism for encoding continuous task-relevant variables Quotation withheld because this record is not cleared for redistribution. neurons formed discrete firing fields at particular sound frequencies, and overlapped with the known spatial cell types Quotation withheld because this record is not cleared for redistribution. common circuit mechanisms are proposed for representations of diverse behavioural tasks Quotation withheld because this record is not cleared for redistribution. the cognitive map frame already allowed the related entities to be distinct stimuli or abstract concepts, not only locations Quotation withheld because this record is not cleared for redistribution. hippocampal firing was already known to be modulated by non-spatial variables, discrete stimuli and time points in delay tasks Quotation withheld because this record is not cleared for redistribution. TRAVERSAL SPEED WAS RANDOMISED SO THAT FREQUENCY AND ELAPSED TIME WERE UNCOUPLED, which is what makes a frequency field distinguishable from a time field Quotation withheld because this record is not cleared for redistribution. joystick releases were predicted by sound frequency alone with almost no added influence of elapsed time Quotation withheld because this record is not cleared for redistribution. and trial durations were about three times more variable than release frequencies, which is how the strategy was identified Quotation withheld because this record is not cleared for redistribution. 40.0% of CA1 units and 51.3% of MEC units were significantly modulated during the task Quotation withheld because this record is not cleared for redistribution. activity was largely confined to discrete firing fields akin to those of spatial navigation, clustered at trial boundaries but spanning the entire task Quotation withheld because this record is not cleared for redistribution. AND THE NEW THING IS NAMED AFTER THE OLD ONE: frequency fields, called analogous to place fields Quotation withheld because this record is not cleared for redistribution. more than half of the fields during sound presentation aligned best to frequency rather than to the press or the release Quotation withheld because this record is not cleared for redistribution. THE CONTROL SEPARATES THE STIMULUS FROM THE TASK: 1.7% of the same cells responded to identical sweeps outside the task, against 31.1% inside it Quotation withheld because this record is not cleared for redistribution. and the control was then run again WITH a reward, recovering a fifth of the cells Quotation withheld because this record is not cleared for redistribution. with fields more than twice as wide, so behavioural context affected both how many cells were activated and how precise they were, while agency was not strictly required Quotation withheld because this record is not cleared for redistribution. a quarter of place cells and a third of grid cells were modulated in the sound task, with a mixed representation in CA1 Quotation withheld because this record is not cleared for redistribution. MEMBERSHIP OF THE NAMED CLASS BARELY PREDICTED THE SAME CELL IN THE OTHER TASK: r2 of about 0.005 against placeness and gridness Quotation withheld because this record is not cleared for redistribution. so the two sets were not distinct subclasses of the circuit but a shared use of the same neural population between tasks Quotation withheld because this record is not cleared for redistribution. and the grid module a cell belongs to predicted its field width in the sound task as well as in the arena Quotation withheld because this record is not cleared for redistribution. THE ANALYSIS THAT WOULD HAVE DECIDED THE LATTICE READING COULD NOT BE RUN, for want of fields per grid cell Quotation withheld because this record is not cleared for redistribution. the sound task is declared analogous to a linear track, with the shared properties then listed one by one Quotation withheld because this record is not cleared for redistribution. Quotation withheld Quotation withheld because this record is not cleared for redistribution. A CELL TYPE IS NAMED AFTER THE TASK IT WAS DISCOVERED IN: the spatial patterns may be a consequence of the continuity of the task variable rather than a primacy of physical space Quotation withheld because this record is not cleared for redistribution. the rats did not need to represent the whole acoustic space; responding to one particular frequency would have sufficed Quotation withheld because this record is not cleared for redistribution. the conjecture is that task performance activates a progression of fields carrying the order and adjacency of behavioural states Quotation withheld because this record is not cleared for redistribution. with place and grid codes as a manifestation of that general mechanism rather than a spatial faculty Quotation withheld because this record is not cleared for redistribution. because rats sometimes moved their heads while deflecting the joystick in version 1 of the apparatus, version 2 was modified to remove this possible spatial confound Quotation withheld because this record is not cleared for redistribution. frequency is reported in octaves RELATIVE to a 2 kHz start, so the number does not join without its reference Quotation withheld because this record is not cleared for redistribution. and deflections from stepping or leaning on the joystick were removed by a 3 s minimum, so not every deflection is a trial Quotation withheld because this record is not cleared for redistribution. AN EXCLUSION CRITERION THAT DOES NOT EXIST OUTSIDE ITS OWN TASK: ripples are normally removed by rejecting low-velocity time points, and with no velocity here they had to be detected directly in the field potential Quotation withheld because this record is not cleared for redistribution. with the negative disclosure attached - excluding those spikes changed no result, it only raised the in-field to background ratio Quotation withheld because this record is not cleared for redistribution. the reported information is a RATIO TO CHANCE, real rate over the mean of 100 shuffles Quotation withheld because this record is not cleared for redistribution. and the information rate alone was rejected as the criterion because background differences inflate it, with the test placed on the peak rate instead Quotation withheld because this record is not cleared for redistribution. putative interneurons are defined by a bare rate threshold and excluded Quotation withheld because this record is not cleared for redistribution. place cells are defined as cells whose spatial information exceeds 99% of their own shuffled values Quotation withheld because this record is not cleared for redistribution. THE DEFINITION OF A GRID CELL IS A THRESHOLD ON THIS DATASET'S OWN