Left Parahippocampal Gyrus Research Articles

Memory loss and memory reorganization patterns in temporal lobe epilepsy patients undergoing anterior temporal lobe resection, as demonstrated by pre-versus post-operative functional MRI

This study was aimed to longitudinally assess memory function and whole-brain memory circuit reorganization in patients with temporal lobe epilepsy (TLE) by comparing activation potentials before versus after anterior temporal lobe (ATL) resection. Nineteen patients with medically-intractable TLE (10 left TLE, 9 right TLE) and 15 healthy controls were enrolled. Group analyses were conducted pre- and post-ATL of a novelty complex scene-encoding paradigm comparing areas of blood oxygen-level-dependent (BOLD) signal activations on functional magnetic resonance imaging (fMRI). None of the pre-operative patient characteristics we studied predicted the extent of pre- to post-operative memory loss. On fMRI, extra-temporal activations were detected pre-operatively in both LTLE and RTLE, particularly in the frontal lobe. Greater activations also were noted in the contralateral hippocampus and parahippocampus in both groups. Performing within-subject comparisons, post-op relative to pre-op, pronounced ipsilateral activations were identified in the left parahippocampal gyrus in LTLE, versus the right middle temporal gyrus in RTLE patients. Memory function was impaired pre-operatively but declined after ATL resection in both RTLE and LTLE patients. Post-operative fMRI results indicate possible functional adaptations to ATL loss, primarily occurring within the left parahippocampal gyrus versus right middle temporal gyrus in LTLE versus RTLE patients, respectively.

Associations of functional connectivity and walking performance in multiple sclerosis

BackgroundPersons with multiple sclerosis (MS) often demonstrate impaired walking performance, and neuroimaging methods such as resting state functional connectivity (RSFC) may support a link between central nervous system damage and disruptions in walking. ObjectivesThis study examined associations between RSFC in cortical networks and walking performance in persons with MS. Methods29 persons with MS underwent 3-T brain magnetic resonance imaging (MRI) and we computed RSFC among 68 Gy matter regions of interest in the brain. Participants completed the Timed 25-foot Walk as a measure of walking performance. We examined associations using partial Pearson product-moment correlation analyses (r), controlling for age. ResultsThere were eight cortical brain regions that were significantly associated with the T25FW, including the left parahippocampal gyrus and transverse temporal gyrus, and the right fusiform gyrus, inferior temporal gyrus, lingual gyrus, pericalcarine cortex, superior temporal gyrus, and transverse temporal gyrus. ConclusionsWe provide novel evidence that RSFC can be a valuable tool to monitor the motor and non-motor networks impacted in MS that relate to declines in motor impairment. RSFC may identify critical nodes involved in a range of motor tasks such as walking that can be more sensitive to disruption by MS.

Effects of Equine-Assisted Activities and Therapies on the Affective Network of Adolescents with Internet Gaming Disorder.

Internet gaming disorder (IGD) has been suggested to be a mental health disorder. Attachment and emotional status in IGD patients are important for understanding the etiology and progression of IGD because both parameters are considered to be associated with the affective network. Equine-assisted activities and therapies (EAAT) have been reported to improve emotional status and attachment in subjects. We hypothesized that EAAT would improve attachment in IGD adolescents with insecure attachment issues and increase functional connectivity (FC) within the affective network. Subjects completed a demographic questionnaire, the Korean Experiences in Close Relationships Scale Revised version (K-ECRS), the Child Depression Inventory, Young's Internet Addiction Scale, the Korean Attention-Deficit Hyperactivity Disorder Rating Scale, and resting-state functional magnetic resonance imaging at baseline at the end of EAAT. Fifteen IGD adolescents with insecure attachment issues and 15 healthy comparison adolescents with secure attachment agreed to participate in this study. After 7 days of EAAT, K-ECRS avoidance and anxiety scores improved in all adolescents. K-ECRS avoidance scores of the IGD group showed marked improvement compared with those of the healthy group. In all participants, FC from the left amygdala to the left parahippocampal gyrus, left medial frontal gyrus, and left inferior frontal gyrus, as well as from the right amygdala to the left caudate, right claustrum, and left inferior frontal gyrus increased. In IGD adolescents, FC from the left amygdala to the left frontal orbital gyrus, as well as from the right amygdala to the right corpus callosum also increased. These findings suggested that EAAT improves attachment, which could lead to a decrease in the severity of IGD symptoms in IGD patients with insecure attachment issues. In addition, EAAT increases FC within the affective network, which was associated with attachment not only in healthy adolescents but also in adolescents with IGD.

