Anatomical Characteristics of Cingulate Cortex and Neuropsychological Memory Tests Performance

AbstractThe absolute squares of cingulate cortex (anterior, posterior ventral, posterior dorsal, retrosplenial regions) were calculated on magnetic resonance images of 29 subjects (60-76 years old) and compared with subjects’ neuropsychological memory characteristics. The results demonstrate significant correlations between overall performance and the amount of different types of errors in neuropsychological memory tests and the relative size of these regions. The discovered correlations pattern can be explained by a hypothesis of reciprocal functional influence of two major areas of cingulate cortex (anterior and dorsal posterior regions) on the processes of external and internal interference, which results in neuropsychological memory tests performance

Comparison between early-onset and late-onset alzheimer's disease patients with amnestic presentation: CSF and 18F-FDG PET study

BACKGROUND/AIMS To investigate the differences in brain glucose consumption between patients with early onset of Alzheimer's disease (EOAD, aged ≤65 years) and patients with late onset of Alzheimer's disease (LOAD, aged >65 years). METHODS Differences in brain glucose consumption between the groups have been evaluated by means of Statistical Parametric Mapping version 8, with the use of age, sex, Mini-Mental State Examination and cerebrospinal fluid values of AΒ1-42, phosphorylated Tau and total Tau as covariates in the comparison between EOAD and LOAD. RESULTS As compared to LOAD, EOAD patients showed a significant decrease in glucose consumption in a wide portion of the left parietal lobe (BA7, BA31 and BA40). No significant differences were obtained when subtracting the EOAD from the LOAD group. CONCLUSIONS The results of our study show that patients with EOAD show a different metabolic pattern as compared to those with LOAD that mainly involves the left parietal lobe

Cortico-Subcortical Metabolic Changes in Aging Brain: A 18F FDG PET/CT Study

Aim: to investigate the effects of aging on brain glucose consumption on a population of healthy subjects. Materials and methods: 102 chemotherapy-naïve subjects (56 men, 46 women; mean age 57±16 years old; age range 20-89 years) undergoing a whole body 18F FDG PET/CT and found to be completely negative for various diseases in both PET/CT and contrast enhanced CT (performed contextually to PET/CT scan) were enrolled in the study. Age-related changes in brain 18F-FDG uptake were analysed by statistical parametric mapping (SPM8). Results: aging is related to a reduction of brain glucose consumption in right medial frontal gyrus (BA9) and anterior cingulate cortex (BA32) and to an increased 18F-FDG uptake in right sub-cortical structures (lentiform nucleus, claustrum) and in cerebellum bilaterally. Conclusions: The results of our study suggest that a reduced functioning of ACC and medial PFC occur in the elderly. An increased activation of the cerebellum, lentiform nucleus and claustrummay represent a compensatory mechanism, possibly involved in cognitive decline

Cortico-Subcortical Metabolic Changes in Aging Brain

Aim: to investigate the effects of aging on brain glucose consumption on a population of healthy subjects.Materials and methods: 102 chemotherapy-naïve subjects (56 men, 46 women; mean age 57±16 years old; age range 20-89 years) undergoing a whole body 18F FDG PET/CT and found to be completely negative for various diseases in both PET/CT and contrast enhanced CT (performed contextually to PET/CT scan) were enrolled in the study. Age-related changes in brain 18F-FDG uptake were analysed by statistical parametric mapping (SPM8).Results: aging is related to a reduction of brain glucose consumption in right medial frontal gyrus (BA9) and anterior cingulate cortex (BA32) and to an increased 18F-FDG uptake in right sub-cortical structures (lentiform nucleus, claustrum) and in cerebellum bilaterally.Conclusions: The results of our study suggest that a reduced functioning of ACC and medial PFC occur in the elderly. An increased activation of the cerebellum, lentiform nucleus and claustrummay represent a compensatory mechanism, possibly involved in cognitive decline

Frontoparietal function in young people with dysthymic disorder (DSM-5: Persistent depressive disorder) during spatial working memory

