Left Parietal Region Research Articles

A rare case: Penetrating craneoencefalic trauma by knife

Background: Cranioencephalic penetrating trauma (CPT) is caused by a sharp or short- pointed object that passes through the bone, dura mater, brain and other structures. Its incidence is unknown and few cases are described; penetrating injuries represent 0.4%, therefore there is no protocolized management. Case report: A 24-year-old male patient suffered penetrating trauma at left parietal region with a "knife"; he was sutured and sent home with analgesics. Five days after the trauma, he was admitted for headache, disorientation and decreased visual acuity. X-ray (XR) of Cranium evidencing a foreign body, therefore it is sent to a reference hospital. Evolution: The diagnosis is confirmed by a computerized tomography (CT) scan of the skull with 3-dimensional reconstruction (3D) plus CT angiography (angio CT), which shows "knife" in the left parietal region without vascular compromise. Neurosurgeons perform removal of the foreign body plus a dura mater plasty. Patient stay 12 days hospitalized with a favorable evolution and improvement of neurological symptomatology. Conclusion: CPT due to a knife is an emergency and there is no protocolized management. The removal of the foreign body must be done in a hospital for the risk of lesions of large vessels.

A Case Report: A 37 Years-old Women with Takayasu Arteritis

Background: A rarity of form of vasculitis, also known as TAK, induces inflammation in the walls of the major arteries in the body: the aorta and its main branches. The disease results from a body attack and inflammation of the walls of the arteries caused by the body's own immune system.
 Case Presentation: A 37-years-old women had complaints of fever, giddiness, weakness of right upper limb and lower limb since1 day. After undergoing whole blood count, liver function examination, renal and MRI function checks, CT scan, angiography, etc. was studied. She was diagnosed with takayasu arteritis. She had past medical history of neck pain and numbness since January 2020. For these complaints her family members referred her in private hospital. There is no significant history of surgery in present, lower segment caesarean section and piles operation was done previously. Physical findings were normal except the Glasgow Coma Scale score was 11 that is, patient was semi-conscious, In General appearance patient activity was dull and weak due disease condition, Patient’s all routine investigations were normal except few like Total WBC count was increased (21,500cell /cm) due to increased infection, Granulocytes were increased that is 75 % due to infection and autoimmune disease, ESR was increased that is52mm/h. Angiography showed block in the right common carotid artery, MRI- showed Acute infract in left fronto temporo parietal region involving insular par ventricular white matter, absent flow in distal M1 segment of MCA.
 Conclusion: The most frequently involved arteries and the angiographic trends in this Takayasu Arteritis study were subclavian arteries and carotid arteries. The difference between angiographic characteristics may lead to clinical differences. Operations and surgery should be carried out at various points in the course of the disease.

Neural correlates of cognitive resilience differ between experiences of bilingualism and education: A cortical surface‐based morphometry study in dementia

AbstractBackgroundLife‐course experiences such as education and bilingualism can be protective against dementia. The cognitive effects of bilingualism are specific while education has a more pervasive effect on general cognitive abilities, indicating that there is a likelihood of a variability in mechanisms underlying resilience. India is characterised by educational diversity and bilingualism. Importantly, bilingualism is not always associated with confounding effects of education, socioeconomic class or immigration. This makes the population uniquely suited for the study of resilience and opens up the possibility to disentangle the independent effects of bilingualism and education. Recent evidence indicates that surface‐based morphometric features of the cortical thickness and surface area are significantly modulated by life course experiences. Therefore, in this study, the independent influence of bilingualism and education on cortical thickness and surface area in dementia were studied to investigate the mechanisms that underlie resilience.MethodForty‐five patients with Frontotemporal dementia (FTD) were enrolled. 27 bilinguals were matched with 18 monolinguals for demographic factors and clinical severity. We examined the independent associations of bilingualism and education with cortical thickness and surface area using a surface based morphometric approach.ResultBilinguals with FTD had greater cortical thickness and reduced surface area in bilateral dorsolateral and medial frontal areas, and right parietotemporal cortex, regions associated with executive control. Bilinguals also demonstrated lesser cortical thickness in the language processing areas of left superior temporal, inferior parietal and lateral occipital regions compared to monolinguals. On the other hand, higher education was associated with decreased cortical thickness and increased surface area in bilateral frontal, medial temporal, parietal, occipital, and left temporal regions.ConclusionThis study explores for the first‐time, associations of two different proxies of resilience with cortical thickness and surface area in FTD. Our findings indicate that the neural substrate underlying the protective effects of bilingualism differ from education in FTD, and can be related to their differential effects on cognition. Results indicate specific neural correlates of resilience for different life‐course experiences.

