Can neurostimulation reliably enhance your focus in day-to-day activities?
Focus is about giving your full concentration to that one thing while saying no to all those things vying your attention. There is no shortage of distraction in this world, so to increase focus levels, there has been a significant interest in the techniques that can do so including transcranial electrical stimulation (tES).
Attentional disturbances lie at the core of many neurological and psychiatric disorders such as ADHD. That is why focus has primarily been taken into account for cognitive enhancement techniques that include video games, pharmacological stimulants and meditational training. The discovery of transcranial electrical current is another technique to the arsenal. It comprises of a weak current that is made to run through two electrodes placed on the skull that changes the excitability of the brain tissues under the electrodes.
A number of studies have been carried out that paired tasks that required focus and attention, with tES (mostly with transcranial direct current stimulation). We will discuss three important aspects of focus and attention here that have been most broadly been targeted to date.
- Visual Searching
- Spatial orientation
- Sustained Attention
Researchers have reported some very promising effects of tDCS in each of these domains.
The process of scanning the visual field is a common action which makes it an interesting target for cognitive enhancement. Different studies and experiments were performed to examine the results of transcranial electric current on the visual searching.
Visual search performance is supported by an extensive network of brain areas, centered on the right posterior parietal cortex and frontal eye field. Among an array of distracting objects, participants in visual search tasks had to look for a target item. The faster the reaction time in searching, the more efficient the visual search of the participant. The researchers found that anodal tDCS over the right parietal cortex may speed up visual search, while cathodal stimulation may slow it down.
Moreover, it was also found that learning to discover hidden objects fixed in realistic scenes was greatly intensified by anodal tDCS over the right inferior frontal cortex.
Another aspect highly relevant to visual search was spatial orienting. These studies figured out that attention and focus are not symmetrically distributed over the visual field. Most people are exposed to pseudoneglect; they overemphasize features in the left versus the right hemisphere. This happens because the right hemisphere is slightly more active than the left.
Presumably, it was seen that tDCS proved to be very effective in increasing the activity of the left parietal cortex beyond that of the right, and resultantly causing a rightward shift in spatial bias. Similarly, a rightward shift for right cathodal tDCS was observed. It was furthermore observed that a “dual” montage with one electrode on each posterior parietal cortex (anode on left; cathode on right) was even more effective.
Typically after prolonged time-on-tasks, the average performance of a person declines which is called vigilance decrement. To find ways to hinder vigilance decrement, different research work was done that examined the effects of tES on sustained attention.
It was reported that the vigilance decrement could be stopped by applying bilateral tDCS to the dorsolateral prefrontal cortex early into a vigilance task.
Furthermore, prefrontal tDCS did not affect performance on a sustained attention to response task, but they did increase mind wandering. In conclusion, two studies reported that prefrontal tDCS specifically offsets the vigilance decrement, suggesting that its effects may only become apparent after prolonged task performance.
With the applications mentioned above, we come to the conclusion that a person’s focus can be enhanced through transcranial electric current stimulation. The effects of tDCS are not confined to the stimulation period, but can outlast it for minutes to hours, or even months after multiple stimulation sessions!
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