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Neuroreport Oct 2002We can discriminate between the memories of real and imagined events. In this study, the traces of the perceived external events and the imagined internal events were...
We can discriminate between the memories of real and imagined events. In this study, the traces of the perceived external events and the imagined internal events were investigated in the established paradigm of reality monitoring using event-related fMRI. In the retrieval phase, we found that the left parahippocampal gyrus represented the traces of visually encoded memory. The right inferior parietal cortex was activated when subjects judged that the original event was imagined. We suggest that these traces are used to distinguish what is seen from what is thought during reality monitoring. Furthermore, we found that the incorrect judgments were associated with signal increases in the left frontal operculum, suggesting that this area is a candidate for the monitoring system of contextual information or failure in the retrieval phase.
Topics: Adult; Female; Frontal Lobe; Functional Laterality; Humans; Imagination; Magnetic Resonance Imaging; Male; Memory; Neuropsychological Tests; Parahippocampal Gyrus; Parietal Lobe; Pattern Recognition, Visual; Psychomotor Performance; Reaction Time; Verbal Behavior
PubMed: 12395098
DOI: 10.1097/00001756-200210280-00024 -
NeuroImage Feb 2020Neuroimaging has revealed numerous neural predictors of individual differences in creativity; however, with most of these identified in only one study, sometimes...
Neuroimaging has revealed numerous neural predictors of individual differences in creativity; however, with most of these identified in only one study, sometimes involving very small samples, their reliability is uncertain. To contribute to a convergent cognitive neuroscience of creativity, we conducted a pre-registered conceptual replication and extension study in which we assessed previously reported predictors of creativity using a multimodal approach, incorporating volumetric, white matter, and functional connectivity neuroimaging data. We assessed sets of pre-registered predictors against prevailing measures of creativity, including visual and verbal tests of divergent thinking, everyday creative behaviour, and creative achievement. We then conducted whole-brain exploratory analyses. Greater creativity was broadly predicted by features of the inferior frontal gyrus (IFG) and inferior parietal lobe (IPL), including both local grey matter and white matter predictors in the IFG, the superior longitudinal fasciculus that connects them, and IFG-IPL functional connectivity. As IFG and IPL are important nodes within executive control and default mode networks (DMN), respectively, this result supports the view that executive modulation of DMN activity optimizes creative ideation. Furthermore, white matter integrity of the basal ganglia was also a generalizable creativity predictor, and exploratory analyses revealed the anterior lobe of the cerebellum and the parahippocampal gyrus to both be reliable predictors of creativity across neuroimaging modalities. This pattern aligns with proposals ascribing roles of working and long-term memory to problem-solving and imagination. Overall, our findings help to consolidate some, but not all, neural correlates of individual differences that have been discussed in the cognitive neuroimaging of creativity, yielding a subset that appear particularly promising for focused future investigation.
Topics: Adult; Brain; Cerebellum; Connectome; Creativity; Gray Matter; Humans; Magnetic Resonance Imaging; Nerve Net; Parahippocampal Gyrus; Parietal Lobe; Prefrontal Cortex; White Matter
PubMed: 31654758
DOI: 10.1016/j.neuroimage.2019.116292 -
Proceedings of the National Academy of... Jan 2017Imaging, electrophysiological, and lesion studies have shown a relationship between the parahippocampal cortex (PHC) and the processing of spatial scenes. Our present... (Comparative Study)
Comparative Study
Imaging, electrophysiological, and lesion studies have shown a relationship between the parahippocampal cortex (PHC) and the processing of spatial scenes. Our present knowledge of PHC, however, is restricted to the macroscopic properties and dynamics of bulk tissue; the behavior and selectivity of single parahippocampal neurons remains largely unknown. In this study, we analyzed responses from 630 parahippocampal neurons in 24 neurosurgical patients during visual stimulus presentation. We found a spatially clustered subpopulation of scene-selective units with an associated event-related field potential. These units form a population code that is more distributed for scenes than for other stimulus categories, and less sparse than elsewhere in the medial temporal lobe. Our electrophysiological findings provide insight into how individual units give rise to the population response observed with functional imaging in the parahippocampal place area.
