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Parahippocampal subregion

Tolga Çukur, Alexander G Huth, Shinji Nishimoto, Jack L Gallant
: Functional MRI studies suggest that at least three brain regions in human visual cortex-the parahippocampal place area (PPA), retrosplenial complex (RSC), and occipital place area (OPA; often called the transverse occipital sulcus)-represent large-scale information in natural scenes. Tuning of voxels within each region is often assumed to be functionally homogeneous. To test this assumption, we recorded blood oxygenation level-dependent responses during passive viewing of complex natural movies...
October 5, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Christopher Baldassano, Li Fei-Fei, Diane M Beck
Peripherally presented stimuli evoke stronger activity in scene-processing regions than foveally presented stimuli, suggesting that scene understanding is driven largely by peripheral information. We used functional MRI to investigate whether functional connectivity evoked during natural perception of audiovisual movies reflects this peripheral bias. For each scene-sensitive region--the parahippocampal place area (PPA), retrosplenial cortex, and occipital place area--we computed two measures: the extent to which its activity could be predicted by V1 activity (connectivity strength) and the eccentricities within V1 to which it was most closely related (connectivity profile)...
2016: Journal of Vision
Jiu Chen, Xujun Duan, Hao Shu, Zan Wang, Zhiliang Long, Duan Liu, Wenxiang Liao, Yongmei Shi, Huafu Chen, Zhijun Zhang
Altered function of the medial temporal lobe (MTL) is a valuable indicator of conversion from amnestic mild cognitive impairment (aMCI) to Alzheimer's disease. This study is to delineate the functional circuitry of multiple subdivisions of parahippocampal gyrus and hippocampus (HIP) and to examine how this knowledge contributes to a more principled understanding of the contributions of its subregions to memory in aMCI. The functional connectivity (FC) analysis was performed in 85 aMCI and 129 healthy controls...
2016: Scientific Reports
G Russell Glenn, Jens H Jensen, Joseph A Helpern, Maria V Spampinato, Ruben Kuzniecky, Simon S Keller, Leonardo Bonilha
OBJECTIVE: Temporal lobe epilepsy (TLE) is one of the most common forms of epilepsy. Unfortunately, the clinical outcomes of TLE cannot be determined based only on current diagnostic modalities. A better understanding of white matter (WM) connectivity changes in TLE may aid the identification of network abnormalities associated with TLE and the phenotypic characterisation of the disease. METHODS: We implemented a novel approach for characterising microstructural changes along WM pathways using diffusional kurtosis imaging (DKI)...
September 2016: Journal of Neurology, Neurosurgery, and Psychiatry
Junjie Zhuo, Lingzhong Fan, Yong Liu, Yuanchao Zhang, Chunshui Yu, Tianzi Jiang
UNLABELLED: Traditional anatomical studies of the parahippocampal region (PHR) defined the lateral portion into two subregions, the perirhinal (PRC) and parahippocampal (PHC) cortices. Based on this organization, several models suggested that the PRC and the PHC play different roles in memory through connections with different memory-related brain networks. To identify the key components of the human PHR, we used a well accepted connection-based parcellation method on two independent datasets...
March 2, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Pilar Salgado-Pineda, Ramón Landin-Romero, Francisco Portillo, Clara Bosque, Ausias Pomes, Bernhard Spanlang, Jose Carlos Franquelo, Cristina Teixido, Salvador Sarró, Raymond Salvador, Mel Slater, Edith Pomarol-Clotet, Peter J McKenna
BACKGROUND: Structural pathology in the hippocampus is well-documented in schizophrenia, but brain functional changes have not been consistently found. We used spatial navigation in a virtual reality environment, a task that is known to produce robust hippocampal activation in healthy subjects, to examine task-related activations and de-activations in the disorder. METHODS: Twenty-seven DSM IV schizophrenia patients and 32 healthy controls underwent fMRI while they navigated to a goal through a virtual reality town...
April 2016: Schizophrenia Research
Oliver Baumann, Jason B Mattingley
The human parahippocampal cortex has been ascribed central roles in both visuospatial and mnemonic processes. More specifically, evidence suggests that the parahippocampal cortex subserves both the perceptual analysis of scene layouts as well as the retrieval of associative contextual memories. It remains unclear, however, whether these two functional roles can be dissociated within the parahippocampal cortex anatomically. Here, we provide evidence for a dissociation between neural activation patterns associated with visuospatial analysis of scenes and contextual mnemonic processing along the parahippocampal longitudinal axis...
