Navigating from hippocampus to parietal cortex

Navigating from hippocampus to parietal cortex Whitlock Sutherland Witter Moser Moser

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Navigating from hippocampus to parietal cortex 2008 Proceedings of the National Academy of Sciences of the United States of America 10.1073/pnas.0804216105 Whitlock2008-navigating-from-hippocampus-to-parietal-cort Whitlock2008-navigating-from-hippocampus-to-parietal-cort.txt, the project's staged copy c9ba2f0b4433db18725e70044b09e3df545912f6 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 how allocentric spatial maps in entorhinal cortex and hippocampus are converted into body-centred signals that can guide movement Quotation withheld because this record is not cleared for redistribution. which structure performs the transformation from map coordinates to egocentric motor output Quotation withheld because this record is not cleared for redistribution. proposes posterior parietal cortex as the site of that transformation, and assembles the primate and rodent evidence for it Quotation withheld because this record is not cleared for redistribution. mechanism Quotation withheld because this record is not cleared for redistribution. spatial navigation in rodents Quotation withheld because this record is not cleared for redistribution. review review Quotation withheld because this record is not cleared for redistribution. mechanisms Output of the medial entorhinal grid-cell circuit is transformed into body-based coordinates in parietal cortex, and parietal projections to motor and premotor cortex then convert those coordinates into locomotor commands. status: the paper's own words: We propose here that Quotation withheld because this record is not cleared for redistribution. mechanisms World-referenced and body-referenced signals converge multiplicatively on single PPC neurons, and this conjunctive (gain-field) coding is what performs the allocentric-to-egocentric conversion. Quotation withheld because this record is not cleared for redistribution. PPC neurons multiply world-referenced by body-referenced signals, which is what a coordinate transformation requires Quotation withheld because this record is not cleared for redistribution. grid cells are argued to rest on path integration because a periodic firing pattern persists through constantly changing speed and direction Quotation withheld because this record is not cleared for redistribution. grids keep their relative geometry across environments, unlike place fields which remap Quotation withheld because this record is not cleared for redistribution. path integration drifts without recalibration against landmarks, which is why both mechanisms are needed Quotation withheld because this record is not cleared for redistribution. self-motion generates the firing but external cues anchor where it occurs Quotation withheld because this record is not cleared for redistribution. PPC delay activity tracks the movement to be made rather than the target location, switching when the required effector changes Quotation withheld because this record is not cleared for redistribution. Whether PPC deficits actually reflect a failure to transform self-location into locomotor action is not established by the existing evidence. what this limits: the central proposal of the review: WHETHER THEY DO REMAINS OPEN; AT PRESENT, THE EVIDENCE IS AMBIGUOUS Quotation withheld because this record is not cleared for redistribution. The direct medial entorhinal projection to PPC is weak and may not carry usable location information. what this limits: the anatomical route the account depends on: THIS CONNECTION IS RELATIVELY WEAK, AND IT IS UNCERTAIN WHETHER IT IS ABLE TO CONVEY LOCATION INFORMATION Quotation withheld because this record is not cleared for redistribution. It is unknown whether medial entorhinal output actually targets the PPC neurons involved in action preparation. what this limits: the link from grid-cell coding to action preparation: IT HAS NOT BEEN DETERMINED WHETHER THE MEDIAL ENTORHINAL OUTPUT targets the relevant PPC neurons Quotation withheld because this record is not cleared for redistribution. Which of the candidate hippocampal-entorhinal to PPC routes actually carries the signal is unresolved. what this limits: any claim identifying which pathway carries the signal: THE RELATIVE CONTRIBUTIONS OF THE VARIOUS PATHWAYS REMAIN UNCERTAIN Quotation withheld because this record is not cleared for redistribution. The whole account is at an early stage. what this limits: the maturity of the whole account: WE ARE JUST BEGINNING TO SCRATCH THE SURFACE OF THIS MULTITUDE OF NAVIGATIONAL CONTROL PATHWAYS Quotation withheld because this record is not cleared for redistribution. in most lesion studies navigation impairments cannot be separated from memory impairments what this limits: every lesion-based navigation claim cited: THE IMPAIRMENTS IN NAVIGATION CAN UNFORTUNATELY NOT BE DISTINGUISHED FROM EFFECTS ON MEMORY Quotation withheld because this