Posterior Parahippocampal Gyrus Research Articles

Dysconnectivity of the Nucleus Accumbens and Amygdala in Youths with Thought Problems: A Dimensional Approach.

Background: Youths with thought problems (TP) are at risk to develop psychosis and obsessive-compulsive disorder (OCD). Yet, the pathophysiological mechanisms underpinning TP are still unclear. Functional magnetic resonance imaging (fMRI) studies have shown that striatal and limbic alterations are associated with psychosis-like and obsessive-like symptoms in individuals at clinical risk for psychosis, schizophrenia, and OCD. More specifically, nucleus accumbens (NAcc) and amygdala are mainly involved in these associations. The current study aims to investigate the neural correlates of TP in youth populations using a dimensional approach and explore potential cognitive functions and neurotransmitters associated with it. Methods: Seed-to-voxels functional connectivity analyses using NAcc and amygdala as regions-of-interest were conducted with resting-state fMRI data obtained from 1360 young individuals, and potential confounders related to TP such as anxiety and cognitive functions were included as covariates in multiple regression analyses. Replicability was tested in using an adult cohort. In addition, functional decoding and neurochemical correlation analyses were performed to identify the associated cognitive functions and neurotransmitters. Results: The altered functional connectivities between the right NAcc and posterior parahippocampal gyrus, between the right amygdala and lateral prefrontal cortex, and between the left amygdala and the secondary visual area were the best predictors of TP in multiple regression model. These functional connections are mainly involved in social cognition and reward processing. Conclusions: The results show that alterations in the functional connectivity of the NAcc and the amygdala in neural pathways involved in social cognition and reward processing are associated with severity of TP in youths.

The neural correlates of topographical disorientation-a lesion analysis study.

Topographical disorientation refers to the selective inability to orient oneself in familiar surroundings. However, to date its neural correlates remain poorly understood. Here we use quantitative lesion analysis and a lesion network mapping approach in order to investigate seven patients with topographical disorientation. Our findings link not only the posterior parahippocampal gyrus (PHG) and retrosplenial cortex but also the lingual gyrus, the precuneus and the fusiform gyrus to topographical disorientation. We propose that topographical disorientation is due to the inability to integrate familiar landmarks within a framework of allocentric and egocentric orientation, supported by a neural network including the posterior PHG, the retrosplenial and the lingual cortex.

Right inferior frontal gyrus theta-burst stimulation reduces smoking behaviors and strengthens fronto-striatal-limbic resting-state functional connectivity: a randomized crossover trial.

Functional and anatomical irregularities in the right inferior frontal gyrus (rIFG), a ventrolateral prefrontal region that mediates top-down inhibitory control over prepotent behavioral responding, are implicated in the ongoing maintenance of nicotine dependence (ND). However, there is little research on the effects of neuromodulation of the rIFG on smoking behavior, inhibitory control, and resting-state functional connectivity (rsFC) among individuals with ND. In this double-blind, crossover, theta-burst stimulation (TBS) study, adults with ND (N = 31; female: n = 15) completed a baseline session and were then randomized to two counterbalanced sessions of functionally neuronavigated TBS to the rIFG: continuous TBS (cTBS) on 1 day and intermittent TBS (iTBS) on another. Differences in cigarette cravings, smoking, and fronto-striatal-limbic rsFC were assessed. Relative to baseline, cTBS significantly reduced appetitive and withdrawal cravings immediately after treatment. The effects of cTBS on withdrawal craving persisted for 24 h, as well as produced a reduction in smoking. Furthermore, cTBS significantly strengthened rsFC between the rIFG pars opercularis and subcallosal cingulate (fronto-striatal circuit), and between the rIFG pars opercularis and the right posterior parahippocampal gyrus (fronto-limbic circuit). At post-24 h, cTBS-induced increase in fronto-striatal rsFC was significantly associated with less appetitive craving, while the increase in fronto-limbic rsFC was significantly associated with less withdrawal craving and smoking. These findings warrant further investigation into the potential value of rIFG cTBS to attenuate smoking behavior among individuals with ND.

