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Neuropathology : Official Journal of... Dec 2004Semiquantitative morphological analysis of cerebral intraneuronal ubiquitin-positive tau-negative inclusions, a pathologic marker for motor neuron disease with dementia... (Comparative Study)
Comparative Study
Semiquantitative morphological analysis of cerebral intraneuronal ubiquitin-positive tau-negative inclusions, a pathologic marker for motor neuron disease with dementia (MND-D), was performed in the dentate gyrus and parahippocampal gyrus of 20 clinicopathologically confirmed patients with MND-D. The forms of the inclusions were tentatively classified into three types: (i) C-type, consisting of relatively large and intensely stained crescent or circular structures; (ii) L-type, showing fine linear structures around the nuclei; and (iii) G-type, showing faintly stained granular structures. The frequencies of the C-type, L-type and G-type was 0.5-9.3%,0.2-6.5% and 0-6.6% of dentate granule cells, respectively. In contrast to the dentate gyrus, almost all inclusions showed either the C-type or L-type form in the parahippocampal gyrus. A positive correlation was noted only between incidences of C-type inclusion of the dentate gyrus and that of the parahippocampal gyrus (r = 0.69, P < 0.05). The morphological differences of the inclusions probably reflect different stages of their formation.
Topics: Adult; Aged; Dementia; Dentate Gyrus; Humans; Inclusion Bodies; Middle Aged; Motor Neuron Disease; Neurons; Parahippocampal Gyrus; Ubiquitin
PubMed: 15641588
DOI: 10.1111/j.1440-1789.2004.00567.x -
Appetite Jul 2017Food cravings can reflect an intense trait-like emotional-motivational desire to eat palatable food, often resulting in the failure of weight loss efforts. Studies have...
Food cravings can reflect an intense trait-like emotional-motivational desire to eat palatable food, often resulting in the failure of weight loss efforts. Studies have linked trait-based food-cravings to increased risk of overeating. However, little is known about resting-state neural mechanisms that underlie food cravings. We investigated this issue using resting-state functional magnetic resonance imaging (fMRI) to test the extent to which spontaneous neural activity occurs in regions implicated in emotional memory and reward motivation associated with food cravings. Spontaneous regional activity patterns correlating to food cravings were assessed among 65 young healthy women using regional homogeneity analysis to assess temporal synchronization of spontaneous activity. Analyses indicated that women with higher scores on the Food Cravings Questionnaire displayed increased local functional homogeneity in brain regions involved in emotional memory and visual attention processing (i.e., parahippocampal gyrus and fusiform gyrus) but not reward. In view of parahippocampal gyrus involvement in hedonic learning and incentive memory encoding, this study suggests that trait-based food cravings are encoded by emotional memory circuits.
Topics: Adolescent; Adult; Brain Mapping; Craving; Emotions; Feeding Behavior; Female; Humans; Magnetic Resonance Imaging; Male; Motivation; Parahippocampal Gyrus; Students; Young Adult
PubMed: 28344152
DOI: 10.1016/j.appet.2017.03.033 -
Human Brain Mapping Feb 2021Early course schizophrenia is associated with reduced gray matter. The specific structures affected first and how deficits impact symptoms and cognition remain...
Early course schizophrenia is associated with reduced gray matter. The specific structures affected first and how deficits impact symptoms and cognition remain unresolved. We used the Human Connectome Project multimodal parcellation (HCP-MMP) to precisely identify cortical areas and investigate thickness abnormalities in discovery and replication samples of first-episode schizophrenia spectrum individuals (FESz). In the discovery sample, T1w scans were acquired from 31 FESz and 31 matched healthy controls (HC). Thickness was calculated for 360 regions in Freesurfer. In the replication sample, high-resolution T1w, T2w, and BOLD-rest scans were acquired from 23 FESz and 32 HC and processed with HCP protocols. Thickness was calculated for regions significant in the discovery sample. After FDR correction (q < .05), left and right parahippocampal area 3 (PHA3) were significantly thinner in FESz. In the replication sample, bilateral PHA3 were again thinner in FESz (q < .05). Exploratory correlation analyses revealed left PHA3 was positively associated with hallucinations and right PHA3 was positively associated with processing speed, working memory, and verbal learning. The novel use of the HCP-MMP in two independent FESz samples revealed thinner bilateral PHA3, suggesting this byway between cortical and limbic processing is a critical site of pathology near the emergence of psychosis.