SHUFFLES - the 95th percentile, which here was 0.46 Quotation withheld because this record is not cleared for redistribution. AND THE COUNT OF A CELL TYPE DEPENDS ON THE ARENA: fewer grid cells in the smaller environment, so every grid comparison was re-verified on the subset recorded in the larger environment Quotation withheld because this record is not cleared for redistribution. fields with more than one significant alignment coefficient are labelled mixed rather than forced into one class Quotation withheld because this record is not cleared for redistribution. THETA FREQUENCY DID NOT TRACK SPEED HERE, unlike in navigation, which is read as that relationship depending on locomotion-related signals Quotation withheld because this record is not cleared for redistribution. and fields did not broaden across the trial as time cells do, attributed to a sensory variable being continuously available Quotation withheld because this record is not cleared for redistribution. a head-direction confound was tested directly, since those cells overlap the modulated population Quotation withheld because this record is not cleared for redistribution. and two simultaneously recorded cells with similar head direction tuning had dissimilar sound-task firing, which is what rules it out Quotation withheld because this record is not cleared for redistribution. field tightening at the press and release is left with two rival explanations, denser sensory cues or greater salience Quotation withheld because this record is not cleared for redistribution. each interval is linearly warped to its median duration before any average is taken Quotation withheld because this record is not cleared for redistribution. sound manipulation task sound manipulation task Quotation withheld because this record is not cleared for redistribution. cognitive map cognitive map Quotation withheld because this record is not cleared for redistribution. frequency fields frequency fields Quotation withheld because this record is not cleared for redistribution. press press Quotation withheld because this record is not cleared for redistribution. grid score grid score Quotation withheld because this record is not cleared for redistribution. spatial information spatial information Quotation withheld because this record is not cleared for redistribution. cognitive map cognitive map Quotation withheld because this record is not cleared for redistribution. place cell place cell Quotation withheld because this record is not cleared for redistribution. grid cell grid cell Quotation withheld because this record is not cleared for redistribution. interneuron interneuron Quotation withheld because this record is not cleared for redistribution. modulated modulated Quotation withheld because this record is not cleared for redistribution. spatial information spatial information Quotation withheld because this record is not cleared for redistribution. mutual information rate mutual information rate Quotation withheld because this record is not cleared for redistribution. firing field width firing field width Quotation withheld because this record is not cleared for redistribution. putative interneurons putative interneurons Quotation withheld because this record is not cleared for redistribution. brief trials brief trials Quotation withheld because this record is not cleared for redistribution. frequency frequency Quotation withheld because this record is not cleared for redistribution. duration duration Quotation withheld because this record is not cleared for redistribution. grid score grid score Quotation withheld because this record is not cleared for redistribution. spatial information spatial information Quotation withheld because this record is not cleared for redistribution. speed speed Quotation withheld because this record is not cleared for redistribution. environment environment Quotation withheld because this record is not cleared for redistribution. 2208 / 1164 — units recorded in dorsal CA1 (5 rats) and dorsal MEC (9 rats) Quotation withheld because this record is not cleared for redistribution. 40.0% and 51.3% — proportion of CA1 and MEC cells significantly modulated by the sound task Quotation withheld because this record is not cleared for redistribution. 70.8±2.6% — proportion of trials on which rats released the joystick inside the reward target zone Quotation withheld because this record is not cleared for redistribution. 1.7% compared to 31.1% — CA1 cells responding during passive playback versus during the active task Quotation withheld because this record is not cleared for redistribution. 25.1% of 295 — share of place cells that were also modulated by the sound task Quotation withheld because this record is not cleared for redistribution. 34.3% of 105 — share of grid cells that were also modulated by the sound task Quotation withheld because this record is not cleared for redistribution. r 2 =0.0054 and r 2 =0.0053 — variance in sound-task modulation explained by placeness and by gridness Quotation withheld because this record is not cleared for redistribution. 2.49±0.29 s and 1.16±0.05 s — mean field width in the rewarded passive-playback task versus the active sound task Quotation withheld because this record is not cleared for redistribution. 26%, 23% and 51% — share of CA1 sound-period fields aligned to joystick press, to release, and to sound frequency Quotation withheld because this record is not cleared for redistribution. 0.78±0.02 s and 1.36±0.05 s — sound-task field widths for grid module 1 versus modules 2/3 Quotation withheld because this record is not cleared for redistribution. 0.46 — the grid score above which a cell is a grid cell - the 95th percentile of THIS dataset's own shuffles, not a constant Quotation withheld because this record is not cleared for redistribution. r 2 =0.0054 — a very weak correlation between the amount of SMT modulation and placeness, against 0.0053 for gridness, suggesting nearly independent activity patterns in the two tasks Quotation withheld because this record is not cleared for redistribution. 1.7% — cells responding to the identical sweeps outside the task, against 31.1% inside it Quotation withheld because this record is not cleared for redistribution. 20.2% — cells responding once a reward was added to the same passive sweeps Quotation withheld because this record is not cleared for redistribution. 25.1% — of 295 place cells modulated in the sound task, against 34.3% of 105 grid cells Quotation withheld because this record is not cleared for redistribution. 0.146±0.002 — coefficient of variation of trial duration against 0.046±0.005 for release frequency - the ratio that identifies the strategy 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/10.1038/nature21692.