Short-Term Memory and the Human Hippocampus

Short-Term Memory and the Human Hippocampus Kumaran

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Short-Term Memory and the Human Hippocampus 2008 Journal of Neuroscience 10.1523/jneurosci.0046-08.2008 Kumaran2008-short-term-memory-and-the-human-hippocampus Kumaran2008-short-term-memory-and-the-human-hippocampus.txt, the project's staged copy 6b0d873c0d5a0c5606390b541073e8cb98499941 not-redistributable neuroscience

the paper's own words

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0 spans located by searching the stored text for the quote's exact words, allowing any whitespace between them Hannula and Ranganath's fMRI study of short-term associative memory, read for what it shows about the hippocampal contribution to holding novel associations in mind. Quotation withheld because this record is not cleared for redistribution. How — at which task phase and by what signal — does the hippocampus support short-term memory for novel associative information? Quotation withheld because this record is not cleared for redistribution. mechanism Quotation withheld because this record is not cleared for redistribution. hippocampal contribution to short-term associative memory Quotation withheld because this record is not cleared for redistribution. review review Quotation withheld because this record is not cleared for redistribution. mechanisms the hippocampus holds short-term associative information by transiently changing synaptic efficacy rather than by sustained firing across the delay status: the paper's own words: One possibility is that Quotation withheld because this record is not cleared for redistribution. mechanisms the task being performed sets the amplitude of the hippocampal response to novel or familiar input, so top-down task demands determine whether match or mismatch produces the larger signal Quotation withheld because this record is not cleared for redistribution. The hippocampus may hold associations through transient changes in synaptic efficacy rather than sustained firing, which would explain why no delay-period signal appears Quotation withheld because this record is not cleared for redistribution. Active maintenance might still occur by a mechanism fMRI cannot see, such as theta/gamma oscillations Quotation withheld because this record is not cleared for redistribution. The hippocampus is proposed to act as a comparator, detecting discrepancies between predictions from past experience and current input Quotation withheld because this record is not cleared for redistribution. The commentary's own resolution of the conflicting match/mismatch results: the size of the hippocampal response to novelty depends on what task is being performed, with top-down influence present in explicit recognition and absent in automatic detection Quotation withheld because this record is not cleared for redistribution. Under explicit recognition the pattern resembles match enhancement in monkey inferotemporal and perirhinal cortex, whereas automatic novelty detection may show the comparator signal uncontaminated by top-down input Quotation withheld because this record is not cleared for redistribution. The commentary's central conclusion rests on a null delay-period result in the study it reviews, which it flags as requiring caution. what this limits: the commentary's central conclusion, which rests on an absence: ALTHOUGH CAUTION IS ADVISED IN INTERPRETING SUCH A NULL FINDING, THIS RESULT DOES SUGGEST THAT PERSISTENT NEURAL FIRING IN THE HIPPOCAMPUS DOES NOT OCCUR DURING THE DELAY PERIOD Quotation withheld because this record is not cleared for redistribution. Absent confidence ratings, a performance/confidence confound in the match-versus-mismatch comparison it relies on cannot be entirely excluded. what this limits: the match-versus-mismatch comparison it relies on: WITHOUT CONFIDENCE RATING DATA, IT IS DIFFICULT TO ENTIRELY EXCLUDE THE POSSIBILITY THAT SUBJECTS MAY HAVE BEEN MORE CONFIDENT IN MAKING (CORRECT) MATCH ... JUDGMENTS Quotation withheld because this record is not cleared for redistribution. The commentary's own caution: without confidence ratings, better performance on match trials cannot be fully separated from the neural difference attributed to match what this limits: the same scope as limitations[1], and it is a re-raising rather than a new objection: THE AUTHORS CAREFULLY CONSIDERED AND DISCOUNTED SUCH AN EFFECT Quotation withheld because this record is not cleared for redistribution. The central conclusion about maintenance rests on an absence of difference, which the commentary flags as a null result duplicate of: limitations[0] · what this limits: the same scope as limitations[0] - the maintenance conclusion is a null finding Quotation withheld because this record is not cleared for redistribution. The formal models that would make the comparator account testable do not yet exist in the required form what this limits: the comparator account: ONE IMPORTANT DIRECTION FOR FUTURE RESEARCH WILL BE TO DEVELOP AND EMPIRICALLY TEST FORMAL COMPUTATIONAL MODELS OF RECOGNITION MEMORY ... AND AUTOMATIC NOVELTY PROCESSING Quotation withheld because this record is not cleared for redistribution. Match enhancement, established in monkey inferotemporal and perirhinal single-unit work, imported to read a human hippocampal