Perioral somatosensory determinants of nursing behavior in Norway rats (Rattus norvegicus)

Prior to assuming the upright crouching posture over their pups during nursing bouts, lactating rats typically engage in several oral behaviors, including nuzzling, licking and rearranging pups. By acutely depriving dams of various aspects of perioral stimulation from pups (with anesthesia of the mystacial pads or of the tongue, with mouth suturing, or with muzzling), we found the following: (1) Distal stimulation from pups maintains proximity-seeking behavior, but is insufficient to stimulate nursing behavior. (2) Lack of tongue feedback decreases pup licking and hastens the onset of crouching. (3) Snout, but not tongue, contact with pups is required for hovering over them. (4) The position of the dam while hovering over her litter enables the pups to gain access to her ventrum, thereby provoking her upright, crouching posture. (5) Older pups are capable of bypassing the dam's perioral attentions and stimulating crouching directly by burrowing under the dam's ventrum.     

The role of propulsive muscles of the shoulder during quadrupedalism in vervet monkeys (Cercopithecus aethiops): implications for neural control of locomotion in primates

In comparative anatomical studies of the shoulder, the humeral retractors are often grouped together as propulsive muscles, which are important in the propulsive stroke of the forelimb during quadrupedal locomotion. Electromyographic (EMG) analyses of these muscles in opossums, cats, and dogs in general have confirmed such conclusions. An EMG study of chimpanzee shoulder muscles during knuckle-walking found, however, that the humeral retractors are either inactive or perform a function unrelated to propulsion (Larson & Stern, 1987). This contrast in muscle recruitment patterns between chimpanzees and more "typical" mammalian quadrupeds was attributed to the derived morphology of the chimpanzee shoulder. The present study examines the activity patterns of the humeral retractors in the vervet monkey, a primate more closely resembling nonprimate mammals in its shoulder morphology. The results of this EMG analysis show that despite the significant differences in anatomy between chimpanzees and vervets, the two species display very similar muscle recruitment patterns during quadrupedalism, and there is evidence for this same pattern in other species of primates. These differences in muscle activity patterns between primates and nonprimate mammals may be related to changes in the neurological control of locomotion in primates due to the evolutionary development of manipulative abilities in the primate forelimb.     

Regional cerebral glucose metabolism in aphemia: A case report

Local cerebral metabolism was determined in a patient suffering aphemia following cerebral infarction using the 18FDG-PET technique. The syndrome was characterized by profound ictal nonfluency with sparing of other language functions. Speech subsequently improved so that content and grammar were appropriate but mild dysprosody persisted. Conventional CT showed no lesion of the left hemisphere while PET revealed a discrete focus of hypometabolism on the left which partially resolved on serial studies. The metabolic lesion could be localized to the region of the inferior precentral gyrus and the adjacent subcortical space.     

Semantic emphasis in causal sentences

A shift in emphasis can change the truth-value of a singular causal sentence. This poses a challenge to the view that singular sentences predicate a relation. I argue that emphasized causal sentences conjoin predication of a causal relation between events with predication of a relation of causal relevance between states of affairs (or perhaps facts). This is superior to the treatments of such sentences offered by Achinstein, Dretske, Kim, Sanford, Bennett, and Levin. My proposal affords clarity regarding logical structure, at least at a certain level of detail. It makes the relation between the content of an emphasized causal sentence and the unemphasized version clear. It answers some questions about the ontological requirements of the truth of emphasized causal sentences, without introducing new entities (as do some other accounts) or unacceptable consequences for identity and individuation of events.     

Maternal aggression: disruption by perioral anesthesia in lactating Long-Evans rats (Rattus norvegicus)

Role of perioral somatosensation in the display of maternal aggression in Long-Evans Norway rats (Rattus norvegicus) was investigated during early lactation by local anesthesia of the mystacial pads with lidocaine, which blocks conduction in the infraorbital nerve. Acute perioral anesthesia markedly reduced the likelihood that maternal aggression was expressed; this effect of perioral anesthesia was not ameliorated by a repeated test with the same treatment or by pretreatment fighting experience. The dams that fought with the intruder during perioral anesthesia did so after greatly increased sniffing contact and with decreased vigor compared with controls. Males that were attacked tended to freeze, whereas males that were not attacked were active. Thus, trigeminal afferents are critical for the initiation and normal execution of maternal aggression responses in Norway rats.     

The lost e-mail method: Milgram’s lost-letter technique in the age of the Internet

We examined Milgram’s (1977) lost-letter technique using e-mail. In the first experiment, 79 college faculty received mock lost e-mail messages. Nineteen percent of those who received the messages responded, in all cases by returning the message to the “sender” instead of forwarding it to the “recipient.” In the second study, attitudes toward presidential candidate Ross Perot were examined by sending out two different messages to 200 randomly selected e-mail addresses in the United States. Although there was no differential response rate, examination of content revealed attitudes consistent with concurrent poll data.