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Neurosurgical Focus Sep 2008The most common surgical procedure for the mesial temporal lobe is the standard anterior temporal resection or what is commonly called the anterior temporal lobectomy.... (Review)
Review
The most common surgical procedure for the mesial temporal lobe is the standard anterior temporal resection or what is commonly called the anterior temporal lobectomy. There are, however, a number of other more selective procedures for removal of the mesial temporal lobe structures (amygdala, hippocampus, and parahippocampal gyrus) that spare much of the lateral temporal neocortex. Included in these procedures collectively referred to as selective amygdalohippocampectomy are the transsylvian, subtemporal, and transcortical (trans-middle temporal gyrus) selective amygdalohippocampectomy. In this manuscript the author reviews some of the surgical details of the trans-middle temporal gyrus approach to the mesial temporal structures.
Topics: Amygdala; Anterior Temporal Lobectomy; Epilepsy, Temporal Lobe; Hippocampus; Humans; Neurosurgical Procedures; Parahippocampal Gyrus; Patient Selection; Temporal Lobe
PubMed: 18759628
DOI: 10.3171/FOC/2008/25/9/E4 -
Annals of the New York Academy of... Jun 2000The hippocampus has long been thought to be critical for memory, including memory for objects. However, recent neuropsychological studies in nonhuman primates have... (Review)
Review
The hippocampus has long been thought to be critical for memory, including memory for objects. However, recent neuropsychological studies in nonhuman primates have indicated that other regions within the medial temporal lobe, specifically, structures in the parahippocampal region, are primarily responsible for object recognition and object identification. This article reviews the behavioral effects of removal of structures within the parahippocampal region in monkeys, and cites relevant work in rodents as well. It is argued that the perirhinal cortex, in particular, contributes to object identification in at least two ways: (i) by serving as the final stage in the ventral visual cortical pathway that represents stimulus features, and (ii) by operating as part of a network for associating together sensory inputs within and across sensory modalities.
Topics: Animals; Memory; Parahippocampal Gyrus; Pattern Recognition, Visual; Perception
PubMed: 10911873
DOI: 10.1111/j.1749-6632.2000.tb06725.x -
Cortex; a Journal Devoted To the Study... Feb 2024Procrastination has adverse effects on personal growth and social development. Behavior research has found reward sensitivity is positively correlated with...
Procrastination has adverse effects on personal growth and social development. Behavior research has found reward sensitivity is positively correlated with procrastination. However, it remains unclear that the neural substrates underlie the relationship between reward sensitivity and procrastination. To address this issue, the present study used voxel-based morphometry (VBM) and resting-state functional connectivity (RSFC) analyses to investigate the neural substrates underlying the association with reward sensitivity and procrastination in two independent samples (N1 = 388, N2 = 330). In Sample 1, the behavioral result indicated reward sensitivity was positively correlated with procrastination. Moreover, the VBM analysis showed that reward sensitivity was positively associated with the gray matter volume (GMV) of the right parahippocampal gyrus. Furthermore, the RSFC result found reward sensitivity was negatively associated with the functional connectivity of the right parahippocampal gyrus-precuneus. Crucially, the mediation analysis revealed that functional connectivity of the right parahippocampal gyrus-precuneus mediated the relationship between reward sensitivity and procrastination. To verify the robustness of the results, confirmatory analysis was carried out in Sample 2. The results of Sample 1 (i.e., the behavioral, VBM, RSFC, and mediation results) can be verified in Sample 2. In brief, these findings suggested that the functional connectivity of the right parahippocampal gyrus-precuneus involved in reward impulsive control could modulate the relationship between reward sensitivity and procrastination, which is the first to reveal the neural underpinning of the association between reward sensitivity and procrastination.
Topics: Humans; Prefrontal Cortex; Brain Mapping; Procrastination; Magnetic Resonance Imaging; Parahippocampal Gyrus; Gray Matter; Parietal Lobe
PubMed: 38000138
DOI: 10.1016/j.cortex.2023.10.017 -
Journal of Psychiatric Research Nov 2021Alterations of brain signal complexity may reflect brain functional abnormalities. In adolescent bipolar disorder (ABD) distribution of brain regions showing abnormal...