Background Dysthymic disorder (DD) is a depressive disorder characterised by persistent low and/or irritable mood and has been identified as a major risk factor for developing major depressive disorder (MDD). MDD and DD have been associated with executive function difficulties of working memory and attention. Little is known about how executive function networks in the brain are affected in children and adolescents with MDD and even less in DD. This study used fMRI and two spatial working memory paradigms to investigate associated brain function in young people with DD and an age-, gender- and IQ- matched typically developing group. Methods Nineteen male patients with DD (mean age 11.2±1.5 years) diagnosed according to DSM-IV criteria and 16 typically developing boys (mean age 10.5±1.1 years) performed a mental rotation and a delay-match to sample (DMTS) task while undergoing fMRI. All participants were medication-naïve at the time of testing. Results Compared to typically developing young people, the DD group showed less activation in left frontal regions including left ventro- and dorsolateral prefrontal cortices (PFC) during mental rotation. Medial frontal regions including dorsomedial PFC, anterior cingulate cortex and frontal pole also showed relatively reduced activation. During the DMTS task patients showed significantly more activation in the right precuneus and posterior cingulate cortex. Limitations This was a cross-sectional study with a small sample limiting the generalizability of the results. Conclusions The results complement previous findings in adults with MDD that have shown differential activation of left PFC regions during working memory tasks. Additionally, altered function of cortical midline structures in young patients with DD was identified. This supports findings in children, adolescents and adults with MDD suggesting that the pathophysiology of depressive disorders extends to DD as a risk factor for MDD and exhibits continuity over the lifespan

Resting state functional connectivity provides mechanistic predictions of future changes in sedentary behavior

Sedentary behaviors are increasing at the cost of millions of dollars spent in health care and productivity losses due to physical inactivity-related deaths worldwide. Understanding the mechanistic predictors of sedentary behaviors will improve future intervention development and precision medicine approaches. It has been posited that humans have an innate attraction towards effort minimization and that inhibitory control is required to overcome this prepotent disposition. Consequently, we hypothesized that individual differences in the functional connectivity of brain regions implicated in inhibitory control and physical effort decision making at the beginning of an exercise intervention in older adults would predict the change in time spent sedentary over the course of that intervention. In 143 healthy, low-active older adults participating in a 6-month aerobic exercise intervention (with three conditions: walking, dance, stretching), we aimed to use baseline neuroimaging (resting state functional connectivity of two a priori defined seed regions), and baseline accelerometer measures of time spent sedentary to predict future pre-post changes in objectively measured time spent sedentary in daily life over the 6-month intervention. Our results demonstrated that functional connectivity between (1) the anterior cingulate cortex and the supplementary motor area and (2) the right anterior insula and the left temporoparietal/temporooccipital junction, predicted changes in time spent sedentary in the walking group. Functional connectivity of these brain regions did not predict changes in time spent sedentary in the dance nor stretch and tone conditions, but baseline time spent sedentary was predictive in these conditions. Our results add important knowledge toward understanding mechanistic associations underlying complex out-of-session sedentary behaviors within a walking intervention setting in older adults

The Neuronal Correlates of Digits Backward Are Revealed by Voxel-Based Morphometry and Resting-State Functional Connectivity Analyses

Digits backward (DB) is a widely used neuropsychological measure that is believed to be a simple and effective index of the capacity of the verbal working memory. However, its neural correlates remain elusive. The aim of this study is to investigate the neural correlates of DB in 299 healthy young adults by combining voxel-based morphometry (VBM) and resting-state functional connectivity (rsFC) analyses. The VBM analysis showed positive correlations between the DB scores and the gray matter volumes in the right anterior superior temporal gyrus (STG), the right posterior STG, the left inferior frontal gyrus and the left Rolandic operculum, which are four critical areas in the auditory phonological loop of the verbal working memory. Voxel-based correlation analysis was then performed between the positive rsFCs of these four clusters and the DB scores. We found that the DB scores were positively correlated with the rsFCs within the salience network (SN), that is, between the right anterior STG, the dorsal anterior cingulate cortex and the right fronto-insular cortex. We also found that the DB scores were negatively correlated with the rsFC within an anti-correlation network of the SN, between the right posterior STG and the left posterior insula. Our findings suggest that DB performance is related to the structural and functional organizations of the brain areas that are involved in the auditory phonological loop and the SN