Functional connectivity with medial temporal regions differs across cultures during post-encoding rest.

Connectivity of the brain at rest can reflect individual differences and impact behavioral outcomes, including memory. The present study investigated how culture influences functional connectivity with regions of the medial temporal lobe. In this study, 46 Americans and 59 East Asians completed a resting state scan after encoding pictures of objects. To investigate cross-cultural differences in resting state functional connectivity, left parahippocampal gyrus (anterior and posterior regions) and left hippocampus were selected as seed regions. These regions were selected, because they were previously implicated in a study of cultural differences during the successful encoding of detailed memories. Results revealed that left posterior parahippocampal gyrus had stronger connectivity with temporo-occipital regions for East Asians compared with Americans and stronger connectivity with parieto-occipital regions for Americans compared with East Asians. Left anterior parahippocampal gyrus had stronger connectivity with temporal regions for East Asians than Americans and stronger connectivity with frontal regions for Americans than East Asians. Although connectivity did not relate to memory performance, patterns did relate to cultural values. The degree of independent self-construal and subjective value of tradition were associated with functional connectivity involving left anterior parahippocampal gyrus. Findings are discussed in terms of potential cultural differences in memory consolidation or more general trait or state-based processes, such as holistic versus analytic processing.

Early-life stress exposure and large-scale covariance brain networks in extremely preterm-born infants

The stressful extrauterine environment following premature birth likely has far-reaching and persistent adverse consequences. The effects of early “third-trimester” ex utero stress on large-scale brain networks’ covariance patterns may provide a potential avenue to understand how early-life stress following premature birth increases risk or resilience. We evaluated the impact of early-life stress exposure (e.g., quantification of invasive procedures) on maturational covariance networks (MCNs) between 30 and 40 weeks of gestational age in 180 extremely preterm-born infants (<28 weeks of gestation; 43.3% female). We constructed MCNs using covariance of gray matter volumes between key nodes of three large-scale brain networks: the default mode network (DMN), executive control network (ECN), and salience network (SN). Maturational coupling was quantified by summating the number of within- and between-network connections. Infants exposed to high stress showed significantly higher SN but lower DMN maturational coupling, accompanied by DMN-SN decoupling. Within the SN, the insula, amygdala, and subthalamic nucleus all showed higher maturational covariance at the nodal level. In contrast, within the DMN, the hippocampus, parahippocampal gyrus, and fusiform showed lower coupling following stress. The decoupling between DMN-SN was observed between the insula/anterior cingulate cortex and posterior parahippocampal gyrus. Early-life stress showed longitudinal network-specific maturational covariance patterns, leading to a reprioritization of developmental trajectories of the SN at the cost of the DMN. These alterations may enhance the ability to cope with adverse stimuli in the short term but simultaneously render preterm-born individuals at a higher risk for stress-related psychopathology later in life.

Diffusion MRI–guided theta burst stimulation enhances memory and functional connectivity along the inferior longitudinal fasciculus in mild cognitive impairment

Mild cognitive impairment (MCI) during aging is often a harbinger of Alzheimer’s disease, and, therefore, early intervention to preserve cognitive abilities before the MCI symptoms become medically refractory is particularly critical. Functional MRI–guided transcranial magnetic stimulation is a promising approach for modulating hippocampal functional connectivity and enhancing memory in healthy adults. Here, we extend these previous findings to individuals with MCI and leverage theta burst stimulation (TBS) and white matter tractography derived from diffusion-weighted MRI to target the hippocampus. Our preliminary findings suggested that TBS could be used to improve associative memory performance and increase resting-state functional connectivity of the hippocampus and other brain regions, including the occipital fusiform, frontal orbital cortex, putamen, posterior parahippocampal gyrus, and temporal pole, along the inferior longitudinal fasciculus in MCI. Although the sample size is small, these results shed light on how TBS propagates from the superficial cortex around the parietal lobe to the hippocampus.

