Long-term analyses of spastic muscle behavior in chronic poststroke patients after near-infrared low-level laser therapy (808 nm): a double-blinded placebo-controlled clinical trial.

Stroke results in impairment of basic motor functions, such as muscle weakness in limbs affected by spasticity, leading to peripheral fatigue and impaired functionality. The clinical use of photobiomodulation therapy (PBMT) has provided major advances in the treatment of muscular disorders and prevention of muscle fatigue. The aim of this study was to analyze the effects of two distinct therapies in biceps spasticity of chronic hemiparetic patients. We analyzed range of elbow motion, torque, electromyography, and mean spectral frequency after 10 sessions of PBMT (Laser 100 mW, 808 nm, 159.24 J/cm2/point, 5 J/point); PBMT active or placebo was associated with exoskeleton-assisted functional treatment. A double-blind placebo-controlled sequential clinical trial was conducted with 12 healthy volunteers and 15 poststroke patients who presented upper-limb spasticity. The healthy volunteers performed only the evaluation protocol, and the poststroke volunteers participated in three consecutive phases (PBMT, PBMT + exoskeleton, placebo + PBMT) with a washout period of 4 weeks between each phase. We could observe significant increases in range of elbow motion after PBMT from 57.7 ± 14 to 84.3 ± 27.6 degrees (p < 0.001). The root mean square (RMS) values also increased after PBMT + exoskeleton from 23.2 ± 15 to 34.9 ± 21 µV (p = 0.0178). Our results suggest that the application of PBMT may contribute to an increased range of elbow motion and muscle fiber recruitment, increases in muscle strength, and, hence, to increase signal conduction on spastic muscle fibers in spastic patients.

Tadpoles respond to background colour under threat.

The ability to respond to background colour is an important feature of species that might benefit from background matching camouflage. Tadpole colour patterns vary and could be associated with several functions, including defense. Because tadpoles are exposed to a wide array of visually oriented predators, they represent good models to study defensive colouration and associated behaviours. We tested whether a potentially disruptively camouflaged tadpole with a dark body crossed by yellow bars (Ololygon machadoi) is able to respond differently to matching light and dark natural background colours and an artificial blue contrasting background. We used a syntopic contrasting black tadpole (Bokermannohyla martinsi) as a control, expecting it not to respond to background colour in search for camouflage. Ololygon machadoi tadpoles chose light over blue backgrounds under threat, as expected, however they did not show preferential use of dark vs. blue backgrounds. Bokermannohyla martinsi did not respond to any combination of background colours. Our results suggest that O. machadoi tadpoles are able to respond to background colour, and may favor matching backgrounds under some circumstances. The potentially disruptive colouration of O. machadoi tadpoles may increase their repertoire of escape strategies, background matching being one of the options to escape predation.