Multi-level decoding of task sets in neurophysiological data during cognitive flexibility

SummaryCognitive flexibility is essential to achieve higher level goals. Cognitive theories assume that the activation/deactivation of goals and task rules is central to understand cognitive flexibility. However, how this activation/deactivation dynamic is implemented on a neurophysiological level is unclear. Using EEG-based multivariate pattern analysis (MVPA) methods, we show that activation of relevant information occurs parallel in time at multiple levels in the neurophysiological signal containing aspects of stimulus-related processing, response selection, and motor response execution, and relates to different brain regions. The intensity with which task sets are activated and processed dynamically decreases and increases. The temporal stability of these activations could, however, hardly explain behavioral performance. Instead, task set deactivation processes associated with left orbitofrontal regions and inferior parietal regions selectively acting on motor response task sets are relevant. The study shows how propositions from cognitive theories stressing the importance task set activation/deactivation during cognitive flexibility are implemented on a neurophysiological level.

Structural brain network correlations with amyloid burden in elderly individuals at risk of Alzheimer's disease

Alzheimer's disease (AD) has a long preclinical phase during which beta-amyloid accumulates in the brain without cognitive impairment. However, the pattern of brain network alterations in this early stage of the disease remains to be clarified. In this study we examined the relationships between regional brain network indices and beta-amyloid deposits. Twenty-four elderly subjects with the APOE4 allele underwent both a 1.5-Tesla magnetic resonance imaging (MRI) scan and a positron emission tomography (PET) scan using [18F]Florbetapir. We computed network metrics such as the degree, betweenness centrality, and clustering coefficient, and examined the relationships between the beta-amyloid accumulation and these regional brain network connectivity metrics. We found a significant positive correlation between the global standardized uptake value ratio (SUVR) of [18F]Florbetapir and the betweenness centrality in the left parietal region. However, there were no significant correlations between the SUVR score and other network indices or the regional gray matter volume. Our data suggest a relationship between the beta-amyloid accumulation and the regional brain network connectivity in subjects at risk of AD. The brain connectome may provide an adjunct biomarker for the early detection of AD.

Default mode and dorsal attention network involvement in visually guided motor sequence learning

Motor sequence learning (MSL) paradigms are often used to investigate the neural processes underlying the acquisition of complex motor skills. Behavioral and neuroimaging studies have indicated an early stage in which spatial learning is prominent and a late stage of automatized performance after multiple training periods. Functional magnetic resonance imaging (fMRI) studies yielded both decreased and increased activations of the sensorimotor and association areas. However, task-negative and task-positive intrinsic connectivity networks (ICNs), the default mode (DMN) and dorsal attention (DAN) networks involved in governing attention demands during various task conditions were not specifically addressed in most studies. In the present fMRI study, a visually guided MSL (VMSL) task was used for bringing roles of visuospatial and motor attention into foreground in order to investigate the role of attention-related ICNs in MSL. Seventeen healthy, right-handed participants completed training and test sessions of VMSL during fMRI on the 1st day. Then, after daily training for three consecutive days outside the scanner, they were re-tested during the 5th day's scanning session. When test session after early learning period was compared with training session, activation decrease was observed in the occipito-temporal fusiform cortex, while task-related suppression of DMN was reduced. Reduced deactivation after early learning was correlated with decreased error rates. After late learning stage we observed activation decreases in bilateral superior parietal lobules of task-positive DAN, dorsal precunei, and cerebellum. Reduced activity in left posterior parietal and right cerebellar regions were correlated with gains in speed, error rate, respectively. This dissociation in activity changes of DMN and DAN related areas suggests that DAN shows high contribution during both early and late MSL stages, possibly due to attention requirement for automatization of spatial and temporal aspects of motor sequence. In contrast, spatial learning occurring during early MSL stage was sufficient for releasing DMN resources.

