Repetitive transcranial magnetic stimulation reshaped the dynamic reconfiguration of the executive and reward networks in individuals with tobacco use disorder.

BACKGROUND: Studies have demonstrated the potential of repetitive transcranial magnetic stimulation (rTMS) to decrease smoking cravings in individuals with tobacco use disorder (TUD). However, the neural features underlying the effects of rTMS treatment, especially the dynamic attributes of brain networks associated with the treatment, remain unclear. METHODS: Using dynamic functional connectivity analysis, this study first explored the differences in dynamic functional network features between 60 subjects with TUD and 64 nonsmoking healthy controls (HCs). Then, the left dorsolateral prefrontal cortex (DLPFC) was targeted for a five-day course of rTMS treatment in the 60 subjects with TUD (active rTMS in 42 subjects and sham treatment in 18 subjects). We explored the effect of rTMS on the dynamic network features associated with rTMS by comparing the actively treated group and the sham group. RESULTS: Compared to nonsmokers, TUD subjects exhibited an increased integration coefficient between the frontoparietal network (FPN) and the basal ganglia network (BGN) and a reduced integration coefficient between the medial frontal network (MFN) and the FPN. Analysis of variance revealed that rTMS treatment reduced the integration coefficient between the FPN and BGN and improved the recruitment coefficient of the FPN. LIMITATIONS: This study involved a limited sample of young male smokers, and the findings may not generalize to older smokers or female smokers with an extensive history of smoking. CONCLUSION: rTMS treatment of the left DLPFC exhibited significant effectiveness in restructuring the neural circuits associated with TUD while significantly mitigating smoking cravings.

More widespread functionality of posterior language area in patients with brain tumors.

Damage to the posterior language area (PLA), or Wernicke's area causes cortical reorganization in the corresponding regions of the contralateral hemisphere. However, the details of reorganization within the ipsilateral hemisphere are not fully understood. In this context, direct electrical stimulation during awake surgery can provide valuable opportunities to investigate neuromodulation of the human brain in vivo, which is difficult through the non-invasive approaches. Thus, in this study, we aimed to investigate the characteristics of the cortical reorganization of the PLA within the ipsilateral hemisphere. Sixty-two patients with left hemispheric gliomas were divided into groups depending on whether the lesion extended to the PLA. All patients underwent direct cortical stimulation with a picture-naming task. We further performed functional connectivity analyses using resting-state functional magnetic resonance imaging (MRI) in a subset of patients and calculated betweenness centrality, an index of the network importance of brain areas. During direct cortical stimulation, the regions showing positive (impaired) responses in the non-PLA group were localized mainly in the posterior superior temporal gyrus (pSTG), whereas those in the PLA group were widely distributed from the pSTG to the posterior supramarginal gyrus (pSMG). Notably, the percentage of positive responses in the pSMG was significantly higher in the PLA group (47%) than in the non-PLA group (8%). In network analyses of functional connectivity, the pSMG was identified as a hub region with high betweenness centrality in both the groups. These findings suggest that the language area can spread beyond the PLA to the pSMG, a hub region, in patients with lesion progression to the pSTG. The change in the pattern of the language area may be a compensatory mechanism to maintain efficient brain networks.

Additive effects of depression and obesity on neural correlates of inhibitory control.

