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Query: UMLS:C0851184 (thinning)
 11,252 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Autism is a common developmental disorder associated with structural and inferred neurochemical abnormalities of the brain. Cerebellar abnormalities frequently have been identified, based on neuroimaging or neuropathology. Recently, the cholinergic neurotransmitter system has been implicated on the basis of nicotinic receptor loss in the cerebral cortex. Cerebellar cholinergic activities were therefore investigated in autopsy tissue from a series of autistic individuals. The presynaptic cholinergic enzyme, choline acetyltransferase, together with nicotinic and muscarinic receptor subtypes were compared in the cerebellum from age-matched mentally retarded autistic (eight), normal control (10) and non-autistic mentally retarded individuals (11). The nicotinic receptor binding the agonist epibatidine (the high affinity receptor subtype, consisting primarily of alpha3 and alpha4, together with beta2 receptor subunits) was significantly reduced by 40-50% in the granule cell, Purkinje and molecular layers in the autistic compared with the normal group (P < 0.05). There was an opposite increase (3-fold) in the nicotinic receptor binding alpha-bungarotoxin (to the alpha7 subunit) which reached significance in the granule cell layer (P < 0.05). These receptor changes were paralleled by a significant reduction (P < 0.05) and non-significant increase, respectively, of alpha4 and alpha7 receptor subunit immunoreactivity measured using western blotting. Immunohistochemically loss of alpha(4 )reactivity was apparent from Purkinje and the other cell layers, with increased alpha7 reactivity in the granule cell layer. There were no significant changes in choline acetyltransferase activity, or in muscarinic M1 and M2 receptor subtypes in autism. In the non-autistic mentally retarded group, the only significant abnormality was a reduction in epibatidine binding in the granule cell and Purkinje layers. In two autistic cases examined histologically, Purkinje cell loss was observed in multiple lobules throughout the vermis and hemispheres. This was more severe in one case with epilepsy, which also showed vermis folial malformation. The case with less severe Purkinje cell loss also showed cerebellar white matter thinning and demyelination. These findings indicate a loss of the cerebellar nicotinic alpha4 receptor subunit in autism which may relate to the loss of Purkinje cells, and a compensatory increase in the alpha7 subunit. It remains to be determined how these receptor abnormalities are involved in neurodevelopment in autism and what is the relationship to mental function. Since nicotinic receptor agonists enhance attentional function and also induce an elevation in the high affinity receptor, nicotinic therapy in autism may be worth considering.
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PMID:Nicotinic receptor abnormalities in the cerebellar cortex in autism. 1207 99

Functional communication training (FCT) is a widely used treatment for individuals with developmental disabilities who exhibit severe behavior problems. One inherent challenge of employing FCT as a treatment in the community is that reinforcement for appropriate communication cannot always be immediate or even possible in some circumstances. Of the few studies that have incorporated some form of schedule thinning for communication, most have reported disruption of communication or increases in problem behavior when the schedule of reinforcement is thinned. In the current study, we compared FCT with extinction to FCT with extinction and access to competing stimuli. After conducting a functional analysis, a competing stimulus assessment was performed to identify stimuli that produce reinforcement that ostensibly competes with reinforcement that maintains problem behavior. It was hypothesized that FCT with competing stimuli would result in more stable reductions in problem behavior during schedule thinning, which would ultimately result in quicker achievement of the treatment goal (low levels of problem behavior under the terminal reinforcement schedule for communication) than FCT without competing stimuli. Results confirmed this hypothesis.
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PMID:Schedule thinning following communication training: using competing stimuli to enhance tolerance to decrements in reinforcer density. 1603 65

We evaluated interventions designed to reduce multiply controlled problem behavior exhibited by a young boy with developmental disabilities, using a multiple baseline design. Each intervention was designed to address a specific social function of problem behavior. Results showed that the separate interventions were useful in reducing problem behavior, and terminal schedules were reached by way of schedule thinning (attention condition) and delays to reinforcement (tangible and escape conditions).
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PMID:Experimental analysis and treatment of multiply controlled problem behavior: a systematic replication and extension. 1702 Feb 18

Hypoxia is a consistent challenge for aquatic animals. It is a pressing environmental problem; hypoxia can cause cranial edema and ovarium dysfunction in fish. Although several studies have reported the effect of hypoxic insult to the visual system, the hypoxic effect on perinatal animals and in particular their offspring has yet to be elucidated. In this study, activated caspase-3 activity was investigated using immunohistochemistry in order to examine the perinatal hypoxic damage in offspring fish. Offspring were divided into groups based on different time points of sacrifice. This allowed assessment of ocular development for different age groups. The results indicated that perinatal hypoxia induced ocular developmental defects in the offspring. The defects took the form of trabecular cell death and fibre degeneration, corneal thinning and lens fibre derangement. A concomitant change in intraocular pressure was recorded by tonometer in the experimental animals compared with the controls. Further investigation should be initiated to develop strategies to prevent developmental disability due to perinatal hypoxia and to increase survivability of the offspring.
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PMID:Perinatal hypoxia induces anterior chamber changes in the eyes of offspring fish. 1769 1