record is not cleared for redistribution. the exact anatomical definition of rodent PPC remains a subject of debate what this limits: every result attributed to rodent PPC: AN EXACT ANATOMICAL DEFINITION FOR THE PPC IN RODENTS REMAINS A SUBJECT OF DEBATE - the region quantified over is not agreed Quotation withheld because this record is not cleared for redistribution. whether to include parts of Oc2 is still controversial what this limits: the extent of that region specifically: WHETHER OR NOT TO INCLUDE PARTS OF OC2 IN THE PPC ... IS STILL CONTROVERSIAL Quotation withheld because this record is not cleared for redistribution. head restraint in the primate work prevents any analysis of PPC during free locomotion what this limits: the transfer of the primate PPC findings to navigation: MOVEMENT RESTRICTIONS INHERENT TO THE HEAD-RESTRAINED SYSTEM PREVENT AN ANALYSIS during free locomotion Quotation withheld because this record is not cleared for redistribution. a study contradicting the hippocampal path-integration account is set aside on the grounds that a dragged food cup may have left odour trails what this limits: the standing of the evidence against the path-integration hypothesis: WE SUGGEST THAT THE STUDY IS NOT DECISIVE IN NEGATING THE HYPOTHESIS, on the stated ground that odour trails may have been available Quotation withheld because this record is not cleared for redistribution. the multiplicative gain-field mechanism for coordinate transformation, imported as the account of how a rodent map becomes motor output Quotation withheld because this record is not cleared for redistribution. the dorsal and ventral stream distinction and the deficits of parietal patients, used to motivate PPC's spatial role Quotation withheld because this record is not cleared for redistribution. parietal cortex is defined in the first line of the definition box by an overlying BONE, then immediately refined by cytoarchitecture, myeloarchitecture, neurochemistry and connectivity Quotation withheld because this record is not cleared for redistribution. PPC is delimited by what it is between and by which thalamic inputs it lacks - a definition by exclusion and by neighbours rather than by intrinsic property Quotation withheld because this record is not cleared for redistribution. place cells remap between environments while grid cells keep their relative geometry - the distinction that makes one a map of a place and the other a metric Quotation withheld because this record is not cleared for redistribution. the primate PPC literature shifted from a general spatial framework to multiple action-specific representations, so PPC function means something different before and after that shift Quotation withheld because this record is not cleared for redistribution. claim_type: mechanism a second reading reaching the same value. Recorded: mechanism — 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: narrative review across rodent and primate literatures, with an explicit proposal and a boxed treatment of how the target region is defined a second reading DIFFERING from the recorded value. Recorded: review — 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: path integration and goal-directed navigation a second reading DIFFERING from the recorded value. Recorded: spatial navigation in rodents — 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. extends → previous models in which parietal cortex mediates translation between external and first-person spatial representations (ref. 32) Quotation withheld because this record is not cleared for redistribution. builds-on → O'Keefe and Dostrovsky (1971) (ref. 4) Quotation withheld because this record is not cleared for redistribution. contradicts → the study reporting that rats with partial hippocampal lesions returned to the start position (ref. 30) Quotation withheld because this record is not cleared for redistribution. extends → models proposing that parietal cortex translates between external and first-person spatial representations Quotation withheld because this record is not cleared for redistribution. qualifies → the study reporting intact path integration after partial hippocampal lesions Quotation withheld because this record is not cleared for redistribution. supports → the cognitive map account of hippocampal place cells Quotation withheld because this record is not cleared for redistribution. supports → the intention account of primate PPC delay activity Quotation withheld because this record is not cleared for redistribution. grid cells —distinct-from→ place cells grid cells place cells differs in: THE AXIS IS DEPENDENCE ON THE PARTICULAR ENVIRONMENT. 