Abstract
Purpose :
Individuals with central vision loss, for example, those in macular degeneration (MD), primarily use their peripheral for navigation and other daily living activities. Previously, we reported that peripheral attentive motion tracking, which is critical for navigation, can be improved by perceptual learning (PL) in individuals with MD. In this study, we investigated whether transcranial random noise stimulation (tRNS), a form of non-invasive brain stimulation, can enhance this perceptual learning effect.
Methods :
10 participants (42-65y, 6 males), including 6 with unilateral macular degeneration (UMD) and 4 with bilateral macular degeneration (BMD), were assigned into treatment (tRNS) and control (sham stimulation) groups using a stratified random sampling (3 UMD and 2 BMD in each group). Participants in both groups completed 5 x 40-min PL sessions across consecutive days, while tRNS/sham stimulation was delivered to the motion-sensitive extrastriate area MT+ (3 cm above and 5 cm to the left/right of inion). MOT speed thresholds (8 elements, starting speed 4°/s, partial report procedure) were measured for both hemifields separately during the preliminary baseline visit, pre- and post-intervention on each stimulation day, and then every 24h for 3 days after the stimulation day. tRNS/sham stimulation was applied on the MT+ contralateral; while MOT training was conducted in the hemifield ipsilateral to the affected eye (UMD) or eye with poorer visual acuity (BMD).
Results :
MOT task performance improved in both the trained and untrained hemifield in all participants following perceptual learning. However, the tRNS group exhibited a larger improvement in both the trained (tRNS: 37 ± 18%, sham stimulation: 28 ± 11%; p = 0.008) and untrained (tRNS: 21 ± 9%, sham stimulation: 15 ± 11%; p = 0.02) hemifield than the sham group. In addition, the improvement in MOT performance in both hemispheres was sustained in the tRNS group for at least 72h (trained hemifield: 22 ± 10%, untrained 13 ± 8%, p = 0.03) after the final perceptual learning session. For the sham stimulation group, the improvement was sustained only for 48h in the trained hemifield and for 24h in the untrained hemifield.
Conclusions :
These initial results suggest that tRNS boosts the efficacy of perceptual learning in enhancing peripheral attentive motion tracking in individuals with macular degeneration.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.