Cortical Effects on Ipsilateral Hindlimb Muscles Revealed with Stimulus-Triggered Averaging of EMG Activity
While a large body of evidence supports the view that ipsilateral motor cortex may make an important contribution to normal movements and to recovery of function following cortical injury (Chollet et al. 1991; Fisher 1992; Caramia et al. 2000; Feydy et al. 2002), relatively little is known about the properties of output from motor cortex to ipsilateral muscles. Our aim in this study was to characterize the organization of output effects on hindlimb muscles from ipsilateral motor cortex using stimulus-triggered averaging of EMG activity. Stimulus-triggered averages of EMG activity were computed from microstimuli applied at ...
Source: Cerebral Cortex - June 7, 2016 Category: Neurology Authors: Messamore, W. G., Van Acker, G. M., Hudson, H. M., Zhang, H. Y., Kovac, A., Nazzaro, J., Cheney, P. D. Tags: Articles Source Type: research
Are Developmental Trajectories of Cortical Folding Comparable Between Cross-sectional Datasets of Fetuses and Preterm Newborns?
Magnetic resonance imaging has proved to be suitable and efficient for in vivo investigation of the early process of brain gyrification in fetuses and preterm newborns but the question remains as to whether cortical-related measurements derived from both cases are comparable or not. Indeed, the developmental folding trajectories drawn up from both populations have not been compared so far, neither from cross-sectional nor from longitudinal datasets. The present study aimed to compare features of cortical folding between healthy fetuses and early imaged preterm newborns on a cross-sectional basis, over a developmental perio...
Source: Cerebral Cortex - June 7, 2016 Category: Neurology Authors: Lefevre, J., Germanaud, D., Dubois, J., Rousseau, F., de Macedo Santos, I., Angleys, H., Mangin, J.-F., Huppi, P. S., Girard, N., De Guio, F. Tags: Articles Source Type: research
Selective Neural Synchrony Suppression as a Forward Gatekeeper to Piecemeal Conscious Perception
The emergence of conscious visual perception is assumed to ignite late (~250 ms) gamma-band oscillations shortly after an initial (~100 ms) forward sweep of neural sensory (nonconscious) information. However, this neural evidence is not utterly congruent with rich behavioral data which rather point to piecemeal (i.e., graded) perceptual processing. To address the unexplored neural mechanisms of piecemeal ignition of conscious perception, hierarchical script sensitivity of the putative visual word form area (VWFA) was exploited to signal null (i.e., sensory), partial (i.e., letter-level), and full (i.e., word-level) conscio...
Source: Cerebral Cortex - June 7, 2016 Category: Neurology Authors: Levy, J., Vidal, J. R., Fries, P., Demonet, J.-F., Goldstein, A. Tags: Articles Source Type: research
Evidence for a Specific Integrative Mechanism for Episodic Memory Mediated by AMPA/kainate Receptors in a Circuit Involving Medial Prefrontal Cortex and Hippocampal CA3 Region
We asked whether episodic-like memory requires neural mechanisms independent of those that mediate its component memories for "what," "when," and "where," and if neuronal connectivity between the medial prefrontal cortex (mPFC) and the hippocampus (HPC) CA3 subregion is essential for episodic-like memory. Unilateral lesion of the mPFC was combined with unilateral lesion of the CA3 in the ipsi- or contralateral hemispheres in rats. Episodic-like memory was tested using a task, which assesses the integration of memories for "what, where, and when" concomitantly. Tests for novel object recognition (what), object place (where)...
