scholarly journals Task set and instructions influence the weight of figural priors: A psychophysical study with extremal edges and familiar configuration

2021 ◽  
Author(s):  
Tandra Ghose ◽  
Mary A. Peterson
Keyword(s):  
Medial Temporal Lobe ◽  
Perirhinal Cortex ◽  
Shape Prior ◽  
Task Set ◽  
Cross Border ◽  
Within Subjects ◽  
Extremal Edges ◽  
Psychophysical Study ◽  
Ground Organization ◽  
Familiar Objects

AbstractIn figure–ground organization, the figure is defined as a region that is both “shaped” and “nearer.” Here we test whether changes in task set and instructions can alter the outcome of the cross-border competition between figural priors that underlies figure assignment. Extremal edge (EE), a relative distance prior, has been established as a strong figural prior when the task is to report “which side is nearer?” In three experiments using bipartite stimuli, EEs competed and cooperated with familiar configuration, a shape prior for figure assignment in a “which side is shaped?” task.” Experiment 1 showed small but significant effects of familiar configuration for displays sketching upright familiar objects, although “shaped-side” responses were predominantly determined by EEs. In Experiment 2, instructions regarding the possibility of perceiving familiar shapes were added. Now, although EE remained the dominant prior, the figure was perceived on the familiar-configuration side of the border on a significantly larger percentage of trials across all display types. In Experiment 3, both task set (nearer/shaped) and the presence versus absence of instructions emphasizing that familiar objects might be present were manipulated within subjects. With familiarity thus “primed,” effects of task set emerged when EE and familiar configuration favored opposite sides as figure. Thus, changing instructions can modulate the weighing of figural priors for shape versus distance in figure assignment in a manner that interacts with task set. Moreover, we show that the influence of familiar parts emerges in participants without medial temporal lobe/ perirhinal cortex brain damage when instructions emphasize that familiar objects might be present.

The Perceptual-Mnemonic/Feature Conjunction Model of Perirhinal Cortex Function

2005 ◽  
Vol 58 (3-4b) ◽  
pp. 269-282 ◽  
Author(s):  
Timothy J. Bussey ◽  
Lisa M. Saksida ◽  
Elisabeth A. Murray
Keyword(s):  
Present Article ◽  
Visual Discrimination ◽  
Medial Temporal Lobe ◽  
Declarative Memory ◽  
Perirhinal Cortex ◽  
Alternative View ◽  
Special Role ◽  
Visual Stream ◽  
Feature Conjunction ◽  
High Degree

The perirhinal cortex was once thought to be “silent cortex”, virtually ignored by researchers interested in the neurobiology of learning and memory. Following studies of brain damage associated with cases of amnesia, perirhinal cortex is now widely regarded as part of a “medial temporal lobe (MTL) memory system”. This system is thought to be more or less functionally homogeneous, having a special role in declarative memory, and making little or no contribution to other functions such as perception. In the present article, we summarize an alternative view. First, we propose that components of the putative MTL system such as the hippocampus and perirhinal cortex have distinct and dissociable functions. Second, we provide evidence that the perirhinal cortex has a role in visual discrimination. In addition, we propose a specific role for perirhinal cortex in visual discrimination: the contribution of complex conjunctive representations to the solution of visual discrimination problems with a high degree of “feature ambiguity”. These proposals constitute a new view of perirhinal cortex function, one that does not assume strict modularity of function in the occipito-temporal visual stream, but replaces this idea with the notion of a hierarchical representational continuum.

scholarly journals Functional specialization of the medial temporal lobes in human recognition memory: dissociating effects of hippocampal vs parahippocampal damage

2020 ◽  
Author(s):  
Georgios P. D. Argyropoulos ◽  
Carola Dell’Acqua ◽  
Emily Butler ◽  
Clare Loane ◽  
Adriana Roca-Fernandez ◽  
...  
Keyword(s):  
Recognition Memory ◽  
Medial Temporal Lobe ◽  
Single Case ◽  
Memory Performance ◽  
Perirhinal Cortex ◽  
Process Models ◽  
Dual Process ◽  
Hippocampal Damage ◽  
Material Type ◽  
Brain Behavior