FC092: The Relationship between Cerebrovascular Reactivity and Intradialytic Cerebral Perfusion

Abstract BACKGROUND AND AIMS Cerebral perfusion can decline in hemodialysis (HD) patients during HD and may have severe consequences on cerebral integrity. The declines in cerebral perfusion are often related to intradialytic changes in blood pressure (BP), indicating that the ability of cerebrovasculature to maintain perfusion during systemic BP drop is impaired. Preliminary data using transcranial Doppler ultrasound demonstrated that cerebrovascular reactivity (CVR), a physiologic mechanism for maintaining cerebral perfusion, is impaired in HD patients. we hypothesize that CVR can serve as a measure for how a patients’ cerebrovasculature can respond to intradialytic hypotension. We aim to measure CVR in a cohort of HD patients and evaluate the relationship between CVR, intradialytic BP fluctuation and risk of intradialytic cerebral hypoperfusion. METHOD In a cross-sectional analysis, we used resting state fMRI to estimate CVR and determine if CVR is related to changes in cerebral oxygen saturation (ScO2) measured during HD. We recruited ESRD patients ≥50 years of age who were treated with in-center HD to complete an MRI with T1 weighted anatomical images and resting state fMRI. CVR was obtained from the resting state fMRI data by first bandpass filtering and detrending the global blood oxygenation level dependent (BOLD) signal within the frequency range that correlated with end tidal CO2 (vasoactive stimulus for CVR). The CVR was then calculated as the coefficient relating the filtered fMRI signal to each unfiltered voxel. Intradialytic ScO2 was continuously measured during an entire HD session using near-infrared spectroscopy with oximetry sensors secured to the forehead. Change in cerebral perfusion was quantified as the % change in ScO2 from baseline during the HD session. Due to the forehead placement of our sensors, we focused our CVR analysis to the frontal brain regions. Univariate linear regression models were run within each region for association with change in ScO2. Further analysis added intradialytic BP change to the model. RESULTS We included 26 participants with complete MRI and ScO2 data in analysis. Mean (SD) age was 65.7 (7.1), 81% had hypertension and 69% had diabetes mellitus. On average, the systolic BP (SBP) and ScO2 declined during HD. Results demonstrated that lower CVR in the anterior cingulate gyrus (ACG r2 = 0.19; P = 0.03, Figure 1), insular cortex (IC, r2 = 0.19; P = 0.03, Figure 1) and posterior parahippocampal gyrus (PPG, r2 = 0.20; P = 0.02) regions were associated with a decrease in ScO2 during HD. When adding the change in SBP during HD to the model, the ACG (r2 = 0.35, &amp;lt;0.01) and IC (r2 = 0.26; P = 0.03) models remained significant with increased correlation coefficients. CONCLUSION We were able to demonstrate a relationship between lower CVR in frontal gray matter regions and greater decline in cerebral perfusion during HD. This relationship was further strengthened when adding the intradialytic change in SBP to the model. This suggests that both the hemodynamic fluctuations and the patient's ability to regulate cerebral perfusion are contributing factors for the risk of intradialytic cerebral hypoperfusion and subsequent cerebral ischemic injury in HD patients.

Three cortical scene systems and their development.

Since the discovery of three scene-selective regions in the human brain, a central assumption has been that all three regions directly support navigation. We propose instead that cortical scene processing regions support three distinct computational goals (and one not for navigation at all): (i) The parahippocampal place area supports scene categorization, which involves recognizing the kind of place we are in; (ii) the occipital place area supports visually guided navigation, which involves finding our way through the immediately visible environment, avoiding boundaries and obstacles; and (iii) the retrosplenial complex supports map-based navigation, which involves finding our way from a specific place to some distant, out-of-sight place. We further hypothesize that these systems develop along different timelines, with both navigation systems developing slower than the scene categorization system.

