Coordination between respiration and deglutition in a preterm infant mammal, Sus scrofa

In adult mammals, the path of a swallowed bolus of solid food crosses the laryngeal opening, so that coordination between respiration and deglutition is critical for airway protection. The nature of such coordination in preterm, low-birth-weight infants with immature nervous systems, is not clear. Using preterm pigs as a model, two measures of respiration were recorded and then coordinated with a high-resolution cineradiographic record of swallowing. Swallows, divided into three distinct events, began before inhalation ended, but expiration did not start until after the milk had passed around the laryngeal opening. These results support the idea that a high degree of coordination between swallowing and respiration exists in preterm infant pigs, although other aspects of the nervous system have not fully matured.     

A Modification of the French and Stein Neural Analog

The way in which accommodation is modeled in the French and Stein (1970) electronic neural analog may cause it to behave differently from a real neuron during an `inhibitory potential. This has been overcome by incorporating half-wave rectification into that part of the circuit modeling accommodation.     

The effect of food consistency upon jaw movement in the macaque: a cineradiographic study

Variation in the form of masticatory cycles in individuals is often assumed to be limited. The contrary hypothesis, that jaw cycles vary widely but systematically with food consistency, was tested in macaques fed similarsized pieces of monkey chow, apple, and banana. With the animals under general anesthesia, radiopaque markers were inserted into the jaw, tongue, and hyoid. Oral movements were recorded by cineradiography at 100 frames/sec in lateral projection synchronously with frontal view cinephotography (50 frames/sec). The films were examined for the events that subdivide each jaw movement cycle into its constituent phases (fast closing, slow closing, intercuspal, slow or early opening, final opening). The frame numbers at which these events occurred were used to define phase durations. The numbers of cycles preceding a swallow increased with the hardness of the ingested food item. Regardless of the test food, every feeding sequence (initial ingestion to final clearance of mouth) contained multiple swallows, each of which defined the end of a sub-sequences when the animals were feeding on chow, the sub-sequences were initially long (20 cycles or more), but when they were feeding on banana, the sub-sequences were short (10 cycles or fewer). Although the form of individual cycles (defined by phase durations) was often unrelated to that of neighboring cycles, the general cycle characteristics in a sub-sequence typified a particular food. Chow feeding cycles were characterized by slow-closing (SC) phases of long duration with slow-opening (SO) phases of short duration; the characteristics of banana feeding cycles were the reverse. SC duration correlated directly and SO duration correlated inversely with food hardness (p < 0.001). The evidence supports the view that the centrally generated pattern of movement is highly dependent upon intra-oral sensory feedback.     

Wide-Band Multi-Channel Transient Monitor System

The premature reset of a flight programmer followed by the destruction of a multi-million dollar space vehicle could easily result from a single spurious transient. Because of these potentially catastrophic effects, methods of detecting and analyzing electrical transients have generated vivid interest within the aerospace industry. Even assuming that an effective transient monitor system was available, a basic problem still exists?the acquisition of sufficient paper/ pen recording channels to conduct an effective transient investigation. Since paper/pen recording devices are usually at a premium, especially during the integrated systems testing of a complex vehicle, transient investigations are usually compromised if not altogether deleted. To cope with the problem, the authors have developed a Wide-Band Multi-Channel Transient Monitor System. The system has the capability of storing transient information from many test points on a single channel of magnetic tape. Upon playback of the tape, the information can be displayed, in real time, with no loss of highfrequency information, and all the data are easily correlated with system test time.     

Transition from suckling to drinking at weaning: a kinematic and electromyographic study in miniature pigs

The movements of the tongue, hyoid, and jaw were recorded cineradiographically in preweaning pigs as they suckled bariumized milk from a veterinary teat or drank it from a bowl. The movements were quantified by measuring the X, Y coordinates of radioopaque markers embedded in the tongue and attached to both jaws and to the hyoid. EMG activity in masseter, anterior digastric, geniohyoid, genioglossus, hyoglossus, sternohyoid, stylohyoid, and omohyoid muscles was recorded synchronously with cineradiography at 100 frames/sec. In both suckling and drinking, the movements were characterized by minimal movements of the jaw and hyoid but extensive movements of the tongue. In suckling, the movements were largely confined to the midposterior part of the tongue. A seal was formed between the posterior tongue and soft palate while a depression formed in the mid-tongue; this was associated with fluid moving into the depression probably because of a reduced intraoral pressure. The depression was associated with increased EMG activity in the genioglossus muscle and overlapping activity in digastric, geniohyoid, hyoglossus, and sternohyoid muscles. In drinking cycles, significant movement occurred in all parts of the tongue; milk ingestion was associated with tongue movements that combined elements characteristic both of suckling (mid-tongue depression with a posterior seal) and of lapping (extensive anteroposterior movements within the tongue itself). In drinking, compared to suckling, there was a major reduction in EMG activity in masseter, digastric, geniohyoid, and sternohyoid muscles. After milk had accumulated in the valleculae, swallows usually occurred in every other cycle during suckling and in every third or fourth cycle during drinking. The emptying of the valleculae was an event that was embedded in the early jaw-opening phase of an otherwise normal suckling or drinking cycle. Emptying of the valleculae was associated with posteriorly directed movement of the back of the tongue and increased EMG activity in hyoglossus, styloglossus, and omohyoid muscles. No differences were noted in the kinematics associated with swallowing in the two activities, but, in the normalized and averaged EMG data, there were significant differences in the timing of genioglossus activity and in the relative balance of hyoglossal and stylohyoid activity.