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Posterior parietal cortex

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https://www.readbyqxmd.com/read/28821678/individual-movement-variability-magnitudes-are-explained-by-cortical-neural-variability
#1
Shlomi Haar, Opher Donchin, Ilan Dinstein
Humans exhibit considerable motor variability even across trivial reaching movements. This variability can be separated into specific kinematic components such as extent and direction, which are thought to be governed by distinct neural processes. Here, we report that individual subjects (males and females) exhibit different magnitudes of kinematic variability, which are consistent (within individual) across movements to different targets and regardless of which arm (right or left) was used to perform the movements...
August 18, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28808819/separating-the-idea-from-the-action-a-sloreta-study
#2
Martin Rakusa, Pierpaolo Busan, Piero Paolo Battaglini, Janez Zidar
Simple imaginary movements activate similar cortical and subcortical areas to actual movements, chiefly in the sensory-motor network. However, only a few studies also examined the imagery of more skilful movements such as reaching. Ten volunteers performed reaching movements or imagined the same movements. EEG was simultaneously recorded and analysed with sLORETA, which compared the preparation for actual and imagined reaching with respect to their baseline and between tasks. Major differences between them were found at three time intervals after target presentation, always in favour of the actual reaching condition...
August 14, 2017: Brain Topography
https://www.readbyqxmd.com/read/28803349/scary-symptoms-functional-magnetic-resonance-imaging-evidence-for-symptom-interpretation-bias-in-pathological-health-anxiety
#3
Zhimin Yan, Michael Witthöft, Josef Bailer, Carsten Diener, Daniela Mier
Patients with pathological health anxiety (PHA) tend to automatically interpret bodily sensations as sign of a severe illness. To elucidate the neural correlates of this cognitive bias, we applied an functional magnetic resonance imaging adaption of a body-symptom implicit association test with symptom words in patients with PHA (n = 32) in comparison to patients with depression (n = 29) and healthy participants (n = 35). On the behavioral level, patients with PHA did not significantly differ from the control groups...
August 12, 2017: European Archives of Psychiatry and Clinical Neuroscience
https://www.readbyqxmd.com/read/28802727/brain-activation-during-processing-of-genuine-facial-emotion-in-depression-preliminary-findings
#4
REVIEW
Samantha J Groves, Toni L Pitcher, Tracy R Melzer, Jennifer Jordan, Janet D Carter, Gin S Malhi, Lucy C Johnston, Richard J Porter
OBJECTIVE: The current study aimed to examine the neural correlates of processing genuine compared with posed emotional expressions, in depressed and healthy subjects using a novel functional magnetic resonance imaging (fMRI) paradigm METHOD: During fMRI scanning, sixteen depressed patients and ten healthy controls performed an Emotion Categorisation Task, whereby participants were asked to distinguish between genuine and non-genuine (posed or neutral) facial displays of happiness and sadness...
July 27, 2017: Journal of Affective Disorders
https://www.readbyqxmd.com/read/28797109/upper-limb-movements-can-be-decoded-from-the-time-domain-of-low-frequency-eeg
#5
Patrick Ofner, Andreas Schwarz, Joana Pereira, Gernot R Müller-Putz
How neural correlates of movements are represented in the human brain is of ongoing interest and has been researched with invasive and non-invasive methods. In this study, we analyzed the encoding of single upper limb movements in the time-domain of low-frequency electroencephalography (EEG) signals. Fifteen healthy subjects executed and imagined six different sustained upper limb movements. We classified these six movements and a rest class and obtained significant average classification accuracies of 55% (movement vs movement) and 87% (movement vs rest) for executed movements, and 27% and 73%, respectively, for imagined movements...
2017: PloS One
https://www.readbyqxmd.com/read/28794195/object-comparison-in-the-lateral-intraparietal-area
#6
Wei Song Ong, Koorosh Mirpour, James W Bisley
We can search for and locate specific objects in our environment by looking for objects with similar features. Object recognition involves stimulus similarity responses in ventral visual areas and task related responses in prefrontal cortex. We tested whether neurons in the lateral intraparietal area (LIP) of posterior parietal cortex could form an intermediary representation, collating information from object specific similarity map representations to allow general decisions about whether a stimulus matches the object being looked for...
August 9, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28780219/neurofunctionally-dissecting-the-reading-system-in-children
#7
Johanna Liebig, Eva Froehlich, Carmen Morawetz, Mario Braun, Arthur M Jacobs, Hauke R Heekeren, Johannes C Ziegler
The reading system can be broken down into four basic subcomponents in charge of prelexical, orthographic, phonological, and lexico-semantic processes. These processes need to jointly work together to become a fluent and efficient reader. Using functional magnetic resonance imaging (fMRI), we systematically analyzed differences in neural activation patterns of these four basic subcomponents in children (N=41, 9-13 years) using tasks specifically tapping each component (letter identification, orthographic decision, phonological decision, and semantic categorization)...