A magnetic resonance imaging study on brain surface morphology change in patients with first-episode obsessive compulsive disorder

Objective To analyze the brain structure changes of the first-episode obsessive compulsive disorder (OCD) patients who were scanned by three-dimensional structure magnetic resonance imaging. Methods According to the diagnostic criteria of OCD in American Diagnostic and Statistical Manual of Mental Disorders Fourth Edition (DSM-IV), the fist-episode obsessive compulsive disorder patients as case group(OCD, n=26) and the adult healthy volunteers as control group (control group, n=25) were selected.All subjects were assessed with Yale-Brown obsessive-compulsive scale(Y-BOCS), Hamilton Anxiety rating Scale (HAMA) and Hamilton Depression Rating Scale(HAMD), and then, they received 3D-MRI scanning runs.All the data was processed with freesurfer software and analyzed about cerebral cortical volume, cortical thickness, cortical surface area, the local gyrification index and subcortical nuclei volume. Results Compared with control group, the cerebral cortical thickness of OCD group increased at the left postcentral gyrus((2.223±0.118)mm), left supramarginal gyrus((2.486±0.027)mm) and left parahippocampal gyrus((2.399±0.164)mm). The cerebral cortical surface area larged at the right inferior frontal gyrus((1.036±0.079)mm2), right paracentral lobule((0.827±0.048)mm2)and medial orbitofrontal((0.990±0.083)mm2), and decreased at right superior parietal lobule((0.779±0.040)mm2), right inferior parietal lobule((0.767±0.093)mm2)and right inferior temporal gyrus((0.888±0.070)mm2). The cerebral cortical volume increased at the right inferior frontal gyrus((2.330±0.223)mm3). The cerebral cortical local gyrification index decreased at right middle temporal gyrus(2.893±0.288)and left inferior temporal gyrus(2.589±0.100). Conclusion The first-episode OCD patients have multiple changes of brain structures, and this changes were priority for the frontal lobes, orbital frontal, parietal lobe, temporal lobe and hippocampus.The changes in these regions maybe have close relationship with symptoms of OCD. Key words: First-episode obsessive-compulsive disorder; Magnetic resonance imaging; Freesurfer scanning images software; The local gyrification index

GABAA Receptor Availability Changes Underlie Symptoms in Isolated Cervical Dystonia.

GABAA receptor availability changes within sensorimotor regions have been reported in some isolated forms of dystonia. Whether similar abnormalities underlie symptoms in cervical dystonia is not known. In the present study, a total of 15 cervical dystonia patients and 15 age- and sex-matched controls underwent 11C-flumazenil PET/CT scanning. The density of available GABAA receptors was estimated using a Simplified Reference Tissue Model 2. Group differences were evaluated using a two-sample T-test, and correlations with dystonia severity, as measured by the Toronto Western Spasmodic Torticollis Rating Scale, and disease duration were evaluated using a regression analysis. Voxel-based analyses revealed increased GABAA availability within the right precentral gyrus in brain motor regions previously associated with head turning and the left parahippocampal gyrus. GABAA availability within the bilateral cerebellum was negatively correlated with dystonia severity, and GABAA availability within the right thalamus and a variety of cerebellar and cortical regions were negatively correlated with disease duration. While GABAA availability changes within primary motor areas could represent a partial compensatory response to loss of inhibition within sensorimotor network, GABAergic signaling impairment within the cerebellum may be a key contributor to dystonia severity.