Topics: Animals; Entorhinal Cortex; Environment; Evoked Potentials, Visual; Hippocampus; Humans; Neurons; Parahippocampal Gyrus; Photic Stimulation; Space Perception; Visual Perception
PubMed: 28096381
DOI: 10.1073/pnas.1608159113 -
Human Brain Mapping Apr 2020Natural scenes are inherently structured, with meaningful objects appearing in predictable locations. Human vision is tuned to this structure: When scene structure is...
Natural scenes are inherently structured, with meaningful objects appearing in predictable locations. Human vision is tuned to this structure: When scene structure is purposefully jumbled, perception is strongly impaired. Here, we tested how such perceptual effects are reflected in neural sensitivity to scene structure. During separate fMRI and EEG experiments, participants passively viewed scenes whose spatial structure (i.e., the position of scene parts) and categorical structure (i.e., the content of scene parts) could be intact or jumbled. Using multivariate decoding, we show that spatial (but not categorical) scene structure profoundly impacts on cortical processing: Scene-selective responses in occipital and parahippocampal cortices (fMRI) and after 255 ms (EEG) accurately differentiated between spatially intact and jumbled scenes. Importantly, this differentiation was more pronounced for upright than for inverted scenes, indicating genuine sensitivity to spatial structure rather than sensitivity to low-level attributes. Our findings suggest that visual scene analysis is tightly linked to the spatial structure of our natural environments. This link between cortical processing and scene structure may be crucial for rapidly parsing naturalistic visual inputs.
Topics: Adult; Brain Mapping; Cerebral Cortex; Electroencephalography; Female; Humans; Magnetic Resonance Imaging; Male; Occipital Lobe; Parahippocampal Gyrus; Photic Stimulation; Space Perception; Visual Perception; Young Adult
PubMed: 31758632
DOI: 10.1002/hbm.24875 -
Hippocampus 2000The structures forming the medial temporal lobe appear to be necessary for the establishment of long-term declarative memory. In particular, they may be involved in the... (Review)
Review
The structures forming the medial temporal lobe appear to be necessary for the establishment of long-term declarative memory. In particular, they may be involved in the "consolidation" of information in higher-order associational cortices, perhaps through feedback projections. This review highlights the fact that the medial temporal lobe is organized as a hierarchy of associational networks. Indeed, associational connections within the perirhinal, parahippocampal, and entorhinal cortices enables a significant amount of integration of unimodal and polymodal inputs, so that only highly integrated information reaches the remainder of the hippocampal formation. The feedback efferent projections from the perirhinal and parahippocampal cortices to the neocortex largely reciprocate the afferent projections from the neocortex to these areas. There are, however, noticeable differences in the degree of reciprocity of connections between the perirhinal and parahippocampal cortices and certain areas of the neocortex, in particular in the frontal and temporal lobes. These observations are particularly important for models of hippocampal-neocortical interaction and long-term storage of information in the neocortex. Furthermore, recent functional studies suggest that the perirhinal and parahippocampal cortices are more than interfaces for communication between the neocortex and the hippocampal formation. These structures participate actively in memory processes, but the precise role they play in the service of memory or other cognitive functions is currently unclear.
