Introduction: Manual dexterity requires multi-sensory (e.g., vision and touch) integration with movement, and is often impaired due to sensorimotor deficits in stroke survivors. Currently, neurorehabilitation involves repetitive visually-guided motor practice without particular emphasis on tactile feedback for movement. As a first step to improve post-stroke hand function, we studied the effects of providing enhanced tactile feedback during motor practice on dexterity of the non-dominant hand in healthy volunteers.
Hypothesis: We hypothesized that 2, 45-minute sessions of enhanced tactile-motor practice would improve non-dominant hand dexterity more than the same duration of visuo-motor practice.
Methods: Twenty healthy adults (8 males; mean age = 27.7 ± 22 years) were randomized to an enhanced tactile-motor (TM) or visuo-motor (VM) group. Volunteers performed 3, 15-minute blocks of motor practice that required 1) sorting small (< 2.5 cm) wood-chips, 2) completing 3-D puzzles using small (<1.25 cm) cubes, and 3) copying patterns using 3.6 cm3 interlocking building bricks. Motor practice was either based on tactile cues of textured objects with vision partially obscured by a blurry screen (TM) or visual cues of smooth colored objects (VM). Motor practice occurred twice, seven days apart, with the non-dominant hand. Nine-hole peg test (9HPT) was the primary outcome to measure manual dexterity of non-dominant hand. Scores on the 9HPT were measured at 4 times: T1) pre-practice day 1, T2) post-practice day 1, T3) pre-practice day 2, and T4) post-practice day 2. A mixed-methods ANOVA was used to test the effect of motor practice (TM, VM), and time (T1, T2, T3, T4) on manual dexterity (9HPT).
Results: The 2x4 mixed ANOVA showed a significant interaction between time and motor practice (F (3, 51) = 2.96, p = 0.04, partial η2 = .148), revealing that the change in 9HPT scores over time was different for the 2 groups. The TM group significantly improved on 9HPT from T1 to T4 (Mean difference = 2.7 s, SE = 0.53, p = 0.001), but the VM group did not improve.
Conclusions: Tactile enhancement during 2 motor practice sessions can significantly improve dexterity. Future work will translate these methods to stroke rehabilitation.