F175. NEUROLOGICAL SOFT SIGNS (NSS) AND BRAIN MORPHOLOGY IN PATIENTS WITH CHRONIC SCHIZOPHRENIA AND HEALTHY CONTROLS

BackgroundSubtle abnormalities in sensory integration, motor coordination and sequencing of complex motor acts or neurological soft signs (NSS) are a characteristic phenomenon in patients with schizophrenia at any stage of the illness. Previous MRI studies in schizophrenia have shown that NSS are associated with abnormal cortical, thalamic and cerebellar structure. However, these studies mainly focused on first-episode or recent onset schizophrenia and the respective correlates between brain structure and NSS in patients with a chronic course of the disorder remain rather unclear.Methods49 middle-aged patients with chronic schizophrenia with a mean duration of illness of 20.3 ± 14.0 years and 29 healthy subjects matched for age and sex were included. NSS were examined on the Heidelberg Scale and correlated to grey matter by using whole brain high resolution magnetic resonance imaging (3 Tesla) with SPM12 analyses.ResultsAs expected, NSS in patients were significantly elevated in contrast to healthy controls, a finding, which not only applied to NSS sumscore, but also to the respective subscores motor coordination, sensory integration, complex motor tasks, right/left and spatial orientation and hard signs (p≤0.001).Patients and healthy controls differed referring to right inferior frontal gyrus and left parahippocampal gyrus, with patients showing significantly reduced gray matter volumes, respectively. Within the patient group NSS total score was significantly correlated to reduced grey matter in right occipital lobe, left parahippocampal gyrus, left superior temporal gyrus, left thalamus (medial dorsal nucleus) and left posterior lobe of the cerebellum (declive). The respective findings remained significant after FDR correction for multiple comparisons (k=100 voxels). These results were confirmed when chlorpromazine (CPZ)-equivalents were introduced as additional covariate; moreover, no significant correlates arose between NSS and CPZ-equivalents. In the control group, VBM revealed that higher NSS total scores were significantly correlated with volume of right lentiform nucleus (medial globus pallidus).DiscussionOur study leads further support to the model of ‘cognitive dysmetria’ with a disrupted cortico-cerebellar-thalamic-cortical circuit in schizophrenia. This interpretation is also maintained by a different correlational pattern in our control group. Furthermore, the middle temporal/parahippocampal region may correspond to reduced mnestic functions, which are – besides elevated NSS – consistently reported to be impaired in patients with a chronic course of the disorder.

S7-5. Repetitive transcranial magnetic stimulation (rTMS) modulates resting EEG functional connectivity in patients with treatment-resistant depression

Aims Repetitive transcranial magnetic stimulation (rTMS) is a neuromodulation technique for treating patients with depression who do not respond to medications. However, the effects of rTMS on functional connectivity are still not clear. The aims of this study were to examine changes in resting EEG functional connectivity before and after rTMS treatments. Methods Resting EEG of patients with treatment-resistant depression was recorded for approximately 5 min twice at baseline and at week 4 respectively. The patients received high-frequency left prefrontal rTMS, 5 days a week, for 4 weeks. To examine changes in resting EEG functional connectivity, the EEG data were analyzed using the functional independent component analysis (fICA) and functional wire connectivity analysis (fWCA) in the standardized low-resolution brain electromagnetic tomography (sLORETA). Results fICA showed that rTMS enhanced the anti-correlated gamma band activities between the left dorsolateral prefrontal cortex (DLPFC) and precuneus. fWCA revealed that there was significant increased functional connectivity in middle beta band between the left DLPFC and parahippocampal gyrus, and between the subgenual cingulate cortex and parahippocampal gyrus. Conclusion These findings suggest that rTMS might modulate neural networks between the left DLPFC and posterior cingulate, and between the left DLPFC and limbic regions.

Safety feelings and anticipatory control: An fMRI study on safety and risk perception

Car driving as goal-directed behavior is based on anticipations. In everyday driving, most of the time a car is operated in a rather implicit anticipatory mode with little disparity between an anticipated and actual driving result. A disruption of this driving mode goes along with heightened risk perception and changes in somatic states. In an fMRI study, safety and risk perception was investigated in male car drivers with regard to anticipatory control. Neural correlates revealed that perceived safety is accompanied by a higher involvement of primary visual areas, motor areas, the left anterior cingulate cortex (ACC), right hippocampus, right temporo-parietal junction, and in particular – as supported by contrasts with a further condition – of the left parahippocampal gyrus and bilateral precentral gyrus. This indicates stronger retrieval of memory and stored movement programs for impressions of safety, corresponding to an anticipatory mode of driving. Additionally, activation levels in the left ACC were marginally negatively correlated with perceived situational control in risky driving situations. These results highlight the role of anticipatory control in perceived safety on an implicit level relevant for everyday driving.

