Short-term memory effects of an auditory biofeedback on isometric force control: Is there a differential effect as a function of transition trials?

The effect of lower leg sensory impulses on the force sense of knee extensor muscles in healthy adults: The accuracy of sense-of-force studies

BACKGROUND

Producing the target force of a muscle group by using visual feedback and reproducing the same force fully blind are regarded as a common approach for quantifying the sense of force. Force sense error is considered to be the difference between the produced target force and reproduced force. The present study aimed to evaluate the effects of tactile sensory feedback in the lower leg on the perceived magnitude of force sense.

METHODS AND MATERIALS

In this cross-sectional study, 18 healthy men (mean age 24.31 ± 3.94 years) were selected based on a simple randomized method. First, the quantity of force sense error of the knee extensor muscle group was measured before and after manipulating the tactile inputs of the leg. Then, methods A, B, and C were applied to measure force sense errors. In addition, the tactile impulses were manipulated in methods B and C by placing a piece of thick foam between the distal portion of lower leg among the subjects and the dynamometer. The tactile inputs remained intact during method A.

RESULTS

The accuracy of the reproduced target force was significantly affected following the disturbance of tactile inputs in the lower leg in methods B and C, compared to method A (p < 0.05).

CONCLUSION

Altering tactile inputs in the lower leg can affect the force sense of the knee extensor muscles. The received somatosensory inputs across the lower leg can affect the whole process of force perception at this joint.

Force Control under Auditory Feedback: Effector Differences and Audiomotor Memory

Audiomotor integration is a basic form of sensorimotor control for regulating vocal pitch and vocal loudness, but its contribution to general motor control has only been studied minimally. In this paper, auditory feedback for prolonged force control was investigated by comparing manual and oral force generation and testing short-term audiomotor memory for these effectors. Ten healthy volunteers between the ages of 20 and 30 years old were recruited. The participants produced continuous force for 30 sec. with the lip or finger to match auditory targets. In the feedback condition, when auditory feedback was provided for 30 sec., lip force was more variable than finger force. In the memory condition, the force output of both effectors remained stable for approximately 4 sec. after feedback removal, followed by significant decay. A longer short-term memory capacity could facilitate encoding of motor memories for tasks having acoustic goals. The results demonstrate that “audiomotor” integration was effective for sustaining forces, and that audiomotor force memory is comparable to reports of visuomotor force memory.