bluuebunny/crossref_metadata_2025 huggingface dataset:
Neuroendocrine control of reproductive aging: roles of GnRH neurons
Authors: Yin Weiling , Gore Andrea C
Published: March 2006

The process of reproductive senescence in many female mammals, including humans, is characterized by a gradual transition from regular reproductive cycles to irregular cycles to eventual acyclicity, and ultimately a loss of fertility. In the present review, the role of the hypothalamic gonadotropin-releasing hormone (GnRH) neurons is considered in this context. GnRH neurons provide the primary driving force upon the other levels of the reproductive axis. With respect to aging, GnRH cells undergo changes in biosynthesis, processing and release of the GnRH decapeptide. GnRH neurons also exhibit morphologic and ultrastructural alterations that appear to underlie these biosynthetic properties. Thus, functional and morphologic changes in the GnRH neurosecretory system may play causal roles in the transition to acyclicity. In addition, GnRH neurons are regulated by numerous inputs from neurotransmitters, neuromodulators and glia. The relationship among GnRH cells and their inputs at the cell body (thereby affecting GnRH biosynthesis) and the neuroterminal (thereby affecting GnRH neurosecretion) is crucial to the function of the GnRH system, with age-related changes in these relationships contributing to the reproductive senescent process. Therefore, the aging hypothalamus is characterized by changes intrinsic to the GnRH cell, as well as its regulatory inputs, which summate to contribute to a loss of reproductive competence in aging females.
Reduced recruitment and survival of primordial and growing follicles in GH receptor-deficient mice
Authors: Slot Karin A , Kastelijn Jan , Bachelot Anne , Kelly Paul A , Binart Nadine , Teerds Katja J
Published: March 2006

GH influences female fertility. The goal of the present study was to obtain more insight into the effect of loss of GH signalling, as observed in humans suffering from Laron syndrome, on ovarian function. Therefore, serial paraffin sections of ovaries of untreated and IGF-I-treated female GH receptor knock-out (GHR/GHBP-KO) mice were examined to determine the follicular reserve and the percentage of follicular atresia in each ovary. Our observations demonstrate that the amount of primordial follicles was significantly elevated in GHR/GHBP-KO mice, while the numbers of primary, preantral and antral follicles were lower compared with wild-type values. The reduced number of healthy growing follicles in GHR/GHBP-KO mice was accompanied by a significant increase in the percentage of atretic follicles. IGF-I treatment of GHR/GHBP-KO mice for 14 days resulted in a reduced number of primordial follicles, an increased number of healthy antral follicles, and a decreased percentage of atretic follicles. The results of the present study suggest that GH may play a role, either directly or indirectly, via for instance IGF-I, in the recruitment of primordial follicles into the growing pool. Furthermore, GH seems to protect antral follicles, directly or indirectly from undergoing atresia.
Expression of c-Kit receptor mRNA and protein in the developing, adult and irradiated rodent testis
Authors: Prabhu Sridurga Mithra , Meistrich Marvin L , McLaughlin Eileen A , Roman Shaun D , Warne Sam , Mendis Sirisha , Itman Catherine , Loveland Kate Lakoski
Published: March 2006

Germ cell proliferation, migration and survival during all stages of spermatogenesis are affected by stem cell factor signalling through the c-Kit receptor, the expression and function of which are vital for normal male reproductive function. The present study comprehensively describes the c-Kit mRNA and protein cellular expression profiles in germ cells of the postnatal and adult rodent testis, revealing their significant elevation in synthesis at the onset of spermatogenesis. Real-time PCR analysis for both mice and rats matched the cellular mRNA expression profile where examined. Localization studies in normal mouse testes indicated that both c-Kit mRNA and protein are first detectable in differentiating spermatogonia. In addition, all spermatogonia isolated from 8-day-old mice displayed detectable c-Kit mRNA, but 30–50% of these lacked protein expression. The c-Kit mRNA and protein profile in normal rat testes indicated expression in gonocytes, in addition to differentiating spermatogonia. However, in the irradiated adult rat testes, in which undifferentiated spermatogonia are the only germ cell type, mRNA was also detected in the absence of protein. This persisted at 3 days and 1 and 2 weeks following treatment with gonadotrophin-releasing hormone (GnRH) antagonist to stimulate spermatogenesis recovery. By 4 weeks of GnRH antagonist treatment, accompanying the emergence of differentiating spermatogonia, both mRNA and protein were detected. Based on these observations, we propose that c-Kit mRNA and protein synthesis are regulated separately, possibly by influences linked to testis maturation and circulating hormone levels.
Functional Abnormalities in the Neural Circuitry of Reading in Men with Nonsyndromic Clefts of the Lip or Palate
Authors: Goldsberry Grant , O'Leary Dan , Hichwa Rich , Nopoulos Peg
Published: March 2006

Objective:

The current study was designed to evaluate the neurobiology of reading in a group of men with nonsyndromic clefts of the lip or palate (NSCLP) compared with healthy controls by positron emission tomography.

Design:

Subjects included eight men with NSCLP compared with six healthy control men. By using radioactively labeled water (O15), regional brain blood flow was obtained during the performance of three simple reading tasks: reading unrelated words, reading unrelated sentences, and reading a story.