Distinct patterns of posterior default mode network‐medial temporal lobe connectivity in mild cognitive impairment and subjective cognitive decline

AbstractBackgroundOlder adults with subjective cognitive decline (SCD) show alterations in functional connectivity of the posterior default mode network (DMN), but both increases and decreases have been reported, suggesting that changes in connectivity may be nonlinear across the AD spectrum. Alternatively, the variable findings may be attributable to heterogeneity within SCD samples. Specifically, studies of SCD exclude individuals with current depression, but history of past remitted depression is not typically ascertained. This is problematic because emerging evidence suggests that state‐independent aberrations in neural networks, including within posterior DMN, persist following recovery from depression. In the current study, we compared posterior DMN connectivity using resting state functional magnetic resonance imaging (rs‐fMRI) amongst SCD, mild cognitive impairment (MCI) or cognitively unimpaired (CU) older adults free of current or remitted depression.MethodParticipants were 58 older adults who were screened via psychiatric/medical assessment for current or past history of depression and neurological conditions, and consisted of 21 SCD [12F, mean age 70.6(SD5.5)] defined as perception of memory decline with concern or worry and normal neuropsychological (NP) test scores, 12 MCI [4F, mean age 73(SD6.8)] defined as subjective cognitive complaints with functional independence and impaired performance on &gt;=2 NP tests, and 25 CU [15F, mean age 71.8(SD7.2)] based on normal NP scores and absence of subjective memory decline with worry. Rs‐fMRI was acquired using gradient‐echo EPI BOLD at 3T and processed using CONN toolbox. Seed analysis using a posterior cingulate cortex (PCC) seed (x=‐6, y=‐52, z=40) was performed. Hippocampus and parahippocampal gyrus were target regions‐of‐interest. Multivariate ANOVA was used to examine group differences in PCC connectivity followed by post hoc comparisons using Dunnett’s test.ResultGroups differed in PCC connectivity with the right hippocampus [F(2, 55)=3.74, P=.03] and left posterior parahippocampal gyrus [F(2, 55)=3.35, P=.042]. Relative to CU, PCC‐right hippocampal connectivity was reduced in MCI (P=.028), while PCC‐left parahippocampal connectivity was found in SCD (P=.024).ConclusionDisruptions in posterior DMN connectivity were observed in SCD and MCI that were not attributable to current or remitted depression. The distinct patterns of posterior DMN disruption are consistent with putative non‐linear changes in neural network connectivity with AD progression.

P.189 Unruptured Posterior Cerebral Artery aneurysm causing temporal lobe epilepsy

Background: Cerebral aneurysms are an unusal cause of epilepsy. To date, several groups have reported temporal lobe seizures caused by aneurysms projecting into the parahippocampal gyrus. Given the low incidence of posterior cerebral artery aneurysms, they are a very rare cause of temporal lobe seizures. Methods: Here, we report a rare case of temporal lobe epilepsy caused by an unruptured aneurysm. We also present a review of the literature yielding two similar cases. Results: A previosuly well 56 year old male presented to a neurologist with symptoms consistent with temporal lobe epilepsy. He was started on carbamzepine and underwent imaging and neuropsychological assessments. An MRI suggested the existance of a 7mm posterior cerebral artery aneurysm arising from the P2 segment of the posterior cerebral artery and projecting into the parahippocampal gyrus. This was also confirmed with CT angiography and the patient elected to have the aneurysm clipped. Conclusions: Temporal lobe epilepsy is an uncommon presentation for unruptured cerebral aneurysms. We report a rare case wherein a laterally pointing PCA aneurysm was buried in the posterior parahippocampal gyrus. This aneurysm had caused perifocal gliosis leading to stereotyped seizures. Post-operatively, the patient has been seizure free.