BACKGROUND
Alterations of brain signal complexity may reflect brain functional abnormalities. In adolescent bipolar disorder (ABD) distribution of brain regions showing abnormal complexity in different mood states remains unclear. We aimed to analyze brain entropy (BEN) alteration of functional magnetic resonance imaging (fMRI) signal to observe spatial distribution of complexity in ABD patients, as well as the relationship between this variation and clinical variables.
METHODS
Resting-state fMRI data were acquired from adolescents with bipolar disorder (BD) who were in manic (n = 19) and euthymic (n = 20) states, and from healthy controls (HCs, n = 17). The differences in BEN among the three groups, and their associations with clinical variables, were examined.
RESULTS
Compared to HCs, manic and euthymic ABD patients showed increased BEN in right parahippocampal gyrus (PHG) and left dorsolateral prefrontal cortex (DLPFC). There was no significant difference of BEN between the manic and the euthymic ABD groups. In manic ABD patients, right PHG BEN exhibited significantly positive relationship with episode times.
CONCLUSIONS
Increased BEN in right PHG and left DLPFC in ABD patients may cause dysfunction of corticolimbic circuitry which is important to emotional processing and cognitive control. The positive correlation between PHG BEN and episode times of manic ABD patients further expressed a close association between brain complexity and clinical symptoms. From the perspective of brain temporal dynamics, the present study complements previous findings that have reported corticolimbic dysfunction as an important contributor to the pathophysiology of BD. BEN may provide valuable evidences for understanding the underlying mechanism of ABD.
Topics: Adolescent; Bipolar Disorder; Brain; Entropy; Humans; Parahippocampal Gyrus; Prefrontal Cortex
PubMed: 34479001
DOI: 10.1016/j.jpsychires.2021.08.025 -
Nature Jan 2024The medial entorhinal cortex (MEC) hosts many of the brain's circuit elements for spatial navigation and episodic memory, operations that require neural activity to be...
The medial entorhinal cortex (MEC) hosts many of the brain's circuit elements for spatial navigation and episodic memory, operations that require neural activity to be organized across long durations of experience. Whereas location is known to be encoded by spatially tuned cell types in this brain region, little is known about how the activity of entorhinal cells is tied together over time at behaviourally relevant time scales, in the second-to-minute regime. Here we show that MEC neuronal activity has the capacity to be organized into ultraslow oscillations, with periods ranging from tens of seconds to minutes. During these oscillations, the activity is further organized into periodic sequences. Oscillatory sequences manifested while mice ran at free pace on a rotating wheel in darkness, with no change in location or running direction and no scheduled rewards. The sequences involved nearly the entire cell population, and transcended epochs of immobility. Similar sequences were not observed in neighbouring parasubiculum or in visual cortex. Ultraslow oscillatory sequences in MEC may have the potential to couple neurons and circuits across extended time scales and serve as a template for new sequence formation during navigation and episodic memory formation.
Topics: Animals; Mice; Entorhinal Cortex; Neurons; Parahippocampal Gyrus; Running; Time Factors; Darkness; Visual Cortex; Periodicity; Neural Pathways; Spatial Navigation; Memory, Episodic
PubMed: 38123682
DOI: 10.1038/s41586-023-06864-1 -
Annual Review of Vision Science Sep 2019Humans are remarkably adept at perceiving and understanding complex real-world scenes. Uncovering the neural basis of this ability is an important goal of vision... (Review)
Review
Humans are remarkably adept at perceiving and understanding complex real-world scenes. Uncovering the neural basis of this ability is an important goal of vision science. Neuroimaging studies have identified three cortical regions that respond selectively to scenes: parahippocampal place area, retrosplenial complex/medial place area, and occipital place area. Here, we review what is known about the visual and functional properties of these brain areas. Scene-selective regions exhibit retinotopic properties and sensitivity to low-level visual features that are characteristic of scenes. They also mediate higher-level representations of layout, objects, and surface properties that allow individual scenes to be recognized and their spatial structure ascertained. Challenges for the future include developing computational models of information processing in scene regions, investigating how these regions support scene perception under ecologically realistic conditions, and understanding how they operate in the context of larger brain networks.