February 24, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Sabine Krumm, Sasa L Kivisaari, Alphonse Probst, Andreas U Monsch, Julia Reinhardt, Stephan Ulmer, Christoph Stippich, Reto W Kressig, Kirsten I Taylor
The stereotypical pattern of neurofibrillary tangle spreading in the earliest stages of typical Alzheimer's dementia (AD) predicts that medial perirhinal cortex (mPRC) atrophy precedes entorhinal cortex (ERC) atrophy, whereas the status of the parahippocampal cortex (PHC) remains unclear. Atrophy studies have focused on more advanced rather than early AD patients, and usually segment the entire PRC as opposed to the mPRC versus lateral PRC (lPRC). The present study therefore determined the extent of ERC, mPRC, lPRC, and PHC atrophy in very early AD (mean Mini-Mental State Examination score = 26) patients and its presumed prodrome amnestic mild cognitive impairment (mean Mini-Mental State Examination score = 28) compared to demographically matched controls...
February 2016: Neurobiology of Aging
Shao-Fang Wang, Maureen Ritchey, Laura A Libby, Charan Ranganath
Regional differences in large-scale connectivity have been proposed to underlie functional specialization along the anterior-posterior axis of the medial temporal lobe (MTL), including the hippocampus (HC) and the parahippocampal gyrus (PHG). However, it is unknown whether functional connectivity (FC) can be used reliably to parcellate the human MTL. The current study aimed to differentiate subregions of the HC and the PHG based on patterns of whole-brain intrinsic FC. FC maps were calculated for each slice along the longitudinal axis of the PHG and the HC...
October 2016: Neurobiology of Learning and Memory
Wen-Ying Wang, Ying Liu, Hui-Fu Wang, Lin Tan, Fu-Rong Sun, Meng-Shan Tan, Chen-Chen Tan, Teng Jiang, Lan Tan, Jin-Tai Yu
The cluster of differentiation 33 (CD33) has been proved as a susceptibility locus associated with late-onset Alzheimer's disease (LOAD) based on recent genetic studies. Numerous studies have shown that multiple neuroimaging measures are potent predictors of AD risk and progression, and these measures are also affected by genetic variations in AD. Figuring out the association between CD33 genetic variations and AD-related brain atrophy may shed light on the underlying mechanisms of CD33-related AD pathogenesis...
January 23, 2016: Molecular Neurobiology
Heidrun Schultz, Tobias Sommer, Jan Peters
Connectivity studies in animals form the basis for a representational view of medial temporal lobe (MTL) subregions. In this view, distinct subfields of the entorhinal cortex (EC) relay object-related and spatial information from the perirhinal and parahippocampal cortices (PRC, PHC) to the hippocampus (HC). Relatively recent advances in functional magnetic resonance imaging (fMRI) methodology allow examining properties of human EC subregions directly. Antero-lateral and posterior-medial EC subfields show remarkable consistency to their putative rodent and nonhuman primate homologs with regard to intra- and extra-MTL functional connectivity...
2015: Frontiers in Human Neuroscience
Hongkeun Kim
It remains unclear whether and to what extent the default network subregions involved in episodic memory (EM) and semantic memory (SM) processes overlap or are separated from one another. This study addresses this issue through a controlled meta-analysis of functional neuroimaging studies involving healthy participants. Various EM and SM task paradigms differ widely in the extent of default network involvement. Therefore, the issue at hand cannot be properly addressed without some control for this factor. In this regard, this study employs a two-stage analysis: a preliminary meta-analysis to select EM and SM task paradigms that recruit relatively extensive default network regions and a main analysis to compare the selected task paradigms...
January 8, 2016: Neuropsychologia
A Garrett, S Gupta, A L Reiss, J Waring, K Sudheimer, L Anker, N Sosa, J F Hallmayer, R O'Hara
Studies have shown that a functional polymorphism of the serotonin transporter gene (5-HTTLPR) impacts performance on memory-related tasks and the hippocampal structures that subserve these tasks. The short (s) allele of 5-HTTLPR has been linked to greater susceptibility for impaired memory and smaller hippocampal volume compared to the long allele (l). However, previous studies have not examined the associations between 5-HTTLPR allele and activation in subregions of the hippocampus. In this study, we used functional magnetic resonance imaging (fMRI) to measure activation in hippocampal and temporal lobe subregions in 36 elderly non-clinical participants performing a face-name encoding and recognition task...
2015: Translational Psychiatry
Anne Maass, David Berron, Laura A Libby, Charan Ranganath, Emrah Düzel
The entorhinal cortex (EC) is the primary site of interactions between the neocortex and hippocampus. Studies in rodents and nonhuman primates suggest that EC can be divided into subregions that connect differentially with perirhinal cortex (PRC) vs parahippocampal cortex (PHC) and with hippocampal subfields along the proximo-distal axis. Here, we used high-resolution functional magnetic resonance imaging at 7 Tesla to identify functional subdivisions of the human EC. In two independent datasets, PRC showed preferential intrinsic functional connectivity with anterior-lateral EC and PHC with posterior-medial EC...
