Neurocognitive dysfunction and pharmacological intervention using guanfacine in a rhesus macaque model of self-injurious behavior.

Self-injurious behavior (SIB) is a common comorbidity of psychiatric disorders but there is a dearth of information about neurological mechanisms underlying the behavior, and few animal models exist. SIB in humans is characterized by any intentional self-directed behavior that leads to wounds, whereas in macaques it is not always accompanied by wounds. We describe a cohort of rhesus macaques displaying SIB as adults, in which changes within the central nervous system were associated with the SIB. In these macaques, increases in central nervous system striatal dopamine (DA) receptor binding (BPND) measured by positron emission tomography (PET) [11C]raclopride imaging correlated with severity of wounding (rs=0.662, P=0.014). Furthermore, utilizing standardized cognitive function tests, we showed that impulsivity (stop signal reaction time, SSRT) and deficits in attentional set shifting (intra-/extradimensional shift) were correlated with increased severity of SIB (rs=0.563, P=0.045 and rs=0.692, P=0.009, respectively). We also tested the efficacy of guanfacine, an α2A adrenergic agonist that acts to improve postsynaptic transmission of neuronal impulses, in reducing SIB. A subset of these animals were enrolled in a randomized experimenter-blinded study that demonstrated guanfacine decreased the severity of wounding in treated animals compared with vehicle-only-treated controls (P=0.043), with residual beneficial effects seen for several weeks after cessation of therapy. Animals with the highest severity of SIB that received guanfacine also showed the most significant improvement (rs=-0.761, P=0.009). The elevated PET BPND was likely due to low intrasynaptic DA, which in turn may have been improved by guanfacine. With underlying physiology potentially representative of the human condition and the ability to affect outcome measures of disease using pharmacotherapy, this model represents a unique opportunity to further our understanding of the biology and treatment of SIB in both animals and humans.

Self-injurious behavior: gene-brain-behavior relationships.

This paper summarizes a conference held at the National Institute of Child Health and Human Development on December 6-7, 1999, on self-injurious behavior [SIB] in developmental disabilities. Twenty-six of the top researchers in the U.S. from this field representing 13 different disciplines discussed environmental mechanisms, epidemiology, behavioral and pharmacological intervention strategies, neurochemical substrates, genetic syndromes in which SIB is a prominent behavioral phenotype, neurobiological and neurodevelopmental factors affecting SIB in humans as well as a variety of animal models of SIB. Findings over the last decade, especially new discoveries since 1995, were emphasized. SIB is a rapidly growing area of scientific interest to both basic and applied researchers. In many respects it is a model for the study of gene-brain-behavior relationships in developmental disabilities.

Examination of relative reinforcement effects of stimuli identified through pretreatment and daily brief preference assessments.

Several brief preference assessments have recently been developed to identify reinforcers for individuals with developmental disabilities. One purported advantage of brief assessments is that they can be administered frequently, thus accommodating shifts in preference and presumably enhancing reinforcement effects. In this study, we initially conducted lengthy paired-choice preference assessments and identified a hierarchy of preferred items for 5 individuals with developmental disabilities. Subsequently, brief multiple-stimulus-without-replacement assessments using the same items were completed each day prior to work sessions. On days when results of the daily brief assessment differed from the one-time lengthy assessment, the relative reinforcing effects of the top items from each assessment were compared in a concurrent-schedule arrangement. The results revealed that when the two assessments differed, participants generally allocated more responses to the task associated with the daily top-ranked item.

Choices between positive and negative reinforcement during treatment for escape-maintained behavior.

Positive reinforcement was more effective than negative reinforcement in promoting compliance and reducing escape-maintained problem behavior for a child with autism. Escape extinction was then added while the child was given a choice between positive or negative reinforcement for compliance and the reinforcement schedule was thinned. When the reinforcement requirement reached 10 consecutive tasks, the treatment effects became inconsistent and reinforcer selection shifted from a strong preference for positive reinforcement to an unstable selection pattern.

Competition between noncontingent and contingent reinforcement schedules during response acquisition.

