Showing papers by "Harvey J. Grill published in 1990"
TL;DR: The findings reveal that the anterior oral receptive field (innervated by the CTn) containing only 15% of the total taste bud population is critical for the normal detection of NaCl.
Abstract: Electrophysiological data support the existence of sodium-specific taste receptors that appear to be limited to the anterior tongue. However, previous behavioral findings suggest that bilateral transection of the chorda tympani nerve (CTn) has minimal consequences on NaCl intake and preference. This study employed a conditioned avoidance procedure to measure detection thresholds to NaCl and sucrose both before and after bilateral transection of the CTn. Rats were trained to maintain spout contact in response to water presentations (70 microliters) and to avoid spout contact when a taste solution (70 microliters) was presented. In experiment 1, all rats (n = 3) showed statistically significant impairments in the detectability of NaCl after bilateral section of the CTn. The mean increase in the NaCl detection threshold was 1.41 log units. In contrast, sucrose threshold in these same rats was marginally affected by CTn section (mean increase = 0.22 log units). Experiment 2 (n = 4) replicated the findings of the first experiment. The mean increase in the NaCl detection threshold was 2.23 log units. Sucrose threshold in these rats was, again, only marginally affected by CTn section (mean increase = 0.83 log units). Histological examination of the anterior tongue from the rats in experiment 2 indicated that the CTn transections were complete. These findings reveal that the anterior oral receptive field (innervated by the CTn) containing only 15% of the total taste bud population is critical for the normal detection of NaCl.
64 citations
TL;DR: It is demonstrated here that when a normally avoided taste (quinine or HCl) signals a preferred taste (sucrose), the oral motor responses gradually undergo two types of change as a function of trials, including aversive and ingestive responses.
51 citations
TL;DR: Quantitative analysis of experiment II indicated that across sessions with common part B infusion rates, total session intake remained stable regardless of whether the part A ingestion rate was greater than or equal to that of part B, and systematic differences in part A intake and duration.
Abstract: A novel intake testing paradigm, allowing explicit adjustment of the rate of sucrose ingestion via intraoral delivery, was used to investigate the effects of ingestion rate on ingestion duration and amount consumed. In experiment I, 12 rats were tested under each of three sucrose concentrations (0.1, 0.3, and 1.0 M) delivered at each of four rates (0.5, 1.0, 1.5, and 2.0 ml/min). For each stimulus concentration, intraoral intake varied as a decreasing linear function of ingestion rate (infusion rate). In experiment II, a second (part B) infusion (0.5, 1.0, or 1.5 ml/min) was initiated 30 s after an initial (part A) infusion (0.5, 1.0, or 1.5 ml/min) of the same stimulus was rejected. Amount consumed during the part B infusion was substantial only when the part B infusion rate was lower than that of part A. Quantitative analysis of experiment II indicated that across sessions with common part B infusion rates, total session intake remained stable regardless of 1) whether the part A ingestion rate was greater than or equal to that of part B, 2) systematic differences in part A intake and duration, 3) differences in total session duration, and 4) differences in average ingestion rate for the session (total session intake/total session duration). The behavioral results are discussed in relation to the analysis of satiety under traditional intake testing paradigms and to gastric and postgastric theories of satiety.
25 citations