BACKGROUND: Depression and obesity are associated with impaired inhibitory control. Behavioral evidence indicates an exacerbating additive effect when both conditions co-occur. However, the underlying neural mechanisms remain unclear. Moreover, systemic inflammation affects neurocognitive performance in both individuals with depression and obesity. Here, we investigate additive effects of depression and obesity on neural correlates of inhibitory control, and examine inflammation as a connecting pathway. METHODS: We assessed inhibitory control processing in 64 individuals with obesity and varying degrees of depressed mood by probing neural activation and connectivity during an fMRI Stroop task. Additionally, we explored associations of altered neural responses with individual differences in systemic inflammation. Data were collected as part of the BARICO (Bariatric surgery Rijnstate and Radboudumc neuroimaging and Cognition in Obesity) study. RESULTS: Concurrent depression and obesity were linked to increased functional connectivity between the supplementary motor area and precuneus and between the inferior occipital and inferior parietal gyrus. Exploratory analysis revealed that circulating inflammation markers, including plasma leptin, IL-6, IL-8, and CCL-3 correlated with the additive effect of depression and obesity on altered functional connectivity. LIMITATIONS: The observational design limits causal inferences. Future research employing longitudinal or intervention designs is required to validate these findings and elucidate causal pathways. CONCLUSION: These findings suggest increased neural crosstalk underlying impaired inhibitory control in individuals with concurrent obesity and depressed mood. Our results support a model of an additive detrimental effect of concurrent depression and obesity on neurocognitive functioning, with a possible role of inflammation.

Effects of early monocular enucleation on cortical spreading depression in well-nourished and malnourished adult rats.

Sensory development is a complex process that can influence physiological and pathological factors. In laterally-eyed mammals, monocular enucleation (ME) during development and the subsequent lack of external sensory stimuli can result in permanent morphological and physiological changes. Malnutrition, especially in early life, also can cause permanent morphofunctional changes due to inadequate nutrient intake in both hemispheres. This study investigated the effects of early (postnatal day 7) ME and malnutrition during the suckling period on cortical excitability in adulthood (110-140 days of life). For this, we compared the speed propagation of cortical spreading depression in the occipital and parietal cortex of malnourished and well-nourished adult rats, previously suckled small-sized litters with three pups (L3/dam) medium-sized litters with six pups (L6/dam), and large-sized litters with twelve pups (L12/dam). The CSD velocity was augmented by the ME in the contralateral side of the removed eye in the parietal and occipital cortex. These findings suggest that visual sensory input deprivation is associated with permanent functional changes in the visual pathways, which can alter cortical excitability and lead to modifications in CSD propagation.

Multimodal 7T imaging reveals enhanced functional coupling between salience and frontoparietal networks in young adult tobacco cigarette smokers.

Tobacco cigarette smoking is associated with disrupted brain network dynamics in resting brain networks including the Salience (SN) and Fronto parietal (FPN). Unified multimodal methods [Resting state connectivity analysis, Diffusion Tensor Imaging (DTI), neurite orientation dispersion and density imaging (NODDI), and cortical thickness analysis] were employed to test the hypothesis that the impact of cigarette smoking on the balance among these networks is due to alterations in white matter connectivity, microstructural architecture, functional connectivity and cortical thickness (CT) and that these metrics define fundamental differences between people who smoke and nonsmokers. Multimodal analyses of previously collected 7 Tesla MRI data via the Human Connectome Project were performed on 22 people who smoke (average number of daily cigarettes was 10 ± 5) and 22 age- and sex-matched nonsmoking controls. First, functional connectivity analysis was used to examine SN-FPN-DMN interactions between people who smoke and nonsmokers. The anatomy of these networks was then assessed using DTI and CT analyses while microstructural architecture of WM was analyzed using the NODDI toolbox. Seed-based connectivity analysis revealed significantly enhanced within network [p = 0.001 FDR corrected] and between network functional coupling of the salience and R-frontoparietal networks in people who smoke [p = 0.004 FDR corrected]. The network connectivity was lateralized to the right hemisphere. Whole brain diffusion analysis revealed no significant differences between people who smoke and nonsmokers in Fractional Anisotropy, Mean diffusivity and in neurite orienting and density. There were also no significant differences in CT in the hubs of these networks. Our results demonstrate that tobacco cigarette smoking is associated with enhanced functional connectivity, but anatomy is largely intact in young adults. Whether this enhanced connectivity is pre-existing, transient or permanent is not known. The observed enhanced connectivity in resting state networks may contribute to the maintenance of smoking frequency.

Rehabilitation of somatoparaphrenia with misoplegia: insights from a single case-pilot study.