Results:

During each of the reading conditions, NSCLP subjects compared with healthy controls showed increased blood flow in areas previously reported to be involved in language processing and reading (inferior frontal lobe, cerebellum, and occipital lobe). The increased blood flow suggests a possible neural inefficiency. In contrast, when analyzing the brain regions involved in more complex language functioning (reading stories compared with reading only words), control subjects showed an increase in blood flow in a distributed neural circuit, whereas the NSCLP subjects showed a decrease in flow in these regions. Additionally, the NSCLP subjects had activation of several regions not activated in the healthy controls, suggesting a compensatory circuit used for this more complex reading task.

Conclusions:

These results indicate that subjects with NSCLP show abnormalities in the function of the distributed neural circuitry used for oral reading.
ESCAPE BEHAVIOR UNDER DIFFERENT FIXED RATIOS AND SHOCK INTENSITIES1
Authors: Winograd Eugene
Published: March 2006

The effects of ratio length and shock intensity on bar pressing were examined in three rats in two escape‐from‐shock experiments. In Experiment I, shock intensity was held constant while the schedule was varied from FR 1 to FR 20. The latency of the first escape response increased with FR length while the escape rate, computed as over‐all rate in shock minus latency of the first response, decreased at FR 20. In Experiment II, the schedule was held constant at FR 5 while shock intensity was manipulated. Latency decreased as intensity increased, while escape rate increased with intensity, passing through a maximum for two subjects. Responses occurring during the last 100 sec of the 2‐min escape period decreased as the FR increased for all subjects, and decreased as shock intensity increased for two subjects.
FACILITATION OF LARGE RATIO PERFORMANCE BY USE OF CONDITIONED REINFORCEMENT1
Authors: Findley Jack D. , Brady Joseph V.
Published: March 2006

Fixed ratio performance was examined in the chimpanzee under two alternating conditions. In one, conditioned reinforcement followed successive fractions of the total ratio, and in the other it was omitted. Shorter pauses and working times, and the development of a strong preference resulted for the condition affording conditioned reinforcement.
SOME PROPERTIES OF SPACED RESPONDING IN PIGEONS1
Authors: Staddon J. E. R.
Published: March 2006

Pigeons exposed to a schedule which reinforces interresponse times (IRTs) longer than a given value (DRL schedule) eventually reach a stable pattern of responding which is shown to be a function both of the DRL value and of previous experience with other DRL values. On any given DRL schedule, the stable performance of most pigeons which have been previously exposed to a variety of such schedules, shows an IRT distribution with median equal to the DRL value. For DRL values longer than about 30 sec, however, the median IRT falls short of the DRL value; this failure of adjustment to longer values appears to be a species characteristic of pigeons. The function relating reinforcement rate to 1/DRL value is also shown to be approximately linear over the same range, with variable slope (less than 45°) and a downturn in the vicinity of DRL 30.
WIND AS AN AVERSIVE STIMULUS1
Authors: Rohles Frederick H.
Published: March 2006

Two monkeys were trained on an escape‐avoidance procedure in which a lever press delayed exposure to wind by 20 sec. For 5 hr, subjects alternately worked 15 min and rested 15 min, and performed this schedule when the wind was 5, 10, and 20 mph and the temperatures were 50, 60, and 70° F. Analysis of variance showed that the percent of wind avoided was related to both the velocity of the wind and the temperature during the exposure. When the wind was 10 and 20 mph it was avoided almost continuously regardless of the temperature.
DIFFERENTIAL RESPONSE RATES CORRELATED WITH THE PRESENCE OF “NEUTRAL” STIMULI1
Authors: Kieffer J. David
Published: March 2006

Five out of six rats, pressing a lever for food reinforcement, showed differential rates of responding that were correlated with the presence of a buzzer, under conditions where the buzzer might have been assumed to be neutral. The effect was demonstrated when the presence versus absence of the buzzer distinguished the components of Mult FI 2 min FI 2 min, as well as when the buzzer was present throughout entire sessions of simple FI 2 min for n/2 of every n such sessions. The cause of the phenomenon was not determined.
SOLUTION OF THE INTERMEDIATE SIZE PROBLEM BY PIGEONS1
Authors: Zeiler Michael D.
Published: March 2006

Pigeons learned to respond to the middle‐sized member (SD) of a set of three simultaneously presented stimuli with responses to: the SD reinforced on a VI 1 schedule. They were then tested for several days with other sets of three stimuli. One procedure presented reinforcements on a VI 1 schedule during the test independent of the stimulus chosen when a reinforcement was programmed. The tests were also given under extinction conditions. With the testing carried out with extinction, preference consistently was for the test stimulus most similar in physical size to the SD. However, when the tests were with reinforcement, random responding resulted. Another effect of testing with reinforcement was an increase in incorrect responding with the training set. Such a test procedure was unsatisfactory for determining the effective aspect of the SD. The conclusion, based on the data of the extinction series, was that pigeons learned the intermediate size problem on the basis of the discrimination of absolute stimulus properties.
BEHAVIORAL CONTRAST DURING MULTIPLE AVOIDANCE SCHEDULES1
Authors: Wertheim George A.
Published: March 2006

Changes were observed in the rate of avoidance responding in both components of a multiple schedule of Sidman‐avoidance after the shock frequency was changed in only one component. The rate change in each component was positively correlated, in direction and magnitude, with the change in the relative rate of reinforcement (percentage of total shocks) in that component.
SALINE PREFERENCE IN RATS DETERMINED BY CONTINGENT LICKING1
Authors: Fisher G. L.
Published: March 2006