Topics: Animals; Brain; Brain Mapping; Humans; Magnetic Resonance Imaging; Occipital Lobe; Parahippocampal Gyrus; Spatial Navigation; Visual Cortex; Visual Perception
PubMed: 31226012
DOI: 10.1146/annurev-vision-091718-014809 -
Journal of Behavioral Addictions Apr 2020Understanding the neural mechanisms underlying Internet gaming disorder (IGD) is essential for the condition's diagnosis and treatment. Nevertheless, the pathological...
OBJECTIVES
Understanding the neural mechanisms underlying Internet gaming disorder (IGD) is essential for the condition's diagnosis and treatment. Nevertheless, the pathological mechanisms of IGD remain elusive at present. Hence, we employed multi-voxel pattern analysis (MVPA) and spectral dynamic causal modeling (spDCM) to explore this issue.
METHODS
Resting-state fMRI data were collected from 103 IGD subjects (male = 57) and 99 well-matched recreational game users (RGUs, male = 51). Regional homogeneity was calculated as the feature for MVPA based on the support vector machine (SVM) with leave-one- out cross-validation. Mean time series data extracted from the brain regions in accordance with the MVPA results were used for further spDCM analysis.
RESULTS
Results display a high accuracy of 82.67% (sensitivity of 83.50% and specificity of 81.82%) in the classification of the two groups. The most discriminative brain regions that contributed to the classification were the bilateral parahippocampal gyrus (PG), right anterior cingulate cortex (ACC), and middle frontal gyrus (MFG). Significant correlations were found between addiction severity (IAT and DSM scores) and the ReHo values of the brain regions that contributed to the classification. Moreover, the results of spDCM showed that compared with RGU, IGD showed decreased effective connectivity from the left PG to the right MFG and from the right PG to the ACC and decreased self-connection in the right PG.
CONCLUSIONS
These results show that the weakening of the PG and its connection with the prefrontal cortex, including the ACC and MFG, may be an underlying mechanism of IGD.
Topics: Adult; Connectome; Female; Gyrus Cinguli; Humans; Internet Addiction Disorder; Magnetic Resonance Imaging; Male; Parahippocampal Gyrus; Prefrontal Cortex; Sensitivity and Specificity; Support Vector Machine; Video Games; Young Adult
PubMed: 32359234
DOI: 10.1556/2006.2020.00012 -
Journal of Diabetes Investigation Oct 2021We aimed to examine the association between diabetes-related parameters and hippocampal and parahippocampal gyrus atrophy (HPGA) in patients with type 2 diabetes...
AIMS/INTRODUCTION
We aimed to examine the association between diabetes-related parameters and hippocampal and parahippocampal gyrus atrophy (HPGA) in patients with type 2 diabetes mellitus to elucidate the risk factors for HPGA, which is often accompanied by Alzheimer's disease.
MATERIALS AND METHODS
A total of 137 patients aged ≥50 years with type 2 diabetes mellitus (mean age 67.8 ± 9.8 years) underwent brain magnetic resonance imaging scans and comprehensive health examinations. We measured the volume of interest - a portion of the inner temporal lobe that includes the hippocampus, amygdala and entorhinal cortex (frontal part of the parahippocampal gyrus) - using the voxel-based specific regional analysis system for Alzheimer's disease in each patient. The diabetes-related parameters included glycated hemoglobin, fasting plasma glucose, C-peptide (CPR) index (serum CPR / fasting plasma glucose × 100) and duration of diabetes.
RESULTS
The mean glycated hemoglobin was 9.3 ± 2.2%, the median CPR index was 1.29 (interquartile range 0.85-1.74) and the median duration of diabetes was 10 years (interquartile range 3-20 years). The severity score of volume of interest atrophy was >1.0 in 36 patients. Using multivariate logistic regression analysis, we found that age (odds ratio 1.09, 95% confidence interval 1.02-1.15) and CPR index (odds ratio 0.451, 95% confidence interval 0.216-0.940) were significantly associated with HPGA.