2015: ELife
Kai J Miller, Dora Hermes, Nathan Witthoft, Rajesh P N Rao, Jeffrey G Ojemann
The human ventral temporal cortex has regions that are known to selectively process certain categories of visual inputs; they are specialized for the content ("faces," "places," "tools") and not the form ("line," "patch") of the image being seen. In our study, human patients with implanted electrocorticography (ECoG) electrode arrays were shown sequences of simple face and house pictures. We quantified neuronal population activity, finding robust face-selective sites on the fusiform gyrus and house-selective sites on the lingual/parahippocampal gyri...
July 2015: Journal of Neurophysiology
James E Kragel, Neal W Morton, Sean M Polyn
Neural circuitry in the medial temporal lobe (MTL) is critically involved in mental time travel, which involves the vivid retrieval of the details of past experience. Neuroscientific theories propose that the MTL supports memory of the past by retrieving previously encoded episodic information, as well as by reactivating a temporal code specifying the position of a particular event within an episode. However, the neural computations supporting these abilities are underspecified. To test hypotheses regarding the computational mechanisms supported by different MTL subregions during mental time travel, we developed a computational model that linked a blood oxygenation level-dependent signal to cognitive operations, allowing us to predict human performance in a memory search task...
February 18, 2015: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Emilie T Reas, James B Brewer
INTRODUCTION: The medial temporal lobe supports integrating the "what," "where," and "when" of an experience into a unified memory. However, it remains unclear how representations of these contextual features are neurally encoded and distributed across medial temporal lobe subregions. METHODS: This study conducted functional magnetic resonance imaging of the medial temporal lobe, while participants retrieved pair, spatial, and temporal source memories. Multivoxel classifiers were trained to distinguish between retrieval conditions before and after correction for mean signal and response times, to more thoroughly characterize the multivoxel signal associated with memory context...
February 2015: Brain and Behavior
Paul A Yushkevich, Robert S C Amaral, Jean C Augustinack, Andrew R Bender, Jeffrey D Bernstein, Marina Boccardi, Martina Bocchetta, Alison C Burggren, Valerie A Carr, M Mallar Chakravarty, Gaël Chételat, Ana M Daugherty, Lila Davachi, Song-Lin Ding, Arne Ekstrom, Mirjam I Geerlings, Abdul Hassan, Yushan Huang, J Eugenio Iglesias, Renaud La Joie, Geoffrey A Kerchner, Karen F LaRocque, Laura A Libby, Nikolai Malykhin, Susanne G Mueller, Rosanna K Olsen, Daniela J Palombo, Mansi B Parekh, John B Pluta, Alison R Preston, Jens C Pruessner, Charan Ranganath, Naftali Raz, Margaret L Schlichting, Dorothee Schoemaker, Sachi Singh, Craig E L Stark, Nanthia Suthana, Alexa Tompary, Marta M Turowski, Koen Van Leemput, Anthony D Wagner, Lei Wang, Julie L Winterburn, Laura E M Wisse, Michael A Yassa, Michael M Zeineh
OBJECTIVE: An increasing number of human in vivo magnetic resonance imaging (MRI) studies have focused on examining the structure and function of the subfields of the hippocampal formation (the dentate gyrus, CA fields 1-3, and the subiculum) and subregions of the parahippocampal gyrus (entorhinal, perirhinal, and parahippocampal cortices). The ability to interpret the results of such studies and to relate them to each other would be improved if a common standard existed for labeling hippocampal subfields and parahippocampal subregions...
May 1, 2015: NeuroImage
Laura A Libby, Deborah E Hannula, Charan Ranganath
Several models have proposed that different medial temporal lobe (MTL) regions represent different kinds of information in the service of long-term memory. For instance, it has been proposed that perirhinal cortex (PRC), parahippocampal cortex (PHC), and hippocampus differentially support long-term memory for item information, spatial context, and item-context relations present during an event, respectively. Recent evidence has indicated that, in addition to long-term memory, MTL subregions may similarly contribute to processes that support the retention of complex spatial arrangements of objects across short delays...
October 22, 2014: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Soon-Beom Hong, Ben J Harrison, Alex Fornito, Chul-Ho Sohn, In-Chan Song, Jae-Won Kim
BACKGROUND: Brain frontostriatal circuits have been implicated in the pathophysiology of attention-deficit/hyperactivity disorder (ADHD). However, effects of methylphenidate on circuit-level functional connectivity are as yet unclear. The aim of the present study was to comprehensively investigate the functional connectivity of major striatal subregions in children with ADHD, including subanalyses directed at mapping cognitive and treatment response characteristics. METHODS: Using a comprehensive seeding strategy, we examined resting-state functional connectivity of dorsal and ventral subdivisions of the caudate nucleus and putamen in children and adolescents with ADHD and in age- and sex-matched healthy controls...
January 2015: Journal of Psychiatry & Neuroscience: JPN
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