Does transcranial direct current stimulation during writing alleviate upper limb freezing in people with Parkinson’s disease? A pilot study

Transcranial direct current stimulation (tDCS) over the primary motor cortex (M1) can boost motor performance in Parkinson’s disease (PD) when it is applied at rest. However, the potential supplementary therapeutic effect of the concurrent application of tDCS during the training of motor tasks is largely unknown. The present study examined the effects of tDCS on upper limb motor blocks during a freezing-provoking writing task (the funnel task) requiring up- and down-stroke movements at alternating amplitudes. Ten PD patients and 10 age-matched controls underwent two sessions of writing combined with 20 min of anodal or sham tDCS on the left M1 in a randomized cross-over design. The primary outcome was the number of upper limb freezing episodes during five trials of the funnel task on a touch-sensitive tablet. PD patients showed a significant reduction in freezing episodes during tDCS compared to sham. No effects of tDCS were found for the amplitude, variability and speed of the strokes outside the freezing episodes. However, patients who reported freezing episodes in daily life (N = 6) showed a beneficial effect of tDCS on stroke characteristics. These results indicate a subgroup-dependent variability in response to non-invasive brain stimulation applied during the performance of motor tasks in PD. This warrants future studies to examine tDCS as an adjuvant tool for training programs aimed to reduce motor deficits related to freezing.     

An acute application of transcranial random noise stimulation does not enhance motor skill acquisition or retention in a golf putting task

Transcranial random noise stimulation (tRNS) is a brain stimulation technique that has been shown to increase motor performance in simple motor tasks. The purpose was to determine the influence of tRNS on motor skill acquisition and retention in a complex golf putting task. Thirty-four young adults were randomly assigned to a tRNS group or a SHAM stimulation group. Each subject completed a practice session followed by a retention session. In the practice session, subjects performed golf putting trials in a baseline test block, four practice blocks, and a post test block. Twenty-four hours later subjects completed the retention test block. The golf putting task involved performing putts to a small target located 3 m away. tRNS or SHAM was applied during the practice blocks concurrently with the golf putting task. tRNS was applied over the first dorsal interosseus muscle representation area of the motor cortex for 20 min at a current strength of 2 mA. Endpoint error and endpoint variance were reduced across the both the practice blocks and the test blocks, but these reductions were not different between groups. These findings suggest that an acute application of tRNS failed to enhance skill acquisition or retention in a golf putting task.     

The effects of transcranial direct current stimulation (tDCS) on multitasking performance and oculometrics

Multitasking is the ability to perform more than one task simultaneously. The need to multitask is common in many industries especially within the military with tasks such as air traffic controllers, cyber defense operators and image analysts. However, as the time on task increases, information throughput can become overwhelming resulting in a performance decrement. Through task prioritizing, the operator is able to maintain performance on specific subtasks in which they selected as high importance while other subtasks experience a decrement. The objective of this study was to evaluate the effects of transcranial direct current stimulation (tDCS) applied to the left dorsolateral prefrontal cortex (ldLPFC) on information processing capabilities to improve individual and overall multitasking performance while performing the multi-attribute task battery (MATB). Two groups of 8 participants each received either 2 mA of anodal or sham tDCS while performing MATB. In addition, eye tracking was implemented to record eye movement patterns. In doing so, we were able to determine how much time the operator allocated to each of the subtasks within MATB and how their task priorities changed as workload demands increased. The findings provided evidence that 2 mA of anodal tDCS during MATB significantly improved overall information throughput compared to the sham group. With respect to the individual subtasks, communication and system monitoring displayed the greatest enhancement with anodal tDCS. Our data suggests that tDCS could be a useful tool to enhance information processing capabilities during a multitasking paradigm resulting in improved processing capabilities and information throughput.     