Spontaneous Calvarial Infarction with Epidural Hematoma and Subgaleal Hemorrhage in a Teenager with Sickle Cell SS Disease and Glucose-6-Phosphate Dehydrogenase Deficiency

Introduction:Sequelae of sickle cell disease (SCD) are often the result of vaso-occlusion (VOC) related to the dysmorphic shape of sickled red blood cells (RBC). Bone infarction occurs commonly in patients with sickle cell, most notably in long bones and axial skeleton. Infarct occurs much less frequently in the bones of the skull. Calvarial bone infarct results in MRI findings of T2 hyperintensity in areas of bone marrow edema with associated swelling or hemorrhage. Symptomatic headaches in children with SCD are more likely to be due to severe underlying cerebral pathologies than in those children without SCD. When evaluating a child with SCD presenting with headache, it is important to consider calvarial infarct.Case Description:A 15 year old male with a history of sickle cell disease (type SS) and G6PD deficiency presented with chief complaints of headache and swelling over the left parietal region of the skull for two days with associated left sided visual disturbance. He denied head trauma or seizure-like activity. Upon presentation he was febrile with tachycardia and a normal neurological exam. CT scan of his head was significant for a left subgaleal hemorrhage and bilateral epidural midline and left parietal fluid collections consistent with bone marrow infarcts and associated subacute epidural hematomas, without evidence of brain parenchymal injury or sinus venous thrombosis. A follow up MRI obtained during hospitalization indicated that the left subgaleal hematoma remained stable with breakdown of subgaleal blood products. The patient was treated primarily with supportive care including hydration, packed red blood cell transfusions and pain management. He did not require neurosurgical intervention. His hospital course was complicated by VOC, sickle cell hepatopathy and acute chest syndrome.Discussion:Rarely, cranial VOC has resulted in epidural hematoma. In this case, calvarial infarct with unilateral headache, acute vision loss and acute cranial swelling resulted in subgaleal hemorrhage. This clinically significant finding results from bleeding between the periosteum and scalp galea aponeurosis, which may lead to hypovolemic shock. Calvarial infarcts should be considered on the differential in sickle cell disease patients presenting with a headache as prompt diagnosis can improve morbidity outcomes. DisclosuresNo relevant conflicts of interest to declare.

Cerebriform congenital melanocytic nevus of scalp and its management using tissue expansion

Congenital melanocytic nevi are benign proliferations of cutaneous nevomelanocytes. Usually, they manifest at birth or become apparent within the first few years of life. The nevi show variable surface morphology (papular, rugose, verrucous, or cerebriform). Congenital melanocytic nevus showing cerebriform morphology is a rarity. Early diagnosis and surgical excision are usually recommended in congenital melanocytic nevus to prevent the future risk of malignant transformation which is higher in larger lesions, especially in giant forms (>20 cm in size). An excision of the lesion also helps to avoid the social and psychological consequences arising out of significant cosmetic deformity. We report a 21-year-old patient who presented with a cerebriform congenital melanocytic nevus measuring 10 cm × 7 cm × 2 cm in the right parietal region. Early-onset, pigmented lesion with a cerebriform surface, and the histopathology features of congenital melanocytic nevus were the points that favored the diagnosis of cerebriform congenital melanocytic nevus in our patient. He was treated with excision of the lesion and defect coverage with tissue expansion in two stages. Two rectangular tissue expanders were placed beneath the galea aponeurotica (one with a capacity of 300 cc in the left parietal region and another with 500 cc in the occipital region). Both the expanders were inflated twice to their capacity. Second stage surgery was performed after about 3 months in which the tissue expanders were removed and the pre-expanded scalp skin was used to drape the scalp defect that resulted from the excision of the lesion. An excision and a two staged reconstruction of the scalp using tissue expanders, may ensure a good aesthetic outcome in the management of intermediate to large sized congenital melanocytic nevus.

