Transcranial direct current stimulation (tDCS) is a non-invasive tool, which effectively modulates behavior, and related brain activity. When applied to the primary motor cortex (M1), tDCS affects ...motor function, enhancing or decreasing motor learning and action execution in both healthy participants and brain-damaged patients. Evidence in both humans and macaques has shown that multiple cortical areas beyond M1 are involved in controlling and guiding movement, including the posterior parietal cortex (PPC) and the premotor cortex (PMC). Recent evidence in healthy humans and brain-damaged showed that the modulation of cortical excitability of PPC and PMC can be used to improve action-related cognitive processes, highlighting interesting hemispheric asymmetries. Indeed, the anodal tDCS of the PPC of the left hemisphere can be used to selectively facilitate action planning and gesture recognition, while excitability shifts within the PM of the right hemisphere affects action monitoring and awareness. These results indicate that a left parietal system contributes to the activation of motor engrams (such as the pattern and sequence of movements needed to execute an action), while left premotor areas are mostly involved in the operation of the motor monitoring, namely detecting the mismatch between the actual motor output and intended action goal. The final relay is M1, which converts the motor program into the desired action. In conclusion, this evidence offers a functional and anatomical framework for understanding how selective neuromodulatory effects on different higher-level (action planning and monitoring) stages of motor processing can be induced by tDCS in order to optimize motor control and learning. This knowledge opens up novel perspectives in the neurorehabilitation of stroke patients with apraxic and motor awareness disorders, which represents a considerable burden for motor and cognitive rehabilitation.
A dynamic encryption scheme is demonstrated based on chirp z-transform (CZT). The novel design of this setup allows us to protect multiple images in a multiplexed format and fully recover them ...without the influence of crosstalk and sample noise. The encoding stage is implemented using the 2D CZT and a Fourier lens. The CZT works with proper frequency parameters to control the position and size of the input frequency spectrum. The accurate positioning leads to an efficient packing of the multiplexed images and a remarkable improvement of the signal-to-noise ratio of the decrypted pictures. The introduction of the CZT in the field of encryption is significant, since it can expand the functionality to a dynamic regime of optical and digital architectures for static encoding. We validated the feasibility of our proposal with the encryption and decryption of a color image sequence and a set of binary images.
Abstract
The field of transcranial electrical stimulation (tES) has experienced significant growth in the past 15 years. One of the tES techniques leading this increased interest is transcranial ...direct current stimulation (tDCS). Significant research efforts have been devoted to determining the clinical potential of tDCS in humans. Despite the promising results obtained with tDCS in basic and clinical neuroscience, further progress has been impeded by a lack of clarity on international regulatory pathways. Therefore, a group of research and clinician experts on tDCS were convened to review the research and clinical use of tDCS. This report reviews the regulatory status of tDCS and summarizes the results according to research, off-label, and compassionate use of tDCS in the following countries: Australia, Brazil, France, Germany, India, Iran, Italy, Portugal, South Korea, Taiwan, and the US. Research use, off label treatment, and compassionate use of tDCS are employed in most of the countries reviewed in this study. It is critical that a global or local effort is organized to pursue definite evidence to either approve and regulate or restrict the use of tDCS in clinical practice on the basis of adequate randomized controlled treatment trials.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Background and purpose
Neuromodulation is a promising approach to increasing motor recovery in stroke; however, to date, there is a scarcity of evidence documenting the clinical potential of ...transcranial direct current stimulation (tDCS) administered in the acute phase of stroke. The present study aims to examine the clinical effects of a treatment involving the application of tDCS in the acute stage post‐stroke.
Methods
This was a randomized, double‐blind, sham‐controlled trial. A cohort of 32 stroke patients with severe motor impairment underwent 5 days of treatment with real or sham bi‐hemispheric tDCS over the motor cortex. During the treatment, tDCS was applied twice per day (two daily applications each of 15 min), starting 48 to 72 h after stroke onset.
Results
We found statistically significant improvements after both real and sham tDCS treatments in primary (hand grip strength, Motricity Index) and secondary (National Institutes of Health Stroke Scale score, Barthel Index) outcomes. Patients receiving real tDCS showed a larger improvement of upper‐limb muscle strength at the end of treatment phase; this advantage was no longer present after 6 months.
Conclusions
Transcranial direct current stimulation may be used to accelerate the rate of upper‐limb motor recovery during the spontaneous recovery period.
