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https://www.readbyqxmd.com/read/28634307/prefrontal-neurons-encode-a-solution-to-the-credit-assignment-problem
#1
Wael F Asaad, Peter M Lauro, János A Perge, Emad N Eskandar
To adapt successfully to our environments, we must use the outcomes of our choices to guide future behavior. Critically, we must be able to correctly assign credit for any particular outcome to the causal features which preceded it. In some cases, the causal features may be immediately evident, whereas in others they may be separated in time or intermingled with irrelevant environmental stimuli, creating a potentially nontrivial credit assignment problem. We examined the neuronal representation of information relevant for credit assignment in the dorsolateral prefrontal cortex (dPFC) of two male rhesus macaques performing a task that elicited key aspects of this problem...
June 20, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28634306/representations-of-time-varying-cochlear-implant-stimulation-in-auditory-cortex-of-awake-marmosets-callithrix-jacchus
#2
Luke A Johnson, Charles C Della Santina, Xiaoqin Wang
Electrical stimulation of the auditory periphery organ by cochlear implant (CI) generates highly synchronized inputs to the auditory system. It has long been thought such inputs would lead to highly synchronized neural firing along the ascending auditory pathway. However, neurophysiological studies with hearing animals have shown that the central auditory system progressively converts temporal representations of time-varying sounds to firing rate-based representations. It is not clear whether this coding principle also applies to highly synchronized CI inputs...
June 20, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28633971/manganese-enhanced-magnetic-resonance-imaging-depicts-brain-activity-in-models-of-acute-and-chronic-pain-a-new-window-to-study-experimental-spontaneous-pain
#3
I M Devonshire, J J Burston, L Xu, A Lillywhite, M J Prior, D J G Watson, C M Greenspon, S J Iwabuchi, D P Auer, V Chapman
Application of functional imaging techniques to animal models is vital to understand pain mechanisms, but is often confounded by the need to limit movement artefacts with anaesthesia, and a focus on evoked responses rather than clinically relevant spontaneous pain and related hyperalgesia. The aim of the present study was to investigate the potential of manganese-enhanced magnetic resonance imaging (MEMRI) to measure neural responses during on-going pain that underpins hyperalgesia in pre-clinical models of nociception...
June 17, 2017: NeuroImage
https://www.readbyqxmd.com/read/28633028/visual-perception-neural-networks-for-stereopsis
#4
Jenny C A Read, Bruce G Cumming
How does our brain use differences between the images in our two eyes, binocular disparities, to generate depth perception? New work shows that a type of neural network trained on natural binocular images can learn parameters that match key properties of visual cortex. Most information is conveyed by cells which sense differences between the two eyes' images.
June 19, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28632961/increased-neural-response-to-social-rejection-in-major-depression
#5
Poornima Kumar, Gordon D Waiter, Magda Dubois, Maarten Milders, Ian Reid, J Douglas Steele
BACKGROUND: Being a part of community is critical for survival and individuals with major depressive disorder (MDD) have a greater sensitivity to interpersonal stress that makes them vulnerable to future episodes. Social rejection is a critical risk factor for depression and it is said to increase interpersonal stress and thereby impairing social functioning. It is therefore critical to understand the neural correlates of social rejection in MDD. METHODS: To this end, we scanned 15 medicated MDD and 17 healthy individuals during a modified cyberball passing game, where participants were exposed to increasing levels of social exclusion...
June 20, 2017: Depression and Anxiety
https://www.readbyqxmd.com/read/28632774/short-term-eeg-dynamics-and-neural-generators-evoked-by-navigational-images
#6
Axelle Leroy, Carlos Cevallos, Ana-Maria Cebolla, Stéphanie Caharel, Bernard Dan, Guy Cheron
The ecological environment offered by virtual reality is primarily supported by visual information. The different image contents and their rhythmic presentation imply specific bottom-up and top-down processing. Because these processes already occur during passive observation we studied the brain responses evoked by the presentation of specific 3D virtual tunnels with respect to 2D checkerboard. For this, we characterized electroencephalograhy dynamics (EEG), the evoked potentials and related neural generators involved in various visual paradigms...
