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Effects of Transcranial Direct Current Stimulation (tDCS) Over the Frontal Polar Area on Motor and Executive Functions in Parkinson’s Disease; A Pilot Study

Effects of Transcranial Direct Current Stimulation (tDCS) Over the Frontal Polar Area on Motor and Executive Functions in Parkinson’s Disease; A Pilot Study

Article Date: 2018-07-30 (Revised: 2018-08-16)
Authors: Ishikuro K, Dougu N, Nukui T, Yamamoto M, Nakatsuji Y, Kuroda S, Matsushita I, Nishimaru H, Araujo MFP, Nishijo H
PMID Link: 30104971


Journal Information
Title: Frontiers in aging neuroscience
Abbreviation: Front Aging Neurosci
Volume: 10
Issue:
Date: 2018-01-01
Citation: Front Aging Neurosci 2018;10:231

Abstract

Parkinson’s disease (PD) is a neurodegenerative disorder with motor and non-motor symptoms due to degeneration of dopaminergic neurons. The current pharmacological treatments induce complications associated with long-term use. However, current stimulation techniques for PD treatment, such as deep brain stimulation (DBS), are too invasive. In this context, non-invasive brain stimulation including transcranial direct current stimulation (tDCS) may be a safe and effective alternative treatment for PD. We previously reported that anodal tDCS over the frontal polar area (FPA) improved motor functions in heathy subjects. Therefore, in the present study, effects of tDCS over the FPA on motor and cognitive functions of PD patients were analyzed. Nine PD patients (3 men and 6 women) participated in this cross over study with three tDCS protocols; anodal, cathodal or sham tDCS over the FPA. Each tDCS protocol was applied for 1 week (5 times/week). Before and after each protocol, motor and cognitive functions of the patients were assessed using Unified PD Rating Scale [UPDRS (part III: motor examination)], Fugl Meyer Assessment set (FMA), Simple Test for Evaluating hand Function (STEF) and Trail Making Test A (TMT-A). The results indicated that anodal stimulation significantly decreased scores of motor disability in UPDRS-III compared with sham and cathodal stimulation, and significantly increased scores of motor functions in FMA compared with sham stimulation. Furthermore, anodal stimulation significantly decreased time to complete a motor task requiring high dexterity in STEF compared with those requiring low and medium levels of dexterity. In addition, anodal stimulation significantly decreased time to complete the TMT-A task, which requires executive functions, compared with sham stimulation. To the best of our knowledge, this is the first clinical research reporting that tDCS over the FPA successfully improved the motor and non-motor functions in PD patients. These findings suggest that tDCS over the FPA might be a useful alternative for the treatment of PD patients.

tDCS Modulatory Effect on Reading Processes: A Review of Studies on Typical Readers and Individuals With Dyslexia

tDCS Modulatory Effect on Reading Processes: A Review of Studies on Typical Readers and Individuals With Dyslexia

Article Date: 2018-07-31 (Revised: 2018-08-17)
Authors: Cancer A, Antonietti A
PMID Link: 30108491


Journal Information
Title: Frontiers in behavioral neuroscience
Abbreviation: Front Behav Neurosci
Volume: 12
Issue:
Date: 2018-01-01
Citation: Front Behav Neurosci 2018;12:162

Abstract

The possibility to use non-invasive brain stimulation to modulate reading performance in individuals with developmental dyslexia (DD) has been recently explored by few empirical investigations. The present systematic review includes nine studies which have employed transcranial direct current stimulation (tDCS) aiming at improving reading abilities in both typical readers and individuals with DD. Anodal tDCS over the left temporo-parietal cortex-a region which is typically involved in phonological and orthographic processing during reading tasks and underactive in individuals with DD-was the most frequently used montage. The majority of studies employing such stimulation protocol showed significant improvement in differential reading subprocesses. More precisely, word decoding was improved in adult readers, whereas non-word and low-frequency word reading in younger individuals. Furthermore, tDCS was found to be specifically effective in poor readers and individuals with DD rather than typical readers, in spite of the specific brain region targeted by the stimulation; Left frontal, left temporo-parietal, and right cerebellar tDCS failed to modulate reading in already proficient readers. Overall, tDCS appears to be a promising remedial tool for reading difficulties, even when applied to younger populations with reading problems. Further empirical evidence is needed to confirm the potential of neuromodulation as a successful intervention method for DD.

