Motor Cortex Research Papers - Academia.edu (original) (raw)

Reading involves phonologic decoding, in which readers ``sound out'' a word; orthographic decoding, in which readers recognize a word visually, as in ``sight reading''; and comprehension. Because reading can involve... more

Reading involves phonologic decoding, in which readers ``sound out'' a word; orthographic decoding, in which readers recognize a word visually, as in ``sight reading''; and comprehension. Because reading can involve multiple processes, dyslexia might be a heterogeneous disorder. This study investigated behavior and gross lobar anatomy in subtypes of dyslexic and control subjects. Subjects aged 18 to 25 years with identified reading problems and a group of healthy controls were given cognitive and behavioral tests and volumetric brain magnetic resonance imaging (MRI). Because atypical cerebral laterality has been proposed as a potential neural risk for dyslexia, dyslexic and control subjects were compared on anatomy of gross lobar regions. On asymmetry quotients, no significant differences were found between groups. Examination of the percentage of total brain volume of each structure revealed that control and dyslexic subjects were significantly different (P = .018)....

Muscle fatigue has been known to differentially affect the activation level of the primary motor cortices (MIs) of the brain's two hemispheres. Whether this fatigue-related decoupling influence on the motor cortical signals extends beyond... more

Muscle fatigue has been known to differentially affect the activation level of the primary motor cortices (MIs) of the brain's two hemispheres. Whether this fatigue-related decoupling influence on the motor cortical signals extends beyond the motor action to the after-fatigue-task resting state is unknown. This question can be addressed by analyzing functional connectivity (FC) of low-frequency oscillations of resting-state functional MRI (fMRI) signals of the MIs. Low-frequency oscillations (<0.08 Hz) have been detected in many fMRI studies and appear to be synchronized between functionally related areas. These patterns of FC have been shown to differ between normal and various pathological states. The purpose of this study was to examine muscle fatigue-induced resting-state interhemispheric motor cortex FC changes in healthy subjects. We hypothesized that muscle fatigue would create a temporary “disrupted state” in the brain, and would decrease resting state interhemispheric motor cortical FC. Ten healthy subjects performed repetitive unilateral handgrip contractions that induced significant muscle fatigue, with resting state fMRI data collected before and after the task. After excluding two subjects due to gross head motion, interhemispheric motor cortex FC was assessed by cross-correlating the MI fMRI signal time courses. We found that the number of significant interhemispheric correlations in the MI fMRI signals decreased significantly after the performance of the fatigue task. These results suggest that resting state interhemispheric motor cortex FC may be used as an index of recovery from fatigue.

Transcranial alternating current stimulation (tACS) is a non-invasive stimulation technique for shaping neuroplastic processes and possibly entraining ongoing neural oscillations in humans. Despite the growing number of studies using... more

Transcranial alternating current stimulation (tACS) is a non-invasive stimulation technique for shaping neuroplastic processes and possibly entraining ongoing neural oscillations in humans. Despite the growing number of studies using tACS, we know little about the procedural sensations caused by stimulation. In order to fill this gap, we explored the cutaneous sensation and phosphene perception during tACS. Twenty healthy participants took part in a randomized, single-blinded, sham-controlled study, where volunteers received short duration stimulation at 1.0 mA intensity between 2 to 250 Hz using the standard left motor cortex-contralateral supraorbital montage. We recorded the perception onset latency and the strength of the sensations assessed by visual rating scale as dependent variables. We found that tACS evoked both cutaneous sensation and phosphene perception in a frequency-dependent manner. Our results show that the most perceptible procedural sensations were induced in the ...