Somatoparaphrenia lacka ownership of a paralyzed limb, i.e., the illusion that one's limbs belong to someone else. Somatoparaphrenia is one of the many forms of body misperceptions. We report a case of somatoparaphrenia with misoplegia, characterized by the absence of anosognosia for hemiplegia and personal neglect, following a surgical operation for left parietal meningioma. The patient received a novel multidisciplinary treatment, including motor rehabilitation training, traditional physiotherapy and robotic rehabilitation using the Hunova Movendo Technology and psychological counseling. At the end of the training, the patient improved in global cognitive functioning, mood, motor abilities, and the perception of herself and her body, reducing the sense of estrangement and repulsion in the lower right limb. Our result showed the importance of a specific neuropsychological assessment in patients with parietal brain lesions and the usefulness of an integrated psychological and motor approach in rehabilitating patients with somatoparaphrenia, primarily when associated with misoplegia.

Parieto-premotor functional connectivity changes during parietal lobe seizures are associated with motor semiology.

OBJECTIVES: Parietal lobe seizures (PLS) are characterized by multiple clinical manifestations including motor signs. The mechanisms underlying the occurrence of motor signs are poorly understood. The main objective of this work was to estimate the functional coupling of brain regions associated with this clinical presentation. METHODS: We retrospectively selected patients affected by drug-resistant epilepsy who underwent Stereoelectroencephalography (SEEG) for pre-surgical evaluation and in whom the seizure onset zone (SOZ) was located in the parietal cortex. The SOZ was defined visually and quantitatively by the epileptogenicity index (EI) method. Two groups of seizures were defined according to the presence ("motor seizures") or the absence ("non-motor seizures") of motor signs. Functional connectivity (FC) estimation was based on pairwise nonlinear regression analysis (h2 coefficient). To study FC changes between parietal, frontal and temporal regions, for each patient, z-score values of 16 cortico-cortical interactions were obtained comparing h2 coefficients of pre-ictal, seizure onset and seizure propagation periods. RESULTS: We included 22 patients, 13 with "motor seizures" and 9 with "non-motor seizures". Resective surgery was performed in 14 patients, 8 patients had a positive surgical outcome (Engel's class I and II). During seizure onset period, a decrease of FC was observed and was significantly more important (in comparison with background period) in "motor" seizures. This was particularly observed between parietal operculum/post-central gyrus (OP/PoCg) and mesial temporal areas. During seizure propagation, a FC increase was significantly more important (in comparison with seizure onset) in "motor seizures", in particular between lateral pre-motor (pmL) area and precuneus, pmL and superior parietal lobule (SPL) and between inferior parietal lobule (IPL) and supplementary motor area (SMA). CONCLUSIONS: Our study shows that motor semiology in PLS is accompanied by an increase of FC between parietal and premotor cortices, significantly different than what is observed in PLS without motor semiology. SIGNIFICANCE: Our results indicate that preferential routes of coupling between parietal and premotor cortices are responsible for the prominent motor presentation during PLS.

Detrended fluctuation analysis in the presurgical evaluation of parietal lobe epilepsy patients.

OBJECTIVE: To examine the usability of long-range temporal correlations (LRTCs) in non-invasive localization of the epileptogenic zone (EZ) in refractory parietal lobe epilepsy (RPLE) patients. METHODS: We analyzed 10 RPLE patients who had presurgical MEG and underwent epilepsy surgery. We quantified LRTCs with detrended fluctuation analysis (DFA) at four frequency bands for 200 cortical regions estimated using individual source models. We correlated individually the DFA maps to the distance from the resection area and from cortical locations of interictal epileptiform discharges (IEDs). Additionally, three clinical experts inspected the DFA maps to visually assess the most likely EZ locations. RESULTS: The DFA maps correlated with the distance to resection area in patients with type II focal cortical dysplasia (FCD) (p<0.05), but not in other etiologies. Similarly, the DFA maps correlated with the IED locations only in the FCD II patients. Visual analysis of the DFA maps showed high interobserver agreement and accuracy in FCD patients in assigning the affected hemisphere and lobe. CONCLUSIONS: Aberrant LRTCs correlate with the resection areas and IED locations. SIGNIFICANCE: This methodological pilot study demonstrates the feasibility of approximating cortical LRTCs from MEG that may aid in the EZ localization and provide new non-invasive insight into the presurgical evaluation of epilepsy.