We examined the extent to which noncontingent reinforcement (NCR), when used as treatment to reduce problem behavior, might interfere with differential reinforcement contingencies designed to strengthen alternative behavior. After conducting a functional analysis to identify the reinforcers maintaining 2 participants' self-injurious behavior (SIB), we delivered those reinforcers under dense NCR schedules. We delivered the same reinforcers concurrently under differential-reinforcement-of-alternative-behavior (DRA) contingencies in an attempt to strengthen replacement behaviors (mands). Results showed that the NCR plus DRA intervention was associated with a decrease in SIB but little or no increase in appropriate mands. In a subsequent phase, when the NCR schedule was thinned while the DRA schedule remained unchanged, SIB remained low and mands increased. These results suggest that dense NCR schedules may alter establishing operations that result in not only suppression of problem behavior but also interference with the acquisition of appropriate behavior. Thus, the strengthening of socially appropriate behaviors as replacements for problem behavior during NCR interventions might best be achieved if the NCR schedule is first thinned.

A comparison of procedures for programming noncontingent reinforcement schedules.

We compared two methods for programming and thinning noncontingent reinforcement (NCR) schedules during the treatment of self-injurious behavior (SIB). The participants were 3 individuals who had been diagnosed with mental retardation. Results of functional analyses indicated that all participants' SIB was maintained by positive reinforcement (i.e., access to attention or food). Following baseline, the effects of two NCR schedule-thinning procedures were compared in multielement designs. One schedule (fixed increment) was initially set at fixed-time 10-s reinforcer deliveries and was also thinned according to fixed-time intervals. The other schedule (adjusting IRT) was initially determined by participants' baseline interresponse times (IRTs) for SIB and was thinned based on IRTs observed during subsequent treatment sessions. Results indicated that both schedules were effective in initially reducing SIB and in maintaining response suppression as the schedules were thinned.

The effects of noncontingent delivery of high- and low-preference stimuli on attention-maintained destructive behavior.

An adolescent with severe mental retardation and cerebral palsy who displayed attention-maintained destructive behavior was exposed to noncontingent reinforcer delivery (NCR) with either a high-preference or a low-preference stimulus while reinforcement for destructive behavior with attention remained in effect (i.e., NCR without extinction). NCR without extinction was effective only when the high-preference stimulus was available, suggesting that systematic assessment of stimulus quality may enhance the effectiveness of NCR with alternative stimuli.

Assessment of a response bias for aggression over functionally equivalent appropriate behavior.

We evaluated the effects of a dense (fixed-ratio 1) schedule of reinforcement for an 11-year-old boy's mands for toys while aggression produced the same toys on various schedules chosen on the basis of a progressive-ratio probe. Based on the probe session data, we accurately predicted that aggression would be more probable than mands when the schedules were equal or slightly discrepant, but that mands would be more probable when the schedule discrepancy was large.

Effects of noncontingent reinforcement on problem behavior and stimulus engagement: the role of satiation, extinction, and alternative reinforcement.

This study examined the effects of noncontingent reinforcement (NCR) with and without extinction on problem behavior and stimulus engagement (consumption of reinforcement) of 4 participants. Reductions in problem behavior using NCR have frequently been attributed to both satiation of the reinforcer and extinction. In the current study, aspects of the NCR treatment effects were difficult to explain based solely on either a satiation or an extinction account. Specifically, it was found that stimulus engagement remained high throughout the NCR treatment analysis, and that problem behavior was reduced to near-zero levels during NCR without extinction. The implications of these findings are discussed with respect to the satiation and extinction hypotheses frequently described in the applied literature. Findings from basic studies examining the effects of response-independent schedules are presented, and are used as the basis for a matching theory account of NCR-related effects. It is proposed that reductions in problem behavior observed during NCR interventions may be a function of the availability of alternative sources of reinforcement.

Treatment of covert food stealing in an individual with Prader-Willi syndrome.

Covert food stealing is common among individuals with Prader-Willi syndrome. We found that verbal reprimands, delivered contingent upon eating prohibited foods, were sufficient to decrease the food stealing of a girl with Prader-Willi syndrome. Warning stimuli were then used to help her discriminate between permitted and prohibited foods during sessions in which food stealing was not directly observed. This procedure resulted in decreases in food stealing from containers labeled with the warning stimuli.

