Impairment and Facilitation of Transverse Patterning after Lesions of the Perirhinal Cortex and Hippocampus, Respectively

Saksida, Lisa M.; Bussey, Timothy J.; Buckmaster, Cindy A.; Murray, Elisabeth A.

doi:10.1093/cercor/bhj128

Cited by 67 publications

(55 citation statements)

References 48 publications

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“…The finding that configural manipulations that adversely affect subjects with PRh lesions in visual discrimination tasks (Buckley and Gaffan 1998;Eacott et al 2001;Bussey et al 2003;Saksida et al 2007) also adversely affect PRh and PPRh-lesioned rats in object recognition and oddity tasks also provides additional evidence that a common mechanism underlies the involvement of PRh in visual discrimination and recognition tasks.…”

Section: Configural Tasksmentioning

confidence: 84%

“…However, the conjunctions AB and CD are always rewarded and the conjunctions BC and AD are never rewarded; therefore, these conjunctions can be used to solve the task. Damage to PRh has been shown to disrupt performance in the biconditional discrimination and other configural tasks (Buckley and Gaffan 1998;Eacott et al 2001;Saksida et al 2007). However, these functions mediated by PRh-object recognition and the resolution of feature ambiguity in configural discrimination tasks-are usually regarded separately.…”

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confidence: 99%

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Perirhinal cortex resolves feature ambiguity in configural object recognition and perceptual oddity tasks

Bartko

Winters²,

Cowell³

et al. 2007

Learn. Mem.

169

147

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The perirhinal cortex (PRh) has a well-established role in object recognition memory. More recent studies suggest that PRh is also important for two-choice visual discrimination tasks. Specifically, it has been suggested that PRh contains conjunctive representations that help resolve feature ambiguity, which occurs when a task cannot easily be solved on the basis of features alone. However, no study has examined whether the ability of PRh to resolve configural feature ambiguity is related to its role in object recognition. Therefore, we examined whether bilateral excitotoxic lesions of PRh or PPRh (perirhinal plus post-rhinal cortices) in the rat would cause deficits in a configural spontaneous object recognition task, and a configural simultaneous oddity discrimination task, in which the task could not be solved on the basis of features, but could only be solved using conjunctive representations. As predicted by simulations using a computational model, rats with PPRh lesions were impaired during a minimal-delay configural object recognition task. These same rats were impaired during a zero-delay configural object recognition task. Furthermore, rats with localized PRh lesions were impaired in a configural simultaneous oddity discrimination task. These findings support the idea that PRh contains conjunctive representations for the resolution of feature ambiguity and that these representations underlie a dual role for PRh in memory and perception.Although the perirhinal cortex (PRh) has a well-established role in object recognition memory (Meunier et

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Section: Configural Tasksmentioning

confidence: 84%

mentioning

confidence: 99%

Perirhinal cortex resolves feature ambiguity in configural object recognition and perceptual oddity tasks

Bartko

Winters²,

Cowell³

et al. 2007

Learn. Mem.

169

147

View full text Add to dashboard Cite

show abstract

“…Other alterations in stimulus processing, such as overunitization of discrimination problems (Bussey et al, 1998;Saksida et al, 2007) or an impairment in pattern separation of the stimulus pairings (Kesner and Hopkins, 2006), may be consistent with impaired learning of re-paired discrimination problems, especially those in which the reward associations of individual stimuli are the same as in the previous set. However, these views would seem to predict facilitation of repaired problems in which reward associations are inconsistent with the previous set, which is the opposite result to ours.…”

Section: Discussionmentioning

confidence: 99%

Fornix Transection Impairs Learning of Randomly Changing Object Discriminations

Wilson

Charles²,

Buckley³

et al. 2007

J. Neurosci.

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The hippocampus has a well established role in spatial memory, but increasing evidence points to a role in nonspatial aspects of memory. To investigate such a role, six macaque monkeys received a bilateral transection of the fornix to disconnect subcortical inputs and outputs of the hippocampus. An additional six macaque monkeys constituted an unoperated control group. To test the involvement of the hippocampus in nonspatial aspects of memory, both groups were trained postoperatively on four concurrent visual object discrimination problems, each problem having one rewarded object and one unrewarded. After acquisition to criterion of these discriminations, the monkeys learned five subsequent stages of discriminations using the same objects. In each of these stages, both the pairings of objects one with another, and the reward assignments for the objects, were randomly reassigned. In the initial acquisition stage, control and fornix animals were equally proficient in learning the discriminations. In the five reassigned stages, however, monkeys with fornix transection made on average three times as many errors as the controls in learning the discriminations. This impairment was noted even in trials where the reward assignments from the previous stage were maintained in the new stage. These findings are consistent with other recent evidence for a role beyond the spatial domain for the fornix in monkeys.

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“…For example, rats with hippocampal damage tend to unitize pairs of odor stimuli that are presented in close juxtaposition in simultaneous discrimination problems, and they subsequently perform poorly when required to identify individual stimuli selected from different pairs. Also, in monkeys, the explicit learning of visual stimulus configurations is facilitated over that of normal animals by damage limited to the hippocampus, whereas configural representation is severely impaired following damage to the perirhinal cortex 15 . Consistent with these findings, we suggest that rats with hippocampal damage and preserved perirhinal function have an increased tendency to unitize the elements of stimulus pairs, allowing them to employ familiarity as a compensatory strategy for distinguishing new and old pairs.…”

mentioning

confidence: 99%

Recognition memory: opposite effects of hippocampal damage on recollection and familiarity

et al. 2007

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A major controversy in memory research concerns whether recognition is subdivided into distinct cognitive mechanisms of recollection and familiarity that are supported by different neural substrates. Here we developed a new associative recognition protocol for rats that enabled us to show that recollection is reduced, whereas familiarity is increased following hippocampal damage. These results provide strong evidence that these processes are qualitatively different and that the hippocampus supports recollection and not familiarity.Some of the most compelling data on recognition memory and hippocampal function involve the use of signal detection analyses. In these analyses, subjects are initially presented with a stimulus list and are then required to identify test stimuli as the same (old) items or different (new) stimuli across a range of confidence levels or response biases. In normal human subjects, the receiver operating characteristic (ROC) function for lists of single items is typically asymmetrical (featuring an above-zero y intercept), interpreted by some to reflect a threshold for recollection, and has a curvilinear shape, reflecting the strength of familiarity (the dual process model 1 ). A major alternative view is that recognition is supported by qualitatively similar memory signals, wherein for each the degree of curvilinearity reflects the sum of the strengths of memory components and the asymmetry reflects greater variability in strength for old than for new items (the unequal variance model 2 ). According to this latter view, familiarity and recollection differ only in sensitivity, such that familiarity reflects the detection of weaker memories, whereas recollection is experienced when memories are stronger or involve more information.There is also compelling evidence indicating that recollection and familiarity may have distinct neural substrates, but the question of whether specific brain areas make qualitatively different contributions to recognition memory remains controversial 1 , 3 . Evidence from

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Impairment and Facilitation of Transverse Patterning after Lesions of the Perirhinal Cortex and Hippocampus, Respectively

Cited by 67 publications

References 48 publications

Perirhinal cortex resolves feature ambiguity in configural object recognition and perceptual oddity tasks

Perirhinal cortex resolves feature ambiguity in configural object recognition and perceptual oddity tasks

Fornix Transection Impairs Learning of Randomly Changing Object Discriminations

Recognition memory: opposite effects of hippocampal damage on recollection and familiarity

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