Hypoactivation in the precuneus and posterior cingulate cortex during ambiguous decision making in individuals with HIV.

People with human immunodeficiency virus (HIV) often have neurocognitive impairment. People with HIV make riskier decisions when the outcome probabilities are known, and have abnormal neural architecture underlying risky decision making. However, ambiguous decision making, when the outcome probabilities are unknown, is more common in daily life, but the neural architecture underlying ambiguous decision making in people with HIV is unknown. Eighteen people with HIV and 20 controls completed a decision making task while undergoing functional magnetic resonance imaging scanning. Participants chose between a certain reward and uncertain reward with a known (risky) or unknown (ambiguous) probability of winning. There were three levels of risk: high, medium, and low. Ambiguous > risky brain activity was compared between groups. Ambiguous > risky brain activity was correlated with emotional/psychiatric functioning in people with HIV. Both groups were similarly ambiguity-averse. People with HIV were more risk-averse than controls and chose the high-risk uncertain option less often. People with HIV had hypoactivity in the precuneus, posterior cingulate cortex (PCC), and fusiform gyrus during ambiguous > medium risk decision making. Ambiguous > medium risk brain activity was negatively correlated with emotional/psychiatric functioning in individuals with HIV. To make ambiguous decisions, people with HIV underrecruit key regions of the default mode network, which are thought to integrate internally and externally derived information to come to a decision. These regions and related cognitive processes may be candidates for interventions to improve decision-making outcomes in people with HIV.

APOE genotype influences P3b amplitude and response to smoking abstinence in young adults.

RATIONALE: There is strong evidence that nicotine can enhance cognitive functions and growing evidence that this effect may be larger in young healthy APOE ε4 carriers. However, the moderating effects of the APOE ε4 allele on cognitive impairments caused by nicotine deprivation in chronic smokers have not yet been studied with brain indices. OBJECTIVE: We sought to determine whether young female carriers of the APOE ε4 allele, relative to noncarriers, would exhibit larger abstinence-induced decreases in P3b amplitude during a two-stimulus auditory oddball task. METHODS: We compared parietal P3bs in female chronic smokers with either APOE ε3/ε3 (n = 54) or ε3/ε4 (n = 20) genotype under nicotine-sated conditions and after 12-17-h nicotine deprivation. RESULTS: Nicotine deprivation significantly reduced P3b amplitudes in APOE ε4 carriers, but not in APOE-ε3/ε3 individuals, such that the difference seen prior to nicotine deprivation was eliminated. CONCLUSIONS: The results suggest that subjects with the APOE ε4 allele are more sensitive to nicotine, which could influence smoking patterns, the risk for nicotine dependence, and the cognitive effects of nicotine use in these individuals.

Awake surgery for skills preservation during a sensory area tumor resection in a clarinet player.

Tumors in primary sensory area are challenging to remove without causing a neurological deficit, especially in musicians who present complex neuronal networks. Indeed, in this kind of patients, somatosensory evoked potentials (SSEPs) are not plenty. We describe our experience for sensory and proprioception preservation in a professional clarinet player undergoing surgery for a right parietal glioblastoma. The patient underwent surgery for a right parietal glioblastoma. Intraoperative monitoring and awake surgery while playing instrument, were performed. During resection, intraoperative stimulation caused a transient impairment of left hand movements, without SSEPs alteration. The resection was stopped anytime there was a movement impairment. We obtained a gross total tumor resection. Patient did not present neurological deficits. Standard neurophysiological monitoring is fundamental but cannot be sufficient. More complex strategies of monitoring, such as awake surgery and playing an instrument could be of help for preserving complex sensory-motor functions.

Time-to-contact perception in the brain.

