Christopher J. Conway

Bladder representation in the pontine-mesencephalic reticular formation ☆

Abstract Ablation and stimulation investigations of the rostral pons and caudal mesencephalic reticular formation of the cat have indicated an area exclusively concerned with the organization of the micturition reflex. Contrary hypothesis suggests that these effects result from nonspecific innervation of spinal cord reflex areas. An extracellular microelectrode analysis of the rostral pons has demonstrated the presence of units responding exclusively to bladder stimulation. This latter was evoked by pelvic nerve stimulation and induction of spontaneous reflex activity. Units responding to visceral stimulation were either potentiated or depressed in firing rate, the former being predominant. Convergence to somatosensory stimuli was observed. With the latter, no units were observed to be potentiated by visceral input and depressed by somatic input. Opposite effects were obtained from somatosensory stimulation of perineal and forepaw regions. Phasically active neuronal pools were found in the rostral pons responding to initiation and termination of micturition reflex activity.

Urinary incontinence: Treatment with electrical stimulation of the pelvic floor

Electrical pelvic floor stimulation may be administered either externally by the transrectal tampon or internally with the implantable pelvic floor stimulator. This treatment modality requires intact pelvic floor innervation and therefore is unsuccessful in patients with pelvic floor denervation. Pelvic floor stimulation has been successful in patients with stress and with congenital, iatrogenic, and postoperative urinary incontinence.

Electrophysiological maturation of the pyramidal tract in the post-natal rabbit

Abstract 1. 1. The medullary pyramidal tract of rabbits ranging in age from newborn to adult was stimulated electrically, and the evoked cortical and pyramidal unit responses investigated. 2. 2. The cortical evoked response in the adult consisted of an early positive wave of two components (waves 1 and 2), followed by a negative wave (wave 3). These waves were followed by larger variable waves. 3. 3. Laminar analysis data and the discharge distribution of antidromically activated units indicated that the early positive wave is an intra-cortical event reflecting antidromic invasion of pyramidal cell bodies. Wave 3 was considered to originate in the apical dendrites, and to be partially antidromic in origin, and partially the result of post-synaptic potentials. 4. 4. The cortical evoked response in the newborn rabbit was similar in configuration to that of the adult, but the latency was greatly prolonged, not reaching adult values until animals were 30 days old. The amplitude variability of wave 3 observed in the adult with repetitive stimulation was not present in newborns. 5. 5. Pyramidal units could be activated antidromically in the newborn animals, but no spontaneous firing was seen, and no unit responses to peripheral stimulation could be elicited. Spontaneous cortical units were seen after 3 days of age, but units responding synaptically to stimulation of the pyramid were not seen until 10 days. 6. 6. The ability of responses to follow rapid stimulation was considerably less in the immature animal than in the adult. Pyramidal units in the newborn failed to follow stimulation rates in excess of 50/sec. Immature spikes showed decrease of amplitude with rapid stimulation, and frequent fracturing of the spike. 7. 7. The data suggest that pyramidal tract cells in the newborn animal are excitable, functionally isolated from sensory input, and display different membrane characteristics and greater disparity in the threshold of the individual portions of the membrane than the adult.

Discriminator and integrator instrument for an on line frequency analysis of single unit discharges.

Abstract An instrument has been described for use in analysis of neural spikes which combines the functions of pulse amplitude discriminator and pulse frequency meter. The instrument will select spikes of a given amplitude from a background of spikes of assorted amplitudes and measure the discharge rate of the selected spike. Output may be read directly on a meter or fed into a recorder.

Clinical Experience with the Mentor Bladder Stimulator

A new bladder stimulator which limits current spread to adjacent pelvic floor structures has been tested in four patients with a variety of neurological lesions. The device successfully emptied the bladders of all patients tested. However, electrical stimulation produced a spinal-cord-mediated pelvic floor contraction in the patient who had an upper motor-neuron lesion. Voiding was successful in the latter patient following chemical rhizotomy.

Z-Axis modulation in neural spike display

Abstract A device has been described which automatically controls the intensity of the CRT spot to provide even brightness for a slow moving baseline and fast vertical spikes. The device operates in the frequency range of neural unit spikes and provides great improvement in the quality of negatives photographed from the CRO screen. It is in addition very inexpensive and easy to build.

Selective amplification of neural spike responses

Abstract An instrument has been described that may be employed to selectively amplify isolated random digital neural events. The wave form of the spike and background are preserved, but the relative amplitude changed.