The effects of noncontingent access to single- versus multiple-stimulus sets on self-injurious behavior.

The automatically reinforced self-injury of a girl with autism was treated by providing noncontingent access to a single set of preferred toys during 30-min sessions. The reductive effects of the intervention waned as the session progressed. Rotating toy sets after 10 min or providing access to multiple toy sets resulted in reductions that lasted the entire 30 min.

DRO contingencies: an analysis of variable-momentary schedules.

We conducted several comparative analyses to determine the relative effectiveness of variable-momentary differential-reinforcement-of-other-behavior (VM DRO) schedules. Three individuals who had been diagnosed with mental retardation participated. Results of functional analyses indicated that their self-injurious behavior (SIB) was maintained by social-positive reinforcement. Two individuals participated in a two-stage comparative analysis within multielement and multiple baseline designs. Fixed-interval (FI) and variable-interval (VI) DRO were compared in the first stage; VI DRO and VM DRO were compared in the second. All three schedules effectively reduced the participants' SIB. Treatment for the 3rd individual was conducted in a reversal design to examine the effects of VM DRO when it was implemented in isolation, and results indicated that the procedure was effective in reducing SIB. These findings suggest that VM DRO schedules may represent attractive alternatives to traditional FI schedules because momentary schedules do not require continuous monitoring and may result in higher rates of reinforcement.

Clarifying an ambiguous functional analysis with matched and mismatched extinction procedures.

Results of functional analysis were ambiguous in suggesting that self-injurious behavior (SIB) was maintained by escape, sensory reinforcement, or both. To help clarify these results, we compared escape extinction, sensory extinction, and the combined treatments. Sensory extinction proved to be a necessary and sufficient treatment, whereas escape extinction failed to decrease SIB. These analyses helped to clarify the function of SIB and to identify an effective and efficient treatment.

Decreasing signs of negative affect and correlated self-injury in an individual with mental retardation and mood disturbances.

We evaluated the effects of an enriched environment, based on a paired-choice preference assessment, on both rates of self-injurious behavior (SIB) and percentage of session intervals during which signs of negative affect were displayed by a woman with mental retardation and a mood disorder. Results suggested that SIB and signs of negative affect were highly correlated and that the enriched environment effectively reduced both.

Examination of ambiguous stimulus preferences with duration-based measures.

Items that produced ambiguous results in an approach-based preference assessment were reassessed using a duration-based assessment. The reinforcing effects of three items on free-operant responding were subsequently tested. The results suggested that the duration-based assessment produced slightly more differentiated results and that predictions about reinforcer value, based on this assessment, were accurate.

Noncontingent reinforcement: effects of satiation versus choice responding.

Recent research findings suggest that the initial reductive effects of noncontingent reinforcement (NCR) schedules on destructive behavior result from the establishing effects of an antecedent stimulus (i.e., the availability of "free" reinforcement) rather than extinction. A number of authors have suggested that these antecedent effects result primarily from reinforcer satiation, but an alternative hypothesis is that the individual attempts to access contingent reinforcement primarily when noncontingent reinforcement is unavailable, but chooses not to access contingent reinforcement when noncontingent reinforcement is available. If the satiation hypothesis is more accurate, then the reductive effects of NCR should increase over the course of a session, especially for denser schedules of NCR, and should occur during both NCR delivery and the NCR inter-reinforcement interval (NCR IRI). If the choice hypothesis is more accurate, then the reductive effects of NCR should be relatively constant over the course of a session for both denser and leaner schedules of NCR and should occur almost exclusively during the NCR interval (rather than the NCR IRI). To evaluate these hypotheses, we examined within-session trends of destructive behavior with denser and leaner schedules of NCR (without extinction), and also measured responding in the NCR interval separate from responding in the NCR IRI. Reductions in destructive behavior were mostly due to the participants choosing not to access contingent reinforcement when NCR was being delivered and only minimally due to reinforcer satiation.

Displacement of leisure reinforcers by food during preference assessments.