2017: PloS One
https://www.readbyqxmd.com/read/28632736/from-the-motor-cortex-to-the-movement-and-back-again
#7
Wondimu W Teka, Khaldoun C Hamade, William H Barnett, Taegyo Kim, Sergey N Markin, Ilya A Rybak, Yaroslav I Molkov
The motor cortex controls motor behaviors by generating movement-specific signals and transmitting them through spinal cord circuits and motoneurons to the muscles. Precise and well-coordinated muscle activation patterns are necessary for accurate movement execution. Therefore, the activity of cortical neurons should correlate with movement parameters. To investigate the specifics of such correlations among activities of the motor cortex, spinal cord network and muscles, we developed a model for neural control of goal-directed reaching movements that simulates the entire pathway from the motor cortex through spinal cord circuits to the muscles controlling arm movements...
2017: PloS One
https://www.readbyqxmd.com/read/28632204/successful-pharmacotherapy-for-the-treatment-of-severe-feeding-aversion-with-mechanistic-insights-from-cross-species-neuronal-remodeling
#8
W G Sharp, A G Allen, K H Stubbs, K K Criado, R Sanders, C E McCracken, R G Parsons, L Scahill, S L Gourley
Pediatric feeding disorders affect up to 5% of children, causing severe food intake problems that can result in serious medical and developmental outcomes. Behavioral intervention (BI) is effective in extinguishing feeding aversions, and also expert-dependent, time/labor-intensive and not well understood at a neurobiological level. Here we first conducted a double-blind, placebo-controlled trial comparing BI with BI plus d-cycloserine (DCS). DCS is a partial N-methyl-d-aspartate (NMDA) receptor agonist shown to augment extinction therapies in multiple anxiety disorders...
June 20, 2017: Translational Psychiatry
https://www.readbyqxmd.com/read/28631147/the-motor-cortical-representation-of-a-muscle-is-not-homogeneous-in-brain-connectivity
#9
Jo Armour Smith, Alaa Albishi, Sarine Babikian, Skulpan Asavasopon, Beth E Fisher, Jason J Kutch
Functional connectivity patterns of the motor cortical representational area of single muscles have not been extensively mapped in humans, particularly for the axial musculature. Functional connectivity may provide a neural substrate for adaptation of muscle activity in axial muscles that have both voluntary and postural functions. The purpose of this study was to combine brain stimulation and neuroimaging to both map the cortical representation of the external oblique (EO) in primary motor cortex (M1) and supplementary motor area (SMA), and to establish the resting-state functional connectivity associated with this representation...
June 19, 2017: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/28630880/prominent-lateral-spread-of-imaged-evoked-activity-beyond-cortical-columns-in-barrel-cortex-provides-foundation-for-coding-whisker-identity
#10
Nathan S Jacobs, Ron D Frostig
The posterior medial barrel subfield (PMBSF) of a rat primary somatosensory cortex exquisitely demonstrates topography and columnar organization, defining features of sensory cortices in the mammalian brain. Optical imaging and neuronal recordings in rat PMBSF demonstrate how evoked cortical activity following single whisker stimulation also rapidly spreads laterally into surrounding cortices, disregarding columnar and modality boundaries. The current study quantifies the spatial prominence of such lateral activity spreads by demonstrating that functional connectivity between laterally spaced cortical locations is actually stronger than between vertically spaced cortical locations...