Dynamic Alterations in Neural Networks Supporting Aversive Learning in Children Exposed to Trauma: Neural Mechanisms Underlying Psychopathology

BackgroundAltered aversive learning represents a potential mechanism through which childhood trauma (CT) might influence risk for psychopathology. This study examines the temporal dynamics of neural activation and patterns of functional connectivity during aversive learning in children with and without exposure to CT involving interpersonal violence and evaluates whether these neural patterns mediate the association of CT with psychopathology in a longitudinal design. MethodsA total of 147 children (aged 8–16 years, 77 with CT) completed a fear conditioning procedure during a functional magnetic resonance imaging scan. Dynamic patterns of neural activation were examined, and functional connectivity was assessed with generalized psychophysiological interaction analyses. We evaluated whether the associations between CT and psychopathology symptoms at baseline and 2-year follow-up were mediated by neural activation and connectivity during aversive learning. ResultsChildren exposed to trauma displayed blunted patterns of neural activation over time to the conditioned threat versus safety stimuli (CS+>CS−) in the right amygdala. In addition, trauma was associated with reduced functional connectivity of right amygdala with the hippocampus, posterior parahippocampal gyrus, and posterior cingulate cortex and with elevated connectivity with the anterior cingulate cortex to CS+>CS−. The longitudinal association between CT and later externalizing symptoms was mediated by blunted activation in the right amygdala. Reduced amygdala-hippocampal connectivity mediated the association of CT with transdiagnostic anxiety symptoms, and elevated amygdala–anterior cingulate cortex connectivity mediated the association of CT with generalized anxiety symptoms. ConclusionsCT is associated with poor threat-safety discrimination and altered functional coupling between salience and default mode network regions during aversive learning. These altered dynamics may be key mechanisms linking CT with distinct forms of psychopathology.

Theory of mind processing in expectant fathers: Associations with prenatal oxytocin and parental attunement.

Social cognition may facilitate fathers' sensitive caregiving behavior. We administered the Why-How Task, an fMRI task that elicits theory of mind processing, to expectant fathers (n=39) who also visited the laboratory during their partner's pregnancy and provided a plasma sample for oxytocin assay. Three months postpartum, fathers reported their beliefs about parenting. When rating "Why" an action was being performed versus "How" the action was being performed (Why > How contrast), participants showed activation in regions theorized to support theory of mind, including the dorsomedial prefrontal cortex and superior temporal sulcus. Fathers' prenatal oxytocin levels predicted greater signal change during the Why > How contrast in the inferior parietal lobule. Both prenatal oxytocin and attunement parenting beliefs were associated with Why > How activation in the dorsolateral prefrontal cortex, a theory of mind region implicated in emotion regulation. Posterior parahippocampal gyrus and dorsolateral prefrontal cortex activation during the Why > How contrast predicted fathers' attunement parenting beliefs. In conclusion, fathers' neural activation when engaging in a theory of mind task was associated with their prenatal oxytocin levels and their postpartum attunement parenting beliefs. Results suggest biological and cognitive components of fathering may track with the theory of mind processing.

The impact of a multi-domain intervention on cerebral glucose metabolism: analysis from the randomized ancillary FDG PET MAPT trial.

