Distinct coordinate systems for adaptations of movement direction and extent
Learned compensations for perturbed visual feedback of movement extent and direction generalize differently to unpracticed movement directions, which suggests different underlying neural mechanisms. Here we investigated whether gain and rotation adaptations are consistent with representation in different coordinate systems. Subjects performed a force-aiming task with the wrist and learned different gains or rotations for different force directions. Generalization was tested without visual feedback for the same extrinsic directions but with the forearm in a different pronation-supination orientation. When the change in fore...
Source: Journal of Neurophysiology - November 3, 2017 Category: Neurology Authors: Poh, E., Carroll, T. J., de Rugy, A. Tags: Research Articles Source Type: research
Parkinsonism and vigilance: alteration in neural oscillatory activity and phase-amplitude coupling in the basal ganglia and motor cortex
This study improves our understanding of the role of oscillatory activity and phase-amplitude coupling in the pathophysiology of Parkinson’s disease and supports the development of more effective DBS therapies based on pathophysiological biomarkers. (Source: Journal of Neurophysiology)
Source: Journal of Neurophysiology - November 3, 2017 Category: Neurology Authors: Escobar Sanabria, D., Johnson, L. A., Nebeck, S. D., Zhang, J., Johnson, M. D., Baker, K. B., Molnar, G. F., Vitek, J. L. Tags: Research Articles Source Type: research
Unbounded evidence accumulation characterizes subjective visual vertical forced-choice perceptual choice and confidence
Humans can subjectively yet quantitatively assess choice confidence based on perceptual precision even when a perceptual decision is made without an immediate reward or feedback. However, surprisingly little is known about choice confidence. Here we investigate the dynamics of choice confidence by merging two parallel conceptual frameworks of decision making, signal detection theory and sequential analyses (i.e., drift-diffusion modeling). Specifically, to capture end-point statistics of binary choice and confidence, we built on a previous study that defined choice confidence in terms of psychophysics derived from signal d...
Source: Journal of Neurophysiology - November 3, 2017 Category: Neurology Authors: Lim, K., Wang, W., Merfeld, D. M. Tags: Research Articles Source Type: research
Intermittent cortical involvement in the preservation of tremor in essential tremor
Cortical involvement in essential tremor, an involuntary action tremor supposedly of subcortical origin, is uncertain. Conflicting results of corticomuscular coherence studies in essential tremor suggest an intermittent corticomuscular coupling. On the basis of the literature, we hypothesized that corticomuscular coupling is influenced by bilateral motor synchronization and "cognitive states" such as awareness of tremor. In the present study, we investigated 1) the existence of intermittent corticomuscular coherence (CMC) in essential tremor and 2) factors that influence CMC strength. In 18 essential tremor patients and 18...
Source: Journal of Neurophysiology - November 3, 2017 Category: Neurology Authors: Sharifi, S., Luft, F., Verhagen, R., Heida, T., Speelman, J. D., Bour, L. J., van Rootselaar, A.-F. Tags: Research Articles Source Type: research
Face percept formation in human ventral temporal cortex
Loci in ventral temporal cortex are selectively active during viewing of faces and other objects, but it remains unclear whether these areas represent accumulation of simple visual information or processing of intact percept. We measured broadband electrocorticographic changes from implanted electrodes on the ventral temporal brain surface while showing patients noise-degraded images of faces and houses. In a subset of posterior fusiform gyrus face-selective regions, cortical activity decreased parametrically with noise increase, until the perceptual threshold was surpassed. At noise levels higher than the perceptual thres...
Source: Journal of Neurophysiology - November 1, 2017 Category: Neurology Authors: Miller, K. J., Hermes, D., Pestilli, F., Wig, G. S., Ojemann, J. G. Tags: Research Articles Source Type: research
The neural basis of temporal individuation and its capacity limits in the human brain
We present novel findings into the neural bases of temporal individuation and repetition blindness (RB)—the perceptual deficit that arises when this process reaches its capacity limit. Specifically, we found that temporal individuation is a widely distributed process in the brain and identified a number of candidate brain regions that appear to underpin RB. These findings enhance our understanding of how these fundamental perceptual processes are reflected in the human brain. (Source: Journal of Neurophysiology)
Source: Journal of Neurophysiology - November 1, 2017 Category: Neurology Authors: Naughtin, C. K., Tamber-Rosenau, B. J., Dux, P. E. Tags: Research Articles Source Type: research
Time-of-day influences on respiratory sequelae following maximal electroshock-induced seizures in mice
In this study we found that time of day independently affects the physiological consequences of seizures. (Source: Journal of Neurophysiology)
Source: Journal of Neurophysiology - November 1, 2017 Category: Neurology Authors: Purnell, B. S., Hajek, M. A., Buchanan, G. F. Tags: Research Articles Source Type: research
Induced cortical oscillations in turtle cortex are coherent at the mesoscale of population activity, but not at the microscale of the membrane potential of neurons
In conclusion, neuronal oscillations at distant locations in visual cortex are coherent at the mesoscale of population activity, but coherence is largely absent at the microscale of the membrane potential of neurons.
NEW & NOTEWORTHY Coherent oscillatory neural activity has long been hypothesized as a potential mechanism for communication across locations in the brain. In this study we confirm the existence of coherent oscillations at the mesoscale of integrated cortical population activity. However, at the microscopic level of neurons, we find no evidence for coherence among oscillatory membrane potential fluctuations...
