Parallel gain modulation mechanisms set the resolution of color selectivity in human visual cortex.

Color discrimination is fundamental to human behavior. We find bananas by coarsely searching for yellow but then differentiate nuances of yellow to pick the best exemplars. How does the brain adjust the resolution of color selectivity to our changing needs? Here, we analyze the brain magnetic response in the human visual cortex to show that color selectivity is adaptively set by coarse- and fine-resolving processes running in parallel at different hierarchical levels.

Location- and Object-Based Representational Mechanisms Account for Bilateral Field Advantage in Multiple-Object Tracking.

Keeping track of multiple visually identical and independently moving objects is a remarkable feature of the human visual system. Theoretical accounts for this ability focus on resource-based models that describe parametric decreases of performance with increasing demands during the task (i.e.

Serial attentional resource allocation during parallel feature value tracking.

The visual system has evolved the ability to track features like color and orientation in parallel. This property aligns with the specialization of processing these feature dimensions in the visual cortex. But what if we ask to track changing feature-values within the same feature dimension? Parallel tracking would then have to share the same cortical representation, which would set strong limitations on tracking performance.

The locations of stroke lesions next to the posterior internal capsule may predict the recovery of the related proprioceptive deficits.

Background: Somatosensory deficits after stroke correlate with functional disabilities and impact everyday-life. In particular, the interaction of proprioception and motor dysfunctions affects the recovery. While corticospinal tract (CST) damage is linked to poor motor outcome, much less is known on proprioceptive recovery.

A cortical zoom-in operation underlies covert shifts of visual spatial attention.

Shifting the focus of attention without moving the eyes poses challenges for signal coding in visual cortex in terms of spatial resolution, signal routing, and cross-talk. Little is known how these problems are solved during focus shifts. Here, we analyze the spatiotemporal dynamic of neuromagnetic activity in human visual cortex as a function of the size and number of focus shifts in visual search.

Adaptive and Maladaptive Brain Functional Network Reorganization After Stroke in Hemianopia Patients: An Electroencephalogram-Tracking Study.

Hemianopia after occipital stroke is believed to be mainly due to local damage at or near the lesion site. However, magnetic resonance imaging studies suggest functional connectivity network (FCN) reorganization also in distant brain regions. Because it is unclear whether reorganization is adaptive or maladaptive, compensating for, or aggravating vision loss, we characterized FCNs electrophysiologically to explore and brain plasticity and correlated FCN reorganization with visual performance.

Electrophysiological hallmarks of location-based and object-based visual multiple objects tracking.

Converging evidence shows that our visual system can track multiple visual, independently moving items over time. This is accomplished location-based by maintaining the individual spatial information of each target item or object-based by constructing an abstract object-based representation out of the tracked items. Previous work showed specific behavioural, electrophysiological and haemodynamic markers for location-based or object-based representations of the relevant targets by probing the encoded information subsequently after tracking.

Attention expedites target selection by prioritizing the neural processing of distractor features.

Whether doing the shopping, or driving the car - to navigate daily life, our brain has to rapidly identify relevant color signals among distracting ones. Despite a wealth of research, how color attention is dynamically adjusted is little understood. Previous studies suggest that the speed of feature attention depends on the time it takes to enhance the neural gain of cortical units tuned to the attended feature.

Brain activity is contingent on neuropsychological function in a functional magnetic resonance imaging study of verbal working memory in amyotrophic lateral sclerosis.

Background And Purpose: Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease that causes progressive degeneration of neurons in motor and non-motor brain regions, affecting multiple cognitive domains such as memory. A functional magnetic resonance imaging (fMRI) study was performed to explore working memory function in ALS.

Methods: To contribute to the growing research field that employs structural and functional neuroimaging to investigate the effect of ALS on different working memory components, the localization and intensity of alterations in neural activity was explored using fMRI.

A simple metric to study the mechanisms generating event-related potentials.

Background: There is an active debate about the mechanism underlying the generation of event-related potentials, and, particularly, whether these are generated by additive components, independent of the background EEG, or the phase-resetting of ongoing oscillations.

Method: We present a new metric to evaluate trial-by-trial covariations of successive ERP components. Our main assumption is that if two successive ERP components are generated by phase-resetting of a unitary oscillation, they should be time-locked to each other and their single-trial latencies should covary.

Increased Amygdala Activity Associated With Cognitive Reappraisal Strategy in Functional Neurologic Disorder.

Cognitive reappraisal is an emotion regulation strategy to reduce the impact of affective stimuli. This regulation could be incomplete in patients with functional neurologic disorder (FND) resulting in an overflowing emotional stimulation perpetuating symptoms in FND patients. Here we employed functional MRI to study cognitive reappraisal in FND.

Behavioral and neurophysiological effects of an intensified robot-assisted therapy in subacute stroke: a case control study.