BackgroundThe Multidomain Alzheimer Preventive Trial (MAPT) was designed to assess the efficacy of omega-3 fatty acid supplementation, multidomain intervention (MI), or a combination of both on cognition. Although the MAPT study was negative, an effect of MI in maintaining cognitive functions compared to placebo group was showed in positive amyloid subjects. A FDG PET study (MAPT-NI) was implemented to test the impact of MI on brain glucose metabolism.MethodsMAPT-NI was a randomized, controlled parallel-group single-center study, exploring the effect of MI on brain glucose metabolism. Participants were non-demented and had memory complaints, limitation in one instrumental activity of daily living, or slow gait. Participants were randomly assigned (1:1) to “MI group” or “No MI group.” The MI consisted of group sessions focusing on 3 domains: cognitive stimulation, physical activity, nutrition, and a preventive consultation. [18F]FDG PET scans were performed at baseline, 6 months, and 12 months, and cerebral magnetic resonance imaging scans at baseline. The primary objective was to evaluate the MI effect on brain glucose metabolism assessed by [18F]FDG PET imaging at 6 months. The primary outcome was the quantification of regional metabolism rate for glucose in cerebral regions involved early in Alzheimer disease by relative semi-quantitative SUVr (FDG-based AD biomarker). An exploratory voxel-wise analysis was performed to assess the effect of MI on brain glucose metabolism without anatomical hypothesis.ResultsThe intention-to-treat population included 67 subjects (34 in the MI group and 33 in the No MI group. No significant MI effect was observed on primary outcome at 6 months. In the exploratory voxel-wise analysis, we observed a difference in favor of MI group on the change of cerebral glucose metabolism in limbic lobe (right hippocampus, right posterior cingulate, left posterior parahippocampal gyrus) at 6 months.ConclusionsMI failed to show an effect on metabolism in FDG-based AD biomarker, but exploratory analysis suggested positive effect on limbic system metabolism. This finding could suggest a delay effect of MI on AD progression.Trial registrationClinicalTrials.gov Identifier, NCT01513252.

Neuroanatomic Correlates of Distance and Direction Processing During Cognitive Map Retrieval.

Navigating toward a goal and mentally comparing distances and directions to landmarks are processes requiring reading information off the memorized representation of the environment, that is, the cognitive map. Brain structures in the medial temporal lobe, in particular, are known to be involved in the learning, storage, and retrieval of cognitive map information, which is generally assumed to be in allocentric form, whereby pure spatial relations (i.e., distance and direction) connect locations with each other. The authors recorded functional magnetic resonance imaging activity, while participants were submitted to a variant of a neuropsychological test (the Cognitive Map Reading Test; CMRT) originally developed to evaluate the performance of brain-lesioned patients and in which participants have to compare distances and directions in their mental map of their hometown. Our main results indicated posterior parahippocampal, but not hippocampal, activity, consistent with a task involving spatial memory of places learned a long time ago; left parietal and left frontal activity, consistent with the distributed processing of navigational representations; and, unexpectedly, cerebellar activity, possibly related to the role of the cerebellum in the processing of (here, imaginary) self-motion cues. In addition, direction, but not distance, comparisons elicited significant activation in the posterior parahippocampal gyrus.

Functional connectivity changes of nucleus Accumbens Shell portion in left mesial temporal lobe epilepsy patients.

Growing evidence has supported that the nucleus accumbens (NAc), especially its shell portion, has been involved in epileptogenesis. However, relevant studies on vivo human brain are quite limited. In this study, we investigated left mesial temporal lobe epilepsy (MTLE) related function connectivity (FC) changes of NAc subregions using resting-state functional magnetic resonance imaging. We calculated functional connectivity from two NAc subregions to both whole brain and 16 related targets. Two-sample t-test (Alphasim multiple comparisons corrected) was performed to identify the effect of the disease on each seed's whole brain network. Repeated-measures ANOVA and Post hoc pairwise t test (Bonferroni corrections) were performed to visualize the seed to target FC group differences in each subdivision. In whole brain FC networks, neither the left or right core show different FC changes. The left shell showed decreased FC with a cluster located around the right inferior frontal gyrus. The right shell portion showed increased FC with a cluster located around the left inferior temporal gyrus. The seed to targets results showed that the left shell of LTLE group exhibited lower FC with left posterior-parahippocampal gyrus and right caudate, putamen, thalamus, paracingulate gyrus but higher FC with right subcallosal cortex. The right core of LTLE group exhibited higher FC with right frontal pole and the right shell exhibited lower FC with left thalamus and left anterior-parahippocampal gyrus. This is the first study to investigate the functional connectivity changes of NAc subdivisions of epilepsy in vivo human brain. Our results showed that the left MTLE related FC changes on NAc are mainly on shell portion rather than core. The decrease FC between the left shell and right frontal area and the decrease FC between the right shell and left temporal area suggested they serve vital roles for MTLE.

