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https://www.readbyqxmd.com/read/28723889/distinct-timescales-of-population-coding-across-cortex
#1
Caroline A Runyan, Eugenio Piasini, Stefano Panzeri, Christopher D Harvey
The cortex represents information across widely varying timescales. For instance, sensory cortex encodes stimuli that fluctuate over few tens of milliseconds, whereas in association cortex behavioural choices can require the maintenance of information over seconds. However, it remains poorly understood whether diverse timescales result mostly from features intrinsic to individual neurons or from neuronal population activity. This question remains unanswered, because the timescales of coding in populations of neurons have not been studied extensively, and population codes have not been compared systematically across cortical regions...
July 19, 2017: Nature
https://www.readbyqxmd.com/read/28714714/no-evidence-for-enhancements-to-visual-working-memory-with-transcranial-direct-current-stimulation-to-prefrontal-or-posterior-parietal-cortices
#2
Matthew K Robison, William P McGuirk, Nash Unsworth
The present study examined the relative contributions of the prefrontal cortex (PFC) and posterior parietal cortex (PPC) to visual working memory. Evidence from a number of different techniques has led to the theory that the PFC controls access to working memory (i.e., filtering), determining which information is encoded and maintained for later use whereas the parietal cortex determines how much information is held at 1 given time, regardless of relevance (i.e., capacity; McNab & Klingberg, 2008; Vogel, McCollough, & Machizawa, 2005)...
August 2017: Behavioral Neuroscience
https://www.readbyqxmd.com/read/28711810/cocaine-dependence-modulates-the-effect-of-hiv-infection-on-brain-activation-during-intertemporal-decision-making
#3
Christina S Meade, Andrea L Hobkirk, Sheri L Towe, Nan-Kuei Chen, Ryan P Bell, Scott A Huettel
BACKGROUND: Both HIV infection and chronic cocaine use alter the neural circuitry of decision making, but the interactive effects of these commonly comorbid conditions have not been adequately examined. This study tested how cocaine moderates HIV-related neural activation during an intertemporal decision-making task. METHODS: The sample included 73 participants who differed on cocaine and HIV status (18 COC+/HIV+, 19 COC+/HIV-, 19 COC-/HIV+, 17 COC-/HIV-). Participants made choices between smaller, sooner and larger, delayed rewards while undergoing functional MRI...
July 8, 2017: Drug and Alcohol Dependence
https://www.readbyqxmd.com/read/28707166/altered-dynamic-functional-connectivity-in-the-default-mode-network-in-patients-with-cirrhosis-and-minimal-hepatic-encephalopathy
#4
Hua-Jun Chen, Hai-Long Lin, Qiu-Feng Chen, Peng-Fei Liu
PURPOSE: Abnormal brain intrinsic functional connectivity (FC) has been documented in minimal hepatic encephalopathy (MHE) by static connectivity analysis. However, changes in dynamic FC (dFC) remain unknown. We aimed to identify altered dFC within the default mode network (DMN) associated with MHE. METHODS: Resting-state functional MRI data were acquired from 20 cirrhotic patients with MHE and 24 healthy controls. DMN seed regions were defined using seed-based FC analysis (centered on the posterior cingulate cortex (PCC))...
July 13, 2017: Neuroradiology
https://www.readbyqxmd.com/read/28704424/examining-distinct-working-memory-processes-in-children-and-adolescents-using-fmri-results-and-validation-of-a-modified-brown-peterson-paradigm
#5
Vanessa Siffredi, Pierre Barrouillet, Megan Spencer-Smith, Maarten Vaessen, Vicki Anderson, Patrik Vuilleumier
Verbal working memory (WM) comprises different processes (encoding, maintenance, retrieval) that are often compromised in brain diseases, but their neural correlates have not yet been examined in childhood and adolescence. To probe WM processes and associated neural correlates in developmental samples, and obtain comparable effects across different ages and populations, we designed an adapted Brown-Peterson task (verbal encoding and retrieval combined with verbal and visual concurrent tasks during maintenance) to implement during functional magnetic resonance imaging (fMRI)...