The albino rat's preference for .1 molar NaCl solution when paired with distilled water was measured using a lick contingent method. The method precluded position bias and revealed some fluid‐deprivation influences in the resulting measured preference. Rats were trained to lick at a drinking tube containing water in order to obtain another tube containing the saline solution, under several levels of water deprivation. When tube contents were varied, the patterns of licking varied concurrently. Preference data was collected at low levels of fluid deprivation. It was shown that the saline solution was the primary controlling stimulus.
A FORCE‐TRANSDUCING MANIPULANDUM FOR USE WITH DOGS1,2
Authors: Kaplan Michael , Loesch Richard V. P.
Published: March 2006

Experimental animals used in this study were handled in accordance with the Principles of Laboratory Animal Care promulgated by the National Society for Medical Research (Ref. ‐AR70‐18, 20 Nov 61). The opinions expressed in this paper are those of the authors and do not necessarily reflect official Department of Army policy.
THE EFFECT OF ACCELERATION ON FOOD‐REINFORCED DRL AND FR1
Authors: BEASLEY JULAINE L. , SELDEEN BARBARA L.
Published: March 2006

Performance on DRL 10 sec and FR 5 was studied after exposure to acceleration. After four rats, two on each of the above schedules, had stabilized they were exposed to 5 hr of acceleration at 5 G immediately before daily experimental sessions. Food intake was also studied in rats given access to food daily in their home cages and exposed to acceleration immediately before the free‐feeding session. Weight gain of free‐feeding animals and reinforcement intake of experimental animals dropped after acceleration. Over‐all response rate on the FR was depressed markedly by acceleration but local response rates did not appear to be affected. IRT distributions of DRL sessions after acceleration were markedly shifted toward the long intervals. A sequential plot of IRTs on acceleration days showed an altered, but relatively stable, temporal patterning of responses followed by an abrupt return to the normal baseline toward the end of the session.
DISCRIMINATED TIME‐OUT AVOIDANCE IN PIGEONS1
Authors: Thomas John R.
Published: March 2006

Performances of two pigeons were studied on a concurrent discriminated TO avoidance‐VR schedule. Each avoidance response postponed a TO from a VR 140 for a specified RS interval. The warning stimulus on the TO avoidance schedule was a discontinuous clock which consisted of a series of discrete color changes that varied systematically with the RS interval. Experimental manipulations established that the avoidance behavior was under the control of the avoidance schedule and the discontinuous clock. Five‐min TOs maintained higher avoidance rates than shorter TO durations; a 15‐min TO maintained less avoidance responding than the 5‐min TO. Chlorpromazine hydrochloride increased TO avoidance behavior and decreased concurrent VR behavior.
FREQUENCY DISTRIBUTION OF INTERRESPONSE TIMES DURING VI AND VR REINFORCEMENT1
Authors: Kintsch Walter
Published: March 2006

A detailed analysis was made of the interresponse times (IRTs) of two rats under both a VI 40‐sec and a VR 15‐sec schedule. Except for the latency of the first response after a reinforcement, the mean IRTs of all further responses differed little. Similarly, the frequency distributions of the successive IRTs did not vary greatly, but were of no simple form. Sequential dependencies between successive IRTs were small, never accounting for more than 1% of the variance.
THE MEASUREMENT AND REINFORCEMENT OF BEHAVIOR OF PSYCHOTICS1
Authors: Ayllon T. , Azrin N. H.
Published: March 2006

An attempt was made to strengthen behaviors of psychotics by applying operant reinforcement principles in a mental hospital ward. The behaviors studied were necessary and/or useful for the patient to function in the hospital environment. Reinforcement consisted of the opportunity to engage in activities that had a high level of occurrence when freely allowed. Tokens were used as conditioned reinforcers to bridge the delay between behavior and reinforcement. Emphasis was placed on objective definition and quantification of the responses and reinforcers and upon programming and recording procedures. Standardizing the objective criteria permitted ward attendants to administer the program. The procedures were found to be effective in maintaining the desired adaptive behaviors for as long as the procedures were in effect. In a series of six experiments, reinforced behaviors were considerably reduced when the reinforcement procedure was discontinued; the adaptive behaviors increased immediately when the reinforcement procedure was re‐introduced.
SUPPLEMENTARY KNOWLEDGE OF RESULTS1
Authors: Maltzman E. , Holz W. C. , Kunze Jean
Published: March 2006

Children learned to respond differentially to four tones when correct responses were indicated by re‐sounding the tone and flashing a signal lamp (simple knowledge of results). Correct responses were then made to advance a display counter. With this procedure, rate of response increased, but accuracy decreased. Mild punishment—points subtracted from the count—was then arranged for incorrect responses. Accuracy returned to or above its previous level. Response rate tended to remain above its initial level. These results indicate that when supplementary reinforcers are employed, precise contingencies must be arranged to ensure desired behavior.
THE EFFECT OF MULTIPLE SΔ PERIODS ON RESPONDING ON A FIXED‐INTERVAL SCHEDULE: III. EFFECT OF CHANGES IN PATTERN OF INTERRUPTIONS, PARAMETERS AND STIMULI1
Authors: Dews P. B.
Published: March 2006