AbstractA central debate in the systems neuroscience of memory concerns whether different medial temporal lobe (MTL) structures support different processes or material-types in recognition memory. We tested a rare patient (Patient MH) with a perirhinal lesion that appeared to spare the hippocampus, using two recognition memory paradigms, each run separately with faces, scenes and words. Replicating reports of a previous case, Patient MH showed impaired familiarity and preserved recollection, relative to controls, with no evidence for any effect of material-type. Moreover, when compared with other amnesic patients, who had hippocampal lesions that appeared to spare the perirhinal cortex, Patient MH showed greater impairment on familiarity and less on recollection, forming a double dissociation. However, when replacing this traditional, binary categorization of patients with a parametric analysis that related memory performance to continuous measures of brain damage across all patients, we found a different pattern: while hippocampal damage predicted recollection, it was parahippocampal instead of perirhinal (or entorhinal) cortex volume that predicted familiarity. Furthermore, there was no evidence that these brain-behavior relationships were moderated by material-type, nor by laterality of damage. Thus, while our data provide the most compelling support yet for dual-process models of recognition memory, in which recollection and familiarity depend on different MTL structures, they suggest that familiarity depends more strongly upon the parahippocampal rather than perirhinal cortex. More generally, our study reinforces the need to go beyond single-case and group studies, and instead examine continuous brain-behavior relationships across larger patient groups.

scholarly journals High feature overlap reveals the importance of anterior and medial temporal lobe structures for learning by means of fast mapping

2020 ◽  
Author(s):  
Ann-Kathrin Zaiser ◽  
Regine Bader ◽  
Patric Meyer
Keyword(s):  
Medial Temporal Lobe ◽  
Declarative Memory ◽  
Perirhinal Cortex ◽  
Semantic Integration ◽  
The Novel ◽  
Fast Mapping ◽  
Learning Procedure ◽  
Feature Overlap ◽  
High Degree ◽  
Novel Associations

AbstractContrary to traditional theories of declarative memory, it has recently been shown that novel, arbitrary associations can be rapidly and directly integrated into cortical memory networks by means of a learning procedure called fast mapping (FM), possibly bypassing time-consuming hippocampal-neocortical consolidation processes. In the typical FM paradigm, a picture of a previously unknown item is presented next to a picture of a previously known item and participants answer a question referring to an unfamiliar label. It is assumed that they thereby incidentally create associations between the unknown item and the label. However, contradictory findings have been reported and factors moderating rapid cortical integration through FM yet need to be identified. In the context of previous behavioral results showing rapid semantic integration through FM especially if the unknown and the known item shared many features, we propose that due to its computational mechanisms during the processing of complex and particularly highly similar objects, the perirhinal cortex might be especially qualified to support the rapid incorporation of these associations into cortical memory networks within the FM paradigm. We therefore expected that a high degree of feature overlap between the unknown and the known item would trigger strong engagement of the perirhinal cortex at encoding, which in turn might enhance rapid cortical integration of the novel picture-label associations. Within an fMRI experiment, we observed stronger activation for subsequent hits than misses during encoding in the perirhinal cortex and an associated anterior temporal network if the items shared many features than if they shared few features, indicating that the perirhinal cortex indeed contributes to the acquisition of novel associations by means of FM if feature overlap is high.

scholarly journals Perirhinal cortex lesions uncover subsidiary systems in the rat for the detection of novel and familiar objects

2011 ◽  
Vol 34 (2) ◽  
pp. 331-342 ◽  
Author(s):  
Mathieu M. Albasser ◽  
Eman Amin ◽  
Mihaela D. Iordanova ◽  
Malcolm W. Brown ◽  
John M. Pearce ◽  
...  
Keyword(s):  
Perirhinal Cortex ◽  
Familiar Objects

scholarly journals Tau pathology in the medial temporal lobe of athletes with chronic traumatic encephalopathy: a chronic effects of neurotrauma consortium study

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Christy M. Kelley ◽  
Sylvia E. Perez ◽  
Elliott J. Mufson
Keyword(s):  
Temporal Lobe ◽  
Medial Temporal Lobe ◽  
Chronic Traumatic Encephalopathy ◽  
Stage Iv ◽  
Perirhinal Cortex ◽  
Stage Ii ◽  
Stage Iii ◽  
Dystrophic Neurites ◽  
Tau Pathology ◽  
African American Athletes