2017: PloS One
https://www.readbyqxmd.com/read/28704292/improvement-of-higher-brain-dysfunction-after-brain-injury-by-repetitive-transcranial-magnetic-stimulation-and-intensive-rehabilitation-therapy-case-report
#6
Takatoshi Hara, Masahiro Abo, Nobuyuki Sasaki, Naoki Yamada, Masachika Niimi, Mari Kenmoku, Kastuya Kawakami, Reiko Saito
Repetitive transcranial magnetic stimulation (rTMS) and intensive cognitive rehabilitation (CR) were administered to two patients with cognitive dysfunction following brain injury. The first case was a 67-year-old man who presented with memory dysfunction, attention dysfunction, and decreased insight following diffuse axonal injury. High-frequency rTMS (10 Hz, 2400 pulses/day) targeting the anterior cingulate using a navigation system and CR were administered for 12 days at 1 year from the onset of injury...
July 12, 2017: Neuroreport
https://www.readbyqxmd.com/read/28700819/posterior-dopamine-d2-3-receptors-and-brain-network-functional-connectivity
#7
Atsuko Nagano-Saito, Jennifer I Lissemore, Paul Gravel, Marco Leyton, Felix Carbonell, Chawki Benkelfat
Recent studies suggest that dopaminergic tone influences resting state activity in multiple brain networks. Although dopamine receptors and transporters have been identified in the posteromedial and parietal cortices, which are linked to functional networks such as the default mode network (DMN), the relationship between dopamine receptor distribution in these posterior regions and resting-state connectivity has yet to be explored. Here, we used a multi-modal neuroimaging strategy, combining resting-state functional magnetic resonance imaging (rsfMRI) and [18F]-fallypride high-resolution positron emission tomography (PET), to examine the association between within-network functional connectivity and the dopamine D2/3 receptor distribution in the posterior portion of the brain in 13 healthy adults...
July 12, 2017: Synapse
https://www.readbyqxmd.com/read/28699704/aberrant-blood-oxygen-level-dependent-signal-oscillations-across-frequency-bands-characterize-the-alcoholic-brain
#8
Jui-Yang Hong, Eva M Müller-Oehring, Adolf Pfefferbaum, Edith V Sullivan, Dongjin Kwon, Tilman Schulte
Chronic alcoholism is associated with widespread regional differences from controls in brain activity and connectivity dynamics measured by blood-oxygen-level-dependent (BOLD) signals. Identification of alcoholism-related neurofunctional power dynamics using functional magnetic resonance imaging (fMRI) that relate to cognition and behavior may serve as biomarkers of alcoholism. Previously, resting-state fMRI studies examined BOLD signals at a single low-frequency (LF) bandwidth. BOLD signals, however, oscillate systematically at different frequencies and are organized in a resting brain where LF oscillation facilitates long-distance communication between regions across cortical regions, whereas high-frequency (HF) oscillation occurs in closely localized, subcortical areas...
July 12, 2017: Addiction Biology
https://www.readbyqxmd.com/read/28698606/reading-induced-shifts-of-perceptual-speech-representations-in-auditory-cortex
#9
Milene Bonte, Joao M Correia, Mirjam Keetels, Jean Vroomen, Elia Formisano
Learning to read requires the formation of efficient neural associations between written and spoken language. Whether these associations influence the auditory cortical representation of speech remains unknown. Here we address this question by combining multivariate functional MRI analysis and a newly-developed 'text-based recalibration' paradigm. In this paradigm, the pairing of visual text and ambiguous speech sounds shifts (i.e. recalibrates) the perceptual interpretation of the ambiguous sounds in subsequent auditory-only trials...
July 11, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28691850/-default-mode-functional-connectivity-is-associated-with-social-functioning-in-schizophrenia-correction-to-fox-et-al-2017
#10
(no author information available yet)
Reports an error in "Default mode functional connectivity is associated with social functioning in schizophrenia" by Jaclyn M. Fox, Samantha V. Abram, James L. Reilly, Shaun Eack, Morris B. Goldman, John G. Csernansky, Lei Wang and Matthew J. Smith (Journal of Abnormal Psychology, 2017[May], Vol 126[4], 392-405). In the article, the email address of corresponding author Matthew J. Smith was set as matthewsmith@northwestern.edu. It should have been mattjsmi@umich.edu. The online version of this article has been corrected...