经颅电刺激与视功能调控

经颅电刺激(Transcranial Electrical Stimulation, TES)通过电极将特定模式的低强度电流作用于大脑头皮以调控皮层活动, 是一种非侵入、无创的神经刺激方法。根据刺激电流的模式的不同, TES分为经颅直流电刺激(tDCS), 经颅交流电刺激(tACS)和经颅随机电刺激(tRNS)。TES能对视功能诸如光幻视阈值、视野、对比敏感度、视知觉运动等进行一定程度上的调控, 并且能够与传统的视觉知觉学习训练相结合以调控视觉功能。对于不同的视觉功能, 不同的TES参数和模式的调控效果有所不同。     

The effects of fine motor movement and tactile stimulation on the math problem solving of students with attention problems

This study evaluated the effectiveness of fine motor physical activity with tactile stimulation during two conditions of math problem solving, visual and auditory. Eight 4th and 5th grade students with attention problems participated. Using an alternating treatments design, students solved as many math story problems as they could, presented on worksheets or verbally during two conditions, with and without tactile stimulation during 20 min. Motor behavior, recorded from videotape, and number of correctly completed word problems were measured. Results suggest that fine motor manipulation of a tactile stimulation object reduced excessive motor movement and increased task completion of students with attention problems.     

刺激呈现时间对责任推论影响的实验研究

在社会认知中,由于所呈现的刺激都具有复杂的社会意义,其必然会在被试的心理上引起复杂的反应。实验通过对刺激时间的控制来了解个体在知觉阶段与记忆阶段所进行的责任推论是否存在差异。结果表明,工读生在刺激快速呈现时的责任判断与刺激缓慢呈现时的责任推论存在显著差异。     

Magnetic stimulation studies of foveal representation

The right and left visual fields each project to the contralateral cerebral hemispheres, but the extent of the functional overlap of the two hemifields along the vertical meridian is still under debate. After presenting the spatial, temporal, and functional specifications of Transcranial Magnetic Stimulation (TMS), we show that TMS is particularly suitable to study the question of foveal representation as it allows one to study the effects of selective disruption of left or right hemisphere functions on the processing of centrally presented stimuli. Future strategies for the use of TMS in further tests of visual word recognition are suggested.     

Eyeblink conditioning in rats using pontine stimulation as a conditioned stimulus

Previous studies using rabbits and ferrets found that electrical stimulation of the pontine nuclei or middle cerebellar peduncle could serve as a conditioned stimulus (CS) in eyeblink conditioning (Bao, Chen, & Thompson, 2000; Hesslow, Svensson, & Ivarsson, 1999; Steinmetz, 1990; Steinmetz, Lavond, & Thompson, 1985; 1989; Steinmetz et al., 1986; Tracy, Thompson, Krupa, & Thompson, 1998). The current study used electrical stimulation of the pontine nuclei as a CS to establish eyeblink conditioning in rats. The goals of this study were to develop a method for directly activating the CS pathway in rodents and to compare the neural circuity underlying eyeblink conditioning in different mammalian species. Rats were given electrical stimulation through a bipolar electrode implanted in the pontine nuclei paired with a periorbital shock unconditioned stimulus (US). Paired training was followed by extinction training. A subset of rats was given a test session of paired training after receiving an infusion of muscimol into the anterior interpositus nucleus. Rats given paired presentations of the stimulation CS and US developed CRs rapidly and showed extinction. Muscimol infusion prior to the test session resulted in a reversible loss of the eyeblink CR. The results demonstrate that electrical stimulation of the pontine nuclei can be used as a CS in rodents and that the CS pathway is similar in rats, rabbits, and ferrets. In addition, the loss of CRs following muscimol inactivation shows that the conditioning produced with pontine stimulation depends on cerebellar mechanisms.     

Playing on the typewriter, typing on the piano: manipulation knowledge of objects

Two experiments investigated sensory/motor-based functional knowledge of man-made objects: manipulation features associated with the actual usage of objects. In Experiment 1, a series of prime-target pairs was presented auditorily, and participants were asked to make a lexical decision on the target word. Participants made a significantly faster decision about the target word (e.g. ‘typewriter’) following a related prime that shared manipulation features with the target (e.g. ‘piano’) than an unrelated prime (e.g. ‘blanket’). In Experiment 2, participants' eye movements were monitored when they viewed a visual display on a computer screen while listening to a concurrent auditory input. Participants were instructed to simply identify the auditory input and touch the corresponding object on the computer display. Participants fixated an object picture (e.g. “typewriter”) related to a target word (e.g. ‘piano’) significantly more often than an unrelated object picture (e.g. “bucket”) as well as a visually matched control (e.g. “couch”). Results of the two experiments suggest that manipulation knowledge of words is retrieved without conscious effort and that manipulation knowledge constitutes a part of the lexical-semantic representation of objects.