Topics: Adult; Female; Gray Matter; Humans; Magnetic Resonance Imaging; Male; Neuroimaging; Parahippocampal Gyrus; Psychotic Disorders; Schizophrenia; Young Adult
PubMed: 33219733
DOI: 10.1002/hbm.25256 -
Trends in Cognitive Sciences Sep 2007The medial temporal lobe (MTL) plays a crucial role in supporting memory for events, but the functional organization of regions in the MTL remains controversial,... (Review)
Review
The medial temporal lobe (MTL) plays a crucial role in supporting memory for events, but the functional organization of regions in the MTL remains controversial, especially regarding the extent to which different subregions support recognition based on familiarity or recollection. Here we review results from functional neuroimaging studies showing that, whereas activity in the hippocampus and posterior parahippocampal gyrus is disproportionately associated with recollection, activity in the anterior parahippocampal gyrus is disproportionately associated with familiarity. The results are consistent with the idea that the parahippocampal cortex (located in the posterior parahippocampal gyrus) supports recollection by encoding and retrieving contextual information, whereas the hippocampus supports recollection by associating item and context information. By contrast, perirhinal cortex (located in the anterior parahippocampal gyrus) supports familiarity by encoding and retrieving specific item information. We discuss the implications of a 'binding of item and context' (BIC) model for studies of recognition memory. This model argues that there is no simple mapping between MTL regions and recollection and familiarity, but rather that the involvement of MTL regions in these processes depends on the specific demands of the task and the type of information involved. We highlight several predictions for future imaging studies that follow from the BIC model.
Topics: Animals; Brain Mapping; Evoked Potentials; Humans; Magnetic Resonance Imaging; Mental Recall; Models, Neurological; Models, Psychological; Parahippocampal Gyrus; Recognition, Psychology; Temporal Lobe
PubMed: 17707683
DOI: 10.1016/j.tics.2007.08.001 -
Brain Imaging and Behavior Jun 2019Procrastination is an almost universal affliction, which occurs across culture and brings serious consequences across multiple fields, such as finance, health and...
Procrastination is an almost universal affliction, which occurs across culture and brings serious consequences across multiple fields, such as finance, health and education. Previous research has showed procrastination can be influenced by future time perspective (FTP). However, little is known about the neural basis underlying the impact of FTP on procrastination. To address this question, we used voxel-based morphometry (VBM) based on brain structure. In line with previous findings, the behavioral result indicated that FTP inventory scores were significantly negatively correlated with procrastination inventory scores (r = -0.63, n = 160). The whole-brain VBM results showed that FTP scores were significantly negatively correlated with the grey matter (GM) volumes of the parahippocampal gyrus (paraPHC) and ventromedial prefrontal cortex (vmPFC) after the multiple comparisons correction. Furthermore, mediation analyses revealed that the effect of GM volumes of the paraPHC and vmPFC on procrastination was mediated by FTP. These results suggested that paraPHC and vmPFC, the critical brain regions about episodic future thinking, could be the neural basis responsible for the impact of FTP on procrastination. The present study extends our knowledge on procrastination, and provides a novel perspective to understand the relationship between FTP and procrastination.
Topics: Brain; Brain Mapping; China; Female; Gray Matter; Humans; Magnetic Resonance Imaging; Male; Parahippocampal Gyrus; Prefrontal Cortex; Procrastination; Time Perception; Young Adult
PubMed: 29744798
DOI: 10.1007/s11682-018-9874-4 -
Learning & Memory (Cold Spring Harbor,... Oct 2009Psychologists and neurobiologists have a long-standing interest in understanding how the context surrounding the events of our lives is represented and how it influences... (Review)
Review
Psychologists and neurobiologists have a long-standing interest in understanding how the context surrounding the events of our lives is represented and how it influences our behavior. The hippocampal formation emerged very early as a major contributor to how context is represented and functions. There is a large literature examining its contribution that on the surface reveals an array of conflicting outcomes and controversy. This review reveals that these conflicts can be resolved by building Nadel and Willner's dual-process theory of context representations. Two general conclusions emerge: (1) There are two neural systems that can support context representations and functions-a neocortical system composed primarily of perirhinal and postrhinal cortices and a hippocampal system that includes perirhinal, postrhinal, entorhinal cortices, and the hippocampal formation. (2) These two systems are not equivalent-some context representations and functions are uniquely supported by the hippocampal system. These conclusions are discussed in the context of canonical ideas about the special properties of the hippocampal system that enable it to make unique contributions to memory.
Topics: Animals; Hippocampus; Humans; Mental Processes; Parahippocampal Gyrus
PubMed: 19794181
DOI: 10.1101/lm.1494409 -
Hippocampus Jan 2014Neuropsychological data in primates demonstrated a pivotal role of the hippocampal formation (HF) and parahippocampal gyrus (PH) in navigation and episodic memory. To...
Neuropsychological data in primates demonstrated a pivotal role of the hippocampal formation (HF) and parahippocampal gyrus (PH) in navigation and episodic memory. To investigate the role of HF and PH neurons in environmental scaling in primates, we recorded neuronal activities in the monkey HF and PH during virtual navigation (VN) and pointer translocation (PT) tasks. The monkeys had to navigate within three differently sized virtual spaces with the same spatial cues (VN task) or move a pointer on a screen (PT task) by manipulating a joystick to receive a reward. Of the 234 recorded neurons, 170 and 61 neurons displayed place-related activities in the VN and PT tasks, respectively. Significant differences were observed between the HF and PH neurons. The spatial similarity of place fields between the two different virtual spaces was lower in PH than in HF, while specificities of the neuronal responses to distal spatial cues were higher in PH than in HF. Spatial view information was predominately processed in posterior PH. The spatial scales (place field sizes) of the HF and PH neurons were reduced in the reduced virtual space, as shown in rodent place cells. These results suggest the complementary roles of HF (allocentric representation of landmarks) and PH (representation of the spatial layout of landmarks) in the recognition of a location during navigation.