July 2017: Neurophotonics
https://www.readbyqxmd.com/read/28630662/sex-differences-in-endogenous-cortical-network-activity-spontaneously-recurring-up-down-states
#11
Charalambos Sigalas, Eleni Konsolaki, Irini Skaliora
BACKGROUND: Several molecular and cellular processes in the vertebrate brain exhibit differences between males and females, leading to sexual dimorphism in the formation of neural circuits and brain organization. While studies on large-scale brain networks provide ample evidence for both structural and functional sex differences, smaller-scale local networks have remained largely unexplored. In the current study, we investigate sexual dimorphism in cortical dynamics by means of spontaneous Up/Down states, a type of network activity that is exhibited during slow-wave sleep, quiet wakefulness, and anesthesia and is thought to represent the default activity of the cortex...
2017: Biology of Sex Differences
https://www.readbyqxmd.com/read/28630661/intrainsular-connectivity-and-somatosensory-responsiveness-in-young-children-with-asd
#12
Michelle D Failla, Brittany R Peters, Haleh Karbasforoushan, Jennifer H Foss-Feig, Kimberly B Schauder, Brynna H Heflin, Carissa J Cascio
BACKGROUND: The human somatosensory system comprises dissociable paths for discriminative and affective touch, reflected in separate peripheral afferent populations and distinct cortical targets. Differences in behavioral and neural responses to affective touch may have an important developmental role in early social experiences, which are relevant for autism spectrum disorder (ASD). METHODS: Using probabilistic tractography, we compared the structural integrity of white matter pathways for discriminative and affective touch in young children with ASD and their typically developing (TD) peers...
2017: Molecular Autism
https://www.readbyqxmd.com/read/28630255/social-context-dependent-activity-in-marmoset-frontal-cortex-populations-during-natural-conversations
#13
Samuel U Nummela, Vladimir Jovanovic, Lisa de la Mothe, Cory T Miller
Communication is an inherently interactive process that weaves together the fabric of both human and nonhuman primate societies. To investigate the properties of the primate brain during active social signaling, we recorded the responses of frontal cortex neurons as freely-moving marmosets engaged in conversational exchanges with a visually occluded Virtual Marmoset (VM). We found that small changes in firing rate (∼1Hz) occurred across a broadly distributed population of frontal cortex neurons when marmosets heard a conspecific vocalization, and that these changes corresponded to subjects' likelihood of producing or withholding a vocal reply...
June 19, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28629874/neural-activity-during-attentional-conflict-predicts-reduction-in-tinnitus-perception-following-rtms
#14
G A James, J D Thostenson, G Brown, G Carter, H Hayes, S P Tripathi, D J Dobry, R B Govindan, J L Dornhoffer, D K Williams, C D Kilts, M S Mennemeier
BACKGROUND: Subjective idiopathic tinnitus is an intrusive, distracting, and potentially disabling disorder characterized by phantom perception of sounds. Although tinnitus has no approved pharmacologic treatment, recent evidence supports the use of repetitive transcranial magnetic stimulation (rTMS) to alleviate tinnitus symptoms. OBJECTIVE/HYPOTHESIS: Repetitive TMS delivered over the middle superior temporal gyrus (STG) may alter ratings of tinnitus awareness and annoyance more than loudness due to change in attentional processing...
June 2, 2017: Brain Stimulation
https://www.readbyqxmd.com/read/28629225/cortical-plasticity-in-depression
#15
Mariagiovanna Cantone, Alessia Bramanti, Giuseppe Lanza, Manuela Pennisi, Placido Bramanti, Giovanni Pennisi, Rita Bella
Neural plasticity is considered the neurophysiological correlate of learning and memory, although several studies have also noted that it plays crucial roles in a number of neurological and psychiatric diseases. Indeed, impaired brain plasticity may be one of the pathophysiological mechanisms that underlies both cognitive decline and major depression. Moreover, a degree of cognitive impairment is frequently observed throughout the clinical spectrum of mood disorders, and the relationship between depression and cognition is often bidirectional...
