Ceiling Effects Prevent Further Improvement of Transcranial Stimulation in Skilled Musicians

Abstract

The roles of the motor cortex in the acquisition and performance of skilled finger movements have been extensively investigated over decades. Yet it is still not known whether these roles of motor cortex are expertise-dependent. The present study addresses this issue by comparing the effects of noninvasive transcranial direction current stimulation (tDCS) on the fine control of sequential finger movements in highly trained pianists and musically untrained individuals. Thirteen pianists and 13 untrained controls performed timedsequence finger movements with each of the right and left hands before and after receiving bilateral tDCS over the primary motor cortices. The results demonstrate an improvement of fine motor control in both hands in musically untrained controls, but deterioration in pianists following anodal tDCS over the contralateral cortex and cathodal tDCS over the ipsilateral cortex compared with the sham stimulation. However, this change in motor performance was not evident after stimulating with the opposite montage. These findings support the notion that changes in dexterous finger movements induced by bihemispheric tDCS are expertise-dependent.

Anodal tDCS to Right Dorsolateral Prefrontal Cortex Facilitates Performance for Novice Jazz Improvisers but Hinders Experts

“…In the other study, Furuya et al (2014) replicated these findings, displaying a ceiling effect on skilled musicians' improvement in fine motor control due to tDCS. As before, the untrained control participants demonstrated improvements in both the left and right hands when receiving concurrent bilateral brain stimulation to motor cortex in both conditions (anode—C3, cathode—C4; anode—C4, cathode—C3).…”

“…Another possible explanation for the lack of a significant positive impact of cathodal tDCS on seasoned jazz musicians may be analogous to studies examining pianists' finger dexterity and motor control (Furuya et al, 2013, 2014). In these studies, only untrained control participants and players that commenced training at an older age saw gains in finger dexterity with stimulation to motor cortex.…”

“…Even fewer have studied the impact of tDCS on creative performance in artistic domains. Though none of these investigations have examined musical creativity directly, two studies examined the effects of targeting motor cortex (C3 and C4) with tDCS on trained and untrained pianists' finger dexterity and fine motor control (Furuya et al, 2013, 2014). In the first study, concurrent bilateral tDCS to motor cortex improved keystrokes for untrained musicians but did not improve performance for professionals.…”

A technical guide to tDCS, and related non-invasive brain stimulation tools

“…When using behavioral outcome measurements, the choice of task and the associated performance metric are critical for reliably detecting tDCS effects. Important parameters include task complexity, type of task (e.g., tDCS can have antagonistic effects in noisy and non-noisy tasks; Antal et al 2004b) and the amount of training, which must be appropriate for the skill level of the participant otherwise facilitatory tDCS effects might be masked by ceiling effects in performance measures (Furuya et al 2014a). Moreover, the brain’s ability to undergo neuroplastic changes differs across populations.…”

An open letter concerning do‐it‐yourself users of transcranial direct current stimulation

“…39 Furthermore, this variability occurs despite controlled experimental conditions designed to reduce it. Factors such as age, 40,41 gender, 42 hormones, 43 handedness, 44,45 cognitive ability, 46,47 neurological or psychiatric disorders, medications, 48,49 recreational drugs, 50 neurotransmitter levels, 49 prior exposure to brain stimulation, 51 and differences in head anatomy 12,36,52,53 are likely to impact and could potentially even reverse a given tDCS effect.…”