Bimanual Passive Movement: Functional Activation and Inter-Regional Coupling

The aim of this study was to investigate intra-regional activation and inter-regional connectivity during passive movement. During fMRI, a mechanic device was used to move the subject's index and middle fingers. We assessed four movement conditions (unimanual left/right, bimanual symmetric/asymmetric), plus Rest. A conventional intra-regional analysis identified the passive stimulation network, including motor cortex, primary and secondary somatosensory cortex, plus the cerebellum. The posterior (sensory) part of the sensory–motor activation around the central sulcus showed a significant modulation according to the symmetry of the bimanual movement, with greater activation for asymmetric compared to symmetric movements. A second set of fMRI analyses assessed condition-dependent changes of coupling between sensory–motor regions around the superior central sulcus and the rest of the brain. These analyses showed a high inter-regional covariation within the entire network activated by passive movement. However, the specific experimental conditions modulated these patterns of connectivity. Highest coupling was observed during the Rest condition, and the coupling between homologous sensory–motor regions around the left and right central sulcus was higher in bimanual than unimanual conditions. These findings demonstrate that passive movement can affect the connectivity within the sensory–motor network. We conclude that implicit detection of asymmetry during bimanual movement relies on associative somatosensory region in post-central areas, and that passive stimulation reduces the functional connectivity within the passive movement network. Our findings open the possibility to combine passive movement and inter-regional connectivity as a tool to investigate the functionality of the sensory–motor system in patients with very poor mobility

Effects of Oxytocin on Working Memory and Executive Control System Connectivity in PTSD

Hypothesis: It is hypothesized that oxytocin will improve working memory function and increase executive control system connectivity in PTSD patients compared to a resilient control group. Specific Aims: Aim 1. To test the hypothesis that oxytocin will improve working memory function in PTSD patients compared to a resilient control group. Participants (n=35) will include men and women with PTSD, and those who have experienced childhood trauma but did not develop PTSD (resilient group). We will test the influence of oxytocin and placebo on performance during an n-back working memory task. Aim 2. To test the hypothesis that oxytocin will increase executive control system connectivity. Functional magnetic resonance imaging (fMRI) will be used to examine cognitive function and executive control system connectivity during a working memory task following placebo or oxytocin administration (24IU). Analysis will include an examination of dorsolateral prefrontal cortex connectivity maps using psychophysiological interaction (PPI) analysis

Functional localization and effective connectivity of cortical theta and alpha oscillatory activity during an attention task

Objectives: The aim of this paper is to investigate cortical electric neuronal activity as an indicator of brain function, in a mental arithmetic task that requires sustained attention, as compared to the resting state condition. The two questions of interest are the cortical localization of different oscillatory activities, and the directional effective flow of oscillatory activity between regions of interest, in the task condition compared to resting state. In particular, theta and alpha activity are of interest here, due to their important role in attention processing. Methods: We adapted mental arithmetic as an attention ask in this study. Eyes closed 61-channel EEG was recorded in 14 participants during resting and in a mental arithmetic task (“serial sevens subtraction”). Functional localization and connectivity analyses were based on cortical signals of electric neuronal activity estimated with sLORETA (standardized low resolution electromagnetic tomography). Functional localization was based on the comparison of the cortical distributions of the generators of oscillatory activity between task and resting conditions. Assessment of effective connectivity was based on the iCoh (isolated effective coherence) method, which provides an appropriate frequency decomposition of the directional flow of oscillatory activity between brain regions. Nine regions of interest comprising nodes from the dorsal and ventral attention networks were selected for the connectivity analysis. Results: Cortical spectral density distribution comparing task minus rest showed significant activity increase in medial prefrontal areas and decreased activity in left parietal lobe for the theta band, and decreased activity in parietal-occipital regions for the alpha1 band. At a global level, connections among right hemispheric nodes were predominantly decreased during the task condition, while connections among left hemispheric nodes were predominantly increased. At more detailed level, decreased flow from right inferior frontal gyrus to anterior cingulate cortex for theta, and low and high alpha oscillations, and increased feedback (bidirectional flow) between left superior temporal gyrus and left inferior frontal gyrus, were observed during the arithmetic task. Conclusions: Task related medial prefrontal increase in theta oscillations possibly corresponds to frontal midline theta, while parietal decreased alpha1 activity indicates the active role of this region in the numerical task. Task related decrease of intracortical right hemispheric connectivity support the notion that these nodes need to disengage from one another in order to not interfere with the ongoing numerical processing. The bidirectional feedback between left frontal-temporal-parietal regions in the arithmetic task is very likely to be related to attention network working memory function. Significance: The methods of analysis and the results presented here will hopefully contribute to clarify the roles of the different EEG oscillations during sustained attention, both in terms of their functional localization and in terms of how they integrate brain function by supporting information flow between different cortical regions. The methodology presented here might be clinically relevant in evaluating abnormal attention function