Malignant Proliferating Trichilemmal Tumor of the Scalp

Malignant proliferating trichilemmal tumor (PTT) is a rare adnexal tumor with follicular differentiation. It mainly occurs in the scalp region of elderly females. It is a solitary, large ulceroproliferative lesion that can have an aggressive clinical course with metastases. Clinically and histologically, it is a close mimicker of squamous cell carcinoma. We report a middle-aged female who came with sudden enlargement of a longstanding nodular scalp lesion in the left parietal region. Incisional biopsy revealed a malignant PTT of the scalp. She underwent wide local excision of the mass and is doing well without any evidence of recurrence after 5 months of follow-up.

Cross-Frequency Coupling in Childhood Absence Epilepsy

Objective: Absence seizures are the prototypic primarily generalized seizures, but there is incomplete understanding regarding their generation and maintenance. A core network for absence seizures has been defined, including focal cortical and thalamic regions that have frequency-dependent interactions. The purpose of this study was to investigate within-frequency coupling and cross-frequency coupling (CFC) during human absence seizures, to identify key regions (hubs) within the absence network that contribute to propagation and maintenance. Methods: Thirteen children with new-onset and untreated childhood absence epilepsy had over 60 typical absence seizures during both electroencephalography-functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG) recordings. The spatial map of the ictal network was defined using fMRI and used as prior information for MEG connectivity. A multilayer network approach was used to investigate within-frequency coupling and CFC for canonical frequency bands. A rigorous null-modeling approach was used to determine connections outside the noise floor. Results: Strong coupling between beta and gamma frequencies, within the left frontal cortex, and between the left frontal and right parietal regions was observed. There was also strong connectivity between left frontal and right parietal nodes within the gamma band. Multilayer versatility analysis identified a cluster of network hubs in the left frontal region. Interpretation: Cortical regions commonly identified as being critical for absence seizure generation (frontal cortex, precuneus) have strong CFC and within-frequency coupling between beta and gamma bands. As nonpharmacologic treatments, such as neuromodulation, become available for generalized epilepsies, detailed mechanistic understanding of how "diffuse" seizures are generated and maintained will be necessary to provide optimal outcomes.

The influence of methadone on cerebral gray matter and functional connectivity.

Methadone maintenance treatment (MMT) is widely used for heroin use disorder. Although its curative effect is remarkable, there are problems associated with its use. While previous studies have found that methadone use may have certain effects on cerebral white matter, its effect on gray matter (GM) and its related neural networks is unclear. This study aimed to observe the effects of long-term methadone use on cerebral GM and the changes in related neural networks. Patients receiving MMT treatment for heroin use disorder (N=50) were recruited. Longitudinal self-control was adopted, and the voxel-based morphometry (VBM) was used to compare the difference in cerebral GM volume before and after 1 year of methadone use, then we select the brain region where the GM volume changed as the region of interest (ROI), and use the DPARSF software for the whole brain function connection, and the differences in brain function connections before and after 1year MMT treatment were compared. Our results demonstrated that, after 1 year of MMT, patients showed smaller GM volume in the bilateral insula, occipital lingual gyrus, right cingulate gyrus, middle temporal gyrus, left inferior parietal lobule, caudate nucleus, temporal, and occipital regions, and the resting neural network of the brain also changed. We speculate that long-term methadone use can lead to damage to GM structure and adaptive changes in the neural network of patients with heroin use disorder, mainly involving emotional perception, spatial localization, working memory, and other related functions.