AbstractChronic traumatic encephalopathy (CTE) is a progressive neurodegenerative condition associated with repetitive traumatic brain injury (rTBI) seen in contact-sport athletes and military personnel. The medial temporal lobe (MTL; i.e., hippocampus, subiculum, and entorhinal and perirhinal cortices) memory circuit displays tau lesions during the pathological progression of CTE. We examined MTL tissue obtained from 40 male Caucasian and African American athletes who received a postmortem CTE neuropathological diagnosis defined as stage II, III, or IV. Sections were immunolabeled using an early (AT8) or a late (TauC3) marker for pathological tau and for amyloid beta (Aβ) species (6E10, Aβ1–42 and thioflavin S). Stereological analysis revealed that stage III had significantly less AT8-positive neurons and dystrophic neurites than stage IV in all MTL regions except hippocampal subfield CA3, whereas significantly more AT8-positive neurons, dystrophic neurites, and neurite clusters were found in the perirhinal cortex, entorhinal cortex, hippocampal CA1, and subiculum of CTE stage III compared with stage II. TauC3-positive pathology was significantly higher in the perirhinal and subicular cortex of stage IV compared to stage III and the perirhinal cortex of stage III compared to stage II. AT8-positive neurite clusters were observed in stages III and IV, but virtually absent in stage II. When observed, Aβ pathology appeared as amyloid precursor protein (APP)/Aβ (6E10)-positive diffuse plaques independent of region. Thioflavine S labeling, did not reveal evidence for fibril or neuritic pathology associated with plaques, confirming a diffuse, non-cored plaque phenotype in CTE. Total number of AT8-positive profiles correlated with age at death, age at symptom onset, and time from retirement to death. There was no association between AT8-positive tau pathology and age sport began, years played, or retirement age, and no difference between CTE stage and the highest level of sport played. In summary, our findings demonstrate different tau profiles in the MTL across CTE stages, proffering CA3 tau pathology and MTL dystrophic neurite clusters as possible markers for the transition between early (II) and late (III/IV) stages, while highlighting CTE as a progressive noncommunicative tauopathy.

scholarly journals Autobiographical Memory Retrieval and Hippocampal Activation as a Function of Repetition and the Passage of Time

2007 ◽  
Vol 2007 ◽  
pp. 1-14 ◽  
Author(s):  
Lynn Nadel ◽  
Jenna Campbell ◽  
Lee Ryan
Keyword(s):  
Autobiographical Memory ◽  
Temporal Lobe ◽  
Memory Retrieval ◽  
Medial Temporal Lobe ◽  
Perirhinal Cortex ◽  
Brain Regions ◽  
Long Term Memory ◽  
Memory Traces ◽  
Multiple Trace Theory

Multiple trace theory (MTT) predicts that hippocampal memory traces expand and strengthen as a function of repeated memory retrievals. We tested this hypothesis utilizing fMRI, comparing the effect of memory retrieval versus the mere passage of time on hippocampal activation. While undergoing fMRI scanning, participants retrieved remote autobiographical memories that had been previously retrieved either one month earlier, two days earlier, or multiple times during the preceding month. Behavioral analyses revealed that the number and consistency of memory details retrieved increased with multiple retrievals but not with the passage of time. While all three retrieval conditions activated a similar set of brain regions normally associated with autobiographical memory retrieval including medial temporal lobe structures, hippocampal activation did not change as a function of either multiple retrievals or the passage of time. However, activation in other brain regions, including the precuneus, lateral prefrontal cortex, parietal cortex, lateral temporal lobe, and perirhinal cortex increased after multiple retrievals, but was not influenced by the passage of time. These results have important implications for existing theories of long-term memory consolidation.

The Role of the Perirhinal Cortex and Hippocampus in Learning, Memory, and Perception

2005 ◽  
Vol 58 (3-4b) ◽  
pp. 246-268 ◽  
Author(s):  
Mark J. Buckley
Keyword(s):  
Medial Temporal Lobe ◽  
Memory Loss ◽  
Anterograde Amnesia ◽  
Perirhinal Cortex ◽  
Memory System ◽  
Object Identity ◽  
Temporal Relationships ◽  
New Findings ◽  
Hippocampal Lesions

One traditional and long-held view of medial temporal lobe (MTL) function is that it contains a system of structures that are exclusively involved in memory, and that the extent of memory loss following MTL damage is simply related to the amount of MTL damage sustained. Indeed, human patients with extensive MTL damage are typically profoundly amnesic whereas patients with less extensive brain lesions centred upon the hippocampus typically exhibit only moderately severe anterograde amnesia. Accordingly, the latter observations have elevated the hippocampus to a particularly prominent position within the purported MTL memory system. This article reviews recent lesion studies in macaque monkeys in which the behavioural effects of more highly circumscribed lesions (than those observed to occur in human patients with MTL lesions) to different subregions of the MTL have been examined. These studies have reported new findings that contradict this concept of a MTL memory system. First, the MTL is not exclusively involved in mnemonic processes; some MTL structures, most notably the perirhinal cortex, also contribute to perception. Second, there are some forms of memory, including recognition memory, that are not always affected by selective hippocampal lesions. Third, the data support the idea that regional functional specializations exist within the MTL. For example, the macaque perirhinal cortex appears to be specialized for processing object identity whereas the hippocampus may be specialized for processing spatial and temporal relationships.

