Different contributions of primary motor cortex, reticular formation, and spinal cord to fractionated muscle activation.

Coordinated movement requires patterned activation of muscles. In this study, we examined differences in selective activation of primate upper limb muscles by cortical and subcortical regions. Five macaque monkeys were trained to perform a reach and grasp task, and electromyogram (EMG) was recorded from 10 to 24 muscles while weak single-pulse stimuli were delivered through microelectrodes inserted in the motor cortex (M1), reticular formation (RF), or cervical spinal cord (SC).

Fractionation of muscle activity in rapid responses to startling cues.

Movements in response to acoustically startling cues have shorter reaction times than those following less intense sounds; this is known as the StartReact effect. The neural underpinnings for StartReact are unclear. One possibility is that startling cues preferentially invoke the reticulospinal tract to convey motor commands to spinal motoneurons.

Chronic moderate sleep restriction in older long sleepers and older average duration sleepers: a randomized controlled trial.

Epidemiologic studies have consistently shown that sleeping <7 h and ≥8 h is associated with increased mortality and morbidity. The risks of short sleep may be consistent with results from experimental sleep deprivation studies. However, there has been little study of chronic moderate sleep restriction and little evaluation of older adults who might be more vulnerable to negative effects of sleep restriction, given their age-related morbidities.