T Drew — Page 4 | Search PubMed

PubMed1984

A study of jaw reflexes of the awake cat during mastication and locomotion.

This paper reports on experiments on the jaw opening reflex carried out while awake unrestrained cats were eating or walking on a treadmill. It is shown that the jaw opening reflex response to low intensity stimulation diminished in all phases of the masticatory cycle. The response to higher threshold afferents, however, is phase modulated so that the largest responses occur during the jaw closing phase. This is in accord with the need for increased protection of the soft tissues in this phase of the movement. In contrast, the digastric reflex amplitude does not change when the cat passes from quiet standing to walking on the treadmill. Evidence is presented that the electromyographic activity of the jaw closing muscles increases during upwards movement of the head during walking and decreases as the head falls. These data support the hypothesis that the myotatic reflex in the elevator muscles plays a role in stabilizing the mandible during locomotion.

Afferent Pathways↗

PubMed1981

A new lack of twist for the Judkins left coronary catheter.

We have developed a modified Judkins left coronary arteriography catheter. The catheter is fabricated from 7 French thin-walled tubing made of extruded polyethylene. This tubing has a larger lumen diameter than either the 7 French or 8 French torque-control tubings used for standard Judkins coronary arteriography catheters. The large lumen substantially improves the pressure-flow characteristics of the catheter. Accordingly, it is considerably easier to inject contrast medium through this tubing. Although this tubing has no torsional rigidity, the lack of torque-control has proved to be an advantage rather than a detriment in the use of the catheter. Based on experience of over 2,000 studies with this catheter, we feel that it is superior to standard torque-control catheters for left coronary angiograms.

Cardiac Catheterization↗

PubMed1980

Responses in the posterior lobe of the rat cerebellum to electrical stimulation of cutaneous afferents to the snout.

1. Responses in the cortex of the posterior lobe of the cerebellum to electrical stimulation of afferent fibres from the skin of the snout have been analysed in decerebrate and pentobarbitone-anaesthetized rats by means of surface and microelectrode records. Single shocks were applied either to the exposed follicles of the mystachial vibrissae or to the infraorbital branch of the trigeminal nerve. 2. In decerebrate rats responses were mediated only via mossy fibre afferents. Stimulation of one side of the snout yielded responses with mean latency 2.4 ms throughout the uvula (largest ipsilaterally and in lobule IXa). Smaller responses with similar latency were present in both cerebellar hemispheres (largest ipsilaterally). The earliest discharges of Purkinje cells in lobule IXa occurred at latencies between 4.5 and 8.5 ms. 3. All components of the extracellular field potentials generated within the cortex by the mossy fibre input were detectable by surface recording with ball electrodes. 4. The earliest surface potentials had a latency of 0.55 ms (peak latency 0.8 ms); they arose through volume conduction from the brain stem of a potential which signalled arrival of the primary afferent volley. The short delay between this event and the arrival of the mossy fibre volley in the cerebellum suggests that only one synaptic relay occurs in the brain stem. 5. In pentobarbitone-anaesthetized rats surface responses mediated via mossy fibres persisted and were accompanied at slightly higher threshold by responses shown to be mediated via climbing fibres. The latter were present in descending order of amplitude in three sagittally directed zones, one in contralateral Crus 2 (minimum latency 13 ms), one in the vermis contralaterally near the mid line in lobule IXa (latency 16 ms) and a third in ipsilateral Crus 2 (latency 20 ms) 6. In the hemisphere the responses mediated via climbing fibres occurred within the somewhat larger zones activated via mossy fibres but in the vermis the two types of trigemino-cerebellar input influenced quite separate areas of cortex.

Animals↗