Is neuroenhancement by noninvasive brain stimulation a net zero-sum proposition?

Abstract

In the past several years, the number of studies investigating enhancement of cognitive functions through non-invasive brain stimulation (NBS) has increased considerably. NBS techniques, such as transcranial magnetic stimulation and transcranial current stimulation, seem capable of enhancing cognitive functions in patients and in healthy humans, particularly when combined with other interventions, including pharmacologic, behavioral and cognitive therapies. The “net zero-sum model”, based on the assumption that brain resources are subjected to the physical principle of conservation of energy, is one of the theoretical frameworks proposed to account for such enhancement of function and its potential cost. We argue that to guide future neuroenhancement studies, the net-zero sum concept is helpful, but only if its limits are tightly defined.

Does transcranial direct current stimulation enhance cognitive and motor functions in the ageing brain? A systematic review and meta- analysis

“…Recently, Brem and colleagues proposed that enhancement through NIBS is a zero-sum proposition (Brem et al, 2014). That is, the induced enhancement of a cognitive or motor function is associated with a cost (Luber, 2014).…”

Transcranial Direct Current Stimulation (tDCS): Modulation of Executive Function in Health and Disease

“…But, perhaps more importantly, we need to better understand the mechanism of action of tDCS and the differences among the most commonly used protocols. The safety of repeated sessions and whether enhancing one brain region is at the expense of another should also be studied more carefully [92]. There is an urgent need to ameliorate executive functions in a host of diseases.…”

The Use of Transcranial Direct Current Stimulation for Cognitive Enhancement

“…In contrast, tDCS over the dlPFC impaired numerical learning but enhanced the automaticity of the learned material. This finding is important because it suggest the possibility of cognitive costs for cognitive enhancement in healthy populations and provokes the question of whether tDCS really enhances functions (Brem et al, 2014). Therefore, future studies should assess other cognitive functions besides the main outcome(s) of interest using sensitive tasks that are not time-consuming and cognitively exhausting to detect any unintended side effects.…”