Time-to-contact (TTC) perception refers to the ability of an observer to estimate the remaining time before an object reaches a point in the environment, and is of crucial importance in daily life. Noninvasive correlational approaches have identified several brain areas sensitive to TTC information. Here we report the results of two studies, including one during an awake brain surgery, that aimed to identify the specific areas causally engaged in the TTC estimation process. In Study 1, we tested 40 patients with brain tumor in a TTC estimation task. The results showed that four of the six patients with impaired performance had tumors in right upper parietal cortex, although this tumoral location represented only six over 40 patients. In Study 2, 15 patients underwent awake brain surgery electrostimulation mapping to examine the implication of various brain areas in the TTC estimation process. We acquired and normalized to MNI space the coordinates of the functional areas that influenced task performance. Our results seem to demonstrate that the early stage of the TTC estimation process involved specific cortical territories in the ventral region of the right intraparietal sulcus. Downstream processing of TTC could also involve the frontal eye field (middle frontal gyrus) related to ocular search. We also found that deactivating language areas in the left hemisphere interfered with the TTC estimation process. These findings demonstrate a fine grained, cortical representation of TTC processing close to the ventral right intraparietal sulcus and complement those described in other human studies.

Connectivity of the Cerebello-Thalamo-Cortical Pathway in Survivors of Childhood Leukemia Treated With Chemotherapy Only.

Importance: Treatment with contemporary chemotherapy-only protocols is associated with risk for neurocognitive impairment among survivors of childhood acute lymphoblastic leukemia (ALL). Objective: To determine whether concurrent use of methotrexate and glucocorticoids is associated with interference with the antioxidant system of the brain and damage and disruption of glucocorticoid-sensitive regions of the cerebello-thalamo-cortical network. Design, Setting, and Participants: This cross-sectional study was conducted from December 2016 to July 2019 in a single pediatric cancer tertiary care center. Participants included survivors of childhood ALL who were more than 5 years from cancer diagnosis, age 8 years or older, and treated on an institutional chemotherapy-only protocol. Age-matched community members were recruited as a control group. Data were analyzed from August 2017 to August 2020. Exposure: ALL treatment using chemotherapy-only protocols. Main Outcomes and Measures: This study compared brain volumes between survivors and individuals in a community control group and examined associations among survivors of methotrexate and dexamethasone exposure with neurocognitive outcomes. Functional and effective connectivity measures were compared between survivors with and without cognitive impairment. The Rey-Osterrieth complex figure test, a neurocognitive evaluation in which individuals are asked to copy a figure and then draw the figure from memory, was scored according to published guidelines and transformed into age-adjusted z scores based on nationally representative reference data and used to measure organization and planning deficits. ß values for neurocognitive tests represented the amount of change in cerebellar volume or chemotherapy exposure associated with 1 SD change in neurocognitive outcome by z score (mm3/1 SD in z score for cerebellum, mm3/[g×hr/L] for dexamethasone and methotrexate AUC, and mm3/intrathecal count for total intrathecal count). Results: Among 302 eligible individuals, 218 (72%) participated in the study and 176 (58%) had usable magnetic resonance imaging (MRI) results. Among these, 89 (51%) were female participants and the mean (range) age was 6.8 (1-18) years at diagnosis and 14.5 (8-27) years at evaluation. Of 100 community individuals recruited as the control group, 82 had usable MRI results; among these, 35 (43%) were female individuals and the mean (range) age was 13.8 (8-26) years at evaluation. There was no significant difference in total brain volume between survivors and individuals in the control group. Survivors of both sexes showed decreased mean (SD) cerebellar volumes compared with the control population (female: 70 568 [6465] mm3 vs 75 134 [6780] mm3; P < .001; male: 77 335 [6210] mm3 vs 79 020 [7420] mm3; P < .001). In female survivors, decreased cerebellar volume was associated with worse performance in Rey-Osterrieth complex figure test (left cerebellum: ß = 55.54; SE = 25.55; P = .03; right cerebellum: ß = 52.57; SE = 25.50; P = .04) and poorer dominant-hand motor processing speed (ie, grooved pegboard performance) (left cerebellum: ß = 82.71; SE = 31.04; P = .009; right cerebellum: ß = 91.06; SE = 30.72; P = .004). In female survivors, increased number of intrathecal treatments (ie, number of separate injections) was also associated with Worse Rey-Osterrieth test performance (ß = -0.154; SE = 0.063; P = .02), as was increased dexamethasone exposure (ß = -0.0014; SE = 0.0005; P = .01). Executive dysfunction was correlated with increased global efficiency between smaller brain regions (Pearson r = -0.24; P = .01) compared with individuals without dysfunction. Anatomical connectivity showed differences between impaired and nonimpaired survivors. Analysis of variance of effective-connectivity weights identified a significant interaction association (F = 3.99; P = .02) among the direction and strength of connectivity between the cerebellum and DLPFC, female sex, and executive dysfunction. Finally, no effective connectivity was found between the precuneus and DLPFC in female survivors with executive dysfunction. Conclusions and Relevance: These findings suggest that dexamethasone exposure was associated with smaller cerebello-thalamo-cortical regions in survivors of ALL and that disruption of effective connectivity was associated with impairment of executive function in female survivors.