Source: Cerebral Cortex - June 7, 2016 Category: Neurology Authors: de Souza Silva, M. A., Huston, J. P., Wang, A.-L., Petri, D., Chao, O. Y.-H. Tags: Articles Source Type: research
Probing the Cognitive Mechanism of Mental Representational Change During Chunk Decomposition: A Parametric fMRI Study
In conclusion, this suggests that chunk decomposition reflects mental transformation of problem representation from an inappropriate state to a new one alongside with an evaluation of novel and insightful solutions by the caudate in the dorsal striatum. (Source: Cerebral Cortex)
Source: Cerebral Cortex - June 7, 2016 Category: Neurology Authors: Tang, X., Pang, J., Nie, Q.-Y., Conci, M., Luo, J., Luo, J. Tags: Articles Source Type: research
Dissociations in Cortical Morphometry in Youth with Down Syndrome: Evidence for Reduced Surface Area but Increased Thickness
Detailed descriptions of cortical anatomy in youth with Down syndrome (DS), the most common genetic cause of intellectual disability (ID), are scant. Thus, the current study examined deviations in cortical thickness (CT) and surface area (SA), at high spatial resolution, in youth with DS, to identify focal differences relative to typically developing (TD) youth. Participants included 31 youth with DS and 45 age- and sex-matched TD controls (mean age ~16 years; range = 5–24 years). All participants completed T1-weighted ASSET-calibrated magnetization prepared rapid gradient echo scans on a 3-T magnetic resonance imagi...
Source: Cerebral Cortex - June 7, 2016 Category: Neurology Authors: Lee, N. R., Adeyemi, E. I., Lin, A., Clasen, L. S., Lalonde, F. M., Condon, E., Driver, D. I., Shaw, P., Gogtay, N., Raznahan, A., Giedd, J. N. Tags: Articles Source Type: research
CREB1 Genotype Modulates Adaptive Reward-Based Decisions in Humans
Cyclic AMP response element-binding protein (CREB) contributes to adaptation of mesocorticolimbic networks by modulating activity-regulated transcription and plasticity in neurons. Activity or expression changes of CREB in the nucleus accumbens (NAc) and orbital frontal cortex (OFC) interact with behavioral changes during reward-motivated learning. However, these findings from animal models have not been evaluated in humans. We tested whether CREB1 genotypes affect reward-motivated decisions and related brain activation, using BOLD fMRI in 224 young and healthy participants. More specifically, participants needed to adapt ...
Source: Cerebral Cortex - June 7, 2016 Category: Neurology Authors: Wolf, C., Mohr, H., Diekhof, E. K., Vieker, H., Goya-Maldonado, R., Trost, S., Kramer, B., Keil, M., Binder, E. B., Gruber, O. Tags: Articles Source Type: research
Neural Mechanisms of Temporal Resolution of Attention
The dynamic nature of the world requires that our visual representations are continuously updated. These representations are more precise if there is a narrow time window over which information is averaged. We assess the neural processes of visual updating by testing patients with lesions including inferior parietal cortex, control patients and healthy adults on a continuous visual monitoring task. In Experiment 1, observers kept track of the changing spatial period of a luminance grating and identified the final spatial period after the stimulus disappeared. Healthy older adults and neurological controls were able to perf...
Source: Cerebral Cortex - June 7, 2016 Category: Neurology Authors: Howard, C. J., Bashir, N., Chechlacz, M., Humphreys, G. W. Tags: Articles Source Type: research
Cdk5 is a New Rapid Synaptic Homeostasis Regulator Capable of Initiating the Early Alzheimer-Like Pathology
Cyclin-dependent kinase 5 (Cdk5) is a serine/threonine kinase implicated in synaptic plasticity, behavior, and cognition, yet its synaptic function remains poorly understood. Here, we report that physiological Cdk5 signaling in rat hippocampal CA1 neurons regulates homeostatic synaptic transmission using an unexpectedly rapid mechanism that is different from all known slow homeostatic regulators, such as beta amyloid (Aβ) and activity-regulated cytoskeleton-associated protein (Arc, aka Arg3.1). Interestingly, overproduction of the potent Cdk5 activator p25 reduces synapse density, and dynamically regulates synaptic si...
Source: Cerebral Cortex - June 7, 2016 Category: Neurology Authors: Sheng, Y., Zhang, L., Su, S. C., Tsai, L.-H., Julius Zhu, J. Tags: Articles Source Type: research
Cajal club krieg cortical kudos for 2016
(Source: Cerebral Cortex)
Source: Cerebral Cortex - May 16, 2016 Category: Neurology Tags: EDITORIAL ANNOUNCEMENT Source Type: research
A Model of Representational Spaces in Human Cortex
Current models of the functional architecture of human cortex emphasize areas that capture coarse-scale features of cortical topography but provide no account for population responses that encode information in fine-scale patterns of activity. Here, we present a linear model of shared representational spaces in human cortex that captures fine-scale distinctions among population responses with response-tuning basis functions that are common across brains and models cortical patterns of neural responses with individual-specific topographic basis functions. We derive a common model space for the whole cortex using a new algor...