Pigeons responding under fixed‐interval schedules of reinforcement were interrupted by SΔ periods during the course of the intervals. Whether intervals were interrupted by 1, 2, or 5 SΔ periods, the general scalloped pattern of FI responding persisted. Parameter values up to 27% hr for the FI and 2¾ hr for the individual SΔ interruptions were studied. The results further weaken the hypothesis that the FI pattern of responding depends crucially on control of responding by continuously chained mediating behavior.
A NOTE ON BEHAVIORAL TOLERANCE TO MEPROBAMATE
Authors: Richelle Marc
Published: March 2006

Behavioral tolerance to meprobamate was demonstrated in a cat, on an FI schedule, without behavior taking place during the chronic treatment. Behavioral factors, such as the development of corrective patterns of behavior, do not explain behavioral tolerance in this case.
THE EFFECT OF MULTIPLE SΔ PERIODS ON RESPONDING ON A FIXED‐INTERVAL SCHEDULE: II. IN A PRIMATE1
Authors: Dews P. B.
Published: March 2006

A squirrel monkey was subjected to a fixed‐interval pattern of reinforcement. During the course of each interval a bright white light was repeatedly presented. In the presence of the white light, a response was never immediately followed by food; the white light thus functioned as SΔ. Responding was interrupted during the SΔ periods, but in the squirrel monkey as in the pigeon, these interruptions did not destroy the characteristic scalloped pattern of the cumulatively recorded responding through each interval.
DISCRIMINATIVE FUNCTIONS BASED ON A DELAY IN THE REINFORCEMENT RELATION1
Authors: Mabry John H.
Published: March 2006

Pigeons were shown to come under discrimination control when the SD and SΔ were temporally separated from reinforcement and non‐reinforcement. SD and SΔ consisted of distinctive key illuminations presented separately. Responding on an FR 5 in the presence of SD or SΔ produced a third stimulus containing a schedule requirement. If this third (or interpolated) stimulus was preceded by SD, responding in its presence produced reinforcement followed by a time‐out (TO). If, on the other hand, the third stimulus was preceded by SΔ, responding produced TO alone. In this fashion, the same stimulus and the same response requirement were imposed between SD and the reinforcement as between SΔ and the TO. In Experiment I, the schedule employed during the interpolated stimulus was FR; in Experiment II, FI. Discrimination reversal was accomplished in both experiments.
INTEROCULAR GENERALIZATION: A STUDY OF MIRROR‐IMAGE REVERSAL FOLLOWING MONOCULAR DISCRIMINATION TRAINING IN THE PIGEON1
Authors: Mello Nancy K.
Published: March 2006

Generalization gradients along a continuum of angular orientation were obtained from four pigeons, following monocular training on a discrimination between a 45° oblique line (S+) and a 135° oblique line (S–). All pigeons were trained on a chain DRO VI 1 schedule of reinforcement. Generalization gradients obtained with the trained and untrained eye were compared. All pigeons responded maximally to the 45° line (S+) when tested with only the trained eye open. During generalization tests of interocular transfer with only the untrained eye open, three pigeons responded maximally to S– (135°), the mirror‐image of the stimulus associated with reinforcement during training (45°). The other pigeon failed to show interocular transfer of the discrimination. Interocular reversal of left‐right mirror‐image stimuli has not been reported for any other species.
THE POST‐REINFORCEMENT PAUSE1
Authors: Felton Mark , Lyon David O.
Published: March 2006

Measurements of the post‐reinforcement pause and response rate were obtained from four birds on a range of fixed ratio schedules from 25 to 150. The results indicated a consistent increase in the length of the pause as the ratio was increased. Response rate tended to decrease, but these data were less consistent and some reversals were apparent.
TWO TYPES OF BEHAVIORAL CONTRAST IN DISCRIMINATION LEARNING1
Authors: Bloomfield T. M.
Published: March 2006

Two groups of pigeons received daily discrimination training at two values on a line‐tilt continuum. S+ (VI 1) and S– (EXT) intervals alternated, and a 30‐sec criterion of no responding to S– was required before S+ returned. Rates of responding to S+ showed two separate contrast effects: at an intermediate stage of training a high peak rate appeared which declined, later in training, to a stable level still in excess of the VI baseline rate. The peak rate was correlated with the total number of responses to S–, while the final rate was not; suggesting that the peak rate and final rate may not be functions of the same variable. These results were compared with performance on a red‐green discrimination where the two stages were not so clear. A line‐tilt discrimination was repeated with fixed length S– intervals terminated by TO, and showed the same contrast magnitude in the final rate without any peak. The peak rate was interpreted as an effect of the ‘punishment’ contingency where responding to S– prolongs S– for 30 sec, while the final rate was taken to be analogous to previous demonstrations of contrast.
BEHAVIORAL CONTROL BY AN IMPRINTED STIMULUS1
Authors: Hoffman Howard S. , Searle John L. , Toffey Sharon , Jr. Frederick Kozma
Published: March 2006