Topics: Animals; Association; Entorhinal Cortex; Hippocampus; Humans; Memory; Neocortex; Parahippocampal Gyrus
PubMed: 10985281
DOI: 10.1002/1098-1063(2000)10:4<420::AID-HIPO8>3.0.CO;2-5 -
Hippocampus 2007The entorhinal cortex (EC) serves a pivotal role in corticohippocampal interactions, but a complete description of its extrinsic connections has not been presented.... (Review)
Review
The entorhinal cortex (EC) serves a pivotal role in corticohippocampal interactions, but a complete description of its extrinsic connections has not been presented. Here, we have summarized the cortical, subcortical, and hippocampal connections of the lateral entorhinal area (LEA) and the medial entorhinal area (MEA) in the rat. We found that the targets and relative strengths of the entorhinal connections are strikingly different for the LEA and MEA. For example, the LEA receives considerably heavier input from the piriform and insular cortices, whereas the MEA is more heavily targeted by the visual, posterior parietal, and retrosplenial cortices. Regarding subcortical connections, the LEA receives heavy input from the amygdala and olfactory structures, whereas the MEA is targeted by the dorsal thalamus, primarily the midline nuclei and also the dorsolateral and dorsoanterior thalamic nuclei. Differences in the LEA and MEA connections with hippocampal and parahippocampal structures are also described. In addition, because the EC is characterized by bands of intrinsic connectivity that span the LEA and MEA and project to different septotemporal levels of the dentate gyrus, special attention was paid to the efferents and afferents of those bands. Finally, we summarized the connections of the dorsocaudal MEA, the region in which the entorhinal "grid cells" were discovered. The subregional differences in entorhinal connectivity described here provide further evidence for functional diversity within the EC. It is hoped that these findings will inform future studies of the role of the EC in learning and memory.
Topics: Animals; Models, Biological; Neural Pathways; Neuroanatomy; Parahippocampal Gyrus; Rats
PubMed: 17607757
DOI: 10.1002/hipo.20315 -
Neurosurgery Jun 2010Corpora amylacea (CA) normally accumulate within perivascular, subpial, and subependymal astrocytic processes. CA are associated with a number of conditions including...
OBJECTIVE
Corpora amylacea (CA) normally accumulate within perivascular, subpial, and subependymal astrocytic processes. CA are associated with a number of conditions including normal aging, hippocampal sclerosis associated with temporal lobe epilepsy, multiple sclerosis, Lafora-type progressive myoclonic epilepsy, and adult polyglucosan body disease. Reports of massive localized accumulation of CA in the brain outside of these conditions are rare.
CLINICAL PRESENTATION
A 49-year-old woman, with a long-standing history of migraine headaches, presented to her primary care provider for increased headache duration. Brain magnetic resonance imaging (MRI) revealed a left parahippocampal lesion, suggestive of low-grade glioma.
INTERVENTION
Given the MRI suggestive of left parahippocampal glioma, left-sided frontotemporal craniotomy was performed for resection of the lesion. Specimens obtained during the operation revealed focal high-density accumulation of CA with no evidence of neoplasm, ischemia, or hypoxic injury.
CONCLUSION
This case illustrates the possibility that localized high-density CA accumulation can present as an intrinsic lesion on brain MRI. CA should be included in the differential diagnosis for patients presenting with brain MRI suggestive of nonenhancing space-occupying lesions.
Topics: Diagnosis, Differential; Female; Glucans; Hippocampus; Humans; Inclusion Bodies; Middle Aged; Migraine Disorders; Parahippocampal Gyrus
PubMed: 20495392
DOI: 10.1227/01.NEU.0000369196.94664.4E -
Proceedings of the National Academy of... May 2012Humans assess the credibility of information gained from others on a daily basis; this ongoing assessment is especially crucial for avoiding exploitation by others. We...