Perirhinal Cortex and its Neighbours in the Medial Temporal Lobe: Contributions to Memory and Perception

2005 ◽  
Vol 58 (3-4b) ◽  
pp. 378-396 ◽  
Author(s):  
Elisabeth A. Murray ◽  
Kim S. Graham ◽  
David Gaffan
Keyword(s):  
Temporal Lobe ◽  
Medial Temporal Lobe ◽  
Nonhuman Primates ◽  
Species Differences ◽  
Perirhinal Cortex ◽  
Future Research ◽  
Special Issue ◽  
Functional Entity

As promised in the Introduction, this Special Issue presents several recurring themes concerning the perirhinal cortex and its neighbours within the medial temporal lobe (MTL). First, although orthodoxy insists that the diverse constituents of the MTL operate as a single functional entity, several papers presented here challenge that idea, although some defend it. Second, although many experts hold that the MTL subserves memory but not perception, several papers presented here point to a role for certain MTL structures in both. Third, although some researchers have invoked “species differences” to account for discrepant findings, several papers presented here document a striking convergence of findings in humans, nonhuman primates, and rodents. We close this Special Issue by high-lighting these recurring themes, acknowledging discrepant findings and pointing to future research that might resolve some current controversies.

scholarly journals Age-related alterations in prelimbic cortical neuron Arc expression vary by behavioral state and cortical layer

2020 ◽  
Author(s):  
Abbi R. Hernandez ◽  
Leah M. Truckenbrod ◽  
Maya E. Barrett ◽  
Katelyn N. Lubke ◽  
Benjamin J. Clark ◽  
...  
Keyword(s):  
Prefrontal Cortex ◽  
Cortical Neuron ◽  
Long Range ◽  
Temporal Lobe ◽  
Cortical Neurons ◽  
Medial Temporal Lobe ◽  
Perirhinal Cortex ◽  
Early Gene ◽  
Projection Neurons ◽  
Age Related

AbstractPrefrontal cortical and medial temporal lobe connectivity is critical for higher cognitive functions that decline in older adults. Likewise, these cortical areas are among the first to show anatomical, functional, and biochemical alterations in advanced age. The prelimbic subregion of the prefrontal cortex and the perirhinal cortex of the medial temporal lobe are densely reciprocally connected and well-characterized as undergoing age-related neurobiological changes that correlate with behavioral impairment. Despite this fact, it remains to be determined how changes within these brain regions manifest as alterations in their functional connectivity. In our previous work, we observed an increased probability of age-related dysfunction for perirhinal cortical neurons that projected to the prefrontal cortex in old rats compared to neurons that were not identified as projection neurons. The current study was designed to investigate the extent to which aged prelimbic cortical neurons also had altered patterns of Arc expression during behavior, and if this was more evident in those cells that had long-range projections to the perirhinal cortex. The expression patterns of the immediate-early gene Arc were quantified in behaviorally characterized rats that also received the retrograde tracer cholera toxin B (CTB) in the perirhinal cortex to identify projection neurons to this region. As in our previous work, the current study found that CTB+ cells were more active than those that did not have the tracer. Moreover, there were age-related reductions in prelimbic cortical neuron Arc expression that correlated with a reduced ability of aged rats to multitask. Unlike the perirhinal cortex, however, the age-related reduction in Arc expression was equally likely in CTB+ and CTB− negative cells. Thus, the selective vulnerability of neurons with long-range projections to dysfunction in old age may be a unique feature of the perirhinal cortex. Together, these observations identify a mechanism involving prelimbic-perirhinal cortical circuit disruption in cognitive aging.

scholarly journals 'Online' integration of sensory and fear memories in the rat medial temporal lobe

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Francesca S Wong ◽  
R Fred Westbrook ◽  
Nathan M Holmes
Keyword(s):  
Temporal Lobe ◽  
Medial Temporal Lobe ◽  
Perirhinal Cortex ◽  
Fear Memory ◽  
Sensory Preconditioning ◽  
Memory Network ◽  
Stage 1 ◽  
Memory Rats

How does a stimulus never associated with danger become frightening? The present study addressed this question using a sensory preconditioning task with rats. In this task, rats integrate a sound-light memory formed in stage 1 with a light-danger memory formed in stage 2, as they show fear when tested with the sound in stage 3. Here we show that this integration occurs ‘online’ during stage 2: when activity in the region that consolidated the sound-light memory (perirhinal cortex) was inhibited during formation of the light-danger memory, rats no longer showed fear when tested with the sound but continued to fear the light. Thus, fear that accrues to a stimulus paired with danger simultaneously spreads to its past associates, thereby roping those associates into a fear memory network.

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