July 2017: Journal of Abnormal Psychology
https://www.readbyqxmd.com/read/28690501/cortical-activation-during-landmark-centered-vs-gaze-centered-memory-of-saccade-targets-in-the-human-an-fmri-study
#11
Ying Chen, J D Crawford
A remembered saccade target could be encoded in egocentric coordinates such as gaze-centered, or relative to some external allocentric landmark that is independent of the target or gaze (landmark-centered). In comparison to egocentric mechanisms, very little is known about such a landmark-centered representation. Here, we used an event-related fMRI design to identify brain areas supporting these two types of spatial coding (i.e., landmark-centered vs. gaze-centered) for target memory during the Delay phase where only target location, not saccade direction, was specified...
2017: Frontiers in Systems Neuroscience
https://www.readbyqxmd.com/read/28688741/stronger-default-mode-network-connectivity-is-associated-with-poorer-clinical-insight-in-youth-at-ultra-high-risk-for-psychotic-disorders
#12
Sarah V Clark, Vijay A Mittal, Jessica A Bernard, Aral Ahmadi, Tricia Z King, Jessica A Turner
Impaired clinical insight (CI) is a common symptom of psychotic disorders and a promising treatment target. However, to date, our understanding of how variability in CI is tied to underlying brain dysfunction in the clinical high-risk period is limited. Developing a stronger conception of this link will be a vital first step for efforts to determine if CI can serve as a useful prognostic indicator. The current study investigated whether variability in CI is related to major brain networks in adolescents and young adults at ultra high-risk (UHR) of developing psychosis...
July 5, 2017: Schizophrenia Research
https://www.readbyqxmd.com/read/28685451/site-specificity-of-changes-in-cortical-oxyhaemoglobin-concentration-induced-by-water-immersion
#13
D Sato, K Yamashiro, Y Yamazaki, A Tsubaki, H Onishi, N Takehara, A Maruyama
Our previous studies have shown that water immersion (WI) changes sensorimotor processing and cortical excitability in the sensorimotor regions of the brain. The present study examined the site specificity of the brain activation during WI using functional near infrared spectroscopy (fNIRS). Cortical oxyhaemoglobin (O2Hb) levels in the anterior and posterior parts of the supplementary motor area (pre-SMA and SMA), primary motor cortex (M1), primary somatosensory cortex (S1), and posterior parietal cortex (PPC) were recorded using fNIRS (OMM-3000; Shimadzu Co...
2017: Advances in Experimental Medicine and Biology
https://www.readbyqxmd.com/read/28682863/increased-interhemispheric-resting-state-functional-connectivity-in-healthy-participants-with-insomnia-symptoms-a-randomized-clinical-consort-study
#14
Xuhua Li, Shougang Guo, Chunjuan Wang, Baojie Wang, Hao Sun, Xiaoting Zhang
BACKGROUND: Abnormalities within the insular cortex of the salience and thalamus of the hyperarousal network have been increasingly reported in healthy participants with insomnia symptoms by recent resting-state functional magnetic resonance imaging (rsfMRI) studies. However, little is known about the changes in functional interaction between the bilateral cerebral hemispheres in healthy participants with insomnia symptoms. METHODS: In a randomized trial, 27 healthy participants with insomnia symptoms and 27 age-, gender-, and educational level-matched healthy participants without insomnia symptoms underwent rsfMRI...
July 2017: Medicine (Baltimore)
https://www.readbyqxmd.com/read/28682013/cocaine-and-hiv-are-independently-associated-with-neural-activation-in-response-to-gain-and-loss-valuation-during-economic-risky-choice
#15
Christina S Meade, Merideth Addicott, Andrea L Hobkirk, Sheri L Towe, Nan-Kuei Chen, Sriramkumar Sridharan, Scott A Huettel
Stimulant abuse is disproportionately common in HIV-positive persons. Both HIV and stimulants are independently associated with deficits in reward-based decision making, but their interactive and/or additive effects are poorly understood despite their prevalent co-morbidity. Here, we examined the effects of cocaine dependence and HIV infection in 69 adults who underwent functional magnetic resonance imaging while completing an economic loss aversion task. We identified two neural networks that correlated with the evaluation of the favorable characteristics of the gamble (i...