Newly hatched ducklings were exposed to imprinting procedures and subsequently trained to peck a key by presenting the imprinting stimulus as the reinforcing (response contingent) event. It was found that the key peck was learned only when imprinting procedures were initiated during the first 6 to 8 hr after hatch. Additional studies revealed that: (1) the duckling's distress vocalizations were reduced in the presence of the imprinting stimulus and enhanced in its absence; (2) when the ducklings had constant access to the imprinted stimulus (via a key peck), pecking responses occurred in bursts and relatively few distress vocalizations occurred; (3) the initial effect of extinction procedures was an increase in key peck rate. When, however, repeated key pecks failed to produce the imprinted stimulus, distress vocalization ensued and peck rate declined; (4) both the presentation of an unfamiliar mechanical figure and delivery of electrical shock enhanced distress vocalization and key pecks; (5) for some ducklings, certain familiar objects in the environment influenced distress calls in a manner comparable to the imprinted stimulus in that distress calls increased when these objects were removed.
THE MOTIVATIONAL PROPERTIES OF SCHEDULE‐INDUCED POLYDIPSIA1
Authors: Falk John L.
Published: March 2006

Schedule‐induced polydipsia occurred during initial magazine training to Noyes pellets (45 mg), disappeared when lever‐pressing was acquired on a continuous reinforcement schedule (CRF), and reappeared when the food contingency was changed to a 1‐min variable interval schedule (VI 1 min). Polydipsia also developed under a VI 1 min food schedule when water was concurrently available on various fixed ratios (FR), rather than being freely available. The level of the polydipsia and its motivating properties allow it to be classified as a form of adjunctive behavior.
CONDITIONED ACCELERATION AND CONDITIONED SUPPRESSION IN PIGEONS1
Authors: Leitenberg Harold
Published: March 2006

Two experiments were performed to investigate the effects on pigeons' keypecking behavior of stimuli that signal different kinds of aversive events: time‐out from positive reinforcement, electric shock, loud noise, and loud tone. Behavior maintained by a variable‐interval schedule of reinforcement was suppressed by a stimulus before shock, was accelerated by a stimulus before time‐out from positive reinforcement, and was unchanged by a stimulus before loud noise or a stimulus before loud tone. Conditioned acceleration with time‐out from positive reinforcement and conditioned suppression with shock were obtained regardless of whether a response contingent or response‐independent procedure was employed.
CONCURRENT FIXED‐RATIO AND AVOIDANCE RESPONDING IN THE SQUIRREL MONKEY
Authors: Catania A. Charles , Deegan John F. , Cook Leonard
Published: March 2006

Squirrel monkeys maintained concurrent performances appropriate to a fixed‐ratio schedule of food reinforcement on one lever and an avoidance schedule on a second lever. The overall rate of responding maintained by either schedule was not systematically affected when the other schedule was discontinued and its lever removed.
A COMPARISON OF DIFFERENT MEASURES OF RESPONSE STRENGTH IN THE STUDY OF STIMULUS GENERALIZATION1
Authors: Thomas David R. , Konick Dorothy S.
Published: March 2006

In Experiment 1, three pigeons were given variable interval training to peck at a light of 550 mμ and then were tested for stimulus generalization in extinction to several different wavelengths. A gradient was obtained for latency of the first response in each test period, for the number of test periods in which responding occurred, and for the measure of response rate. When the response rate gradient was corrected for differences in initial latency and in number of responded trials, the change was minimal, indicating that the major component of response rate as usually measured is rate of responding having once responded. In Experiment 2, three other pigeons were trained to respond to 550 mμ (for variable interval reinforcement) and not to 570 mμ (extinguished). Analysis of generalization gradients dictated the same conclusion as that reported for generalization following single stimulus training.
CONDITIONED SUPPRESSION AND VARIABLE RATIO REINFORCEMENT1
Authors: Lyon David O. , Felton Mark
Published: March 2006

Conditioned suppression is a decrease in response rate during a relatively short duration stimulus that terminates independently of the animal's behavior and coincidentally with a brief unavoidable shock. The degree of conditioned suppression was measured for each of three birds on three variable ratio schedules; that is, the number of responses required for food reinforcement was varied around a mean of 50, 100, or 200. The results indicated a slight and possibly negligible decrease in the degree of suppression as the mean number of responses required on the schedule was increased from 50, to 100, and 200. In general, it was found that all of the variable ratio schedules tested were quite insensitive to the conditioned suppression procedure, although almost complete suppression was obtained on a few occasions. Since the reinforcement was contingent upon the emission of responses, the birds typically displayed a high rate of response during the pre‐shock stimulus on all schedules. In addition, the rate during the pre‐shock stimulus often changed abruptly independent of the presentation of a reinforcement. As a result of the high rate of response and the abrupt changes in rate, the degree of suppression from trial to trial was quite variable. A clear analysis of an experimental variable on this baseline is thus difficult.
RECOVERY OF RESPONSES DURING MILD PUNISHMENT1
Authors: Rachlin Howard
Published: March 2006

Pigeons were punished with mild shock for pecking during one of two components of a multiple schedule. They eventually recovered so that they pecked at the same rate during both components. In one experiment they were extinguished after recovering. When punishment, was maintained during extinction, they extinguished faster during the punished, than during the unpunished component. When punishment was stopped during extinction, they extinguished faster during the unpunished than during the previously punished component. In another experiment, punishment was programmed first during neither of the two components, then during one, then during both, and finally during the other component. The extent of recovery decreased with each successive cycle. It is concluded that, if transient emotional states are ignored, reward and punishment are symmetrical in their effects.
SCHEDULES USING NOXIOUS STIMULI. L MULTIPLE FIXED‐RATIO AND FIXED‐INTERVAL TERMINATION OF SCHEDULE COMPLEXES1
Authors: Morse W. H. , Kelleher R. T.
Published: March 2006

