THE RESPIRATORY CONTROL SYSTEM is not just reflexive; it is smart, it learns, and, in fact, it has a working memory. The respiratory system listens to and carefully remembers how previous respiratory stimuli affect breathing. Respiratory memory is laid down by regulating synaptic strength between respiratory neurons. Repeated hypoxic bouts trigger a form of respiratory memory that functions to ...

The present study examined the effects of strychnine on the tonic hyperpolarization and the changes in membrane properties of lumbar motoneurons that occur during active sleep. To carry out these studies, intracellular recordings from lumbar motoneurons were combined with the juxtacellular microiontophoretic application of strychnine in chronic, undrugged, normally respiring cats. During active...

The recovery of persistent inward currents (PICs) and motoneuron excitability after chronic spinal cord transection is mediated, in part, by the development of supersensitivity to residual serotonin (5HT) below the lesion. The purpose of this paper is to investigate if, like 5HT, endogenous sources of norepinephrine (NE) facilitate motoneuron PICs after chronic spinal transection. Cutaneous-evo...

Performance in sprint exercise is determined by the ability to accelerate, the magnitude of maximal velocity and the ability to maintain velocity against the onset of fatigue. These factors are strongly influenced by metabolic and anthropometric components. Improved temporal sequencing of muscle activation and/or improved fast twitch fibre recruitment may contribute to superior sprint performan...

Individual motoneuron responses to a variety of afferent inputs have been examined. At a given input some motoneurons respond to every trial, some to no trial, and some respond to a certain percentage of trials that is characteristic for the motoneuron at that input. The performance of a motoneuron is expressed by means of a firing index that relates the number of responses to the number of tri...

The effects of excitatory inputs arising from Ia afferent and corticomotoneuronal volleys on repetitively firing flexor carpi radialis (FCR) motoneurons were compared in normal human subjects. Peripheral (Ia) volleys were produced by transcutaneous electrical stimulation of the median nerve and by mechanical taps to the FCR tendon. Transcranial magnetic stimulation (TMS) was used to activate th...

The mean location of Renshaw synapses on spinal motoneurons and their synaptic conductance were estimated from changes in impedance magnitude produced by sustained recurrent inhibition. Motoneuron impedance was determined by injecting quasi-white noise current into lumbosacral motoneurons of pentobarbital-anesthetized cats. Synaptic location and conductance were estimated by comparing observed ...

Dopamine (DA) activates fictive crawling behavior in the medicinal leech. To identify the cellular mechanisms underlying this activation at the level of crawl-specific motoneuronal bursting, we targeted potential cAMP-dependent events that are often activated through DA(1)-like receptor signaling pathways. We found that isolated ganglia produced crawl-like motoneuron bursting after bath applica...