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DeSouza, J. F.

Publications and source records attributed to DeSouza, J. F..

2 recordsLinked to original sources

Visual signals suppress Alpha Power Increases & Frequency Decreases before and after a Mindfulness Meditation Intervention for Problem Gambling

The use of mindfulness meditation (MM) in the treatment of problem gambling (PG), has been used effectively for over five years. However, the neural mechanisms responsible for the improvements are unknown. The literature describes healthy individuals with an increase in alpha power and a decrease in alpha frequency after eight weeks of mindfulness meditation, but it is unknown if changes are similar amongst individuals with PG. Using resting-state electroencephalography (rsEEG), we measured the changes in alpha oscillations before and after an eight-week mindfulness meditation intervention (MMi) and a pre/ post-five-minute mindfulness meditation body scan (MMb). For people with PG, we observed an increase in alpha power and decreased alpha peak frequency after the MMi, while the inverse was true for the MMb. The most considerable alpha rhythm changes occurred in the frontal and temporal lobes, areas sensitive to reward and sensory processing in PG. Our observed changes may reflect theories that MMi for PG may improve attentional control as hypothesized by previous research in alpha oscillations and cue-reward processing.

neuroscience

Neuromagnetic signatures of the spatiotemporal transformation for reaching

Movement planning involves transforming the sensory goal representation into a command in motor coordinates. Surprisingly, the real-time dynamics of sensorimotor transformations at the whole brain level remain unknown, in part due to the spatiotemporal limitations of fMRI and neurophysiological recordings. Here, we used magnetoencephalography (MEG) during pro-/anti-wrist pointing to determine (1) the cortical areas involved in transforming visual signals into appropriate hand motor commands, and (2) how this transformation occurs in real time, both within and across the regions involved. We computed sensory, motor, and sensorimotor indices in 16 bilateral brain regions for direction coding based on hemispherically lateralized de/synchronization in the (7-15Hz) and {beta} (15-35Hz) bands. We found a visuomotor progression, from pure sensory codes in early occipital-parietal areas, to a temporal transition from sensory to motor coding in the majority of parietal-frontal sensorimotor areas, to a pure motor code, in both the and {beta} bands. Further, the timing of these transformations revealed a top-down pro/anti cue influence that propagated backwards from frontal through posterior cortical areas. These data directly demonstrate a progressive, real-time transformation both within and across the entire occipital-parietal-frontal network that follows specific rules of spatial distribution and temporal order.

neuroscience