Lower regional gray matter volume in the absence of higher cortical amyloid burden in late-life depression

Late-life depression (LLD) is associated with a risk of developing Alzheimer’s disease (AD). However, the role of AD-pathophysiology in LLD, and its association with clinical symptoms and cognitive function are elusive. In this study, one hundred subjects underwent amyloid positron emission tomography (PET) imaging with [18F]-flutemetamol and structural MRI: 48 severely depressed elderly subjects (age 74.1 ± 7.5 years, 33 female) and 52 age-/gender-matched healthy controls (72.4 ± 6.4 years, 37 female). The Geriatric Depression Scale (GDS) and Rey Auditory Verbal Learning Test (RAVLT) were used to assess the severity of depressive symptoms and episodic memory function respectively. Amyloid deposition was quantified using the standardized uptake value ratio. Whole-brain voxel-wise comparisons of amyloid deposition and gray matter volume (GMV) between LLD and controls were performed. Multivariate analysis of covariance was conducted to investigate the association of regional differences in amyloid deposition and GMV with clinical factors, including GDS and RAVLT. As a result, there were no significant group differences in amyloid deposition. In contrast, LLD showed significant lower GMV in the left temporal and parietal region. GMV reduction in the left temporal region was associated with episodic memory dysfunction, but not with depression severity. Regional GMV reduction was not associated with amyloid deposition. LLD is associated with lower GMV in regions that overlap with AD-pathophysiology, and which are associated with episodic memory function. The lack of corresponding associations with amyloid suggests that lower GMV driven by non-amyloid pathology may play a central role in the neurobiology of LLD presenting as a psychiatric disorder.Trial registration: European Union Drug Regulating Authorities Clinical Trials identifier: EudraCT 2009-018064-95.

Anatomy of phonemic and semantic fluency: A lesion and disconnectome study in 1231 stroke patients

Disturbances of semantic and phonemic fluency are common after brain damage, as a manifestation of language, executive, or memory dysfunction. Lesion-symptom mapping (LSM) studies can provide fundamental insights in shared and distinct anatomical correlates of these cognitive functions and help to understand which patients suffer from these deficits. We performed a multivariate support vector regression-based lesion-symptom mapping and structural disconnection study on semantic and phonemic fluency in 1231 patients with acute ischemic stroke. With the largest-ever LSM study on verbal fluency we achieved almost complete brain lesion coverage. Lower performance on both fluency types was related to left hemispheric frontotemporal and parietal cortical regions, and subcortical regions centering on the left thalamus. Distinct correlates for phonemic fluency were the anterior divisions of middle and inferior frontal gyri. Distinct correlates for semantic fluency were the posterior regions of the middle and inferior temporal gyri, parahippocampal and fusiform gyri and triangular part of the inferior frontal gyrus. The disconnectome-based analyses additionally revealed phonemic fluency was associated with a more extensive frontoparietal white matter network, whereas semantic fluency was associated with disconnection of the fornix, mesiotemporal white matter, splenium of the corpus callosum. These results provide the most detailed outline of the anatomical correlates of phonemic and semantic fluency to date, stress the crucial role of subcortical regions and reveal a novel dissociation in the left temporal lobe.

Distinct Neural Substrates Support Phonological and Orthographic Working Memory: Implications for Theories of Working Memory.

Prior behavioral and neuroimaging evidence supports a separation between working memory capacities in the phonological and orthographic domains. Although these data indicate distinct buffers for orthographic and phonological information, prior neural evidence does indicate that nearby left inferior parietal regions support both of these working memory capacities. Given that no study has directly compared their neural substrates based on data from the same individuals, it is possible that there is a common left inferior parietal region shared by both working memory capacities. In fact, those endorsing an embedded processes account of working memory might suggest that parietal involvement reflects a domain-general attentional system that directs attention to long-term memory representations in the two domains, implying that the same neural region supports the two capacities. Thus, in this work, a multivariate lesion-symptom mapping approach was used to assess the neural basis of phonological and orthographic working memory using behavioral and lesion data from the same set of 37 individuals. The results showed a separation of the neural substrates, with regions in the angular gyrus supporting orthographic working memory and with regions primarily in the supramarginal gyrus supporting phonological working memory. The results thus argue against the parietal involvement as supporting a domain-general attentional mechanism and support a domain-specific buffer account of working memory.