fMRI result Quotation withheld because this record is not cleared for redistribution. The subsequent-memory design, developed for long-term recognition memory, applied to a short-term task - which required deliberately making the task hard enough to avoid ceiling performance Quotation withheld because this record is not cleared for redistribution. memory - the textbook dichotomy: short-term and long-term as distinct processes with distinct substrates, which is the view under challenge Quotation withheld because this record is not cleared for redistribution. memory - the revised view: short-term and long-term as sharing neural mechanisms rather than being qualitatively distinct Quotation withheld because this record is not cleared for redistribution. subsequent memory - at the sample phase: encoding-side activity predicting later success, which alone cannot distinguish associative from item encoding Quotation withheld because this record is not cleared for redistribution. subsequent memory - at the test phase: retrieval-side activity, whose presence is what rules out the item-encoding explanation Quotation withheld because this record is not cleared for redistribution. hippocampal novelty signal - under explicit recognition: largest for MATCH, resembling match enhancement Quotation withheld because this record is not cleared for redistribution. hippocampal novelty signal - when novelty is incidental to the task: largest for MISMATCH, the opposite direction, which is the discrepancy the commentary sets out to explain Quotation withheld because this record is not cleared for redistribution. spatial strategy - allocentric: world-centred, hippocampally mediated, the one the task was designed to force Quotation withheld because this record is not cleared for redistribution. builds-on → Hannula and Ranganath (2008) Quotation withheld because this record is not cleared for redistribution. contradicts → Kumaran and Maguire (2006) differs in: THE AXIS IS WHETHER THE MEMORY JUDGMENT IS EXPLICIT OR INCIDENTAL. 'Quotation withheld (i.e., subjects are not required to make explicit recognition memory judgments), a qualitatively different pattern of findings has been observed with hippocampal activation maximal under conditions of mismatch rather than match.' The direction of the hippocampal effect REVERSES on a task-instruction parameter - the strongest form this field takes, because the two literatures are not in conflict at all once the parameter is named. Quotation withheld because this record is not cleared for redistribution. builds-on → Norman and O'Reilly (2003) comparator model of the hippocampus Quotation withheld because this record is not cleared for redistribution. contradicts → the dichotomous short-term/long-term memory account (Squire, 1992) Quotation withheld because this record is not cleared for redistribution. critiques → the textbook dichotomy of short-term and long-term memory as separate systems (Squire 1992) Quotation withheld because this record is not cleared for redistribution. supports → Norman and O'Reilly (2003), the hippocampus as comparator Quotation withheld because this record is not cleared for redistribution. extends → Cohen and Eichenbaum (1993), the hippocampus as relational binder in long-term memory Quotation withheld because this record is not cleared for redistribution. perirhinal cortex —contrasted-with→ hippocampus perirhinal cortex hippocampus differs in: THE AXIS IS WHAT KIND OF INFORMATION IS BEING HELD. 'Whereas the perirhinal cortex appears to support short-term memory for novel object information, neuropsychological evidence suggests that the hippocampus is critical when associative information is involved.' Both structures support short-term memory; the division is BY CONTENT, NOT BY DURATION - which is the point, since duration is what the literature usually divides them by. · strength of the relation: 1 Quotation withheld because this record is not cleared for redistribution. allocentric —distinct-from→ egocentric allocentric egocentric differs in: THE AXIS IS THE REFERENCE FRAME, AND THE MANIPULATION THAT ENFORCES IT IS GIVEN. 'Quotation withheld, subjects were asked to FORM A mental image of the scene rotated 90 [degrees].' The two frames are not observed and distinguished - one is INDUCED BY AN INSTRUCTION, so the result is conditional on subjects complying with it. A row of Kravitz2011 in this corpus gives the same axis as an anatomical tendency, hedged on both sides. · strength of the relation: 1 Quotation withheld because this record is not cleared for redistribution. hippocampus —distinct-from→ active maintenance hippocampus active maintenance strength of the relation: 0.8 Audit 2026-09-28: DOUBTFUL - read against its full span and kept, but the hippocampus supports encoding and retrieval 'but PERHAPS NOT' active maintenance; distinct-from is hedged. Quotation withheld because this record is not cleared for redistribution. novelty —contrasted-with→ familiarity novelty familiarity strength of the relation: 1 Quotation withheld because this record is not cleared for redistribution. match enhancement —part-of→ perirhinal cortex match enhancement perirhinal cortex strength of the relation: 0.9 Audit 2026-09-28: DOUBTFUL - read against its full span and kept, but match enhancement was OBSERVED IN monkey inferotemporal/perirhinal cortex; part-of