Transcranial Direct Current Stimulation (tDCS): A Critical Analysis Of The Process And Use In Anatomical Neuroscience

Types of Stimulation in tDCS Administration

The Transcranial direct current stimulation (tDCS) is regarded as one of the forms of neuromodulation which includes the delivery of low direct current at a constant pace via electrodes on the head. According to Bennabi and Haffen (2018), it is a popular method of brain stimulation that is used for modulating cortical excitability to produce facilitator or inhibitory effects over different human behaviours. There are notably three kinds of stimulation present in a tDCS administer which are- positive, negative and sham. In a standard set-up of the tDCS method initially, a target is selected along with a reference electrode. The desired location for passing the electrodes are supposedly needed to be positioned are decided before attaching the electrodes to the scalp, gradually the experimenter ensures that the patient’s skin is neither damaged nor broken (Hannah et al., 2019). This essay aims to critically analyse the process and use of tDCS in the present study of anatomical neuroscience.

The tDCS has been known to be grown quite popular with time due to its nature of providing promising results to patients with different diseases along with improving the cognitive and physical improvement in the health of the patients. According to Boroda et al., (2020), the method of stimulation has considerably provided positive results in a variety of cognitive, emotional and motor outcomes which are otherwise known as group improvements. Due to such versatile results, the tDCS method has been targeted for several investigations in the Vivo and Vito models which signifies the human individuals and non-human animals. Considering the positive outcomes of the method of stimulation, a fair number of ideas have been raised in the field of brain and metal science that this method can prove to be applicable for everyone. However, the ideas might not be regarded as a fully flourished result since the whole method is still considered to be under experimentation. As suggested by Ke et al., (2019), even though the method is still not clear for a declaration and the neurologists have been experimenting upon the idea of treatment, the tDCS method, on the other hand, has forecasted a series of potential advantages than the other prevalent techniques of brain stimulation. The expense of the tDCS has also been observed to be much more affordable for the patients and most importantly the total process is safe and painless. The method has reluctantly presented potential to be valuable for the treatment of different neuropsychiatric conditions like Parkinson’s disease, anxiety, chronic pain and depression. The additional benefits of the tDCS can be noted to have the patients help in controlling the episodes of mood swings which has been considered helpful in improving their concentration and attention in the activities after receiving active stimulation. Other instances that are considered to be beneficial to the context of the tDCS treatments are that it is also effective in curing neuropathic path to a similar effect of spinal block anaesthesia (Davis & Smith, 2019).

Following the notable advantages of the treatment, on the other hand, the arguments presented by Shires et al., (2020), directs the attention of the neuropsychiatric communities on the fact that every individual patient is likely to possess different biological characteristics. This can become quite challenging since the difference in the nature of the disease demands a different style of treatment, which makes the flexibility of tDCS questionable and opposes with the counter though that it is unlikely that tDCS would be effective in the same way for everyone.  The stimulation has been noted to have reflected a polarity-dependent transformation in the neuronal excitability with that of the anodal tDCS resulting in a subthreshold depolarization as well as cathodal tDCS is resulted in hyperpolarization, thus these changes are resistant from inducing neuronal firing. The process of tDCS can be observed to involve attaching the electrodes to the scalp of the patient for channelling a weak electric flow for modulating the tissues of the brain underneath the electrode in a standardised safe and painless manner. As counter argued by Thomas et al., (2021), the works of Australian neuroscientists Jared Horvath, Olivia Crater and Jason Forte can be significantly highlighted to discuss that the tDCS might not have any detectable effect on the cognitive function of individuals. The cognitive functions of the people like mental arithmetic, language and memory have been thoroughly experimented by investigating the effect of placing tDCS electrodes on the active left frontal lobe of the patients to ensure the electrodes be near to the Broca’s area. Since, during the experiment, the neuroscientists, there has been no distinctive difference between the utilized sham and active tDCS on the cognitive tasks performed by the participants. This directs the attention of readers to the factual assumption that the tDCS might be effective in cases with brain diseases or elderly people, who were not part of the investigation (Thomas et al., 2021).