The effects of add-on fronto-temporal transcranial direct current stimulation (tDCS) on auditory verbal hallucinations, other psychopathological symptoms and insight in schizophrenia: A randomized, double-blind, sham-controlled trial

The effects of add-on fronto-temporal transcranial direct current stimulation (tDCS) on auditory verbal hallucinations, other psychopathological symptoms and insight in schizophrenia: A randomized, double-blind, sham-controlled trial

Article Date: 2018-08-09 (Revised: 2018-08-14)
Authors: Chang CC, Tzeng NS, Chao CY, Yeh CB, Chang HA
PMID Link: 30107404


Journal Information
Title: The international journal of neuropsychopharmacology
Abbreviation: Int. J. Neuropsychopharmacol.
Volume:
Issue:
Date: 2018-08-09
Citation: Int. J. Neuropsychopharmacol. 2018 Aug;

Abstract

Background: The efficacy of fronto-temporal transcranial direct current stimulation (tDCS) in treating auditory verbal hallucinations (AVHs) and other psychopathological symptoms of schizophrenia patients has been examined in a small number of clinical trials with limited sample sizes, but the results are mixed. Fronto-temporal tDCS has also been demonstrated to enhance patients’ insight into their mental illness in an open-label pilot study. The current investigation aimed to investigate the therapeutic effects of fronto-temporal tDCS on the severity of AVHs, other schizophrenia symptoms and insight in a large double blind, randomized, sham-controlled trial.

Methods: Sixty patients with medication-refractory AVHs were randomized over two conditions: tDCS with 2-mA, twice-daily sessions for five consecutive days, with anodal stimulation to the left prefrontal cortex and cathodal stimulation to the left temporo-parietal junction, and sham treatment.

Results: Fronto-temporal tDCS failed to cause significant changes in the severity of AVHs and other schizophrenia symptoms. The levels of insight into illness (effect size = 0.511, p < 0.001) and positive symptoms (effect size = 0.781, p < 0.001) were largely promoted by 5 days of tDCS relative to sham treatment. The beneficial effects on the two insight dimensions remained one month after tDCS.

Conclusions: Fronto-temporal tDCS is not more effective for AVHs and other schizophrenia symptoms than sham treatment. But the results of tDCS-associated improvement in awareness of illness and positive symptoms show promise and provide a new direction for future research into insight promotion interventions in schizophrenia.

High-definition transcranial direct current simulation (HD-tDCS) for persistent auditory hallucinations in schizophrenia

High-definition transcranial direct current simulation (HD-tDCS) for persistent auditory hallucinations in schizophrenia

Article Date: 2018-08-09 (Revised: 2018-08-17)
Authors: Sreeraj VS, Dinakaran D, Parlikar R, Chhabra H, Selvaraj S, Shivakumar V, Bose A, Narayanaswamy JC, Venkatasubramanian G
PMID Link: 30110662


Journal Information
Title: Asian journal of psychiatry
Abbreviation: Asian J Psychiatr
Volume: 37
Issue:
Date: 2018-08-09
Citation: Asian J Psychiatr 2018 Aug;37:46-50

Abstract

Conventional transcranial Direct Current Stimulation (tDCS) has been reported to alleviate persistent auditory hallucinations (AH) in schizophrenia as an add-on intervention. High-Definition tDCS (HD-tDCS), an optimized form of tDCS, has the potential for more focalized neuromodulation. In this study, add-on HD-tDCS (5 days twice daily session with 2-mA cathodal current on left temporo-parietal junction) using 4 × 1 ring montage significantly reduced persistent AH (t = 3.6;p < 0.01) in schizophrenia patients (N = 19). Add-on HD-tDCS has promising potential to treat persisting AH in schizophrenia. This needs further systematic research.

The effect of cathodal transcranial direct current stimulation during rapid eye-movement sleep on neutral and emotional memory

The effect of cathodal transcranial direct current stimulation during rapid eye-movement sleep on neutral and emotional memory

Article Date: 2018-07-18 (Revised: 2018-08-17)
Authors: Johnson JM, Durrant SJ
PMID Link: 30109059


Journal Information
Title: Royal Society open science
Abbreviation: R Soc Open Sci
Volume: 5
Issue: 7
Date: 2018-07-01
Citation: R Soc Open Sci 2018 Jul;5(7):172353

Abstract

Sleep-dependent memory consolidation has been extensively studied. Neutral declarative memories and serial reaction time task (SRTT) performance can benefit from slow-wave activity, characterized by less than 1 Hz frequency cortical slow oscillations (SO). Emotional memories can benefit from theta activity, characterized by 4-8 Hz frequency cortical oscillations. Applying transcranial direct current stimulation (tDCS) during sleep entrains specific frequencies to alter sleep architecture. When applying cathodal tDCS (CtDCS), neural inhibition or excitation may depend on the waveform at the applied frequency. A double dissociation was predicted, with CtDCS at SO frequency improving neutral declarative memory and SRTT performance, and theta frequency CtDCS inhibiting negative emotional memory. Participants completed three CtDCS conditions (Theta: 5 Hz, SO: 0.75 Hz and control: sham) and completed an SRTT and word recognition task pre- and post-sleep, comprising emotional and neutral words to assess memory. In line with predictions, CtDCS improved neutral declarative memory when applied at SO frequency. When applied at theta frequency, no negative emotional word memory impairment was found but a positive association was found between post-stimulation theta power and emotional word recognition. SRTT performance was also not altered by either CtDCS frequency. Future studies should investigate overnight theta CtDCS and examine the effects of CtDCS during and after stimulation.