is loose. Quotation withheld because this record is not cleared for redistribution. hippocampal amnesia —causes→ short-term memory hippocampal amnesia short-term memory strength of the relation: 0.9 Audit 2026-09-28: DOUBTFUL - read against its full span and kept, but patients with hippocampal amnesia were IMPAIRED at remembering locations across a short delay; the edge lacks its direction (reduces). Quotation withheld because this record is not cleared for redistribution. Hippocampal activity measured during the sample (encoding) phase predicted whether the later recognition judgment would be correct. Quotation withheld because this record is not cleared for redistribution. A subsequent-memory effect in the perirhinal cortex appeared only in the sample phase, consistent with that region encoding item-specific rather than associative information. Quotation withheld because this record is not cleared for redistribution. Hippocampal delay-period activity did not differ with later recognition accuracy. Quotation withheld because this record is not cleared for redistribution. On correct trials, hippocampal activation was higher for match displays than for either type of mismatch display. WHOSE RESULT THIS IS: The authors used a region-of-interest analysis to demonstrate - THE EVIDENCE FOR THIS ROW ATTRIBUTES THE WORK TO SOMEBODY ELSE. The cited name is the subject of a result verb and the sentence carries no first-person marker, so the finding, quantity or definition is the CITED author's rather than this record's. The claim is true and the quote is verbatim - what is wrong is whose result the corpus says it is. Nothing edited, nothing withdrawn: the row is marked so a page can name the source. Where the record is a commentary or review, its claim relations layer usually already names the paper being discussed - the record knows at one layer and forgets at another. Quotation withheld because this record is not cleared for redistribution. The direction of the hippocampal match/mismatch response reverses when novelty is incidental rather than the object of an explicit recognition judgment, with activation then peaking for mismatch. Quotation withheld because this record is not cleared for redistribution. The hippocampus contributes to short-term memory for novel associations at encoding and retrieval but apparently not during active maintenance. Quotation withheld because this record is not cleared for redistribution. Finding a hippocampal subsequent-memory effect at test as well as at sample excludes the alternative that sample-phase activity merely reflected encoding of the individual objects rather than the object-location associations. Quotation withheld because this record is not cleared for redistribution. short-term memory short-term memory Quotation withheld because this record is not cleared for redistribution. match-mismatch detector match-mismatch detector Quotation withheld because this record is not cleared for redistribution. short-term memory short-term memory Quotation withheld because this record is not cleared for redistribution. comparator comparator Quotation withheld because this record is not cleared for redistribution. allocentric allocentric Quotation withheld because this record is not cleared for redistribution. egocentric egocentric Quotation withheld because this record is not cleared for redistribution. match enhancement match enhancement Quotation withheld because this record is not cleared for redistribution. Journal Club Journal Club Quotation withheld because this record is not cleared for redistribution. types of test trials types of test trials Quotation withheld because this record is not cleared for redistribution. memory for the positions memory for the positions Quotation withheld because this record is not cleared for redistribution. hippocampal activation hippocampal activation WHOSE RESULT THIS IS: The authors used a region-of-interest analysis to demonstrate - THE EVIDENCE FOR THIS ROW ATTRIBUTES THE WORK TO SOMEBODY ELSE. The cited name is the subject of a result verb and the sentence carries no first-person marker, so the finding, quantity or definition is the CITED author's rather than this record's. The claim is true and the quote is verbatim - what is wrong is whose result the corpus says it is. Nothing edited, nothing withdrawn: the row is marked so a page can name the source. Where the record is a commentary or review, its claim relations layer usually already names the paper being discussed - the record knows at one layer and forgets at another. Quotation withheld because this record is not cleared for redistribution. 33% — chance level of correct responses in the three-alternative test classification Quotation withheld because this record is not cleared for redistribution. 78, 65, and 60% — accuracy on match, mismatch-position and mismatch-swap displays respectively Quotation withheld because this record is not cleared for redistribution. 11 s — length of the delay over which the rotated scene had to be maintained Quotation withheld because this record is not cleared for redistribution. four objects (out of a set of nine objects), nine possible locations — composition of each sample scene: four of nine objects placed in nine possible grid positions 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/10.1523/jneurosci.0046-08.2008.