July 17, 2017: Developmental Cognitive Neuroscience
https://www.readbyqxmd.com/read/28768460/a-stranger-in-my-brain-neural-representation-for-unfamiliar-persons-using-fmri-repetition-suppression
#8
Elien Heleven, Siham Boukhlal, Frank Van Overwalle
Prior neuroimaging research demonstrated that the ventromedial prefrontal cortex (vmPFC) houses neural representations for traits and familiar persons that possess these traits. But do such neural representations also exist for people we do not know? We hypothesized that knowledge about unknown persons is encoded in "generic" mentalizing representations as opposed to "specific" representations for well-known individuals. Neural representations for unfamiliar persons were investigated by fMRI repetition suppression, which is a rapid suppression of fMRI responses upon repeated presentation of the same stimulus signaling the neural representation of this stimulus...
August 2, 2017: Social Neuroscience
https://www.readbyqxmd.com/read/28765808/altered-praxis-network-underlying-limb-kinetic-apraxia-in-parkinson-s-disease-an-fmri-study
#9
Stefanie Kübel, Katharina Stegmayer, Tim Vanbellingen, Manuela Pastore-Wapp, Manuel Bertschi, Jean-Marc Burgunder, Eugenio Abela, Bruno Weder, Sebastian Walther, Stephan Bohlhalter
Parkinson's disease (PD) patients frequently suffer from dexterous deficits impeding activities of daily living. There is controversy whether impaired fine motor skill may stem from limb kinetic apraxia (LKA) rather than bradykinesia. Based on classical models of limb praxis LKA is thought to result when premotor transmission of time-space information of skilled movements to primary motor representations is interrupted. Therefore, using functional magnetic resonance imaging (fMRI) we tested the hypothesis that dexterous deficits in PD are associated with altered activity and connectivity in left parieto-premotor praxis network...
2017: NeuroImage: Clinical
https://www.readbyqxmd.com/read/28747592/investigation-of-spinal-nerve-ligation-mediated-functional-activation-of-the-rat-brain-using-manganese-enhanced-mri
#10
Keun-Yeong Jeong, Ji-Hyuk Kang
To provide clear information on the cerebral regions according to peripheral neuropathy, the functional activation was investigated using manganese-enhanced magnetic resonance imaging (MEMRI). L5-spinal nerve ligation (SNL) was applied to the rats to induce neuropathic pain. Mechanical allodynia and thermal hyperalgesia were measured to confirm neuropathic pain induction following before and after gabapentin (GBP) treatment. The cerebral regions were investigated using a 4.7T MRI system in the sham, SNL, and GBP-treated SNL rats...
July 26, 2017: Experimental Animals
https://www.readbyqxmd.com/read/28743011/posterior-parietal-cortex
#11
Jonathan R Whitlock
The posterior parietal cortex, along with temporal and prefrontal cortices, is one of the three major associative regions in the cortex of the mammalian brain. It is situated between the visual cortex at the caudal pole of the brain and the somatosensory cortex just behind the central sulcus. Technically, any cortex covered by the parietal bone is referred to as 'parietal cortex', but the posterior sector, formally referred to as posterior parietal cortex, is indeed its own functional section of cortex, consisting of Brodmann's areas 5, 7, 39, and 40 in humans, areas 5 and 7 in macaques, and area 7 in rodents (Figure 1)...
July 24, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28737061/functional-and-structural-alterations-in-the-migraine-cerebellum
#12
Jan Mehnert, Arne May
The cerebellum plays an important role in pain processing but its function in headache and specifically in migraine is not known. We therefore compared 54 migraineurs with pairwise matched healthy controls in a magnetic resonance imaging study on neuronal cerebellar activity in response to nociceptive trigeminal sensation and also investigated possible structural alterations. Headache frequency, disease duration, and the proximity to a migraine attack were used as co-factors. Migraine patients showed functional and structural alterations in the posterior part of the cerebellum, namely crus I and crus II...