Introduction Motor execution, planning, and learning are altered by transcranial Direct Current Stimulation (tDCS). The potential of this technique for modulating action monitoring and awareness has ...not been explored so far. Optimal motor control relies on internal representations of the intended, predicted, and actual action. The brain is equipped with a “comparator” system, which monitors and detects the congruence between planned and performed movements; based on this comparison motor awareness is constructed. Objectives The study aimed at disrupting motor monitoring and awareness through the neuromodulation of the activity of the Premotor (PMC) and Posterior Parietal (PPC) cortices of the right hemisphere. Methods Real or sham cathodal tDCS (1.5 mA, 6 min) were applied over the right PMC or PPC in 22 healthy participants (8 right-handed men, mean age = 25.5 years). Before and after tDCS, participants performed a 2-digit sequence motor task and rated how well they had executed it on a 5-item questionnaire (Motor Performance Awareness Questionnaire – MPAQ). During the task performed after tDCS, online single-pulse Transcranial Magnetic Stimulation (sTMS) was applied to the right primary motor cortex (M1), contralateral to the executing left hand, with the aim of evoking involuntary muscles twitches, interfering with motor execution. Results Cathodal tDCS to PMC (but not sham tDCS or PPC tDCS) impaired motor monitoring, making participants unconfident about their explicit judgments on their motor performance (MPAQ, tDCS by Time interaction, F = 3.74, pr = .59, p = .004) and PPC ( r = .69, p = .001) tDCS, but not after PMC tDCS ( r = .22, p = .32). Conclusion Cathodal tDCS to the right PMC disrupts the participants’ ability to evaluate their motor performance reliably, disrupting self-confidence about own motor performance and also the ability to detect the discrepancy between their planned and performed movements.
It is widely known that humans have a tendency to imitate each other and that appropriate modulation of automatic imitative behaviors has a crucial function in social interactions. Gilles de la ...Tourette syndrome (GTS) is a childhood-onset neuropsychiatric disorder characterized by motor and phonic tics. Apart from tics, patients with GTS are often reported to show an abnormal tendency to automatically imitate others' behaviors (i.e., echophenomena), which may be related to a failure in top-down inhibition of imitative response tendencies. The aim of the current study is to explore the top-down inhibitory mechanisms on automatic imitative behaviors in youngsters with GTS. Error rates and reaction times from 32 participants with GTS and 32 controls were collected in response to an automatic imitation task assessing the influence of observed movements displayed in the first-person perspective on congruent and incongruent motor responses. Results showed that participants with GTS had higher error rates than controls, and their responses were faster than those of controls in incompatible stimuli. Our findings provide novel evidence of a key difference between youngsters with GTS and typically developing participants in the ability to effectively control the production of own motor responses to sensory inputs deriving from observed actions.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
► The sensory-motor grounded representation is involved in comprehension. ► The motor component of the verb seems preserved in fictive and metaphorical motion. ► The activation of motor ...representations is influenced by the linguistic context.
We used Transcranial Magnetic Stimulation (TMS) to assess whether reading literal, non-literal (i.e., metaphorical, idiomatic) and fictive motion sentences modulates the activity of the motor system. Sentences were divided into three segments visually presented one at a time: the noun phrase, the verb and the final part of the sentence. Single pulse-TMS was delivered at the end of the sentence over the leg motor area in the left hemisphere and motor evoked potentials (MEPs) were recorded from the right gastrocnemius and tibialis anterior muscles. MEPs were larger when participants were presented with literal, fictive and metaphorical motion sentences than with idiomatic motion or mental sentences. These results suggest that the excitability of the motor system is modulated by the motor component of the verb, which is preserved in fictive and metaphorical motion sentences.
Introduction Mirror-touch synaesthesia (MTS) is the condition in which the view of a touch delivered to another person’s body (but not to objects) elicits subjective conscious tactile sensations on ...own body. At a neurophysiological level, MTS has been associated to an unusual hyper-activation of the tactile mirror system (Blakemore et al., 2005; Ward and Banissy, 2015). Recent studies showed that increasing the excitability of primary somatosensory cortex (S1), by mean of non-invasive brain stimulation techniques, induces MTS-like responses even in non-synesthetes in a vision-touch spatial congruity task (Bolognini et al., 2013, 2014). However, it is not clear yet whether synaesthesia-like sensations were induced through direct modulation of S1, or by modulating the functional interplay between SI and other connected brain regions. Objectives This study aims at clarifying this issue by exploring changes in S1 cortical excitability and connectivity by means of TMS-EEG technique. Materials and methods 10 healthy volunteers participated to the study. 4 TMS-EEG recordings were performed; in each 180 TMS single pulses were delivered to right S1 while participants were exposed, in a random order, to three conditions: (i) experiencing a real touch on the left hand (touch), the view of video-clips depicting either (ii) a touch to another person’ hand (mirror-touch) or (iii) a touch to a leaf (control stimulus). Concomitant EEG was recorded by a 60 channels cap. TMS pulses were delivered at two SOAs: 50 ms or 150 ms from stimulus onset. Results In the touch condition, TMS at 50 ms elicited greater TEPs than at 150 ms. Conversely, in the mirror-touch condition, TEPs increased at 150 ms as compared to 50 ms SOA. No difference across SOAs were present instead for TEPs in the control condition. Comparing the three conditions, the greatest mean TEPs on right S1 occurred in the touch condition, followed by the mirror-touch, both eliciting greater TEP than the control condition. Conclusions Preliminary results suggest a rise of S1 cortical excitability at 50 ms SOA in the touch condition, i.e. when the tactile stimulus processing is taking place, and, crucially, at 150 ms SOA in the mirror-touch condition.
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