The termination of a schedule complex, comprising a stimulus in the presence of which brief presentations of electric shocks are scheduled, is a reinforcer. Conditions were studied under which schedule‐controlled patterns of responding characteristic of fixed‐interval, fixed‐ratio, and multiple fixed‐interval fixed‐ratio schedules can be maintained in the squirrel monkey by terminating a schedule complex. The schedule of shock presentation was a critical determinant of the patterns of responding, especially under fixed‐interval schedules of termination. The rates and patterns of responding under various schedules of termination of schedule complexes were generally akin to those maintained under comparable schedules of food presentation. The findings suggest a general similarity in the dynamic aspects of performances under schedules of schedule‐complex termination and comparable schedules of food presentation. The schedule of reinforcement is more important than the nature of the reinforcer in the control of behavior.
THRESHOLD FOR CONDITIONED SUPPRESSION USING X‐RAYS AS THE PRE‐AVERSIVE STIMULUS1
Authors: Morris Dale Duane
Published: March 2006

Four male, 12‐week‐old Sprague‐Dawley rats were used to determine the threshold for behavioral response to X‐irradiation using the conditioned suppression technique. They were maintained at 80 per cent body weight and initially trained to stable performance on a VI 1 min schedule with 16 per cent sucrose solution as reinforcement. After a stable baseline was obtained, animals were placed in the instrumental conditioning box beneath the X‐ray machine for a half‐hour session each day. While subjects were actively pressing the lever for reinforcement, 15‐sec X‐ray exposures of 0.5 R/sec were administered, followed immediately by electric shock. After all animals had exhibited conditioned suppression, the dose‐rate was decreased in subsequent sessions in an effort to establish threshold. The results indicate that X‐rays at a dose‐rate as low as 0.004 R/sec can be an effective pre‐aversive stimulus for the rat.
MULTIPLE PUNISHMENT SCHEDULE1
Authors: DeArmond Diane
Published: March 2006

Concurrent schedules of punishment and fixed‐ratio reinforcement were studied in six white Carneaux pigeons. Two stimuli were alternated on the translucent key which served as the response mechanism. The pigeons were exposed to continuous punishment in one stimulus and first response punishment in the other. It was found that continuous punishment suppressed the fixed‐ratio performance more than did punishment of the first response. Typically, a ratio run of responses was completed in spite of the onset of continuous punishment. Responding was then reduced for the remainder of the continuous punishment stimulus, except for those times when responding was initiated near the end of the stimulus. The results indicate that a multiple schedule can be used to compare different schedules of punishment in the same organism.
OBSERVING BEHAVIOR DURING INTERVAL SCHEDULES1
Authors: Hendry Derek P. , Dillow P. V.
Published: March 2006

Experiment 1 showed that the three stimuli associated with three chained fixed‐interval links could be used to maintain observing behavior. Experiment 2 showed that three stimuli correlated with the passage of time since the last reinforcement in a fixed‐interval schedule could be used to maintain observing behavior. In both experiments most observing responses occurred midway between reinforcements. Few occurred just before or just after reinforcement. Experiment 3 showed that the decline in the rate of observing behavior just before reinforcement was reduced when more stimuli could be observed. The relatively high terminal rate of observing behavior that resulted was maintained even when at least 4 sec intervened between the reinforcement and the last observed stimulus.
A COMPARISON OF TWO TYPES OF EXTINCTION FOLLOWING FIXED‐RATIO TRAINING1
Authors: Weissman Norman W. , Crossman Edward K.
Published: March 2006

Five groups of pigeons were food reinforced on various schedules. Half of each group were extinguished in the normal manner; the others were presented with a stimulus change, previously paired with reinforcement, each time they completed their respective fixed ratios. Response rate in training was an increasing negatively accelerated function of the FR. Increasing the FR produced transitory rate changes, the amount of which yielded a quantitative index of ratio strain. Cumulative records of extinction performance revealed that the stimulus change exerted discriminative control by maintaining the cohesiveness of FR response units. Nevertheless, neither the absolute number of extinction responses nor extinction response units differed appreciably for the two extinction procedures.
PUNISHMENT AS A DISCRIMINATIVE STIMULUS AND CONDITIONED REINFORCER WITH HUMANS1
Authors: Ayllon T. , Azrin N. H.
Published: March 2006

Mental hospital patients were reinforced for responding in a two‐response operant situation. When a noise was used to punish one of the responses, all subjects shifted to the unpunished one. When the noise was then paired with positive reinforcement, the subjects responded to produce the noise. Also, a novel response was reinforced by noise in the absence of other reinforcers. This study with humans extends the findings of previous studies with animals in revealing how a punishing stimulus can acquire discriminative or conditioned reinforcing properties.
PROBABILISTICALLY REINFORCED CHOICE BEHAVIOR IN PIGEONS1
Authors: Shimp Charles P.
Published: March 2006