January 1, 2017: Journal of Cerebral Blood Flow and Metabolism
https://www.readbyqxmd.com/read/28735750/partially-mixed-selectivity-in-human-posterior-parietal-association-cortex
#13
Carey Y Zhang, Tyson Aflalo, Boris Revechkis, Emily R Rosario, Debra Ouellette, Nader Pouratian, Richard A Andersen
To clarify the organization of motor representations in posterior parietal cortex, we test how three motor variables (body side, body part, cognitive strategy) are coded in the human anterior intraparietal cortex. All tested movements were encoded, arguing against strict anatomical segregation of effectors. Single units coded for diverse conjunctions of variables, with different dimensions anatomically overlapping. Consistent with recent studies, neurons encoding body parts exhibited mixed selectivity. This mixed selectivity resulted in largely orthogonal coding of body parts, which "functionally segregate" the effector responses despite the high degree of anatomical overlap...
August 2, 2017: Neuron
https://www.readbyqxmd.com/read/28735133/neurologic-outcome-after-resection-of-parietal-lobe-including-primary-somatosensory-cortex-implications-of-additional-resection-of-posterior-parietal%C3%A2-cortex
#14
Young-Hoon Kim, June Sic Kim, Sang Kun Lee, Chun Kee Chung
OBJECTIVE: Postoperative neurologic outcomes after primary somatosensory cortex (S1) resection have not been well documented. This study was designed to evaluate the neurologic deterioration that follows resection of the S1 areas and to assess the risk factors associated with these morbidities. METHODS: We reviewed 48 consecutive patients with medically intractable epilepsy who underwent resection of the S1 and/or the adjacent cortex. The 48 patients were categorized into 4 groups according to the resected area as seen on postoperative magnetic resonance images: group 1 (resection of S1 only; n = 4), 2 (the posterior parietal cortex [PPC] only; n = 24), 3 (S1 and PPC; n = 10), and 4 (S1 and precentral gyrus; n = 10)...
July 19, 2017: World Neurosurgery
https://www.readbyqxmd.com/read/28735100/attention-modulates-specific-motor-cortical-circuits-recruited-by-transcranial-magnetic-stimulation
#15
J L Mirdamadi, L Y Suzuki, S K Meehan
Skilled performance and acquisition is dependent upon afferent input to motor cortex. The present study used short-latency afferent inhibition (SAI) to probe how manipulation of sensory afference by attention affects different circuits projecting to pyramidal tract neurons in motor cortex. SAI was assessed in the first dorsal interosseous muscle while participants performed a low or high attention-demanding visual detection task. SAI was evoked by preceding a suprathreshold transcranial magnetic stimulus with electrical stimulation of the median nerve at the wrist...
July 20, 2017: Neuroscience
https://www.readbyqxmd.com/read/28729938/abnormal-resting-state-effective-connectivity-within-the-default-mode-network-in-major-depressive-disorder-a-spectral-dynamic-causal-modeling-study
#16
Liang Li, Baojuan Li, Yuanhan Bai, Wenlei Liu, Huaning Wang, Hoi-Chung Leung, Ping Tian, Linchuan Zhang, Fan Guo, Long-Biao Cui, Hong Yin, Hongbing Lu, Qingrong Tan
INTRODUCTION: Understanding the neural basis underlying major depressive disorder (MDD) is essential for the diagnosis and treatment of this mental disorder. Aberrant activation and functional connectivity of the default mode network (DMN) have been consistently found in patients with MDD. It is not known whether effective connectivity within the DMN is altered in MDD. OBJECTS: The primary object of this study is to investigate the effective connectivity within the DMN during resting state in MDD patients before and after eight weeks of antidepressant treatment...
July 2017: Brain and Behavior
https://www.readbyqxmd.com/read/28725547/spatial-working-memory-in-neurofibromatosis-1-altered-neural-activity-and-functional-connectivity
#17
Amira F A Ibrahim, Caroline A Montojo, Kristen M Haut, Katherine H Karlsgodt, Laura Hansen, Eliza Congdon, Tena Rosser, Robert M Bilder, Alcino J Silva, Carrie E Bearden
BACKGROUND: Neurofibromatosis Type 1 (NF1) is a genetic disorder that disrupts central nervous system development and neuronal function. Cognitively, NF1 is characterized by difficulties with executive control and visuospatial abilities. Little is known about the neural substrates underlying these deficits. The current study utilized Blood-Oxygen-Level-Dependent (BOLD) functional MRI (fMRI) to explore the neural correlates of spatial working memory (WM) deficits in patients with NF1. METHODS: BOLD images were acquired from 23 adults with NF1 (age M = 32...
2017: NeuroImage: Clinical
https://www.readbyqxmd.com/read/28723889/distinct-timescales-of-population-coding-across-cortex
#18
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...
August 3, 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
#19
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
#20
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...
September 1, 2017: Drug and Alcohol Dependence
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