July 6, 2017: Addiction Biology
https://www.readbyqxmd.com/read/28679330/altered-brain-network-centrality-in-patients-with-adult-comitant-exotropia-strabismus-a-resting-state-fmri-study
#16
Gang Tan, Zeng-Renqing Dan, Ying Zhang, Xin Huang, Yu-Lin Zhong, Lin-Hong Ye, Rong Rong, Lei Ye, Qiong Zhou, Yi Shao
Objective To investigate the underlying functional network brain-activity changes in patients with adult comitant exotropia strabismus (CES) and the relationship with clinical features using the voxel-wise degree centrality (DC) method. Methods A total of 30 patients with CES (17 men, 13 women), and 30 healthy controls (HCs; 17 men, 13 women) matched in age, sex, and education level participated in the study. DC was used to evaluate spontaneous brain activity. Receiver operating characteristic (ROC) curve analysis was conducted to distinguish CESs from HCs...
January 1, 2017: Journal of International Medical Research
https://www.readbyqxmd.com/read/28674492/aberrant-intrinsic-activity-and-connectivity-in-cognitively-normal-parkinson-s-disease
#17
Deborah L Harrington, Qian Shen, Gabriel N Castillo, J Vincent Filoteo, Irene Litvan, Colleen Takahashi, Chelsea French
Disturbances in intrinsic activity during resting-state functional MRI (rsfMRI) are common in Parkinson's disease (PD), but have largely been studied in a priori defined subnetworks. The cognitive significance of abnormal intrinsic activity is also poorly understood, as are abnormalities that precede the onset of mild cognitive impairment. To address these limitations, we leveraged three different analytic approaches to identify disturbances in rsfMRI metrics in 31 cognitively normal PD patients (PD-CN) and 30 healthy adults...
2017: Frontiers in Aging Neuroscience
https://www.readbyqxmd.com/read/28674392/task-relevance-modulates-the-cortical-representation-of-feature-conjunctions-in-the-target-template
#18
Reshanne R Reeder, Michael Hanke, Stefan Pollmann
Little is known about the cortical regions involved in representing task-related content in preparation for visual task performance. Here we used representational similarity analysis (RSA) to investigate the BOLD response pattern similarity between task relevant and task irrelevant feature dimensions during conjunction viewing and target template maintenance prior to visual search. Subjects were cued to search for a spatial frequency (SF) or orientation of a Gabor grating and we measured BOLD signal during cue and delay periods before the onset of a search display...
July 3, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28674177/retinotopic-organization-of-scene-areas-in-macaque-inferior-temporal-cortex
#19
Michael J Arcaro, Margaret S Livingstone
Primates have specialized domains in inferior temporal (IT) cortex that are responsive to particular image categories. Though IT traditionally has been regarded as lacking retinotopy, several recent studies in monkeys have shown that retinotopic maps extend to face patches along the lower bank of the superior temporal sulcus (STS) and neighboring regions of IT cortex. Here, we used fMRI to map the retinotopic organization of medial ventral temporal cortex in 4 monkeys (2 male and 2 female). We confirm the presence of visual field maps within and around the lower bank of the STS and extend these prior findings to scene-selective cortex in the ventral-most regions of IT...
July 3, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28671558/brain-functional-connectivity-is-modified-by-a-hypocaloric-mediterranean-diet-and-physical-activity-in-obese-women
#20
Natalia García-Casares, María R Bernal-López, Nuria Roé-Vellvé, Mario Gutiérrez-Bedmar, Jose C Fernández-García, Juan A García-Arnés, José R Ramos-Rodriguez, Francisco Alfaro, Sonia Santamaria-Fernández, Trevor Steward, Susana Jiménez-Murcia, Isabel Garcia-Garcia, Pedro Valdivielso, Fernando Fernández-Aranda, Francisco J Tinahones, Ricardo Gómez-Huelgas
Functional magnetic resonance imaging (fMRI) in the resting state has shown altered brain connectivity networks in obese individuals. However, the impact of a Mediterranean diet on cerebral connectivity in obese patients when losing weight has not been previously explored. The aim of this study was to examine the connectivity between brain structures before and six months after following a hypocaloric Mediterranean diet and physical activity program in a group of sixteen obese women aged 46.31 ± 4.07 years...
July 1, 2017: Nutrients
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