Supracerebellar Infratentorial and Occipital Transtentorial Approaches to the Pulvinar: Ipsilateral Versus Contralateral Corridors.

Due to the critical neurovascular structures that surround the pulvinar, deciding the best surgical approach can be challenging, with multiple options available. To analyze and compare the ipsilateral vs the contralateral version of the 2 main approaches to the cisternal pulvinar surface: paramedian supracerebellar infratentorial (PSCI) and interhemispheric occipital transtentorial (IOT). The PSCI and IOT approaches were performed on 7 formalin-fixed adult cadaveric heads to evaluate qualitatively and quantitatively the microsurgical exposure of relevant anatomic structures. We quantitatively measured the corridor distance to our target with each approach. The ipsilateral PSCI approach provided an easier access and a better exposure of the anteromedial portion of the cisternal pulvinar surface. The contralateral approach provided a wider and more accessible exposure of the posterolateral portion of the cisternal pulvinar surface. When protrusion of the posterior parahippocampal gyrus above the free edge of the tentorium was present, the contralateral PSCI approach provided an unobstructed view to both areas. The IOT approach provided a better view of the anteromedial portion of the cisternal pulvinar surface, especially with a contralateral approach. Multiple approaches to the pulvinar have been described, modified, and improved. Based on this anatomic study we believe that although the corridor distance with a contralateral approach is longer, the surgical view and access can be better. We recommend the use of a PSCI contralateral approach especially when a significant protrusion of the posterior parahippocampal gyrus is present.

Integration and segregation of functional segmented anterior and posterior hippocampal networks in memory performance.

To determine the association between functional connectivity (FC) of functional-segmented anterior and posterior portions of the hippocampus and performance on verbal and visual memory tests in a young, healthy population. We recruited 100 healthy participants in the age of 19-29. Resting state fMRI data were acquired and voxel-wise correlation analysis was performed to functionally divide the hippocampus. We investigated the inter-hemispheric hippocampal-cortical functional connectivity after the participants took the assessment of episodic memory using verbal (California Verbal Learning Test II, CVLT-II) and visual subtests (Rey-Osterrieth Complex Figure, ROCF). The partial correlations were used to identify the association between the intra-hemispheric hippocampal-cortical mean resting correlation and memory performance. The results showed that the anterior and posterior hippocampal networks involved differently in verbal and visual memory. Intra-hemispheric FC between left posterior hippocampus and posterior parahippocampal gyrus (PPHG) was positively correlated with CVLT-II Trail 2 Immediate Free Recall (r = 0.223, p = 0.029). Intra-hemispheric FC between left posterior hippocampus and posterior cingulate (PCC) was negatively correlated with ROCF Immediate Recall (r = -0.217 p = 0.034). Intra-hemispheric FC between left anterior hippocampus and temporal pole (TP) negatively correlated with ROCF Delayed Recall (r = -0.228, p = 0.025). Split half resampling procedure results showed some repeatability in our subjects. The present results demonstrated that, the anterior hippocampus was specifically involved in the visual memory processing, whereas the posterior hippocampus contributed to both the verbal and visual memories, which may have implications for a functionally synergetic and dissociable role of the hippocampus in different kinds of memory.

Sledge runner fasciculus: anatomic architecture and tractographic morphology.