Topics: Animals; Cues; Electrophysiology; Hippocampus; Macaca; Male; Memory; Neurons; Parahippocampal Gyrus; Space Perception; Spatial Behavior; User-Computer Interface
PubMed: 24123569
DOI: 10.1002/hipo.22209 -
Nature Communications Apr 2022An essential role of the hippocampal region is to integrate information to compute and update representations. How this transpires is highly debated. Many theories hinge...
An essential role of the hippocampal region is to integrate information to compute and update representations. How this transpires is highly debated. Many theories hinge on the integration of self-motion signals and the existence of continuous attractor networks (CAN). CAN models hypothesise that neurons coding for navigational correlates - such as position and direction - receive inputs from cells conjunctively coding for position, direction, and self-motion. As yet, very little data exist on such conjunctive coding in the hippocampal region. Here, we report neurons coding for angular and linear velocity, uniformly distributed across the medial entorhinal cortex (MEC), the presubiculum and the parasubiculum, except for MEC layer II. Self-motion neurons often conjunctively encoded position and/or direction, yet lacked a structured organisation. These results offer insights as to how linear/angular speed - derivative in time of position/direction - may allow the updating of spatial representations, possibly uncovering a generalised algorithm to update any representation.
Topics: Entorhinal Cortex; Hippocampus; Neurons; Parahippocampal Gyrus
PubMed: 35393433
DOI: 10.1038/s41467-022-29583-z -
Psychiatry Research Dec 2009Emotional liability and mood dysregulation characterize bipolar disorder (BD), yet no study has examined effective connectivity between parahippocampal gyrus and...
Emotional liability and mood dysregulation characterize bipolar disorder (BD), yet no study has examined effective connectivity between parahippocampal gyrus and prefrontal cortical regions in ventromedial and dorsal/lateral neural systems subserving mood regulation in BD. Participants comprised 46 individuals (age range: 18-56 years): 21 with a DSM-IV diagnosis of BD, type I currently remitted; and 25 age- and gender-matched healthy controls (HC). Participants performed an event-related functional magnetic resonance imaging paradigm, viewing mild and intense happy and neutral faces. We employed dynamic causal modeling (DCM) to identify significant alterations in effective connectivity between BD and HC. Bayes model selection was used to determine the best model. The right parahippocampal gyrus (PHG) and right subgenual cingulate gyrus (sgCG) were included as representative regions of the ventromedial neural system. The right dorsolateral prefrontal cortex (DLPFC) region was included as representative of the dorsal/lateral neural system. Right PHG-sgCG effective connectivity was significantly greater in BD than HC, reflecting more rapid, forward PHG-sgCG signaling in BD than HC. There was no between-group difference in sgCG-DLPFC effective connectivity. In BD, abnormally increased right PHG-sgCG effective connectivity and reduced right PHG activity to emotional stimuli suggest a dysfunctional ventromedial neural system implicated in early stimulus appraisal, encoding and automatic regulation of emotion that may represent a pathophysiological functional neural mechanism for mood dysregulation in BD.
Topics: Adult; Bayes Theorem; Bipolar Disorder; Brain Mapping; Case-Control Studies; Emotions; Female; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Male; Models, Statistical; Neural Pathways; Neuropsychological Tests; Nonlinear Dynamics; Oxygen; Parahippocampal Gyrus; Prefrontal Cortex; Young Adult
PubMed: 19910166
DOI: 10.1016/j.pscychresns.2009.04.015 -
Hippocampus 2000The hippocampal memory system, consisting of the hippocampal formation and the adjacent parahippocampal region, is known to play an important role in learning and memory... (Review)
Review
The hippocampal memory system, consisting of the hippocampal formation and the adjacent parahippocampal region, is known to play an important role in learning and memory processes. In recent years, evidence from a variety of experimental approaches indicates that each of the constituting fields of the hippocampal memory system may serve functionally different, yet complementary roles. Understanding the anatomical organization of cortico-parahippocampal-hippocampal connectivity may lead to a further understanding of these potential functional differences. In the present paper we present the two main conclusions of experiments in which we studied the anatomical organization of the hippocampal memory system of the rat in detail, with a focus on the pivotal position of the entorhinal cortex. We first conclude that the simple traditional view of the entorhinal cortex as simply the input and output structure of the hippocampal formation needs to be modified. Second, our data indicate the existence of two parallel pathways through the hippocampal memory system, arising from the perirhinal and postrhinal cortex. These two parallel pathways may be involved in separately processing functionally different types of sensory information. This second proposition will be subsequently evaluated on the basis of series of electrophysiological studies we carried out in rats and some preliminary functional brain imaging studies in humans.
Topics: Animals; Cerebral Cortex; Hippocampus; Neural Pathways; Parahippocampal Gyrus
PubMed: 10985279
DOI: 10.1002/1098-1063(2000)10:4<398::AID-HIPO6>3.0.CO;2-K