Source: Cerebral Cortex - May 16, 2016 Category: Neurology Authors: Guntupalli, J. S., Hanke, M., Halchenko, Y. O., Connolly, A. C., Ramadge, P. J., Haxby, J. V. Tags: Articles Source Type: research
Retrosplenial Cortical Contributions to Anterograde and Retrograde Memory in the Monkey
This study provides the first causal evidence that RSC in macaque monkeys is crucial for postoperative retention of preoperatively and postoperatively acquired memories. Preoperatively, monkeys learned 300 object-in-place scene discriminations across sessions. After RSC removal, one-trial postoperative retention tests revealed significant retrograde memory loss for these 300 discriminations relative to unoperated control monkeys. Less robust evidence was found for a deficit in anterograde memory (new postoperative learning) after RSC lesions as new learning to criterion measures failed to reveal any significant learning im...
Source: Cerebral Cortex - May 16, 2016 Category: Neurology Authors: Buckley, M. J., Mitchell, A. S. Tags: Articles Source Type: research
Role of Dopamine 2 Receptor in Impaired Drug-Cue Extinction in Adolescent Rats
Adolescent drug users display resistance to treatment such as cue exposure therapy (CET), as well as increased liability to relapse. The basis of CET is extinction learning, which involves dopamine signaling in the medial prefrontal cortex (mPFC). This system undergoes dramatic alterations during adolescence. Therefore, we investigated extinction of a cocaine-associated cue in adolescent and adult rats. While cocaine self-administration and lever-alone extinction were not different between the two ages, we observed that cue extinction reduced cue-induced reinstatement in adult but not adolescent rats. Infusion of the selec...
Source: Cerebral Cortex - May 16, 2016 Category: Neurology Authors: Zbukvic, I. C., Ganella, D. E., Perry, C. J., Madsen, H. B., Bye, C. R., Lawrence, A. J., Kim, J. H. Tags: Articles Source Type: research
Shaping Early Reorganization of Neural Networks Promotes Motor Function after Stroke
Neural plasticity is a major factor driving cortical reorganization after stroke. We here tested whether repetitively enhancing motor cortex plasticity by means of intermittent theta-burst stimulation (iTBS) prior to physiotherapy might promote recovery of function early after stroke. Functional magnetic resonance imaging (fMRI) was used to elucidate underlying neural mechanisms. Twenty-six hospitalized, first-ever stroke patients (time since stroke: 1–16 days) with hand motor deficits were enrolled in a sham-controlled design and pseudo-randomized into 2 groups. iTBS was administered prior to physiotherapy on 5 cons...
Source: Cerebral Cortex - May 16, 2016 Category: Neurology Authors: Volz, L. J., Rehme, A. K., Michely, J., Nettekoven, C., Eickhoff, S. B., Fink, G. R., Grefkes, C. Tags: Articles Source Type: research
Predominance of Movement Speed Over Direction in Neuronal Population Signals of Motor Cortex: Intracranial EEG Data and A Simple Explanatory Model
How neuronal activity of motor cortex is related to movement is a central topic in motor neuroscience. Motor-cortical single neurons are more closely related to hand movement velocity than speed, that is, the magnitude of the (directional) velocity vector. Recently, there is also increasing interest in the representation of movement parameters in neuronal population activity, such as reflected in the intracranial EEG (iEEG). We show that in iEEG, contrasting to what has been previously found on the single neuron level, speed predominates over velocity. The predominant speed representation was present in nearly all iEEG sig...
Source: Cerebral Cortex - May 16, 2016 Category: Neurology Authors: Hammer, J., Pistohl, T., Fischer, J., Krsek, P., Tomasek, M., Marusic, P., Schulze-Bonhage, A., Aertsen, A., Ball, T. Tags: Articles Source Type: research
