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Biomedical subjects

J E Staddon

Publications and source records attributed to J E Staddon.

At least 19 recordsLinked to original sources
PubMed1992

Waiting in pigeons: the effects of daily intercalation on temporal discrimination.

Pigeons trained on cyclic-interval schedules adjust their postfood pause from interval to interval within each experimental session. But on regular fixed-interval schedules, many sessions at a given parameter value are usually necessary before the typical fixed-interval "scallop" appears. In the first case, temporal control appears to act from one interfood interval to the next; in the second, it appears to act over hundreds of interfood intervals. The present experiments look at the intermediate case: daily variation in schedule parameters. In Experiments 1 and 2 we show that pauses proportional to interfood interval develop on short-valued response-initiated-delay schedules when parameters are changed daily, that additional experience under this regimen leads to little further improvement, and that pauses usually change as soon as the schedule parameter is changed. Experiment 3 demonstrates identical waiting behavior on fixed-interval and response-initiated-delay schedules when the food delays are short (less than 20 s) and conditions are changed daily. In Experiment 4 we show that daily intercalation prevents temporal control when interfood intervals are longer (25 to 60 s). The results of Experiment 5 suggest that downshifts in interfood interval produce more rapid waiting-time adjustments than upshifts. These and other results suggest that the effects of short interfood intervals seem to be more persistent than those of long intervals.

Animals↗
PubMed1991

Dynamics of time discrimination.

Pigeons tracked sinusoidal sequences of interfood intervals (IFIs) by pausing in each interval for a time proportional to the preceding interval. Schedules with either long (30-90 s) or short (5-15 s) values, with variable numbers of cycles and starting phase each day, were tracked about equally well. Tracking was apparently immediate and did not improve across sessions. Experiment 2, in which long and short series were presented on alternate days, showed that tracking on long was more impaired than on short. Experiment 3 showed that occasional presentation of a short IFI in a series of fixed, longer IFIs caused a reduction in waiting time in the next IFI. These effects are evidence for a fast-acting timing mechanism in which waiting time in the IFI N + 1 is strongly determined by the preceding IFI, N. Earlier IFIs have some cumulative effect, but the details remain to be elucidated.

Animals↗
PubMed1987

Within-session meal-size effects on induced drinking.

As a control for the effects of session duration and hunger on the relation between food magnitude and induced drinking, four food-deprived rats were exposed to a variable-time 50-s schedule of food delivery in which the size of each food delivery varied randomly within sessions. Food-related behavior and schedule-induced drinking per opportunity were examined as functions of meal size and postfood time. All rats showed an inverted-U-shaped relation between drinking per opportunity and meal size. This relation was caused by variation in the percentage of intervals that contained drinking and by variation in the number of drinking bouts per interval, rather than by bout duration or by the amount of drinking within those intervals that actually contained drinking. Head-in-feeder time increased linearly with meal size. Schedule-induced drinking was entrained by food delivery in 3 of 4 subjects; the entrainment was due to regulation of the starting time of each drinking bout rather than to regulation of bout duration.

Animals↗
PubMed1987

Minimum urine collection periods for accurate determination of creatinine clearance in critically ill patients.

The accuracy of creatinine clearance (CLcr) determinations obtained from urine collections of less than 24 hours duration and the cyclical variation in creatinine excretion were studied in 10 critically ill patients with trauma or postoperative complications. Data from patients who received drugs or had diseases known to influence creatinine production or interfere with assay methods were excluded. Twelve consecutive two-hour urine collections and midpoint blood samples were obtained for each patient. Urine and serum samples were assayed for creatinine content by kinetic and enzymatic methods, respectively. The mean 24-hour CLcr was 110.6 +/- 47.0 mL/min. Clearance values determined from 8- and 12-hour collections were within 20% of the 24-hour CLcr value, and values determined from 14- to 22-hour collections were not significantly different from the 24-hour CLcr value. Mean differences between each 2-hour interval and the 24-hour interval were not significant for the 12 collection intervals. In critically ill trauma or postsurgical patients, the 24-hour CLcr can be estimated from an 8-hour urine collection if a deviation of up to 20% from the 24-hour value is clinically acceptable. No significant cyclical variation in creatinine excretion over 24 hours was found.

Adult↗
PubMed1986

Cholecystokinin, diet palatability, and feeding regulation in rats.

Rats ate less food than normal on cyclic-ratio schedules following cholecystokinin and lithium chloride injections. Nevertheless, they defended this lower eating rate in the same way as under control conditions. The pattern of effects produced by cholecystokinin and lithium chloride resembled those following diet adulteration with citric acid and sucrose octa acetate and differed from the effects produced by increases in body weight. Cholecystokinin and lithium chloride injections also produced similar changes in the free-feeding patterns of non-deprived rats: Both meal size and intermeal intervals decreased in manner similar to the effects of citric acid and sucrose octa acetate adulteration. Interpreted in terms of a static regulatory model, these results suggest that cholecystokinin and lithium chloride suppress feeding by degrading the palatability of food, not by promoting satiety, discomfort, or illness.

