Brain transections selectively alter ingestion and behavioral activation in neonatal rats

Food-deprived neonatal rats actively ingest milk that is infused into their mouths through intraoral cannulas. This ingestion is accompanied by behavioral activation. The involvement of various brain regions in ingestion and activation was examined by making transections along the neuraxis from the olfactory bulbs to the anterior pons in 2-day-old rats. Following a 24-hr deprivation period, a series of oral milk infusions was given, and milk intake and activity were measured. Intake was severely reduced only in animals with diencephalic transections. Cuts in front of or behind the diencephalon resulted in normal or slightly decreased intake. In contrast, activity tended to decline as the level of the transection became more caudal. Thus ingestion and its accompanying behavioral activation could be separated neuroanatomically. These results suggest that two brain mechanisms are involved in the ingestive response of the infant rat, one in the diencephalon and another caudal to the mesencephalon. However, behavioral activation appears less discretely organized, involving most of the neuraxis.     

Facial and vocal cues of deception and honesty

Facial expressions and vocal cues (filtered speech) of honest and deceptive messages were examined in posed and spontaneous situations. The question of interest was the degree to which nonverbal cues transmit information about deception. Results indicated that (a) for both the facial and vocal channels, posing (as compared to spontaneous behavior) produced a higher level of communication accuracy; (b) facial expressions of deceptive (as compared to honest) messages were rated as less pleasant, while vocal expressions of deception were rated as less honest, less assertive, and less dominant, particularly in the posed condition; (c) the sender's ability to convey honesty was negatively correlated with his/her ability to convey deception, suggesting the existence of a demeanor bias—individual senders tend to appear and sound consistently honest (or dishonest) regardless of whether they deliver an honest or a deceptive message; (d) in the posing condition, the sender's abilities to convey honesty/deception via facial and vocal cues were positively and significantly correlated, whereas in the spontaneous condition they were not; and (e) senders whose full (unfiltered) speech indicated more involvement with their responses were judged as more honest from both their vocal (filtered speech) and facial cues, in both the honest and deceptive conditions.     

Measuring circadian cycles: A simple temperature recording preparation

While measurement of temperature as an index of circadian rhythmicity is not a difficult task with infrahuman subjects, long-term monitoring of deep body temperature with human subjects poses numerous measurement and safety problems. A preparation is described that is highly accurate, inexpensive, chronic, comfortable, and eliminates safety problems associated with more traditional methods of temperature measurement.     

Lump detection in simulated human breasts

Sixteen observers palpated silicone models of human breasts containing lumps 1.6-12.1 mm in diameter. Detectability depended on the size of the lump, producing a systematic psychometric function. In eight observers who participated in three or more sessions, performance improved with practice, with most improvement occurring within one or two 26-trial sessions. Three-week retention measures disclosed no appreciable decrease in performance, but a significant correlation was found between the number of lumps detected and duration of trial (p < .01). There was no difference in performance between four observers who used their preferred hands and four observers who used their nonpreferred hands. These data establish that examination of breast models for the detection of lumps simulating cancer is a task amenable to experimental analysis.     

Perceived orientation in depth from line-of-sight movement

Twelve college students viewed computer-generated displays of a cross comprised of two orthogonal dotted lines, and judged the apparent in-depth orientation of the horizontal arm by positioning a horizontal bar mounted on a rotary potentiometer. The vertical arm of the simulated cross was always in the observer’s frontal plane, but the randomly textured horizontal arm was in one of nine orientations relative to the line of sight. Each observer viewed displays in which the simulated cross was, alternately, (a) stationary, (b) approaching the viewer, and (c) stationary but expanding in size. The static texture density gradient in the horizontal arm of the simulated stationary cross mediated perceived orientation in depth. Further, when motion perspective was added to the detail perspective, the impression of depth was enhanced, with the greatest enhancement obtaining at the near viewing distance. When dynamic magnification was added to the detail perspective, the impression of depth was attenuated; this effect was interpreted as an illusory case of motion perspective.