Reduced Gray Matter Volume of the Thalamus and Hippocampal Region in Elderly Healthy Adults with no Impact of APOE ɛ4: A Longitudinal Voxel-Based Morphometry Study

Many cross-sectional voxel-based morphometry (VBM) investigations have shown significant inverse correlations between chronological age and gray matter (GM) volume in several brain regions in healthy humans. However, few VBM studies have documented GM decrements in the healthy elderly with repeated MRI measurements obtained in the same subjects. Also, the extent to which the APOE ɛ4 allele influences longitudinal findings of GM reduction in the healthy elderly is unclear. Verify whether regional GM changes are associated with significant decrements in cognitive performance taking in account the presence of the APOE ɛ4 allele. Using structural MRI datasets acquired in 55 cognitively intact elderly subjects at two time-points separated by approximately three years, we searched for voxels showing significant GM reductions taking into account differences in APOE genotype. We found global GM reductions as well as regional GM decrements in the right thalamus and left parahippocampal gyrus (p < 0.05, family-wise error corrected for multiple comparisons over the whole brain). These findings were not affected by APOE ɛ4. Irrespective of APOE ɛ4, longitudinal VBM analyses show that the hippocampal region and thalamus are critical sites where GM shrinkage is greater than the degree of global volume reduction in healthy elderly subjects.

Meta-analysis of voxel-based morphometry studies of gray matter abnormalities in patients with mesial temporal lobe epilepsy and unilateral hippocampal sclerosis.

We aimed to perform a meta-analysis to systematically determine the most consistent regions of gray matter volume (GMV) abnormality in patients of unilateral mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS), and to reveal the difference of GMV abnormality between the patients with left-sided and right-sided MTLE-HS. A comprehensive and systematic search was performed in PubMed for voxel-based morphometry (VBM) studies of MTLE-HS. A total of 12 MTLE-HS studies, including 9 left-sided MTLE-HS (LMTLE-HS) and 8 right-sided MTLE-HS (RMTLE-HS) studies were included. The activation likelihood estimation (ALE) method was applied in our meta-analysis. Compared to the healthy controls, MTLE-HS patients showed significant GMV decrease in the parahippocampal gyrus, left pulvinar and right pyramis. For LMTLE-HS, the most consistent GMV decrease was detected in the left parahippocampal gyrus. For RMTLE-HS, the most consistent GMV decrease was found in the right parahippocampal gyrus. No shared regions of significant GMV reduction were found between LMTLE-HS and RMTLE-HS either. This meta-analysis revealed that MTLE-HS patients had significant GMV reduction even beyond the hippocampus, and the subtypes showed distinct reduction patterns. Our findings, if were further verified with larger samples, would have implications for the clinical diagnosis of MTLE-HS.

Seizure freedom from temporal lobe epilepsy with mesial temporal lobe tumor by tumor removal alone without hippocampectomy despite remaining abnormal discharges on intraoperative electrocorticography: Report of two pediatric cases and reconsideration of the surgical strategy.

Background:In the surgical treatment of temporal lobe epilepsy with mesial temporal lobe tumor, whether to remove the hippocampus aiming for a better seizure outcome in addition to removing the tumor is a dilemma. Two pediatric cases treated successfully with tumor removal alone are presented.Case Description:The first case was an 11-year-old girl with a ganglioglioma in the left uncus, and the second case was a 9-year-old girl with a pleomorphic xanthoastrocytoma in the left parahippocampal gyrus. In both cases, the hippocampus was not invaded, merely compressed by the tumor. Tumor removal was performed under intraoperative electrocorticography (ECoG) monitoring. After tumor removal, abnormal discharges remained at the hippocampus and adjacent temporal cortices, but further surgical interventions were not performed. The seizures disappeared completely in both cases.Conclusions:When we must decide whether to remove the hippocampus, the side of the lesion, the severity and chronicity of the seizures, and the presence of invasion to the hippocampus are the factors that should be considered. Abnormal discharges on ECoG at the hippocampus or adjacent cortices are one of the factors related to epileptogenicity, but it is simply a result of interictal irritation, and it is not an absolute indication for additional surgical intervention.