Humans assess the credibility of information gained from others on a daily basis; this ongoing assessment is especially crucial for avoiding exploitation by others. We used a repeated, two-person bargaining game and a cognitive hierarchy model to test how subjects judge the information sent asymmetrically from one player to the other. The weight that they give to this information is the result of two distinct factors: their baseline suspicion given the situation and the suspicion generated by the other person's behavior. We hypothesized that human brains maintain an ongoing estimate of the credibility of the other player and sought to uncover neural correlates of this process. In the game, sellers were forced to infer the value of an object based on signals sent from a prospective buyer. We found that amygdala activity correlated with baseline suspicion, whereas activations in bilateral parahippocampus correlated with trial-by-trial uncertainty induced by the buyer's sequence of suggestions. In addition, the less credible buyers that appeared, the more sensitive parahippocampal activation was to trial-by-trial uncertainty. Although both of these neural structures have previously been implicated in trustworthiness judgments, these results suggest that they have distinct and separable roles that correspond to their theorized roles in learning and memory.
Topics: Adult; Algorithms; Amygdala; Behavior; Brain Mapping; Female; Games, Experimental; Humans; Magnetic Resonance Imaging; Male; Models, Neurological; Models, Psychological; Parahippocampal Gyrus; Task Performance and Analysis; Young Adult
PubMed: 22582170
DOI: 10.1073/pnas.1200738109 -
Cerebral Cortex (New York, N.Y. : 1991) Mar 2021The Hamilton Search Task (HST) is a test of nonnavigational spatial memory that is dependent on the hippocampus. The parahippocampal cortex (PHC) is a major route for...
The Hamilton Search Task (HST) is a test of nonnavigational spatial memory that is dependent on the hippocampus. The parahippocampal cortex (PHC) is a major route for spatial information to reach the hippocampus, but the extent to which the PHC and hippocampus function independently of one another in the context of nonnavigational spatial memory is unclear. Here, we tested the hypotheses that (1) bilateral pharmacological inactivation of the PHC would impair HST performance, and (2) that functional disconnection of the PHC and hippocampus by contralateral (crossed) inactivation would likewise impair performance. Transient inactivation of the PHC impaired HST performance most robustly with 30 s intertrial delays, but not when color cues were introduced. Functional disconnection of the PHC and hippocampus, but not separate unilateral inactivation of either region, also selectively impaired long-term spatial memory. These findings indicate a critical role for the PHC and its interactions with the hippocampus in nonnavigational spatial memory.
Topics: Animals; Excitatory Amino Acid Antagonists; Hippocampus; Kynurenic Acid; Macaca mulatta; Male; Microinjections; Neural Pathways; Parahippocampal Gyrus; Spatial Memory; Spatial Navigation
PubMed: 33270817
DOI: 10.1093/cercor/bhaa358 -
Cortex; a Journal Devoted To the Study... Feb 2022The cortical connections of the human hippocampal memory system are fundamental to understanding its operation in health and disease, especially in the context of the...
The cortical connections of the human hippocampal memory system are fundamental to understanding its operation in health and disease, especially in the context of the great development of the human cortex. The functional connectivity of the human hippocampal system was analyzed in 172 participants imaged at 7T in the Human Connectome Project. The human hippocampus has high functional connectivity not only with the entorhinal cortex, but also with areas that are more distant in the ventral 'what' stream including the perirhinal cortex and temporal cortical visual areas. Parahippocampal gyrus TF in humans has connectivity with this ventral 'what' subsystem. Correspondingly for the dorsal stream, the hippocampus has high functional connectivity not only with the presubiculum, but also with areas more distant, the medial parahippocampal cortex TH which includes the parahippocampal place or scene area, the posterior cingulate including retrosplenial cortex, and the parietal cortex. Further, there is considerable cross connectivity between the ventral and dorsal streams with the hippocampus. The findings are supported by anatomical connections, which together provide an unprecedented and quantitative overview of the extensive cortical connectivity of the human hippocampal system that goes beyond hierarchically organised and segregated pathways connecting the hippocampus and neocortex, and leads to new concepts on the operation of the hippocampal memory system in humans.
Topics: Entorhinal Cortex; Hippocampus; Humans; Neural Pathways; Parahippocampal Gyrus; Perirhinal Cortex; Temporal Lobe
PubMed: 35026557
DOI: 10.1016/j.cortex.2021.11.014