The Emergence of a Brain Network for Numerical Thinking

AbstractEducated adults and children engage a network of frontal and parietal brain regions for numerical thinking. Recent studies document some prominent changes as this network emerges over development, including a unilateral right to bilateral shift in number‐selective parietal brain activity, a strengthening of intra‐ and interhemispheric parietal connections, reduced engagement of prefrontal regions, and decoupling between prefrontal and parietal regions. Based on these findings, it appears that right parietal regions form an innate or early‐emerging basis for representing numerical magnitudes, whereas left parietal regions support the representation of culturally acquired symbolic numbers that begin to emerge over childhood. Functional connections between parietal hemispheres and the parietal and prefrontal cortex likely support associations between magnitudes and symbols, as they are associated with numerical proficiency. Prefrontal regions appear to provide general cognitive resources to support these associations, engaging and correlating positively during the learning process and disengaging and correlating negatively after mastery.

Reduced cortical thickness of the paracentral lobule in at-risk mental state individuals with poor 1-year functional outcomes

Although widespread cortical thinning centered on the fronto-temporal regions in schizophrenia has been reported, the findings in at-risk mental state (ARMS) patients have been inconsistent. In addition, it remains unclear whether abnormalities of cortical thickness (CT) in ARMS individuals, if present, are related to their functional decline irrespective of future psychosis onset. In this multicenter study in Japan, T1-weighted magnetic resonance imaging was performed at baseline in 107 individuals with ARMS, who were subdivided into resilient (77, good functional outcome) and non-resilient (13, poor functional outcome) groups based on the change in Global Assessment of Functioning scores during 1-year follow-up, and 104 age- and sex-matched healthy controls recruited at four scanning sites. We measured the CT of the entire cortex and performed group comparisons using FreeSurfer software. The relationship between the CT and cognitive functioning was examined in an ARMS subsample (n = 70). ARMS individuals as a whole relative to healthy controls exhibited a significantly reduced CT, predominantly in the fronto-temporal regions, which was partly associated with cognitive impairments, and an increased CT in the left parietal and right occipital regions. Compared with resilient ARMS individuals, non-resilient ARMS individuals exhibited a significantly reduced CT of the right paracentral lobule. These findings suggest that ARMS individuals partly share CT abnormalities with patients with overt schizophrenia, potentially representing general vulnerability to psychopathology, and also support the role of cortical thinning in the paracentral lobule as a predictive biomarker for short-term functional decline in the ARMS population.

The neurocognitive basis of morphological processing in typical and impaired readers.

Morphological awareness, or sensitivity to units of meaning, is an essential component of reading comprehension development. Current neurobiological models of reading and dyslexia have largely been built upon phonological processing models, yet reading for meaning is as essential as reading for sound. To fill this gap, the present study explores the relation between children's neural organization for morphological awareness and successful reading comprehension in typically developing and impaired readers. English-speaking children ages 6-11 (N = 97; mean age = 8.6years, 25% reading impaired) completed standard literacy assessments as well as an auditory morphological awareness task during functional near-infrared spectroscopy (fNIRS) neuroimaging, which included root (e.g., PERSON + al) and derivational (e.g., quick + LY) morphology. Regression analyses revealed that children's morphological awareness predicted unique variance in reading comprehension above and beyond demographic factors, vocabulary knowledge, and decoding ability. Neuroimaging analyses further revealed that children with stronger reading comprehension showed greater engagement of brain regions associated with integrating sound and meaning, including left inferior frontal, middle temporal, and inferior parietal regions. This effect was especially notable for the derivational morphology condition that involved manipulating more analytically demanding and semantically abstract units (e.g., un-, -ly, -ion). Together, these findings suggest that successful reading comprehension, and its deficit in dyslexia, may be related to the ability to manipulate morpho-phonological units of word meaning and structure. These results inform theoretical perspectives on literacy and children's neural architecture for learning to read.

Altered functional connectivity during face processing in children born with very low birth weight.