Source: Journal of Neurophysiology - November 1, 2017 Category: Neurology Authors: Hoseini, M. S., Pobst, J., Wright, N., Clawson, W., Shew, W., Wessel, R. Tags: Research Articles Source Type: research
Altered tactile sensitivity in children with attention-deficit hyperactivity disorder
This study demonstrates impaired tactile processing in children with ADHD, on some, but not all tasks (showing this is not just due to attention), related to impaired cortical mechanisms. Furthermore, both IQ and soft motor skill abnormalities (common in ADHD) are correlated with tactile abnormalities. (Source: Journal of Neurophysiology)
Source: Journal of Neurophysiology - November 1, 2017 Category: Neurology Authors: Puts, N. A. J., Harris, A. D., Mikkelsen, M., Tommerdahl, M., Edden, R. A. E., Mostofsky, S. H. Tags: Research Articles Source Type: research
Limbic-motor integration by neural excitations and inhibitions in the nucleus accumbens
We report that cue-evoked neural responses in the NAc form a likely physiological substrate for its limbic-motor integration function. Across task contexts, individual NAc neurons in behaving rats robustly encode the reward-predictive qualities of a cue, as well as the probability of behavioral response to the cue, as coexisting components of the neural signal. In addition, cue-evoked activity encodes spatial and locomotor aspects of the behavioral response, including proximity to a reward-associated target and the latency and speed of approach to the target. Notably, there are important limits to the ability of NAc neuron...
Source: Journal of Neurophysiology - November 1, 2017 Category: Neurology Authors: Morrison, S. E., McGinty, V. B., du Hoffmann, J., Nicola, S. M. Tags: Research Articles Source Type: research
Altered visual strategies and attention are related to increased force fluctuations during a pinch grip task in older adults
The purpose of the study was to determine the visual strategies used by older adults during a pinch grip task and to assess the relations between visual strategy, deficits in attention, and increased force fluctuations in older adults. Eye movements of 23 older adults (>65 yr) were monitored during a low-force pinch grip task while subjects viewed three common visual feedback displays. Performance on the Grooved Pegboard test and an attention task (which required no concurrent hand movements) was also measured. Visual strategies varied across subjects and depended on the type of visual feedback provided to the subjects....
Source: Journal of Neurophysiology - November 1, 2017 Category: Neurology Authors: Keenan, K. G., Huddleston, W. E., Ernest, B. E. Tags: Research Articles Source Type: research
Characterization of decision commitment rule alterations during an auditory change detection task
In this study we use a novel change detection paradigm to examine how subjects control this balance when invoking different decision stopping rules. The task design allows us to estimate the temporal weighting of sensory information for the decisions, and we find that different stopping rules did not result in systematic differences in that weighting. We also find bidirectional post-error alterations of decision strategy that depend on the type of error and effectively reduce the probability of making consecutive mistakes of the same type. This is a generalization to change detection tasks of the widespread observation of ...
Source: Journal of Neurophysiology - November 1, 2017 Category: Neurology Authors: Johnson, B., Verma, R., Sun, M., Hanks, T. D. Tags: Research Articles Source Type: research
Effective assessments of electroencephalography during stroke recovery: contemporary approaches and considerations
Stroke is one of the leading causes of permanent disability worldwide, relying conventionally on extended periods of physiotherapy to recover functional ability. While neuroimaging techniques and emerging neurorehabilitation paradigms have advanced our understanding of pathophysiological mechanisms underlying stroke, recent evidence has renewed focus on quantifying features of cortical activity present in electroencephalography recordings to greatly enhance our understanding of stroke treatment and recovery. This Neuro Forum article reviews these key advances and discusses the importance of quantifying electroencephalograp...
Source: Journal of Neurophysiology - November 1, 2017 Category: Neurology Authors: Iyer, K. K. Tags: Neuro Forum Source Type: research
Modulation of corticospinal input to the legs by arm and leg cycling in people with incomplete spinal cord injury
This study aimed to demonstrate the importance of arm movements in modulating the corticospinal drive to the legs. It provides direct evidence in humans that active movement of the arms could facilitate corticospinal transmission to the legs and, for the first time, shows that facilitation is absent after spinal cord injury. Active engagement of the arms in lower limb rehabilitation increased the excitability of the corticospinal pathway and may produce more effective improvement in leg function. (Source: Journal of Neurophysiology)
Source: Journal of Neurophysiology - October 17, 2017 Category: Neurology Authors: Zhou, R., Alvarado, L., Kim, S., Chong, S. L., Mushahwar, V. K. Tags: Research Articles Source Type: research
Perception of the dynamic visual vertical during sinusoidal linear motion
The vestibular system provides information for spatial orientation. However, this information is ambiguous: because the otoliths sense the gravitoinertial force, they cannot distinguish gravitational and inertial components. As a consequence, prolonged linear acceleration of the head can be interpreted as tilt, referred to as the somatogravic effect. Previous modeling work suggests that the brain disambiguates the otolith signal according to the rules of Bayesian inference, combining noisy canal cues with the a priori assumption that prolonged linear accelerations are unlikely. Within this modeling framework the noise of t...
Source: Journal of Neurophysiology - October 17, 2017 Category: Neurology Authors: Pomante, A., Selen, L. P. J., Medendorp, W. P. Tags: Research Articles Source Type: research