'Quotation withheld.' Both are spatially tuned; only one re-maps, so a result obtained in a single environment cannot distinguish them at all - the distinction exists only across environments. · strength of the relation: 1 · note: grids keep relative geometry across environments; place fields do not Quotation withheld because this record is not cleared for redistribution. PPC —distinct-from→ somatosensory cortex PPC somatosensory cortex strength of the relation: 1 · note: distinguished by which thalamic inputs it LACKS, plus callosal connections - definition by exclusion Quotation withheld because this record is not cleared for redistribution. The paper's central claim is that the posterior parietal cortex converts the world-centred position signal carried by place cells and grid cells into the body-centred coordinates that locomotion requires. Quotation withheld because this record is not cleared for redistribution. Rats with PPC lesions cannot return directly to a refuge on a curtained circular arena on the basis of their outbound movements. Quotation withheld because this record is not cleared for redistribution. Rat PPC cells fire for conjunctions of a particular movement with a particular place - for instance only during outward forward running, or only during left turns at the end of an arm. Quotation withheld because this record is not cleared for redistribution. PPC firing fields rescale with the size of a maze segment even when hippocampal place fields do not, a dissociation implying PPC does not code perceived space. Quotation withheld because this record is not cleared for redistribution. No direct connections reach PPC from dentate gyrus, hippocampus or subiculum; the dorsal lateral band of medial entorhinal cortex projects to it directly. Quotation withheld because this record is not cleared for redistribution. Retrosplenial cortex damage causes strong, lasting disruption of spatial navigation, in the water maze and in path integration back to a home base in darkness. Quotation withheld because this record is not cleared for redistribution. the entorhinal-hippocampal circuit alone cannot convert spatial information into goal-oriented motor output Quotation withheld because this record is not cleared for redistribution. a multiplicative mechanism is what is needed to translate the allocentric entorhinal representation into goal-directed movement Quotation withheld because this record is not cleared for redistribution. PPC cells are thought to form a distributed representation of movement plans or intentions toward specific goal locations Quotation withheld because this record is not cleared for redistribution. 77% of neurons in a medial PPC region responded to conjunctions of movement and location during virtual navigation Quotation withheld because this record is not cleared for redistribution. grid fields keep their relative shift and rotation across environments, unlike place fields Quotation withheld because this record is not cleared for redistribution. place and grid firing persists without external cues but is anchored by them Quotation withheld because this record is not cleared for redistribution. grid cell grid cell Quotation withheld because this record is not cleared for redistribution. cognitive map cognitive map Quotation withheld because this record is not cleared for redistribution. posterior parietal cortex (PPC) posterior parietal cortex (PPC) Quotation withheld because this record is not cleared for redistribution. path integration path integration Quotation withheld because this record is not cleared for redistribution. parietal cortex parietal cortex Quotation withheld because this record is not cleared for redistribution. PPC PPC Quotation withheld because this record is not cleared for redistribution. place field place field Quotation withheld because this record is not cleared for redistribution. grid grid Quotation withheld because this record is not cleared for redistribution. 77% — proportion of medial-PPC neurons in monkeys responding to conjunctions of specific movements with specific locations during virtual navigation Quotation withheld because this record is not cleared for redistribution. ≈2–6 mm posterior to bregma and 2–5 mm lateral — stereotaxic extent of the rat cortical area targeted in most PPC lesion studies Quotation withheld because this record is not cleared for redistribution. about 2 to 6 mm posterior to bregma and 2 to 5 mm lateral — where most rat PPC lesion studies have focused - compare Bucci2009, which gives 3.5 to 5.0 posterior and 1.0 or 1.5 to 5.0 lateral for the same region Quotation withheld because this record is not cleared for redistribution. four published delineations, in red, yellow, magenta and blue — the number of incompatible published boundaries for rat parietal cortex, drawn on one brain in Figure 3 Quotation withheld because this record is not cleared for redistribution. 77% — neurons responding to movement-location conjunctions in virtual navigation Quotation withheld because this record is not cleared for redistribution. four areas 7a, b, m and ip — the macaque subdivision whose applicability to rat is disputed Quotation withheld because this record is not cleared for redistribution. error in initial heading error in initial heading Quotation withheld because this record is not cleared for redistribution.

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