A single principle, “momentary maximizing”, may account for much of a pigeon's steady‐state behavior in both probability learning and concurrent variable interval experiments. The principle states that a pigeon tends to choose the alternative that momentarily has the higher probability of reinforcement. A successive discrimination procedure, which produced matching in an earlier experiment, produced here a tendency to maximize if training were adequately extended. Maximizing was produced also by other procedures, in which no reinforcing event was presented on some trials: one procedure did and two did not provide a bird with information about the availability of reinforcement on a key after an unreinforced response on the other key. The latter two procedures were analogous to concurrent variable interval schedules in two respects: the reinforcement probability on one key increased while a bird responded on the other key; and they produced matching. But sequential statistics suggested that matching resulted from momentary maximizing. Depending on the procedure, the tendency to maximize produced different relative frequencies of pecking a key for a fixed relative frequency of reinforcement. Computer simulation of maximizing behavior in several concurrent variable interval schedules produced matching and sequential statistics similar to those produced by a real bird.
ATTENTION AND CUE‐PRODUCING BEHAVIOR IN THE MONKEY1
Authors: D'Amato M. R. , Fazzaro James
Published: March 2006

Explicit cue‐producing responses were employed to study attending behavior in the monkey. The subjects learned a discrimination based on compound stimuli, a vertical bar embedded on a red ground versus a horizontal bar on a green ground. On some trials only one of the two stimulus components was presented (red versus green or vertical versus horizontal bar), and the animals had the option of responding on the basis of the component presented or transforming it to the compound discriminanda by means of a cue‐producing response. Analysis of the choice and cue‐producing response behavior showed that (a) both monkeys acquired the discrimination between the compound cues solely on the basis of the color component, (b) mastery of this discrimination did not confer any “habit loading” (discriminative control) on the bar component, and (c) the monkey may prefer to respond on the basis of one component (color) even though it is capable of using both components equally effectively.
THE EFFECTS OF A PRE‐TIME‐OUT STIMULUS ON MATCHING‐TO‐SAMPLE OF HUMANS1,2
Authors: Miller Nuran Baydan , Zimmerman Joseph
Published: March 2006

In each of two experiments human subjects were intermittently reinforced with money on a fixed‐ratio schedule for emitting correct matching responses. A pre‐time‐out stimulus which signaled removal of positive reinforcement was periodically superimposed. In the first experiment the superimposed pre‐time‐out stimulus was paired with a 1‐min or 4‐min response‐independent time out. In the second experiment the pre‐time‐out stimulus was paired with a 1‐min or 4‐min time out contingent on the incorrect responses. The pre‐time‐out stimulus did not markedly influence performance when the time out was response independent. In contrast, the pre‐time‐out stimulus markedly suppressed incorrect responding when the time out was contingent on the incorrect responses. When duration of this time‐out was increased from 1‐min to 4‐min, suppression of incorrect responding increased and correct responding was suppressed. Therefore, behavioral suppression by a pre‐time‐out stimulus was obtained only when the signaled aversive event—time out—was response produced. In this case, suppression was influenced by time‐out duration.
FLICKER THRESHOLDS AS DETERMINED BY A MODIFIED CONDITIONED SUPPRESSION PROCEDURE1,2
Authors: Hendricks Jean
Published: March 2006

Critical flicker fusion frequencies were determined as a function of stimulus intensity for three White Carneaux pigeons using a modified conditioned suppression paradigm as a threshold procedure. Critical frequencies ranged from 6 cps for the lowest intensity of 0.0014 ml to 77 cps for the maximum intensity of 41.86 ml.
DISCRIMINATIVE ECHOLOCATION IN A PORPOISE1,2
Authors: Turner Ronald N. , Norris Kenneth S.
Published: March 2006

Operant conditioning techniques were used to establish a discriminative echolocation performance in a porpoise. Pairs of spheres of disparate diameters were presented in an underwater display, and the positions of the spheres were switched according to a scrambled sequence while the blindfolded porpoise responded on a pair of submerged response levers. Responses which identified the momentary state of the display were food‐reinforced, while those which did not (errors) produced time out. Errors were then studied in relation to decreased disparity between the spheres. As disparity was decreased, errors which terminated runs of correct responses occurred more frequently and were followed by longer strings of consecutive errors. Increased errors and disruption of a stable pattern of collateral behavior were associated. Since some sources of error other than decreased disparity were present, the porpoise's final performance did not fully reflect the acuity of its echolocation channel.
THE EFFECT OF MULTIPLE 5Δ PERIODS ON RESPONDING ON A FIXED‐INTERVAL SCHEDULE: V. EFFECT OF PERIODS OF COMPLETE DARKNESS AND OF OCCASIONAL OMISSIONS OF FOOD PRESENTATIONS1
Authors: Dews P. B.
Published: March 2006

In pigeons under fixed‐interval schedules of reinforcement, responding during most of the interval can be suppressed by stimulus conditions never present when a response is promptly followed by reinforcing stimuli. When the external stimuli obtaining immediately before reinforcement are presented during brief probe periods in the course of the interval, the rate of responding in the probe depends on the temporal position of the probe during the interval; the rate of responding is lower during a probe early in the interval than during one late in the interval. The present experiments show that the temporal dependency still holds (1) in birds with no experience under unmodified fixed‐interval schedules, (2) when the time between probes is spent in complete darkness, and (3) when food presentations are omitted at the end of 50% of intervals. The results strengthen and extend the conclusion from previous studies that the time relations themselves are the primary control of rate of responding under fixed‐interval schedules of reinforcement.
THE REINFORCEMENT OF LEAST‐FREQUENT INTERRESPONSE TIMES1
Authors: Blough Donald S.
Published: March 2006

