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Biomedical subjects

B J Freeman

Publications and source records attributed to B J Freeman.

18 recordsLinked to original sources
PubMed1991

Complex segregation analysis of autism.

A complex segregation analysis of autism in 185 Utah families was carried out using the mixed model. The 209 affected individuals in these families represent nearly complete ascertainment of the autistic cases born in Utah between 1965 and 1984. The sibling recurrence risk for autism was 4.5% (95% confidence limits 2.8%-6.2%). Likelihoods were maximized for major-gene models, a polygenic model, a sibling-effect model, and a mixed model consisting of major-gene and shared-sibling effects. The analysis provided no evidence for major-locus inheritance of autism. Subdivision of the sample according to the probands' IQ levels showed that sibling recurrence risk did not vary consistently with IQ level. A segregation analysis of families in which the proband had an IQ less than 50 also failed to provide evidence for a major locus. However, because of the etiologic heterogeneity of this disorder, genetic analysis of other meaningful subsets of families could prove informative.

Autistic Disorder↗
PubMed1978

The effect of environmental stimulation upon the stereotyped behavior of autistic children.

Two groups of three autistic children, equated for chronological age but differing in IQ and performance MA, were observed for 20-minute sessions. Total duration of time subjects engaged in stereotyped behavior was recorded for each minute. During minutes 6--15, subjects were provided with either minimal or high environmental stimulation. High environmental stimulation was found to increase the mean duration of time the low-IQ group engaged in stereotyped behavior but to decrease the duration for the high-IQ group. The theoretical implications are discussed.

Acoustic Stimulation↗
PubMed1978

Appraising children for mental retardation: the usefulness and limitations of IQ testing.

As a result of their unique relationship with families, pediatricians are often faced with the difficult task of counseling the parents of a mentally retarded child. For this reason it is important that he understand the nature of the tools used to evaluate the retarded. Since the IQ test is still the most commonly used tool to assess presence or absence of retardation, this paper has briefly reviewed the concepts of intelligence, the IQ, and their interrelationships and their usefulness when evaluating the mentally retarded child.

Child↗
PubMed1976

The effects of response contingent vestibular stimulation on the behavior of autistic and retarded children.

The purpose of the present experiment was to examine the reinforcing effects of repetitive vestibular stimulation. While both autistic and retarded children would push a button for vestibular stimulation, frequency of stimulation was an important parameter for autistics but not for retardates. These results were interpreted as evidence for central rather than peripheral locus of control of motility disturbances in autistic children.

Autistic Disorder↗
PubMed1976

The effects of fluorescent and incandescent illumination upon repetitive behaviors in autistic children.

Repetitive behaviors of six autistic children were observed under two conditions of background illumination. During two sessions, the room was illuminated by fluorescent light and during two other sessions, by equal intensity incandescent light. Subjects spent significantly more time engaged in repetitive behavior under fluorescent light. Previous research suggested that these findings were related to the flickering nature of fluorescent ilumination. Practical and theoretical implications were discussed. Further experimentation was suggested to assess relationships between flickering illumination and arousal.

Arousal↗
PubMed1976

Physiological relationships and circadian periodicities in rodent trypanosomes.

Trypanosome circadian rhythms in rats infected with Trypanosoma lewisi and mice infected with T. duttoni (equals T. musculi) were observed. Peak numbers of trypanosomes were recorded at nightfall and fewest organisms seen at daybreak. Reversal of the photoperiod resulted in a comparable reversal of the trypanosome parasitaemia. Periodicities of blood glucose levels and circulating leucocytes were relatively similar in T. lewisi-infected rats to rhythms previously defined in normal aimals. In trypanosome-infected mice, circulating leucocytes had a peak at 1800 hours and were minimal at midnight. Immune serum and epinephrine apparently had opposite effects on numbers of circulating rat trypanosomes; antisera reduced and epinephrine increased the numbers. Increased motor activity appeared to induce increased parasitaemia. Results of these and other studies suggest that in diurnally active hosts, trypanosome periodicities are characterized by increasing numbers in the circulation throughout the day and reach a peak just before darkness. In nocturnally active animals a similar rhythm was observed with only a slight phase change; circulating trypanosomes increased throughout the day and were maximal soon after nocturnal onset.

Animals↗
PubMed1976

Effects of frequency of photic stimulation upon autistic and retarded children.

The present study was designed to determine if frequency of repetitive photic stimulation could affect the response rate of an operant upon which such stimulation was made contingent. To test this hypothesis, we trained retarded and autistic children, equated for mental age, to pull a lever to obtain photic stimulation of different frequencies. It was found that (a) response rates of autistic children were related to the frequency of stimulation, while retarded children showed no such consistency. (b) The two groups did not differ in the average duration of time they engaged in stereotypies. (c) During a subsequent extinction session, two autistic children ceased responding, but one of two retarded children did not. (d) Noncontingent photic stimulation suppressed a food-motivated operant in one autistic child. These results were interpreted as evidence for frequency-dependent properties of repetitive visual feedback in autistic children. In addition, support was given to the position that performance deficits in autistic children correlating with the occurrence of stereotypies result from competition of different sources of reinforcement.

Age Factors↗
PubMed1975

Effects of differential rearing condition on heart rate conditioning and response suppression.

Rats were reared in either an enriched or isolated environment for 60 days following weaning. Neither rearing environment nor sex affected heart rate conditioning. However, when the CS used during conditioning was subsequently presented in a drinking situation, males reared in isolation showed a greater degree of response suppression than did similarly reared females. Males and females reared in the enriched environment did not differ in degree of response suppression.

Acoustic Stimulation↗
PubMed1975

An operant procedure to teach an echolalic, autistic child to answer questions appropriately.

An operant conditioning procedure to teach an autistic patient with rapid immediate echolalia to answer questions correctly was devised. The procedure involved positively reinforcing the patient immediately after a correct response and preventing incorrect responses. It is simple to implement and eliminates some of the structure and constraints inherent in previously described operant methods. This allows the procedure to be administered by a variety of therapeutic personnel and parents and in a variety of living situations.

Autistic Disorder↗
PubMed1975

Systematic observation of play behavior in autistic children.

The play behavior, defined as interaction with peers and objects, of five autistic children was systematically observed in four environments, i.e., a stark environment, a theraplay unit, a playroom, and an outside play deck. The preliminary results suggested that (1) with some children environment has little or no effect on their play behavior; (2) with multiple objects, autistic children frequently related to the objects rather than to their peers; (3) object play was most frequently at the manipulative stage and often included repetitive and negative behavior; (4) within a confined space with no objects present, autistic children frequently engaged in solitary repetitive behavior; and (5) within a confined space designed to facilitate a movement flow (theraplay), autistic children modeled and imitated and were involved in gross motor play together.

Aggression↗