The primate as a model for the human temperature-sensing system: 1. Adapting temperature and intensity of thermal stimuli.

The thermal sensitivity of three humans and two rhesus monkeys was measured behaviorally, using the "yes-no" paradigm of the Theory of Signal Detection. The aim was to evaluate the monkey's thermal-sensing system as a model for that of humans. Three of the principal variables of human thermal sensations--rate of the temperature change, area of stimulation, and site of stimulation--were held constant. The other three variables--adapting skin temperature (AT), intensity, and direction of the temperature change--were varied systematically. Systematic differences between species were not evident for warming or cooling stimuli. Isodetectability curves (d'e = 1) for small cooling stimuli plotted as a function of the AT were isomorphic, and the points for the human and monkey subjects were frequently superimposed. Isodetectability curves for warming stimuli, on the other hand, had similar shapes for ATs between 33 degrees and 40 degrees C, but the points for the different subjects were not superimposed. At ATs below 30 degrees C, one of the two humans in the warming series and the two monkeys continued to show similarly shaped curves, but the other human was markedly different. Qualitative descriptions of the thermal sensations obtained during threshold measurements of human subjects, reported previously, suggest that this unusual subject probably adopted a criterion qualitatively different from that used by the other subjects. The data presented here and in combination with previously published work from this laboratory (Kenshalo, 1970) suggest that thermal stimuli produce similar sensations in rhesus monkeys and humans, and that the neural systems responsible for coding AT and temperature change in the two species are fundamentally similar.

Collateral sprouts are replaced by regenerating neurites in the wounded corneal epithelium.

Following various types of wounds and subsequent denervation, the reinnervation of the rabbit corneal epithelium was found to occur in two distinct phases that overlapped in time. In the first phase large numbers of collateral sprouts originated from the unmyelinated plexus at various distances proximal to the site of transection. Light and electron microscopic observations revealed that the sprouts began to degenerate about 7 days after wounding. Collateral sprouts were replaced by an equally numerous population of regenerating neurites extending from the transected stumps of the pre-terminal axons. We conclude that, in the wounded cornea, normal neurology is reconstituted by regenerating neurites, and not by collateral sprouts, which proliferate and then degenerate early in the healing process.

RIPS: a UNIX-based reference information program for scientists.

A set of programs is described which implement a personal reference management and information retrieval system on a UNIX-based minicomputer. The system operates in a multiuser configuration with a host of user-friendly utilities that assist entry of reference material, its retrieval, and formatted printing for associated tasks. A search command language was developed without restriction in keyword vocabulary, number of keywords, or level of parenthetical expression nesting. The system is readily transported, and by design is applicable to any academic specialty.

Neural remodeling following experimental surgery of the rabbit cornea.

Wounding of the cornea results in extensive damage to the innervation that must be repaired to restore its normal structure and function. Four types of experimental wounds were produced in the corneas of young albino rabbits: 180 degrees penetrating perilimbal incisions, 4-mm central circular keratectomies and keratotomies, and radial keratotomies. Following perilimbal incisions, the denervated half of the cornea was reinnervated primarily by regenerating nerves that penetrated the limbal scar tissue. New neural growth from the innervated portion of the cornea provided a minor contribution to the denervated area. The regenerative response of the nerves following nonpenetrating procedures was found to be a biphasic process. In the first phase, a short period of degeneration of all nerves within the area enclosed by the wound boundary overlapped in time with the appearance of long, large caliber, dense neurites that coursed perpendicularly to the wound margins. The neurites originated from the intact subepithelial plexus at some distance from the wound margins. The second phase was initiated by the degeneration of the wound-oriented neurites and the concomitant appearance of a second generation of neurites. These new neurites originated from the transected stumps of the regenerating subepithelial axons at or near the wound margins. The oblique disposition of the second wave of neurites was similar to that of basal leashes in normal corneas. Nonpenetrating wounding procedures exhibited similar neural remodeling principles. In both types of keratotomies, nerve endings terminated within the wound in enduring and densely packed neuroma-like arrangements, while in keratectomies, nerve endings continued to grow toward the center of the cornea.