The sledge runner fasciculus (SRF) has been recently identified as a discrete fiber tract of the occipital lobe and has been allegedly implicated in the axonal connectivity of cortical areas conveying spatial navigation and visuospatial imagery. However, detailed knowledge regarding its anatomic and tractographic morphology is lacking. We thus opted to investigate the anatomy and connectivity of the SRF through cadaveric dissections and DTI studies. Twenty normal, adult, cerebral, cadaveric hemispheres treated with the Klingler's method were dissected through the fiber microdissection technique and 35 healthy participants from the MGH-USC Adult Diffusion Dataset (Human Connectome available dataset) underwent a tailored DTI protocol aiming to investigate the structural architecture of the SRF. SR was identified as a discrete fiber pathway, just under the U fibers of the medial occipital lobe, exhibiting a dorsomedial-ventrolateral trajectory and connecting the cortical areas of the anterior cuneus, anterior lingula, isthmus of the cingulum and posterior parahippocampal gyrus. The topography of the SR in relation to adjacent fiber pathways such as the cingulum, major forceps and stratum calcarinum is clearly delineated. Dissection and tractographic findings showed a good correspondence regarding SR topography, morphology and axonal connectivity. Our results support the hypothesis that the SRF is involved in the structural axonal connectivity of cerebral areas that strongly activate during spatial navigation and visuospatial imagery. Furthermore detailed anatomo-imaging evidence is provided on the microanatomic architecture of this newly discovered fiber tract.

Changes in functional connectivity are associated with one season of head-to-ball impact exposure in male collegiate soccer athletes

ObjectivesReturn-to-play protocols could be improved by a better understanding of the physiologic effects of mild traumatic brain injury (mTBI). Autonomic dysregulation is thought to underlie many of the multi-dimensional symptoms following mTBI and may derive from altered connectivity in the brain central autonomic network (CAN). Understanding the relationship between injury and CAN connectivity could lead to a useful biomarker for mTBI. Toward this end, the present study aimed to establish a formal relationship between non-symptomatic head-to-ball impacts (“headers”) and CAN connectivity in collegiate soccer athletes.MethodsEleven male NCAA Division I soccer players were monitored by athletic training staff throughout 1 season for the number of headers. Ten male NCAA Division I athletes (3 cross-country and 7 golfers) served as controls. All participants underwent resting-state fMRI pre- and post-season. Twenty ROIs were selected based on regions previously implicated in control and modulation of autonomic function. Graph theoretical analyses were used to probe changes in network architecture and connectivity. Specific contrasts focused on pre- and post-season changes that were explained by individual differences in exposure to headers (p &lt; 0.05 uncorrected).ResultsWithin the 20 node network, increases in headers were associated with reduced degree centrality of the left and right insular cortex and right putamen (p&lt; 0.02), increased degree and betweenness centrality in the left anterior and right posterior Para hippocampal gyri (p&lt; 0.03), and increased betweenness centrality in the anterior cingulate cortex (p = 0.006). Headers were also associated with reduced functional connectivity within the subnetwork including the anterior cingulate cortex (p = 0.0073), right hippocampus, left putamen, and left insular cortex (p&lt; 0.04).ConclusionHighly skilled soccer players who sustained the greatest number of head impacts also experienced the greatest altered connectivity among regions associated with autonomic function. Future work to establish autonomic function as an injury biomarker should consider the importance of cumulative impact magnitudes.

Brain activation to high-calorie food images in healthy normal weight and obese children: a fMRI study

BackgroundUnderstanding how normal weight and obese young children process high-calorie food stimuli may provide information relevant to the neurobiology of eating behavior contributing to childhood obesity. In this study, we used fMRI to evaluate whether brain activation to high-calorie food images differs between normal weight and obese young children.MethodsBrain activation maps in response to high-calorie food images and non-food images for 22 healthy, 8–10-years-old children (N = 11/11 for normal weight/obese respectively) were generated and compared between groups.ResultsWhen comparing brain activation differences in response to viewing high-calorie food versus non-food images between normal weight and obese children, group differences were observed in areas related to memory and cognitive control. Specifically, normal weight children showed higher activation of posterior parahippocampal gyri (PPHG) and dorsomedial prefrontal cortex (DMPFC). Further ROI analyses indicated higher activation strength (Z scores) in the right PPHG (p = 0.01) and higher activation strength (p < 0.001) as well as a larger activation area (p = 0.02) in the DMPFC in normal weight than obese children.ConclusionsNormal weight and obese children process high-calorie food stimuli differently even from a young age. Normal weight children exhibit increased brain activation in regions associated with memory and cognitive control when viewing high-calorie food images.