Meta-Analytic Evidence for the Plurality of Mechanisms in Transdiagnostic Structural MRI Studies of Hallucination Status

BACKGROUND: Hallucinations are transmodal and transdiagnostic phenomena, occurring across sensory modalities and presenting in psychiatric, neurodegenerative, neurological, and non-clinical populations. Despite their cross-category occurrence, little empirical work has directly compared between-group neural correlates of hallucinations. METHODS: We performed whole-brain voxelwise meta-analyses of hallucination status across diagnoses using AES-SDM, and conducted a comprehensive systematic review in PubMed and Web of Science until May 2018 on other structural correlates of hallucinations, including cortical thickness and gyrification. FINDINGS: 3214 abstracts were identified. Patients with psychiatric disorders and hallucinations (eight studies) exhibited reduced gray matter (GM) in the left insula, right inferior frontal gyrus, left anterior cingulate/paracingulate gyrus, left middle temporal gyrus, and increased in the bilateral fusiform gyrus, while patients with neurodegenerative disorders with hallucinations (eight studies) showed GM decreases in the left lingual gyrus, right supramarginal gyrus/parietal operculum, left parahippocampal gyrus, left fusiform gyrus, right thalamus, and right lateral occipital gyrus. Group differences between meta-analyses were formally confirmed and a jackknife sensitivity analysis established the reproducibility of results across nearly all study combinations. For other measures (28 studies), the most consistent findings associated with hallucination status were reduced cortical thickness in temporal gyri in schizophrenia and altered hippocampal volume in Parkinson's disease and dementia. INTERPRETATION: Distinct patterns of neuroanatomical alteration characterize hallucination status in patients with psychiatric and neurodegenerative diseases, suggesting a plurality of anatomical signatures. This approach has implications for treatment, theoretical frameworks, and generates refutable predictions for hallucinations in other diseases and their occurrence within the general population. Funding: None. Declaration of Interest: Ms. Rollins reports a scholarship from Gates Cambridge during the conduct of the study. Professor Rowe reports grants from Wellcome Trust during the conduct of the study, grants from NIHR, McDonnell Foundation, PSP Association, Parkinsons UK, Medical Research Council, Evelyn Trust, and AZ-Medimmune, personal fees from Asceneuron, and other from Guarantors of Brain outside the submitted work. Professor Suckling, Dr. Murray, Dr. Garrison, Dr. Simons, and Dr. O’Callaghan have nothing to disclose.

Repairing the brain with physical exercise: Cortical thickness and brain volume increases in long-term pediatric brain tumor survivors in response to a structured exercise intervention.

There is growing evidence that exercise induced experience dependent plasticity may foster structural and functional recovery following brain injury. We examined the efficacy of exercise training for neural and cognitive recovery in long-term pediatric brain tumor survivors treated with radiation.We conducted a controlled clinical trial with crossover of exercise training (vs. no training) in a volunteer sample of 28 children treated with cranial radiation for brain tumors (mean age = 11.5 yrs.; mean time since diagnosis = 5.7 yrs). The endpoints were anatomical T1 MRI data and multiple behavioral outcomes presenting a broader analysis of structural MRI data across the entire brain. This included an analysis of changes in cortical thickness and brain volume using automated, user unbiased approaches. A series of general linear mixed effects models evaluating the effects of exercise training on cortical thickness were performed in a voxel and vertex-wise manner, as well as for specific regions of interest. In exploratory analyses, we evaluated the relationship between changes in cortical thickness after exercise with multiple behavioral outcomes, as well as the relation of these measures at baseline.Exercise was associated with increases in cortical thickness within the right pre and postcentral gyri. Other notable areas of increased thickness related to training were present in the left pre and postcentral gyri, left temporal pole, left superior temporal gyrus, and left parahippocampal gyrus. Further, we observed that compared to a separate cohort of healthy children, participants displayed multiple areas with a significantly thinner cortex prior to training and fewer differences following training, indicating amelioration of anatomical deficits. Partial least squares analysis (PLS) revealed specific patterns of relations between cortical thickness and various behavioral outcomes both after training and at baseline.Overall, our results indicate that exercise training in pediatric brain tumor patients treated with radiation has a beneficial impact on brain structure. We argue that exercise training should be incorporated into the development of neuro-rehabilitative treatments for long-term pediatric brain tumor survivors and other populations with acquired brain injury. (ClinicalTrials.gov, NCT01944761)

Altered intrinsic brain activities in patients with acute eye pain using amplitude of low-frequency fluctuation: a resting-state fMRI study.