Identification of reinforcers for individuals with developmental disabilities is often based on the outcome of preference assessments in which participants make selections from among a variety of items. We determined the extent to which individuals might show a general preference for food items over leisure items during such assessments and whether leisure items that are "displaced" by food items might nevertheless function as reinforcers. Arrays consisting of food items only and then nonfood items only were presented separately to 14 participants and then were ranked to determined preference. The top selections from these initial assessments were subsequently combined in a third assessment, and preferences were again established. All but 2 participants showed a general preference for food items, such that selection of nonfood items in the combined arrays was displaced downward relative to selection of nonfood in the nonfood-only arrays. Two of the participants were exposed to a condition in which a nonfood item was delivered contingent on the occurrence of an adaptive response, and increased rates of responding by both individuals were observed. Results are discussed in terms of limitations posed by using only food items as reinforcers and the resulting need to take precautionary measures when attempting to identify nonfood reinforcers.

Effects of intermittent punishment on self-injurious behavior: an evaluation of schedule thinning.

Although the use of punishment often raises ethical issues, such procedures may be needed when the reinforcers that maintain behavior cannot be identified or controlled, or when competing reinforcers cannot be found. Results of several studies on the effects of intermittent schedules of punishment suggest that therapists must use fairly rich schedules of punishment to suppress problem behavior. However, residential caretakers, teachers, and parents often have difficulty implementing programs that require constant monitoring of the client's behavior. In this study, we examined the feasibility of gradually thinning the delivery of punishment from a continuous schedule to an intermittent schedule during the course of treatment for self-injurious behavior (SIB). Results of functional analyses for 5 individuals who had been diagnosed with profound mental retardation indicated that their SIB was not maintained by social consequences. Treatment with continuous schedules of time-out (for 1 participant) or contingent restraint (for the other 4 participants) produced substantial reductions in SIB. When they were exposed to intermittent schedules of punishment (fixed-interval [FI] 120 s or FI 300 s), SIB for all but 1 of the participants increased to levels similar to those observed during baseline. For these 4 participants, the schedule of punishment was gradually thinned from continuous to FI 120 s or FI 300 s. For 2 participants, SIB remained low across the schedule changes, demonstrating the utility of thinning from continuous to intermittent schedules of punishment. Results for the other 2 participants showed that intermittent punishment was ineffective, despite repeated attempts to thin the schedule.

Evaluation of the "control over reinforcement" component in functional communication training.

The effectiveness of functional communication training (FCT) as a treatment for behavior disorders has been attributed to a number of variables, one of which is the individual's ability to exert control over the delivery of reinforcement. We evaluated this component of FCT by exposing individuals to conditions in which their behavior either did or did not affect the delivery of reinforcement. Three adults with mental retardation who engaged in self-injurious behavior (SIB) participated. Following a functional analysis of their SIB, the effects of FCT were compared to those of noncontingent reinforcement (NCR) in a multielement design. The amount of reinforcement during both conditions was equated by yoking the schedule of reinforcement during NCR sessions to that in effect during FCT sessions. Results indicated that FCT and NCR were equally effective in reducing the SIB of all participants and suggest that control over reinforcement delivery may not affect the degree to which FCT produces behavioral suppression. However, a different benefit of FCT was evident in the results: More consistent increases in the alternative response were observed during the FCT condition than during the NCR condition.

An analysis of reinforcer substitutability using object manipulation and self-injury as competing responses.

The concept of reinforcer substitutability proposes a continuum of interactions among reinforcers in a given situation. At one end of this continuum, reinforcers are substitutable, with one reinforcer being readily traded for another. We conducted an analysis of reinforcers that were substitutable with those produced by self-injurious behavior (SIB). Three individuals with profound developmental disabilities, whose SIB appeared to be maintained by automatic reinforcement, participated. Results of three experiments showed that (a) object manipulation and SIB were inversely related when leisure materials and SIB were concurrently available, with participants showing almost complete preference for object manipulation; (b) attempts to reduce SIB using the preferred objects as reinforcers in differential reinforcement contingencies were unsuccessful for all 3 participants; and (c) participants' preferences for SIB or object manipulation systematically changed when reinforcer cost (the amount of effort required to obtain the object) was varied. Results of the three experiments illustrate the importance of examining interactions among concurrently available reinforcers when conducting reinforcer assessments.