Newborn rats, 3 hr after birth and before any experience in suckling, were exposed for 10 min to a surrogate nipple providing milk. One hour later, they were exposed to an empty nipple for another 10-min period. The basic characteristics of oral behavior (oral compression activity, OCA) were assessed by recording intranipple pressure during the pups' first attachment to a nipple. The peculiarities of milk-induced changes of OCA were examined with three modes of milk delivery (milk infusions, and intermittent and continuous milk deliveries). The pattern of OCA exerted by the newborn pups on a surrogate nipple consisted of rhythmic oscillations within a frequency range of 0.4 to 1.0 Hz superimposed on slow (frequency < 0.2 Hz), irregular intranipple pressure fluctuations. Oral behavior during the first minute after oral capture of the nipple differed significantly from that during any subsequent 1-min interval in terms of frequency content of OCA. The pattern of OCA changes induced by milk infusions or intermittent milk delivery included an abrupt rise in intranipple pressure, accompanied or followed by a burst of fast nipple compressions (bites). Our data suggest that newborn rats attached to a surrogate nipple demonstrate patterns of oral behavior that simulate, in terms of basic frequency characteristics, patterns of nutritive and nonnutritive suckling observed in more mature pups on the maternal nipple.
The Telemetric Topography Device (TTD) introduces new technology to the measurement of cigarette smoking topography that has advantages over existing instruments. It consists of a 90.8-g miniature vacuum transducer coupled to an FM transmitter contained within a 11/4-in.-diarneter X 4 1 / 4 -in. free-standing plastic cylinder. As a subject smokes through a modified commercial cigarette holder, the TTD transmits a tone proportional to the vacuum pressure change in the cylinder. Received tones are converted to voltage data and then digitized by an AID board in a personal computer. This information can either be displayed and stored on line or recorded on audio tape and digitized during playback. The TTDhas no visible electronic parts, thereby minimizing subjects' awareness of monitoring.
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