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Friedman, J., Raveh, E., Weiss, T., Itkin, S., Niv, D., Hani, M., et al. (2019). Applying Incongruent Visual-Tactile Stimuli during Object Transfer with Vibro-Tactile Feedback (Vol. 147).
Abstract: The application of incongruent sensory signals that involves disrupted tactile feedback is rarely explored, specifically with the presence of vibrotactile feedback (VTF). This protocol aims to test the effect of VTF on the response to incongruent visual-tactile stimuli. The tactile feedback is acquired by grasping a block and moving it across a partition. The visual feedback is a real-time virtual presentation of the moving block, acquired using a motion capture system. The congruent feedback is the reliable presentation of the movement of the block, so that the subject feels that the block is grasped and see it move along with the path of the hand. The incongruent feedback appears as the movement of the block diverts from the actual movement path, so that it seems to drop from the hand when it is actually still held by the subject, thereby contradicting the tactile feedback. Twenty subjects (age 30.2 +/- 16.3) repeated 16 block transfers, while their hand was hidden. These were repeated with VTF and without VTF (total of 32 block transfers). Incongruent stimuli were presented randomly twice within the 16 repetitions in each condition (with and without VTF). Each subject was asked to rate the difficulty level of performing the task with and without the VTF. There were no statistically significant differences in the length of the hand paths and durations between transfers recorded with congruent and incongruent visual-tactile signals – with and without the VTF. The perceived difficulty level of performing the task with the VTF significantly correlated with the normalized path length of the block with VTF (r = 0.675, p = 0.002). This setup is used to quantify the additive or reductive value of VTF during motor function that involves incongruent visual-tactile stimuli. Possible applications are prosthetics design, smart sport-wear, or any other garments that incorporate VTF.
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Ezrati, O., Friedman, J., & Dar, R. (2019). Attenuation of access to internal states in high obsessive-compulsive individuals might increase susceptibility to false feedback: Evidence from a visuo-motor hand-reaching task. Journal of Behavior Therapy and Experimental Psychiatry, 65, 101445.
Abstract: Background and objectives
The Seeking Proxies for Internal States (SPIS) model of obsessive-compulsive disorder (OCD) posits that obsessive-compulsive (OC) individuals have attenuated access to their internal states. Hence, they seek and rely on proxies, or discernible substitutes for these internal states. In previous studies, participants with high OC tendencies and OCD patients, compared to controls, showed increased reliance on external proxies and were more influenced by false feedback when judging their internal states. This study is the first to examine the effects of false feedback on performance of hand movements in participants with high and low OC tendencies.
Method
Thirty-four participants with high OC tendencies and 34 participants with low OC tendencies were asked to perform accurate hand reaches without visual feedback in two separate sessions of a computerized hand-reaching task: once after valid feedback training of their hand location and once with false-rotated feedback. We assessed the accuracy and directional adaptation of participants' reaches.
Results
As predicted, high OC participants evidenced a larger decrease in their hand positioning accuracy after training with false feedback compared to low OC participants.
Limitations
The generalization of our findings to OCD requires replication with a clinical sample.
Conclusions
These results suggest that in addition to self-perceptions, motor performance of OC individuals is prone to be overly influenced by false feedback, possibly due to attenuated access to proprioceptive cues. These findings may be particularly relevant to understanding the distorted sense of agency in OCD.
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Prushansky, T., Kaplan-Gadasi, L., & Friedman, J. (2023). The relationship between thoracic posture and ultrasound echo intensity of muscles spanning this region in healthy men and women. Physiother Theory Pract, 39(6), 1257–1265.
Abstract: PURPOSE: Skeletal muscle echogenicity intensity (EI) is considered a measure of muscle quality, being associated with old age and pathologies. Whether EI variations can be identified in healthy adults, due to habitual shortened or elongated muscle position is unknown. Thus, this study aimed to assess the relationship between thoracic kyphosis angulation and EI scores of muscles spanning this region ((Lower Trapezius (LT), Rhomboid Major (RM), Erector Spine (ES)) in healthy young people and in addition to examine the relationship between the change in thoracic kyphosis angle from relaxed to upright position (� degrees ) and the EI of these muscles. METHODS: Thoracic kyphosis in relaxed and erect standing was measured using a digital inclinometer in 29 healthy adults (16 women, 13 men), aged 25-35 years. The thoracic kyphosis angles including the difference between relaxed and erect postures (� degrees ) were correlated to the EI scores of right and left LT, RM and ES. RESULTS: No significant differences in EI were found between the 3 muscles EI or between sides, hence they were pooled together to a total thoracic EI score (TTEI). Although the TTEI did not correlate with relaxed or erect thoracic kyphosis, it was significantly but negatively correlated with � degrees in the entire group: Pearson's correlation coefficient of r = -0.544; p = .01 and in men; r = -0.732; p = .01, failing to reach significance in women; r = -0.457. CONCLUSION: The negative association between the EI of the explored muscles and � degrees could imply a possible relationship between these muscles range of movement excursions and their composition.
