Naoki Kado

By Masanori Ito, Yuki Takahashi, Satoshi Fujiwara and Naoki Kado

The electromyographic reaction time data responses to various rhythm shifts are discussed in Section 2 of this chapter. The following four experimental designs were introduced: (1) subliminal rhythm shift with shortened interval, (2) subliminal rhythm shift with lengthened interval, (3) subliminal rhythm shift with random interval, and (4) differences in the rate of rhythm shift. We found that the periodic rhythmic stimulation is predicted to comprise some time duration. Furthermore, the reactive movements can be performed without delay under conditions with an interstimulus‐onset interval shift of 7% of 1500 ms. When the physical therapist facilitates rhythmical reactive periodic movement using an external event such as a handclap, it will be desirable to keep the rhythm shift within 7% of the interstimulus‐onset interval. The variabilities of the intertap interval in the continuation paradigm of sensorimotor synchronization are discussed in Section 3. The participants performed self‐paced, synchronization‐continuation, and syncopation‐continuation tapping tasks. We found that the accuracy of the periodic movement with an interstimulus‐onset interval of 1000 ms can be improved by using auditory pacing. However, the consistency of periodic movement is mainly dependent on innate skill; thus, improvement in consistency from pacing alone is unlikely.

Part of the book: Clinical Physical Therapy

By Yoshinori Yamamoto and Naoki Kado

When performing a movement, many features of sensory information are used as inputs and integrated. Smooth movement is possible by selecting necessary information from all‐sensory inputs. The somatosensory input of movement is adjusted at different levels such as at the level of the spinal cord, brainstem, and sensory cortex. However, sensory tests used by physical therapists provide only the sensory information that is perceivable through the parietal association fields. On the other hand, there is a somatosensory‐evoked potentials (SEPs) in the tests of the somatic sensory function. An understanding of the SEPs enables the evaluation of the posterior track. Therefore, it is possible to determine if the adjustment of somatosensory inputs occurs at any stage. The SEP amplitude is decreased by passive and voluntary movement. Further, characteristic decrease in the SEP amplitude is noted with an increase in the speed and intensity of movement. Thus, it is important for us to understand the relationship between motor tasks and somatosensory inputs. In this chapter, we introduce our study on the relationship between physical movements and somatosensory inputs, and make recommendations for practicing physical therapy.

Part of the book: Neurological Physical Therapy

By Naoki Kado, Yuki Takahashi, Satoshi Fujiwara and Masanori Ito

In physical therapy, it is important to understand the influence of the contraction of a particular muscle on other muscles. The mechanism of the facilitation effect of muscle contraction in healthy subjects has been analyzed in previous studies. These studies indicated that muscle contraction with voluntary movement enhances the excitability of spinal motor neurons and motor areas in the cerebral cortex that are not directly associated with the contracting muscle. Furthermore, it has been reported that the facilitation effects on remote muscles not related to movement are affected by the elapsed time since the start of the movement, the strength of muscle contraction, the number of muscle spindles, and the difficulty of the movement. In addition, the facilitation effects of difficult voluntary movements of the unilateral upper limbs on spinal motor neurons in the contralateral upper limb decrease with motor learning. We expect that these findings will be useful not only for physical therapy evaluation but also for patient treatment.

Part of the book: Neurological Physical Therapy

By Naoki Kado

The purpose of this study was to examine the relationship between excitability of the spinal motor neurons in the upper extremity and difficulty of tasks applied to the lower extremities. Twenty healthy volunteers agreed to participate. Our findings suggest that the excitability of spinal motor neurons in the right arm was increased during voluntary movement of the lower extremities. Excitability of the spinal motor neurons might be increased by the facilitatory effect at the spinal and cortical levels. Regarding the facilitatory effects at the cortical level, the effects of difficult tasks might be larger than those of simple tasks, but the most difficult task might be affected by the facilitatory and inhibitory effects of the central nervous system.

Part of the book: Somatosensory and Motor Research