Positive Effects of tDCS on Neuropsychiatric Conditions

On the other hand, the previous arguments have been contradicted by Zaninotto et al., (2019), to focus on the feasibility and tolerance of the patients with PD, the instances of facing side effects have been noticed to be a bare minimum, that is mild transient itching and sensation of burning under the electrode sites. It has been further noticed that the speed of the signals has been benefiting the patients in reducing the sense of fatigue and improving the cognitive process which highlights the point that tDCS can be generalised from RS-tDCS in providing treatment to patients with different neurological disorders within a safe space of “at-home rehabilitation”. According to Klaus and Schutter (2021), the considerable changes that are brought into the neural activity of the human being through the method of tDCS have not only been persistent during the stimulation period but has been found to be lasting for more than an hour post-stimulation implementation. Several instances of patients being revived from issues other than mental disorders through the treatment of tDCS are that improvement in the long-standing problem of visual tracking during activities like reading. Although the stimulation might be sceptical in providing the same result for different individuals, the mechanism of the process can still be considered to have a long-term impact in treating the depression of the neuronal synapses. The density of the stimulation, as well as the duration, are noted to be the effective factors in determining the efficacy of the tDCS since both the online and offline mode of stimulation has the potential to impact the cognitive and motor domains, but the difference in the sizes can be highly evident (Hannah et al., 2019).

From the above analysis, it can be concluded that the Transcranial Direct Current Stimulation (tDCS), have significantly opened a fresh perspective to the field of neuropsychology in focusing on the treatment of patients with different mental disorders. The method is highly popular and effective due to its potential ability of modulating cortical excitability and induce long-lasting effects. There has been several discussion and debates on the effective advantage and disadvantage of the method amongst different neuroscientists and psychologists regarding the flexibility of the treatment. The different instances of experiences faced by various patients have been impactful in directing the idea of treatment through tDCS towards acceptability even though it has not yet been officially dictated by the FDA regulations.

References 

Bennabi, D., & Haffen, E. (2018). Transcranial direct current stimulation (tDCS): A promising treatment for major depressive disorder?. Brain sciences, 8(5), 81. https://dx.doi.org/10.3390/brainsci8050081

Boroda, E., Sponheim, S. R., Fiecas, M., & Lim, K. O. (2020). Transcranial direct current stimulation (tDCS) elicits stimulus-specific enhancement of cortical plasticity. Neuroimage, 211, 116598. https://doi.org/10.1016/j.neuroimage.2020.116598

Davis, S. E., & Smith, G. A. (2019). Transcranial direct current stimulation use in warfighting: benefits, risks, and future prospects. Frontiers in human neuroscience, 13, 114. https://doi.org/10.3389/fnhum.2019.00114

Hannah, R., Iacovou, A., & Rothwell, J. C. (2019). Direction of TDCS current flow in human sensorimotor cortex influences behavioural learning. Brain stimulation, 12(3), 684-692. Doi:10.1136/bmjopen-2020-037654

Ke, Y., Wang, N., Du, J., Kong, L., Liu, S., Xu, M., ... & Ming, D. (2019). The effects of transcranial direct current stimulation (tDCS) on working memory training in healthy young adults. Frontiers in human neuroscience, 13, 19. https://doi.org/10.3389/fnhum.2019.00019

Klaus, J., & Schutter, D. J. (2021). Electrode montage-dependent intracranial variability in electric fields induced by cerebellar transcranial direct current stimulation. Scientific reports, 11(1), 1-11. https://doi.org/10.1038/s41598-021-01755-9

Shires, J., Carrasco, C., & Berryhill, M. E. (2020). No tDCS augmented working memory training benefit in undergraduates rewarded with course credit. Brain Stimulation, 13(6), 1524-1526. https://doi.org/10.1016/j.brs.2020.08.015

Thomas, F., Steinberg, F., Pixa, N. H., Berger, A., Cheng, M. Y., & Doppelmayr, M. (2021). Prefrontal high definition cathodal tDCS modulates executive functions only when coupled with moderate aerobic exercise in healthy persons. Scientific reports, 11(1), 1-14. https://doi.org/10.1038/s41598-021-87914-4

Zaninotto, A. L., El-Hagrassy, M. M., Green, J. R., Babo, M., Paglioni, V. M., Benute, G. G., & Paiva, W. S. (2019). Transcranial direct current stimulation (tDCS) effects on traumatic brain injury (TBI) recovery: A systematic review. Dementia & neuropsychologia, 13(2), 172-179. https://dx.doi.org/10.1590/1980-57642018dn13-020005