The use of metal microelectrodes in broad-band recording.

We checked to what extent the voltage-current relationship of a microelectrode is linear. In the linear domain we measured the impedance characteristic of the electrode. We measured the frequency response curve and the phase characteristic of the electrode and amplifier system.     

A rapid and non leaky way for preparation of the sharp intracellular recording microelectrodes

To fill microelectrodes using backfilling method needs excessive time approximately 4–6  h. It is often difficult to fill microelectrodes without damage or leakage. A main problem is bubble formation in microelectrodes which has an impact on the electrical properties of the electrode and thus it influences the quality of the recording. Based on Archimede's principle there is a force within a solution which pushes insoluble material with a lower specific gravity upward and outside of the solution. Centrifugation can increase the force to eliminate the bubbles.

We designed a microelectrode holder to protect microelectrode sensitive tips from mechanical damage due to the gravity tensions; it can help to eliminate the bubbles easily and simultaneously in 10  min or less.

The tests were performed for 2000, 4000, and 8000  rpm centrifugation each one for 3, 6 and 12  min duration respectively, it was found that the bubbles were completely eliminated at 8000  rpm for 6–12  min and there were no significant differences for resistance, and the number of leaky or damaged electrodes between the two methods.

In the new design of devices, the materials used and the design of the holder are simple and the approach is applicable to many laboratories worldwide.     

A chronic implant for recording of cochlear potentials in primates

A new technique for the continuous recording of peripheral bioelectrical activity in the auditory system of primates is described. Because of basic differences in the anatomy of the temporal bone, the approach to the round window of the cochlea is more difficult in most primates than in lower animals. A relatively simple surgical approach, which made possible the placement of an electrode into the perilymph of the inner ear via the well-demarcated horizontal semicircular canal was therefore developed and is described in detail. The bared tip of a Teflon-coated wire was cemented into the canal opening with carboxylate cement, and the wire attached to a permanent electrical connector on the skull. Cochlear microphonic and action potentials of 50 to 100 μV amplitude were thus recorded on a continuing basis at the same time that behavioral studies of primate auditory acuity were conducted.     

Effects of chronic electrical stimulation on paralyzed expiratory muscles.

Following spinal cord injury, the expiratory muscles develop significant disuse atrophy characterized by reductions in their weight, fiber cross-sectional area, and force-generating capacity. We determined the extent to which these physiological alterations can be prevented with electrical stimulation. Because a critical function of the expiratory muscles is cough generation, an important goal was the maintenance of maximal force production. In a cat model of spinal cord injury, short periods of high-frequency lower thoracic electrical spinal cord stimulation (SCS) at the T(10) level (50 Hz, 15 min, twice/day, 5 days/wk) were initiated 2 wk following spinalization and continued for a 6-mo period. Airway pressure (P)-generating capacity was determined by SCS. Five acute, spinalized animals served as controls. Compared with controls, initial P fell from 43.9 +/- 1.0 to 41.8 +/- 0.7 cmH(2)O (not significant) in the chronic animals. There were small reductions in the weight of the external oblique, internal oblique, transverses abdominis, internal intercostal, and rectus abdominis muscles (not significant for each). There were no significant changes in the population of fast muscle fibers. Because prior studies (Kowalski KE, Romaniuk JR, DiMarco AF. J Appl Physiol 102: 1422-1428, 2007) have demonstrated significant atrophy following spinalization in this model, these results indicate that expiratory muscle atrophy can be prevented by the application of short periods of daily high-frequency stimulation. Because the frequency of stimulation is similar to the expected pattern of clinical use for cough generation, the daily application of electrical stimulation could potentially serve the dual purpose of maintenance of expiratory muscle function and airway clearance.     

Transducer for recording electrical and mechanical chronic intestinal activity.

An extraluminal displacement transducer has been developed for simultaneously recording the mechanical activity in two perpendicular directions and the electrical activity of the intestinal serosa. The length variations in two perpendicular directions were measured by means of strain gauges bounded on two pairs of lamellae embedded in a rigid stand. The electrical activity was recorded by means of four electrodes situated at the extremity of these lamellae. The electrical gauges of each pair of lamellae are connected to form a Wheatstone bridge. This device allows establishment of a correlation between the mechanical displacement of the intestinal wall serosa and electrical potentials by means of studies of long duration.     

A method for the chronic electromagnetic recording of eye and head movements in monkeys

A search-coil method for two-dimensional chronic registration of eye and head movements is described. The method is based on the analysis of the electromotive force induced by a magnetic field in a search coil. The output parameters of the original dual system were measured using both the standard search coil and that implanted into monkey's eye. The precision of eye movement recording was evaluated in real time. Standard deviation of spontaneous noise level for both channels was equal to 0.16 degrees (deg). The same parameters representing eye movement error during gaze fixation in the horizontal (in the range of -20/+20 deg) and vertical (in the range of -13/+13 deg) directions were equal to 0.27-0.38 and 0.23-0.31 deg, respectively. The obtained errors were comparable with the angular size of the peripheral target stimuli (0.20 deg), which had to be traced by an animal with saccadic movements.     

A modification of the dermal-flap canthal lift for correction of the paralyzed lower eyelid.

A modification of the dermal-flap canthoplasty, described by Edgerton and Wolfort for the correction of paralysis of the lower lid, is described. It has produced excellent results in our experience.     

Hypoglossal-facial nerve anastomosis for reinnervation of the paralyzed face.

The hypoglossal-facial nerve crossover is a valuable surgical procedure for the treatment of certain types of facial paralysis. It is most effective when used as an integral part of a primary ablative operation for the treatment of cancer in this region. In the treatment of long-standing facial paralysis, its application requires an intact peripheral facial nerve system and some functioning mimetic muscles with an obliterated proximal facial nerve segment. It is recognized that other procedures are available for repair in patients who meet essentially these same criteria. The disadvantages are minimal intraoral crippling, mass movements of the face and, in some instances, hypertonia of the face. The advantages are improved facial tone, protection of the eye, intentional facial movements controlled by the tongue, and movements associated with physiological functions of the tongue.