Integrity of both cerebral hemispheres is required to control in-phase or anti-phase coupling of ipsilateral hand and foot oscillations, as shown by the impairment of these tasks when performed on the healthy side of hemiplegic patients. On this basis, coupling of hand–foot movements was analysed in a right-handed subject (ME) who underwent a total resection of the corpus callosum. Oscillations of the prone hand and foot, paced by a metronome at different frequencies, as well as EMG activity in extensor carpi radialis (ECR) and tibialis anterior (TA) muscles were analysed by measuring the average phase difference between the hand and foot movements and EMG cycles.
ME performed in-phase movements (right-hand extension coupled to right-foot dorsal flexion) at frequencies up to 3 Hz, though the hand cycle progressively lagged the foot cycle as the frequency increased. At 3 Hz the hand lag reached −142° (as compared to about 25° in healthy subjects). The lag increased even further after application of an inertial load to the hand, reaching 180° at 1.8 Hz (about 50° in healthy subjects). ME's hand lag is caused by the lack of any anticipatory reaction in hand movers. In contrast to healthy subjects, which activate the ECR earlier than the TA when the frequency increases, ME activated the ECR later than TA at all frequencies higher than 0.9 Hz.
Anti-phase movements (hand extension coupled to foot plantar flexion) were performed only upto 1 Hz in unloaded conditions. At 0.6 Hz, movements were in tight phase-opposition (3°), but at 1 Hz, the hand lag reached −34° because of a delayed ECR activation. After hand loading ME was unable to couple movements in anti-phase. In contrast, normal subjects maintain a tight anti-phase coupling up to 2.0 Hz, both with an unloaded or loaded hand. Similar deficits were observed by ME when performing in-phase and anti-phase coupling on the left side, as well as when he was blindfolded.
In normal subjects, an anticipated muscular activation of hand movers compensates for hand loading. Since this compensation must depend on monitoring the hand delay induced by loading, the absence in ME of such compensatory reaction suggests that callosal division had apparently compromised the mechanisms sustaining feedback compensation for differences in the biomechanical limb properties. They also confirm and reinforce the idea that elaboration of the afferent message, aiming at controlling the phase of the movement association, needs the co-operation of both cerebral hemispheres. 相似文献
Dysfunctional beliefs and attitudes about sleep are presumed to play an important mediating role in perpetuating insomnia. The present study evaluated the impact of cognitive-behavioral and pharmacological treatments for insomnia on sleep-related beliefs and attitudes and the relationship between those changes and sleep improvements. The participants were older adults with chronic and primary insomnia. They received cognitive-behavior therapy (CBT), pharmacotherapy (PCT), combined CBT+PCT (COMB), or a medication placebo (PLA). In addition to daily sleep diaries and sleep laboratory measures, the participants completed the dysfunctional beliefs and attitudes about sleep scale (DBAS) at baseline and posttreatment, and at 3-, 12- and 24-month follow-up assessments. The results showed that CBT and COMB treatments produced greater improvements of beliefs and attitudes about sleep at posttreatment than PCT and PLA. Reductions of DBAS scores were significantly correlated with improvements of sleep efficiency as measured by daily sleep diaries and by polysomnography. In addition, more adaptive beliefs and attitudes about sleep at posttreatment were associated with better maintenance of sleep improvements at follow-ups. These findings highlight the importance of targeting sleep-related beliefs and attitudes in the treatment of insomnia. 相似文献
Three experiments investigated whether the presence of more elements in the upper part of a configuration (i.e., up-down asymmetry) plays a role in determining newborns' preference for facelike patterns. Newborns preferred a nonfacelike stimulus with more elements in the upper part over a nonfacelike stimulus with more elements in the lower part (Experiment 1), did not show a preference for a facelike stimulus over a nonfacelike configuration equated for the number of elements in the upper part of the configuration (Experiment 2), and preferred a nonfacelike configuration located in the upper portion of the stimulus over a facelike configuration in the lower portion of the pattern (Experiment 3). Results demonstrated that up-down asymmetry is crucial in determining newborns' face preference. 相似文献