[Temporal plus epilepsy: a review]. / Epilepsia del lóbulo temporal plus: revisión.

Temporal plus epilepsy is defined as focal epilepsy in which the primary epileptogenic area extends beyond the temporal lobe. It involves the neighboring regions such as the insula, the suprasilvian opercular cortex, the orbitofrontal cortex and the temporo-parieto-occipital junction. The objective of this review is to provide an update in temporal plus epilepsy. A previous history of brain trauma, a history of tonic clonic seizures, and previous central nervous system infection are risk factors. They likely allowed the generation of complex hippocampal and extrahypocampic neural networks. Clinical manifestations will depend on the location of the epileptogenic zone as well as the rapid propagation into temporal mesial structures. Video-electroencephalography usually shows involvement of the temporal lobe, with rapid propagation into the perisilvian, orbitofrontal or temporo-parieto-occipital regions. The magnetoelectroencephaography has lesser muscle contamination and could be considered as a biomarker of early states in the diagnosis process. Brain MRI is usually negative or shows non-specific mesial temporal abnormalities. Stereoelectroencephalography is the invasive method of choice. Temporal plus epilepsy is considered to be the most common cause of temporal lobe epilepsy surgery failure and represents up to 30%.

TITLE: Epilepsia del lóbulo temporal plus: revisión.La epilepsia del lóbulo temporal plus se define como la epilepsia en la cual la zona epileptógena primaria se localiza en el lóbulo temporal y se extiende a regiones vecinas, como la ínsula, la corteza opercular suprasilviana, la corteza orbitofrontal y la unión temporoparietooccipital. El objetivo de esta revisión es proveer una actualización de la información en la epilepsia del lóbulo temporal plus. La historia de traumatismo craneoencefálico, infección cerebral (meningitis-encefalitis) o crisis epiléptica tonicoclónica generalizada está involucrada en su etiología, y permite la generación de redes neuronales complejas hipocámpicas y extrahipocámpicas. Las manifestaciones clínicas dependen de la zona epileptógena involucrada y de su rápida proyección a las estructuras temporales mesiales. El videoelectroencefalograma evidencia actividad interictal extensa e ictal en el lóbulo temporal, pero con rápida propagación perisilviana, orbitofrontal o temporoparietooccipital. La magnetoelectroencefalografía tiene menos contaminación muscular y podría considerarse como un biomarcador de estados tempranos en el proceso diagnóstico. La resonancia cerebral generalmente es negativa o muestra una ligera alteración de señal en la zona mesial temporal en grado variable. El estereoelectroencefalograma es el método invasivo de elección, especialmente guiado por robot. La epilepsia temporal plus se considera la causa más frecuente de fracaso de la cirugía de la epilepsia del lóbulo temporal, hasta un 30%.

Networks in Posterior Cortex Epilepsies.