Animals↗
PubMed1984

Time and memory.

Standard animal memory tasks require judgments of event recency: Delayed matching to sample (DMTS) requires that the animal identify the stimulus seen most recently; radial-maze-type (RM) tasks require that the animal identify the place visited least recently. Delayed-reaction tasks are intermediate. I argue that time discrimination (temporal control) and event memory call on the same processes: Proactive and retroactive effects occur in both, brief events have less effect than protracted events, and increases in event duration have smaller and smaller effects. If the "ages" of past events are represented by animals in a way consistent with Weber's and Jost's laws, and if there is a limit to the number of different recencies that can be discriminated, then the major differences between these three types of memory task can be explained. DMTS performance is poor because the animal must discriminate between two sets of recencies (memory arrays) that differ only in respect of the most recent event; RM performance is good because the recencies of places visited on the current versus earlier trials are always clearly discriminable.

Animals↗
PubMed1983

Operant regulation of feeding: a static analysis.

Cyclic-ratio schedules are a rapid method for studying the operant regulation of feeding rate. The cyclic method produces results comparable to traditional but time-consuming parametric methods. Performance on cyclic-ratio schedules is well described by a linear regulatory model that embodies three quantitative feedback assumptions: (a) that rate of feeding is regulated by the rate of operant behavior, (b) that taste factors have an additive effect on the rate of the operant response, and (c) that regulatory "gain" is inversely related to body weight. This model accurately describes poorer regulatory performance at high body weights and following amphetamine administration, and the effects of altered diet palatability on preferred feeding rates.

Animals↗
PubMed1982

Decreased feeding associated with acute hypoxia in rats.

Rats obtained less food than normal on a cyclic-ratio schedule during brief, 1-hr exposure to either moderate hypobaric hypoxia (BP = 435 Torr, PO2 approximately equal to 91 Torr) or to hypoxic hypoxia (BP = 750 Torr, PO2, approximately equal to 90 Torr), but not during hypobaric exposure with 36.5% oxygen (BP = 435 Torr, PO2 approximately equal to 159 Torr). The depressed rate of feeding associated with hypoxia was nevertheless well regulated. Interpreted in terms of a regulatory model, these results suggest that hypoxia suppresses eating because it degrades the taste of food, not because it impairs feeding regulation or general activity.

Altitude↗
PubMed1982

Sensory superstition on multiple interval schedules.

Pigeons were exposed to multiple schedules in which an irregular repeating sequence of five stimulus components was correlated with the same reinforcement schedule throughout. Stable, idiosyncratic, response-rate differences developed across components. Components were rank-ordered by response rate; an approximately linear relation was found between rank order and the deviation of mean response rate from the overall mean rate. Nonzero slopes of this line were found for multiple fixed-interval and variable-time schedules and for multiple variable-interval schedules both when number of reinforcements was the same in all components and when it varied. The steepest function slopes were found in the variable schedules with relatively long interfood intervals and relatively short component durations. When just one stimulus was correlated with all components of a multiple variable-interval schedule, the slope of the line was close to zero. The results suggest that food-rate differences may be induced initially by different reactions to the stimuli and subsequently maintained by food.

Animals↗
PubMed1978

Behavioral competition: a mechanism for schedule interactions.

Rats pressing a lever for food reinforcement showed large positive-contrast effects when provided with the opportunity for a competing wheel-running response. Positive and negative behavioral contrast may reflect reallocation of competing interim and terminal responses between schedule components following changes in the reinforcement conditions in one component.

Animals↗
PubMed1969

The effect of informative feedback on temporal tracking in the pigeon.

Pigeons emitted interresponse times that were reinforced if they fell between an upper and a lower bound (t<IRT<t+t/10). Brief stimuli followed each response; under some experimental conditions the color of these stimuli was correlated with whether the preceding interresponse time was longer or shorter than that specified by the schedule. Preliminary experiments indicated that these "feedback" stimuli acquired no discriminative properties even after prolonged training. A modified procedure, in which t varied cyclically throughout each experimental session, allowed the stimuli to acquire such properties: stimulus control was demonstrated under the training conditions, for two of the pigeons, and under transfer conditions for all three birds. A series of probe conditions, followed by a replication of the simple procedure using a multiple schedule, indicated that the controlling property of the stimuli was not the relation between stimuli, interresponse time, and value of t, but a variable determined by the interaction between the animals' responding and the cyclic procedure. This variable was probably the relative frequency of the less-frequent feedback stimulus.

Animals↗