More than a century of research showed that solving the nine-dot problem was impossible. The exercise involves connecting all nine dots with four straight lines.
Difficulty in solving the problem remained even after giving hints,extended time, and hundred chances, making this problem unsolvable.
None of the 22 participants in the Chi and Snyder experiment (2012) solvedthe nine-dot problem before receiving transcranial direct current stimulation (tDCS). However, after ten minutes of tDCS application, more than 40% of the participants solved the problem while none of the participants in the placebo condition found a solution at any point during the experiment.
tDCS is a non-invasive brain stimulation technique that modulates neuronal activity by using electrical currents to stimulate or inhibit specific parts of the brain. tDCS involves the application ofa weak electrical current (0.5-2 mA) through at least two electrodes, one of which is placed on the scalp, witheach session lasting about 30 minutes.
Types of stimulation
There are two types of stimulation with tDCS: anodal stimulation excites neuronal activity, whereas cathodal stimulation inhibits neuronal activity. As soon as tDCS begins, the current flows through the circuit from the anode to the cathode, making neurons under the anode more likely to fire. Conversely, neurons under the cathode become less likely to fire.
Literature published in the past decade suggests thattDCS can be considered as an intervention capable of modulating learning processes in specific brain areas (motor, sensory, or cognitive) and in both healthy populations and patients with disorders such as dementia or stroke. However, non-invasive brain stimulation techniques are still in an experimental phase.
Therefore, it is essential to define protocols and parameters such as determining target brain regions,current intensity, electrode size, stimulation duration, sessions needed to produce therapeutic effects, and quantifying changes in brain activity and behavior; in addition, a very promising avenue of inquiry has been synergistically combining tDCS with motor or cognitive therapies.
Applying tDCS to a specific neural circuit while simultaneously performing cognitive training should produce better therapeutic effects than stimulating the same cortical area involved in the neural circuit in the absence of cognitive stimulation. In short, tDCS could strengthen synaptic transmissions in the same neural circuits that are stimulated by cognitive training.
We can write brain signals
These are exciting times for neuroscience research; not only are we able to read the signals sent to us by the brain, but we can also write brain signals through neuromodulation. Neuromodulation can modify neuronalfiring properties. The applications of this non-invasive brain stimulation technique might allow us to consider interventions in neurorehabilitation with unlimited potential to improve function and quality of life for people with neurological conditions.
Effects need to be assessed
Before considering the use of non-pharmacological interventions such as the application of tDCS alone or in combination with other therapeutic modalities, it is necessary: 1) to continue to assess the effects produced in different settings with the use of imaging techniques such as electroencephalography or functional magnetic resonance; 2) to assess the specific cognitive changesafter tDCS stimulation or generalization to other cognitive areas; and, above all,3) to measure the effects that it could have on function and performance capability of activities of daily living in patients receiving these neuromodulatory interventions.
If you liked this post, you might find the following interesting as well:
- Chi, R. P., & Snyder, A. W. (2012). Brain stimulation enables the solution of an inherently difficult problem. Neuroscience letters, 515(2), 121-124.
- Nitsche, M. A., Cohen, L. G., Wassermann, E. M., Priori, A., Lang, N., Antal, A., … & Pascual-Leone, A. (2008). Transcranial direct current stimulation: state of the art 2008. Brain stimulation, 1(3), 206-223.
- Nasseri, P., Nitsche, M. A., &Ekhtiari, H. (2015). A framework for categorizing electrode montages in transcranial direct current stimulation. Frontiers in human neuroscience, 9.
- Hauptmann, B., &Karni, A. (2002). From primed to learn: the saturation of repetition priming and the induction of long-term memory. Cognitive Brain Research, 13(3), 313-322.
- Nitsche, M. A., Antal, A., Liebetanz, D., Lang, N., Tergau, F., & Paulus, W. (2007). Induction and modulation of neuroplasticity by transcranial direct current stimulation. In Transcranial Brain Stimulation for Treatment of Psychiatric Disorders (Vol. 23, pp. 172-186). Karger Publishers.
- Birba, A., Ibáñez, A., Sedeño, L., Ferrari, J., García, A. M., &Zimerman, M. (2017). Non-Invasive Brain Stimulation: A New Strategy in Mild Cognitive Impairment? Frontiers in aging neuroscience, 9.
- Miniussi, C., Harris, J. A., &Ruzzoli, M. (2013). Modelling non-invasive brain stimulation in cognitive neuroscience. Neuroscience & Biobehavioral Reviews, 37(8), 1702-1712.
- Ditye, T., Jacobson, L., Walsh, V., &Lavidor, M. (2012). Modulating behavioral inhibition by tDCS combined with cognitive training. Experimental brain research, 219(3), 363-368.
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