Background: Physical training is able to induce changes at neurophysiological and behavioral level associated with performance changes for the trained movements. The current study explores the effects of an additional intense robot-assisted upper extremity training on functional outcome and motor excitability in subacute stroke patients.

Methods: Thirty moderately to severely affected patients < 3 months after stroke received a conventional inpatient rehabilitation.

Longitudinal clinical and neuroanatomical correlates of memory impairment in motor neuron disease.

Memory impairment in motor neuron disease (MND) is still an underrecognized feature and has traditionally been attributed to executive dysfunction. Here, we investigate the rate of memory impairment in a longitudinal cohort of MND patients, its relationship to other cognitive functions and the underlying neuroanatomical correlates. 142 patients with MND and 99 healthy controls (HC) underwent comprehensive neuropsychological testing and structural MRI at 3T up to four times over a period of 18 months.

Functional dissociation of multiple-object tracking mechanisms based on hemispheric asymmetries.

Background: A number of theoretical accounts have been put forward to explain the ability to simultaneously track multiple visually indistinguishable objects over a period of time. Serial processing models of visual tracking focus on the maintenance of the spatial locations of every single item over time. A more recent mechanism describes multiple object tracking as the ability to maintain a higher order representation of an abstract spatial configuration built by the illusory connection of the tracked items through their transition.

Parallel fast and slow recurrent cortical processing mediates target and distractor selection in visual search.

Visual search has been commonly used to study the neural correlates of attentional allocation in space. Recent electrophysiological research has disentangled distractor processing from target processing, showing that these mechanisms appear to operate in parallel and show electric fields of opposite polarity. Nevertheless, the localization and exact nature of this activity is unknown.

Effects of a single mental chronometry training session in subacute stroke patients - a randomized controlled trial.

Background: Motor imagery training might be helpful in stroke rehabilitation. This study explored if a single session of motor imagery (MI) training induces performance changes in mental chronometry (MC), motor execution, or changes of motor excitability.

Methods: Subacute stroke patients ( = 33) participated in two training sessions.

Modulating the global orientation bias of the visual system changes population receptive field elongations.

The topographical structure of the visual system in individual subjects can be visualized using fMRI. Recently, a radial bias for the long axis of population receptive fields (pRF) has been shown using fMRI. It has been theorized that the elongation of receptive fields pointing toward the fovea results from horizontal local connections bundling orientation selective units mostly parallel to their polar position within the visual field.

Electroencephalography reveals a selective disruption of cognitive control processes in craving cigarette smokers.

Addiction to nicotine is extremely challenging to overcome, and the intense craving for the next cigarette often leads to relapse in smokers who wish to quit. To dampen the urges of craving and inhibit unwanted behaviour, smokers must harness cognitive control, which is itself impaired in addiction. It is likely that craving may interact with cognitive control, and the present study sought to test the specificity of such interactions.

Cortical, subcortical and spinal neural correlates of slackline training-induced balance performance improvements.

Humans develop posture and balance control during childhood. Interestingly, adults can also learn to master new complex balance tasks, but the underlying neural mechanisms are not fully understood yet. Here, we combined broad scale brain connectivity fMRI at rest and spinal excitability measurements during movement.

A neural hallmark of auditory implicit learning is altered in older adults.

Temporal regularities in the environment are often learned implicitly. In an auditory target-detection paradigm using EEG, Jongsma and colleagues (2006) showed that the neural response to these implicit regularities results in a reduction of the P3-N2 complex. Here, we utilized the same paradigm, this time in both young and old participants, to determine if this EEG signature of implicit learning was altered with age.

Dissociating Reward- and Attention-driven Biasing of Global Feature-based Selection in Human Visual Cortex.

Objects that promise rewards are prioritized for visual selection. The way this prioritization shapes sensory processing in visual cortex, however, is debated. It has been suggested that rewards motivate stronger attentional focusing, resulting in a modulation of sensory selection in early visual cortex.

Enhanced spatial focusing increases feature-based selection in unattended locations.

Attention is a multifaceted phenomenon, which operates on features (e.g., colour or motion) and over space.

Global Hippocampal Volume Reductions and Local CA1 Shape Deformations in Amyotrophic Lateral Sclerosis.

There is increasing evidence for hippocampal involvement in Amyotrophic Lateral Sclerosis (ALS). Recent neuroimaging studies have been focused on disease-related hippocampal volume alterations while changes in hippocampal shape have been investigated less frequently. Here, we aimed to characterize the patterns of hippocampal degeneration using both an automatic and manual volumetric and surface-based approach in a group of 31 patients with ALS and 29 healthy controls.

Cortical Mechanisms of Prioritizing Selection for Rejection in Visual Search.

In visual search, the more one knows about a target, the faster one can find it. Surprisingly, target identification is also faster with knowledge about distractor-features. The latter is paradoxical, as it implies that to avoid the selection of an item, the item must somehow be selected to some degree.