Noncontingent reinforcement (NCR) is a function-based treatment for problem behavior that has produced robust effects across a variety of response topographies and reinforcement functions among individuals with developmental disabilities. Several narrative reviews have adequately described this literature. The purpose of the present article was to quantitatively analyze and classify the empirical support for NCR using the criteria developed by The Task Force on the Promotion and Dissemination of Psychological Procedures [Task Force Promoting Dissemination of Psychological Procedures. (1995). Training in and dissemination of empirically-validated psychological treatments: Report and recommendations. Clinical Psychology, 48, 3-23]. Of the 59 studies identified for analysis, 24 met the criteria to be included in treatment classification. Fixed-time reinforcer delivery (plus extinction and schedule thinning) was classified as well established, while fixed-time reinforcer delivery (plus extinction) and variable-time reinforcer delivery (plus extinction) were deemed probably efficacious.
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PMID:Noncontingent reinforcement is an empirically supported treatment for problem behavior exhibited by individuals with developmental disabilities. 1846 73

This paper documents a rare nonprogressive developmental disorder-bilateral circumscribed posterior keratoconus-in a 60-year-old man referred for a cataract surgery. For the first time ultrasound biomicroscopy was used to visualise the local anterior bulging of the posterior corneal surface with concomitant thinning of the stroma. The amount of localized posterior depression, corneal thickness and the refractive power of both the posterior and anterior corneal curvature were measured using slit-scanning topography analysis (Orbscan).
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PMID:Bilateral circumscribed posterior keratoconus: visualization by ultrasound biomicroscopy and slit-scanning topography analysis. 2249 63

Past research has demonstrated that pictorial preference assessments can predict subsequent reinforcement effects for individuals with developmental disabilities only when access to the selected stimulus is provided contingent on a pictorial selection. The purpose of the present investigation was to assess more comprehensively the feasibility of the pictorial format with children with developmental disabilities. In Experiment 1, prerequisite skill assessments were conducted, and the role of a contingent reinforcer was assessed by comparing the results from the pictorial assessment without contingent access to a reinforcer assessment. If contingent access was found to be necessary, the effects of schedule thinning were evaluated to determine whether a pictorial format could be made more practical in Experiment 2. The pictorial format without contingent access was successful with only some participants. However, schedule thinning was found to be an effective method to establish conditioned reinforcement properties for pictorial stimuli to create a more practical assessment for a subset of participants.
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PMID:Assessing the efficacy of pictorial preference assessments for children with developmental disabilities. 2752 44

One potential limitation of functional communication training (FCT) is that after the functional communication response (FCR) is taught, the response may be emitted at high rates or inappropriate times. Thus, schedule thinning is often necessary. Previous research has demonstrated that multiple schedules can facilitate schedule thinning by establishing discriminative control of the communication response while maintaining low rates of problem behavior. To date, most applied research evaluating the clinical utility of multiple schedules has done so in the context of behavior maintained by positive reinforcement (e.g., attention or tangible items). This study examined the use of a multiple schedule with alternating Fixed Ratio (FR 1)/extinction (EXT) components for two individuals with developmental disabilities who emitted escape-maintained problem behavior. Although problem behavior remained low during all FCT and multiple schedule phases, the use of the multiple schedule alone did not result in discriminated manding.
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PMID:Further Evaluation of the Use of Multiple Schedules for Behavior Maintained by Negative Reinforcement. 2768 May 84

Functional communication training (FCT) is an evidence-based practice used to mitigate challenging behavior by increasing functional communication skills. To increase the practicality and feasibility of FCT in natural settings, thinning schedules of reinforcement are typically programmed following FCT. In this review, we meta-analyzed 28 studies that incorporated a thinning schedule procedure following FCT for 51 children with intellectual and developmental disabilities ages 8 and younger. Using Tau-U, the results demonstrated overall moderate effect sizes for both challenging behavior and functional communication responses. Additionally, moderator analyses pertaining to participant characteristics, interventions, and study quality were conducted. Thinning procedures were most effective for children who had stronger communication repertoire. Implications for future research and practice are discussed.
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PMID:Thinning Schedules of Reinforcement Following Functional Communication Training for Children with Intellectual and Developmental Disabilities: A Meta-analytic Review. 3145