Posterior cortex epilepsies comprise all epilepsies with seizures generated from the occipital, parietal, and posterior temporal areas. Seizures usually occur early in life. Visual phenomena during seizures are the hallmark for occipital lobe seizures. Most patients show objective semiology mimicking seizures from other brain regions. Separation of symptomatogenic and epileptogenic zones complicates diagnosis. Understanding networks of propagation is crucial for planning surgery. An overview about typical clinical findings and prognostic value is presented. It explains ways to investigate the epileptogenic zone and propagation pathways to identify seizures from the posterior cortex and better categorize epilepsies for precise surgical treatment.

"I do not feel my hand where I see it": causal mapping of visuo-proprioceptive integration network in a surgical glioma patient.

A recent tasked-based fMRI study unveiled a network of areas implicated in the process of visuo-proprioceptive integration of the right hand. In this study, we report a case of a patient operated on in awake conditions for a glioblastoma of the left superior parietal lobule. When stimulating a white matter site in the anterior wall of the cavity, the patient spontaneously reported a discrepancy between the visual and proprioceptive perceptions of her right hand. Using several multimodal approaches (axono-cortical evoked potentials, tractography, resting-state functional connectivity), we demonstrated converging support for the hypothesis that tumor-induced plasticity redistributed the left-lateralized network of right-hand visuo-proprioceptive integration towards its right-lateralized homolog.

Posterior quadrant disconnection for sub-hemispheric drug refractory epilepsy.

The posterior quadratic epilepsy (PQE) is a form of a multilobar epilepsy, involving the temporal-parietal and occipital lobes. Basically, epilepsies with localized networks to the posterior temporal, posterior parietal, and occipital lobes can benefit from this type of surgery. Gliosis due to perinatal insult and cortical dysplasis and angiomas in Sturge Weber syndrome involving the PQ have often been cited in the literature as the etiology for PQE. However, before considering surgery, it is important to localize the epileptogenic focus through a complete pre operative work up involving; EEG (Electro-Encephalo-Graphy), video EEG, single photon emission computed tomography (SPECT), positron emission tomography (PET), and magneto encephalography (MEG). Historically, these pathologies were dealt with multi-lobar resections, which were associated with high morbidity and mortality, owing to blood loss, especially in young children, hydrocephalus, and hemosiderosis. Based on the theory of networks involved in epileptogenesis, the concept of disconnection in epilepsy surgery was introduced. Delalande and colleagues, described the technique of hemispheric disconnection (functional hemispherectomy) for pathologies like: hemimegalencephaly, rasmussens encephalitis involving the entire hemisphere. The technique has evolved with time, moving towards minimally invasive endoscopic vertical hemispherotomy, described by Chandra and colleagues.[1],[2] The posterior quadrant disconnection (PQD) evolved as a tailored disconnection on similar lines as hemispherotomy, for managing refractory epilepsy arising from the posterior quadrant.[3] The technique and principles involved in the PQD surgery are similar to the those of peri-insular hemispherotomy and has been described in the literature by few authors.[3],[4],[5],[6] The technique of performing PQD will be described here in a step-wise fashion with illustrations supplemented by a surgical video.

History of Alcohol Consumption and HIV Status Related to Functional Connectivity Differences in the Brain During Working Memory Performance.