ObjectiveMany previous studies have reported that pain symptoms can lead to significant brain function and anatomical changes, whereas the intrinsic brain activity changes in acute eye pain (EP) patients remain unknown. Using the amplitude of low-frequency fluctuation (ALFF) method, this study aimed to evaluate the spontaneous brain activity alterations and their relationships with clinical features in acute EP patients.Participants and methodsA total of 20 patients with EP (15 males and 5 females) and 20 healthy controls (HCs; 15 males and 5 females) closely matched in age, sex, and education underwent resting-state functional magnetic resonance imaging scans. The ALFF method was applied to assess spontaneous brain activity changes. The ALFF values of the EP patients were distinguished from those of the HCs using a receiver operating characteristic curve. Pearson’s correlation analysis was used to investigate the relationships between the mean ALFF signal values from many brain regions and the clinical features in EP patients.ResultsCompared with the HCs, acute EP patients had significantly lower ALFF in the left and right precentral/postcentral gyrus and left precuneus. In contrast, acute EP patients showed higher ALFF values in the right and left parahippocampal gyri and left caudate. However, no relationship was observed between the mean ALFF signal values from the different areas and clinical manifestations in the acute EP patients.ConclusionWe demonstrated that acute EP patients showed abnormal intrinsic brain activities in the precentral/postcentral gyrus and limbic system, which might provide useful information for explaining neural mechanisms in EP patients.

Reduced parahippocampal theta activity during spatial navigation in low, but not in high elderly performers.

Cognitive aging varies widely among individuals. Whereas optimal cognitive agers show highly preserved cognitive functions throughout life, other subjects experience cognitive deficits in various cognitive domains. Among them, elderly individuals frequently report difficulties in spatial navigation. In this study, we aimed to determine whether elderly participants with different cognitive profiles would perform differently at a navigation task, and explore underlying medial hippocampal activity. Two groups of elderly subjects were selected, high- and low-performing (HP and LP, respectively), based on their performance on a detailed neuropsychological examination. A group of young adults was recruited as controls. Cerebral activity was recorded by electroencephalography (EEG) during a virtual navigation task in which participants had 3 trials to find their way in mazes. We analyzed theta activity during navigation in the mazes and performed source reconstruction analyses. The LP group was less accurate than the HP group during the navigation task. Theta activity during navigation was greater in HP subjects compared with controls, whereas that theta activity was reduced in LP subjects. Moreover, theta activity in the left parahippocampal gyrus increased across trials in HP, but not in LP, subjects. Elderly participants performed differently at a navigation task according to their cognitive profile: elderly with cognitive deficits seem to have greater difficulties in spatial navigation than HP elderly. Navigational difficulties in elderly with cognitive deficits might be related to functional alteration of the parahippocampal gyrus. (PsycINFO Database Record

Memory Deficits After Aneurysmal Subarachnoid Hemorrhage: A Functional Magnetic Resonance Imaging Study.

Patients who have sustained aneurysmal subarachnoid hemorrhage (aSAH) are thought to have cognitive impairment. However, little is known about the characteristics of functional imaging in patients with aSAH. In this study, we explored whole brain activity patterns in patients with aSAH using amplitude of low-frequency fluctuation (ALFF) and functional connectivity (FC). Fifty patients with aSAH and 30 healthy controls were recruited and subjected to a resting-state functional magnetic resonance imaging scan and cognitive tasks. Abnormalities of ALFF and FC in patients with aSAH and the correlations with cognitive tasks were assessed. The aSAH group exhibited increased ALFF mainly in the left parahippocampal gyrus (PHG), left inferior temporal gyrus (ITG), and left thalamus (THAL). FC and regression analysis showed positive correlations between functional connectivity strength (FCS) and memory performance in several connections in the aSAH group. These included (1) decreased FC between the left PHG and left inferior parietal lobe; (2) decreased FC between the left ITG and bilateral inferior frontal gyrus orbital part (ORBinf), right middle frontal gyrus; and (3) increased FC between the left THAL and right inferior frontal gyrus orbital part (ORBinf), and right inferior frontal gyrus opercular part. Our findings not only demonstrate the unique abnormal cerebral functional topology of patients with aSAH on both local and network levels, but also confirm the correlation between specific FCS and memory function in these patients. In addition, we have identified several potential imaging biomarkers for predicting cognitive outcomes in patients with aSAH.