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Grip, H., Tengman, E., Liebermann, D. G., & Hager, C. K. (2019). Kinematic analyses including finite helical axes of drop jump landings demonstrate decreased knee control long after anterior cruciate ligament injury. PLoS One, 14(10), e0224261.
Abstract: The purpose was to evaluate the dynamic knee control during a drop jump test following injury of the anterior cruciate ligament injury (ACL) using finite helical axes. Persons injured 17-28 years ago, treated with either physiotherapy (ACLPT, n = 23) or reconstruction and physiotherapy (ACLR, n = 28) and asymptomatic controls (CTRL, n = 22) performed a drop jump test, while kinematics were registered by motion capture. We analysed the Preparation phase (from maximal knee extension during flight until 50 ms post-touchdown) followed by an Action phase (until maximal knee flexion post-touchdown). Range of knee motion (RoM), and the length of each phase (Duration) were computed. The finite knee helical axis was analysed for momentary intervals of ~15 degrees of knee motion by its intersection (DeltaAP position) and inclination (DeltaAP Inclination) with the knee's Anterior-Posterior (AP) axis. Static knee laxity (KT100) and self-reported knee function (Lysholm score) were also assessed. The results showed that both phases were shorter for the ACL groups compared to controls (CTRL-ACLR: Duration 35+/-8 ms, p = 0.000, CTRL-ACLPT: 33+/-9 ms, p = 0.000) and involved less knee flexion (CTRL-ACLR: RoM 6.6+/-1.9 degrees , p = 0.002, CTRL-ACLR: 7.5 +/-2.0 degrees , p = 0.001). Low RoM and Duration correlated significantly with worse knee function according to Lysholm and higher knee laxity according to KT-1000. Three finite helical axes were analysed. The DeltaAP position for the first axis was most anterior in ACLPT compared to ACLR (DeltaAP position -1, ACLPT-ACLR: 13+/-3 mm, p = 0.004), with correlations to KT-1000 (rho 0.316, p = 0.008), while the DeltaAP inclination for the third axis was smaller in the ACLPT group compared to controls (DeltaAP inclination -3 ACLPT-CTRL: -13+/-5 degrees , p = 0.004) and showed a significant side difference in ACL injured groups during Action (Injured-Non-injured: 8+/-2.7 degrees , p = 0.006). Small DeltaAP inclination -3 correlated with low Lysholm (rho 0.391, p = 0.002) and high KT-1000 (rho -0.450, p = 0.001). Conclusions Compensatory movement strategies seem to be used to protect the injured knee during landing. A decreased DeltaAP inclination in injured knees during Action suggests that the dynamic knee control may remain compromised even long after injury.
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Salzer, Y., & Friedman, J. (2020). Reaching trajectories unravel modality-dependent temporal dynamics of the automatic process in the Simon task: a model-based approach. Psychol Res, 84(6), 1700–1713.
Abstract: The Simon effect represents a phenomenon in which the location of the stimuli affects the speed and accuracy of the response, despite being irrelevant for the task demands. This is believed to be due to an automatic activation of a response corresponding to the location of the stimuli, which conflicts with the controlled decision process based on relevant stimuli features. Previously, differences in the nature of the Simon effect (i.e., the pattern of change of the effect across the distribution of response times) between visual and somatosensory stimuli were reported. We hypothesize that the temporal dynamics of visual and somatosensory automatic and controlled processes vary, thus driving the reported behavioral differences. While most studies have used response times to study the underlying mechanisms involved, in this study we had participants reach out to touch the targets and recorded their arm movements using a motion capture system. Importantly, the participants started their movements before a final decision was made. In this way, we could analyze the movements to gain insights into the competition between the automatic and controlled processes. We used this technique to describe the results in terms of a model assuming automatic activation due to location-based evidence, followed by inhibition. We found that for the somatosensory Simon effect, the decay of the automatic process is significantly slower than for the visual Simon effect, suggesting quantitative differences in this automatic process between the visual and somatosensory modalities.
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