CONCLUSIONS
Lower insulin secretion was significantly associated with HPGA in patients with type 2 diabetes mellitus. The results of this study support the hypothesis that insulin-signaling abnormalities are involved in the pathophysiology of Alzheimer's disease.
Topics: Aged; Cross-Sectional Studies; Diabetes Mellitus, Type 2; Female; Humans; Insulin Secretion; Male; Middle Aged; Parahippocampal Gyrus
PubMed: 33783982
DOI: 10.1111/jdi.13554 -
Trends in Neurosciences Jun 2018A predominant view of perirhinal cortex (PRC) and postrhinal/parahippocampal cortex (POR/PHC) function contends that these structures are tuned to represent objects and... (Review)
Review
A predominant view of perirhinal cortex (PRC) and postrhinal/parahippocampal cortex (POR/PHC) function contends that these structures are tuned to represent objects and spatial information, respectively. However, known anatomical connectivity, together with recent electrophysiological, neuroimaging, and lesion data, indicate that both brain areas participate in spatial and nonspatial processing. Instead of content-based organization, the PRC and PHC/POR may participate in two computationally distinct cortical-hippocampal networks: one network that is tuned to process coarse information quickly, forming gist-like representations of scenes/environments, and a second network tuned to process information about the specific sensory details that are necessary for discrimination across sensory modalities. The available data suggest that the latter network may be more vulnerable in advanced age.
Topics: Age Factors; Animals; Cognition; Cognitive Aging; Humans; Neural Pathways; Parahippocampal Gyrus; Perirhinal Cortex
PubMed: 29555181
DOI: 10.1016/j.tins.2018.03.001 -
Journal of Alzheimer's Disease : JAD 2021Subjective cognitive decline (SCD) is associated with increased risk of developing Alzheimer's disease (AD). However, the underlying mechanisms for this association...
Functional Connectivity Between the Posterior Default Mode Network and Parahippocampal Gyrus Is Disrupted in Older Adults with Subjective Cognitive Decline and Correlates with Subjective Memory Ability.
BACKGROUND
Subjective cognitive decline (SCD) is associated with increased risk of developing Alzheimer's disease (AD). However, the underlying mechanisms for this association remain unclear. Neuroimaging studies suggest the earliest AD-related changes are large-scale network disruptions, beginning in the posterior default mode (pDMN) network.
OBJECTIVE
To examine the association between SCD and pDMN network connectivity with medial temporal lobe (MTL) regions using resting-state functional magnetic resonance imaging.
METHODS
Forty-nine participants with either SCD (n = 23, 12 females; mean age: 70.7 (5.5)) or who were cognitively unimpaired (CU; n = 26, 16 females, mean age: 71.42 (7.3)) completed the Memory Functioning Questionnaire, a measure of subjective memory, and underwent resting state functional MRI at 3 Tesla. Functional connectivity between the posterior cingulate cortex (PCC), as the key pDMN node, and MTL regions were compared between SCD and CU groups. Further, the association between pDMN-MTL connectivity and the Frequency of Forgetting subscale of the Memory Functioning Questionnaire was examined.
RESULTS
Connectivity between the PCC-MTL was observed in the CU group but was absent in SCD (t(47) = 2.69, p = 0.01). Across all participants, self-perception of frequency of forgetting, but not objective memory, was strongly correlated with connectivity between the PCC-left parahippocampal gyrus (r = 0.43, p = 0.002).
CONCLUSION
These findings support the hypothesis that increased AD risk in SCD may be mediated by disrupted pDMN-parahippocampal connectivity. In addition, these findings suggest that frequency of forgetting may serve as a potential biomarker of SCD due to incipient AD.
Topics: Aged; Cognitive Dysfunction; Default Mode Network; Diagnostic Self Evaluation; Female; Functional Neuroimaging; Gyrus Cinguli; Humans; Magnetic Resonance Imaging; Male; Memory Disorders; Middle Aged; Neural Pathways; Parahippocampal Gyrus; Temporal Lobe
PubMed: 34024823
DOI: 10.3233/JAD-201579