BACKGROUND: Poorer working memory function has previously been associated with alcohol misuse, Human Immunodeficiency Virus (HIV) positive status, and risky behavior. Poorer working memory performance relates to alterations in specific brain networks. OBJECTIVE: The current study examined if there was a relationship between brain networks involved in working memory and reported level of alcohol consumption during an individual's period of heaviest use. Furthermore, we examined whether HIV status and the interaction between HIV and alcohol consumption was associated with differences in these brain networks. METHODS: Fifty adults, 26 of whom were HIV positive, engaged in an n-back working memory task (0-back and 2-back trials) administered in a magnetic resonance imaging (MRI) scanner. The Kreek- McHugh-Schluger-Kellogg (KMSK) scale of alcohol consumption was used to characterize an individual's period of heaviest use and correlates well with their risk for alcohol dependence. Connectivity analyses were conducted using data collected during n-back task. RESULTS: Functional connectivity differences associated with greater alcohol consumption included negative connectivity, primarily from parietal attention networks to frontal networks. Greater alcohol consumption was also associated with positive connectivity from working memory nodes to the precuneus and paracingulate. HIV positive status was associated with more nodes of negative functional connectivity relative to alcohol consumption history alone, particularly in the frontoparietal networks. The HIV positive individuals with heavier drinking history related to negative fronto-parietal connectivity, along with positive connectivity from working memory nodes to mesolimbic regions. CONCLUSION: Findings allow for a better understanding of brain networks affected by HIV and alcohol and may provide avenues for interventions.

Association of Inflammation With Pronociceptive Brain Connections in Rheumatoid Arthritis Patients With Concomitant Fibromyalgia.

OBJECTIVE: Rheumatoid arthritis (RA) patients with concomitant fibromyalgia (FM) exhibit alterations in brain connectivity synonymous with central sensitization. This study was undertaken to investigate how peripheral inflammation, the principal nociceptive stimulus in RA, interacts with brain connectivity in RA patients with FM. METHODS: RA patients with concomitant FM and those without FM (FM+ and FM-, respectively; n = 27 per group) underwent functional connectivity magnetic resonance imaging. Seed-to-whole-brain functional connectivity analyses were conducted using seeds from the left mid/posterior insula and left inferior parietal lobule (IPL), which are regions that have been previously linked to FM symptoms and inflammation, respectively. The association between functional connectivity and erythrocyte sedimentation rate (ESR) was assessed in each group separately, followed by post hoc analyses to test for interaction effects. Cluster-level, family-wise error (FWE) rates were considered significant if the P value was less than 0.05. RESULTS: The group of RA patients with FM and those without FM did not differ by age, sex, or ESR (P > 0.2). In FM+ RA patients, increased functional connectivity of the insula-left IPL, left IPL-dorsal anterior cingulate, and left IPL-medial prefrontal cortex regions correlated with higher levels of ESR (all FWE-corrected P < 0.05). Post hoc interaction analyses largely confirmed the relationship between ESR and connectivity changes as FM scores increased. CONCLUSION: We report the first neurobiologic evidence that FM in RA may be linked to peripheral inflammation via pronociceptive patterns of brain connectivity. In patients with such "bottom-up" pain centralization, concomitant symptoms may partially respond to antiinflammatory treatments.

Altered subcallosal and posterior cingulate cortex-based functional connectivity during smoking cue and mental simulation processing in smokers.

BACKGROUND: Long-term cigarette smoking induces sensitization of incentive salience and conditioning of contextual cues which involves brain function alteration across multiple regions. Understanding how nicotine affects hub-based functional connectivities involved in affective and cognitive function can help us determine the treatment strategy for nicotine dependence. METHOD: Functional MRI was conducted on 30 smokers and 30 non-smokers while mentally simulating neutral and smoking hand movements. Smoking cue and mental simulation processing-related changes in functional connectivity strengths of the subcallosal and posterior cingulate cortex (SCC and PCC) with major brain network nodes were examined. RESULTS: Compared to non-smokers, smokers showed cue-induced SCC functional connectivities which were enhanced with the intraparietal sulcus and reduced with the medial prefrontal cortex. The PCC activation and functional connectivity enhancements with the anterior insula cortex and rostro-lateral prefrontal cortex was found during smoking mental simulation. The PCC-lateral prefrontal cortex functional connectivity correlated with nicotine dependence severity. CONCLUSION: The present results demonstrate that smokers can be identified by cue-induced SCC functional connectivity strength decline and increment in the default mode and dorsal attention network nodes. However, nicotine dependence was associated with smoking mental simulation-related PCC-lateral prefrontal cortex functional connectivity strength, suggesting that the development of nicotine dependence may depend on the strength of coupling between the default mode network and the central executive network at the cognitive level.