Structural brain alterations have been reported in key emotional face processing regions following preterm birth; however, few studies have investigated the functional networks underlying these processes in children born with very low birth weight (VLBW). Using magnetoencephalography (MEG), we examined the functional networks related to the implicit processing of happy and angry faces in 5-year-old VLBW (n = 28) and full-term (FT; n = 24) children. We found that VLBW children showed atypical recruitment of emotional face processing networks in theta (4–7 Hz) compared to FT children. VLBW children showed reduced theta connectivity during processing of angry faces only. This hypo-connected theta-band network was anchored in the left orbitofrontal and parietal regions, involved in the higher level processing of faces and emotion regulation. At the behavioural level, despite VLBW children performing within the normal range, FT children had significantly higher affect recognition scores. Our MEG results suggest a selective impairment in processing angry faces, which would negatively impact social functioning in VLBW children. In FT children, greater recruitment of this theta-band network was positively associated with improved affect recognition scores. Thus, our findings suggest an important role of theta oscillations in early face processing, deficits which may contribute to broader socio-emotional impairments in VLBW children.

Proactive inhibition is not modified by deep brain stimulation for Parkinson's disease: An electrical neuroimaging study.

In predictable contexts, motor inhibitory control can be deployed before the actual need for response suppression. The brain functional underpinnings of proactive inhibition, and notably the role of basal ganglia, are not entirely identified. We investigated the effects of deep brain stimulation of the subthalamic nucleus or internal globus pallidus on proactive inhibition in patients with Parkinson's disease. They completed a cued go/no‐go proactive inhibition task ON and (unilateral) OFF stimulation while EEG was recorded. We found no behavioural effect of either subthalamic nucleus or internal globus pallidus deep brain stimulation on proactive inhibition, despite a general improvement of motor performance with subthalamic nucleus stimulation. In the non‐operated and subthalamic nucleus group, we identified periods of topographic EEG modulation by the level of proactive inhibition. In the subthalamic nucleus group, source estimation analysis suggested the initial involvement of bilateral frontal and occipital areas, followed by a right lateralized fronto‐basal network, and finally of right premotor and left parietal regions. Our results confirm the overall preservation of proactive inhibition capacities in both subthalamic nucleus and internal globus pallidus deep brain stimulation, and suggest a partly segregated network for proactive inhibition, with a preferential recruitment of the indirect pathway.

Effect of different parietal hypoperfusion on neuropsychological characteristics in mild cognitive impairment.

In early-stage amnestic mild cognitive impairment (aMCI), differences in the neuropsychological characteristics of each individual are subtle. We investigated differences in neuropsychological performance between aMCI patients with and without hypoperfusion in the medial parietal regions (MP). We further compared patients with hypoperfusion in the left and right lateral parietal regions. We examined 165 aMCI patients (mean age: 76.8 ± 5.5 years; 87 women) who had undergone neuropsychological measurement and single-photon emission computed tomography. We classified participants into two subgroups with and without hypoperfusion: MP hypoperfusion (+) and MP hypoperfusion (-); classification was based on Z-scores (calculated by three-dimensional stereotactic surface projection technique) of three regions of interest in the parietal lobes (i.e. MP regions including posterior cingulate cortex and precuneus and left and right inferior parietal lobules (lateral parietal regions)). The MP hypoperfusion (-) group was classified into left lateral parietal hypoperfusion (+) and right lateral parietal hypoperfusion (+) subgroups. We performed either univariate or multivariate ancova to compare neuropsychological scores for continuous variables between groups and examined dichotomous variables using χ2 tests. In the overall aMCI sample, scores on logical memory delayed recall in the MP hypoperfusion (+) group were significantly lower than those in the MP hypoperfusion (-) group. Total scores on Rey-Osterrieth Complex Figure Test delayed recall were also marginally lower in the MP hypoperfusion (+) group than in the MP hypoperfusion (-) group. Comparisons of neuropsychological test scores between the left and right lateral parietal hypoperfusion (+) groups revealed no significant differences. The present findings suggest that MP hypoperfusion (+) is associated with more robust memory deficits than MP hypoperfusion (-). Combining neuropsychological tests and single-photon emission computed tomography findings may be useful for early detection of cognitive decline in aMCI.