A new schedule of reinforcement was used to maintain key‐pecking by pigeons. The schedule reinforced only pecks terminating interresponse times which occurred least often relative to the exponential distribution of interresponse times to be expected from an ideal random generator. Two schedule parameters were varied: (1) the rate constant of the controlling exponential distribution and (2) the probability that a response would be reinforced, given that it met the interresponse‐time contingency. Response rate changed quickly and markedly with changes in the rate constant; it changed only slightly with a fourfold change in the reinforcement probability. The schedule produced stable rates and high intra‐ and inter‐subject reliability, yet interresponse time distributions were approximately exponential. Such local interresponse time variability in the context of good overall control suggests that the schedule may be used to generate stable, predictable, yet sensitive baseline rates. Implications for the measurement of rate are discussed.
BEHAVIORAL CONTRAST AND THE PEAK SHIFT: EFFECTS OF EXTENDED DISCRIMINATION TRAINING1
Authors: Terrace H. S.
Published: March 2006

Behavioral contrast and the peak shift, two widely observed phenomena in experiments on successive discrimination learning, were shown to disappear during extended discrimination training. This finding and an analysis of the conditions under which behavioral contrast and the peak shift occur suggested that both phenomena were by‐products of emotional responses that resulted from response suppression and that their disappearance after extended discrimination training could be attributed to the dissipation of such emotional responses.
STIMULUS CONTROL IN FIXED RATIO MA TCHING‐TO‐SAMPLE1
Authors: Mintz Donald E. , Mourer Dennis J. , Weinberg Laura S.
Published: March 2006

Pigeons were maintained on a fixed ratio (FR 9) schedule of reinforcement for correct matching‐to‐sample responses. Included in the test situation was a vertical array of lights, illuminated in relation to the successive steps of the fixed ratio. All five subjects showed regular decrements in matching errors across the sequence of unreinforced responses within the ratio cycle. In the form of a randomly introduced probe, the stimulus situation (array of lights) appropriate to having seven of the FR 9 steps already completed was occasionally introduced at the beginning of an FR cycle. Reinforcement followed the illumination of the two remaining lights by two correct matches. The number of errors in this probe condition was sharply lower than the errors characteristic of the first two steps of the basic FR 9.
FREE OPERANT AVOIDANCE AS A FUNCTION OF THE RESPONSE‐SHOCK = SHOCK‐SHOCK INTERVAL1
Authors: Clark Fogle C. , Hull Larry D.
Published: March 2006

Two temporal parameters of free operant or Sidman avoidance behavior are the interval by which responses postpone shocks (Response‐Shock interval) and the interval between shocks when no responses occur (Shock‐Shock interval). Avoidance behavior was examined in three white rats under conditions where the Response‐Shock and Shock‐Shock intervals were always equal. With intervals from 10 to 60 sec response rates and shock rates were similar, decreasing, negatively accelerated functions of increasing Response‐Shock = Shock‐Shock interval. Over this range, response and shock rates were linearly related to the reciprocal of the Response‐Shock = Shock‐Shock interval. It was shown, however, that this relation cannot hold at extremely long intervals. Both the ratio of responses emitted to shocks received and the percentage of shocks possible which were avoided increased at long Response‐Shock = Shock‐Shock intervals. These findings may be related to the fact that long intervals provide optimal conditions for conditioning avoidance behavior in the rat.
DELAYED ESCAPE FROM LIGHT BY THE ALBINO RAT1
Authors: Keller John V.
Published: March 2006

Two albino rats were trained to terminate an aversive light for 1 min by pressing a bar. After 19 hr of conditioning they were exposed to successive delays of 1, 2, 5, and 10 sec imposed between occurrence of the escape response and light termination. No stimulus change accompanied the delay interval, and any additional responses made at this time reset the delay timer. For both rats the relative frequency of escape responses with very long latencies increased as the delay interval increased. The modal escape latency, however, remained essentially unchanged for all delay values of greater than 1 sec. “Superstitious” responding was observed during the delay interval.
STIMULUS ASPECTS OF AVERSIVE CONTROLS: LONG TERM EFFECTS OF SUPPRESSION PROCEDURES1
Authors: Hoffman Howard S. , Selekman Warren , Fleshler Morton
Published: March 2006

Five years ago, pigeons trained to peck a key for food were periodically presented with a 1000 cps tone which ended with electrical shock. They were then tested for the stimulus generalization of conditioned suppression. After an interruption of 2.5 yr, another series of generalization tests showed no loss of suppression. The present study was conducted 1.5 yr later to retest the effect of an extended interruption on retention of suppression. It was found, again, that suppression did not decline over time. The present paper, which summarizes the earlier data and reports the most recent findings, provides an overview of the extended behavioral consequences of the original aversive procedures administered five years ago.
OPERANT STIMULUS CONTROL APPLIED TO MAZE BEHAVIOR: HEAT ESCAPE CONDITIONING AND DISCRIMINATION REVERSAL IN ALLIGATOR MISSISSIPPIENSIS1
Authors: Davidson Robert S.
Published: March 2006

Eight alligators were trained to escape heat by traversing an 8‐ft runway containing right or left approaches to a water tank. All subjects were run until they had satisfied three criteria of stable response time, after which the predominant escape path was blocked, requiring discrimination reversal. Seven subjects again met the criteria; three also met them in a second reversal.