May 2017: ASN Neuro
https://www.readbyqxmd.com/read/28628797/attenuated-error-related-potentials-in-amyotrophic-lateral-sclerosis-with-executive-dysfunctions
#16
Caroline Seer, Max Joop, Florian Lange, Christian Lange, Reinhard Dengler, Susanne Petri, Bruno Kopp
OBJECTIVE: Executive dysfunctions affect up to 50% of the patients with amyotrophic lateral sclerosis (ALS). Executive dysfunctions have been identified as negative prognostic factor and can affect quality of life in patients and their caregivers. Assessment of executive dysfunction may be impeded by the patients' motor impairments. Event-related potentials (ERP) have been proposed as a tool to overcome these assessment difficulties. The error(-related) negativity (Ne/ERN) is an ERP which can be recorded with minimal motor requirements for the patient...
May 18, 2017: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
https://www.readbyqxmd.com/read/28628647/an-efficient-coding-theory-for-a-dynamic-trajectory-predicts-non-uniform-allocation-of-entorhinal-grid-cells-to-modules
#17
Noga Mosheiff, Haggai Agmon, Avraham Moriel, Yoram Burak
Grid cells in the entorhinal cortex encode the position of an animal in its environment with spatially periodic tuning curves with different periodicities. Recent experiments established that these cells are functionally organized in discrete modules with uniform grid spacing. Here we develop a theory for efficient coding of position, which takes into account the temporal statistics of the animal's motion. The theory predicts a sharp decrease of module population sizes with grid spacing, in agreement with the trend seen in the experimental data...
June 19, 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28628541/apathy-due-to-injury-of-the-prefrontocaudate-tract-following-mild-traumatic-brain-injury
#18
Sung Ho Jang, Hyeok Gyu Kwon
In this study, we report on a patient who developed apathy resulting from injury to the prefrontocaudate tract following mild traumatic brain injury (TBI), which was observed on diffusion tensor tractography (DTT). A 46-year-old female patient was involved in a bus accident. Her history included intracerebral hemorrhage (ICH) in the left putamen 4 years ago before the head trauma, and her family reported that she had fully recovered. She developed apathy after the TBI, worsening over time. Decreased neural connectivity of the left caudate nucleus (CN) to the left upper medial prefrontal cortex (PFC) resulting from the ICH was observed on the pre-TBI-DTT, whereas on the post-TBI-DTT (28 months after TBI), the neural connectivity of the left CN to the left upper medial PFC was increased, whereas that to the left lower medial PFC and orbitofrontal cortex was decreased...
July 2017: American Journal of Physical Medicine & Rehabilitation
https://www.readbyqxmd.com/read/28628004/visual-field-map-clusters-in-human-frontoparietal-cortex
#19
Wayne E Mackey, Jonathan Winawer, Clayton E Curtis
The visual neurosciences have made enormous progress in recent decades, in part because of the ability to drive visual areas by their sensory inputs, allowing researchers to reliably define visual areas across individuals and across species. Similar strategies for parcellating higher-order cortex have proven elusive. Here, using a novel experimental task and nonlinear population receptive field modeling we map and characterize the topographic organization of several regions in human frontoparietal cortex. We discover representations of both polar angle and eccentricity that are organized into clusters, similar to visual cortex, where multiple gradients of polar angle of the contralateral visual field share a confluent fovea...
June 19, 2017: ELife
https://www.readbyqxmd.com/read/28627420/distinct-neural-processes-supports-post-success-and-post-error-slowing-in-the-stop-signal-task
#20
Yihe Zhang, Jaime S Ide, Sheng Zhang, Sien Hu, Nikola S Valchev, Xiaoying Tang, Chiang-Shan R Li
Executive control requires behavioral adaptation to environmental contingencies. In the stop signal task (SST), participants exhibit slower go trial reaction time (RT) following a stop trial, whether or not they successfully interrupt the motor response. In previous fMRI studies, we demonstrated activation of the right-hemispheric ventrolateral prefrontal cortex, in the area of inferior frontal gyrus, pars opercularis (IFGpo) and anterior insula (AI), during post-error slowing (PES). However, in similar analyses we were not able to identify regional activities during post-success slowing (PSS)...
June 13, 2017: Neuroscience
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