Sex differences of hippocampal structure in bipolar disorder

Although differential patterns in clinical characteristics have been consistently noted between male and female patients with bipolar disorder (BD), the effect of sex on the hippocampal structure remains unclear. To address this, the present study investigated the effects of BD and sex on the hippocampal structure, and the relationship between the hippocampal structure and cognitive performance. Morphometric and neurocognitive analyses were performed in 91 subjects (patients with BD: male/female = 33/19; normal controls: male/female = 22/17). Patients had significantly decreased left parahippocampal gyrus area and left/right hippocampal volume compared to normal controls. Within the BD group only, female patients presented with smaller right hippocampal volume than males. In the Spatial Span (SS) test (used to assess working memory capacity) and the Maze test (used to evaluate the ability to anticipate), patients demonstrated decreased performance compared to normal controls, with a significant main effect of sex. Left parahippocampal gyrus area and right hippocampal volume were positively correlated with SS and Maze in patients; moreover, right hippocampal volume predicted 17.4% of SS performance variance. These results suggest that there may be a difference between male and female patients with regard to right hippocampal volume, and that female patients may need more attention than males.

The Choline Acetyltransferase (CHAT) Gene is Associated with Parahippocampal and Hippocampal Structure and Short-term Memory Span

The CHAT gene encodes choline acetyltransferase, which is an enzyme responsible for the biosynthesis of the neurotransmitter acetylcholine in the brain. This study collected structural MRI, genetic, and behavioral data from 324 healthy Chinese adults, and examined the associations between CHAT genetic variants, parahippocampal and hippocampal structure, and short-term memory span. After controlling for intracranial volume, sex, and age, CHAT SNP rs12246528 had the strongest association with parahippocampal structure, with the A allele being linked to smaller volume, surface area, and thickness. SNP rs1917814 had the strongest association with hippocampal volume, with the T allele being linked to larger hippocampal volume. After controlling for sex and age, CHAT rs3729496 had the strongest association with memory span, with the T allele being associated with a greater memory span. Finally, the left parahippocampal gyrus surface area was positively associated with memory span. This study provides the first evidence for the involvement of the CHAT gene in parahippocampal and hippocampal structures and memory span in healthy Chinese adults.

Changes in gray and white matter in subgroups within the tinnitus population

In this study, we investigated gray and white matter changes in subgroups within the larger tinnitus population related to differences in severity or duration of tinnitus symptoms. Tinnitus is the illusory perception of sound in the absence of an external source, most often experienced as a chronic condition. The psychological reaction to the sound constitutes the severity, or degree of discomfort experienced, and the duration refers to the time since onset of chronic tinnitus. We used voxel- and surface-based morphometry to investigate gray matter changes and diffusion tensor imaging (using fractional anisotropy, or FA, metrics) to assess changes in orientation of white matter tracts, using both whole brain and region of interest analyses. Whole brain analyses revealed decreased cortical thickness in the left parahippocampal gyrus in those with more severe tinnitus compared to a group with a milder reaction, and reduced gray matter volume in left anterior cingulate in those with mild tinnitus compared to a normal hearing control group without tinnitus. In the analysis based on FA, no significant differences were revealed between the subgroups or with respect to control groups in either whole brain or region of interest analyses. Our results suggest that these subgroups within the tinnitus population likely exhibit different anatomical alterations related to the disorder, which may explain the variable findings in the literature, particularly in terms of gray matter.

Alterations of regional cerebral blood flow after NMDA receptor antagonist administration in patients with alcohol‐related dementia

AbstractAlthough N‐methyl‐d‐aspartate (NMDA) receptor antagonists may have beneficial influences on cognition in patients with alcohol‐related dementia (ARD), their effects on regional cerebral blood flow (rCBF) remain unknown. This study evaluated changes in rCBF in ARD patients after administration of NMDA receptor antagonist for 12 weeks using technetium‐99m ethyl cysteinate dimer (Tc‐99m ECD) single‐photon emission computed tomography (SPECT). Twenty‐eight ARD patients were administered memantine for 12 weeks and underwent clinical evaluations and brain SPECT scans at baseline and follow‐up. Whole‐brain changes in perfusion were examined on a voxel‐by‐voxel basis. At follow‐up, the patients showed reduced rCBF in the left medial frontal gyrus, left cingulate gyrus, left claustrum, right brainstem, left superior temporal gyrus, bilateral fusiform gyrus, and left cerebellum. On the other hand, increased rCBF was found in the bilateral uncus, left parahippocampal gyrus, bilateral superior frontal gyrus, right inferior parietal lobule, left cuneus, and left superior temporal gyrus. Perfusion increases in various brain areas including the superior frontal, parahippocampal, and inferior parietal areas, which may play important roles in the pathophysiology of ARD, suggest potential benefits of NMDA receptor antagonists on brain functions in patients with ARD.