Prepulse effects on magnitude estimation of startle-eliciting stimuli and startle responses

The present studies investigated the relationship between prepulse effects on the modification of the brainstem startle reflex and magnitude estimates of startle-eliciting stimuli. In Experiment 1, startle eyeblink responses were elicited in 24 students, half of whom were instructed to estimate the loudness of the startle stimulus (actual intensities of 80, 90, and 100 dB) and half of whom were instructed to estimate the magnitude of their eyeblink. When weak acoustic prepulses preceded the startle-eliciting stimulus, eyeblink amplitude was inhibited, and estimates of response magnitude decreased, but estimates of startle stimulus magnitude decreased only when 100-dB startle stimuli were presented. In Experiment 2, the same startle stimuli were preceded on some trials by a vibrotactile prepulse to the hand. In conditions in which startle amplitude was inhibited, startle stimulus magnitude estimates were not affected. This suggests that the effect of acoustic prepulses on 100-dB startle stimuli in Experiment 1 may have been due to loudness assimilation, an effect independent of the prepulse inhibition of startle responding.     

Embedding instructive feedback into teacher-student interactions during independent seat work

The effects of embedding a constant time delay procedure into an independent seat work activity and using instructive feedback were evaluated in this study. Seven students with mild disabilities participated in the study that occurred in their special education classroom. A multiple probe design across sets of target behaviors was used, and students' responses to instructive feedback stimuli were evaluated during each probe condition. The procedures were implemented with a high degree of fidelity, and the results indicate that (a) the students acquired the target behaviors taught with the constant time delay procedure that was embedded into independent seat work, and (b) the students acquired some but not all of the responses to the instructive feedback stimuli. These findings are discussed in terms of using instructive feedback in classrooms and future research on instructive feedback.     

Homicide by juvenile girls

We investigated offense characteristics for a national sample of 38,749 homicide arrestees identified in the FBI Supplemental Homicide Reports for 1984 and 1993. Analyses indicated little change from 1984 to 1993 in the circumstances of homicides committed by adolescent girls; however, there were consistent offense differences between girls and boys, and between girls and women. Homicides by adolescent girls were more likely than those committed by boys to involve interpersonal conflict rather than a criminal motive such as robbery. Girls were more likely than boys to use a knife rather than a firearm and their victims were more likely to be under the age of 13 years. Compared to women (18 years or older), girls were more likely to act with an accomplice and their victims were more likely to be female and between 13 and 20 years of age. Results were inconsistent with a stereotypic masculinization theory of the increase in female violence, but provide indirect support for the importance of domestic stress and relational conflict experienced by adolescent girls. Overall, this study supports the need for differentiated study of violence by juvenile girls, and for preventive interventions which target domestic and interpersonal stress.     

Control across the life span: A model for understanding self-direction

A comprehensive four-factor interactive model on physical, psychological, and environmental processes related to the sense of control is presented for adult development with an emphasis on later life. The four experienced components are (1) control from within oneself, (2) control over oneself, (3) control over the environment, and (4) control from the environment. Control over oneself and over the environment measure self-directed control, while control from within oneself and from the environment measure nonself-directed control. Coping (a bidimensional control scale) measures control from powerlessness and suicide to overcontrolling. Findings confirm a significant loss of coping in an older cohort group from a white, rural sample composed primarily of single subjects with low coping representing a significant drop in self-directed behavior. A discussion of the relationship between self-direction and health in the older cohort group follows.     

Matching adolescents with foster mothers and fathers: An evaluation of the role of temperament

We tested the notion that better foster care adjustment would be observed when the temperaments of mothers and fathers were matched with those of adolescent foster children. We hypothesized that families in which foster parents and foster children had high (easy) scores on subscales of the Revised Dimensions of Temperament Scale (DOTS-R) would also report higher family functioning and higher foster care adjustment than parents and children from families in which one or both family members had low (difficult) scores on these scales. The hypotheses were supported when the mothers and fathers family assessments were used but rejected when the observations of the case managers and adolescents were tested. Methodological and substantive explanations for the findings are discussed and recommendation for foster care practice and continuing research are provided.     

Prevalence of traumatic brain injury in an inpatient psychiatric population

This study investigated the prevalence of traumatic brain injury (TBI) in an inpatient psychiatric population. We hypothesized increased prevalence of TBI relative to the general population due to a variety of risk factors observed in psychiatric patients. One hundred (mean age = 34) psychiatric inpatients completed the revised Head Injury Questionnaire. Chart review of 17 subjects reporting injuries established whether injuries were documented in medical records. Sixty-eight percent of this psychiatric population reported one or more injuries in which they were unconscious or dazed. This number is higher than the prevalence in the general population. Injuries were generally of mild to moderate severity; multiple injuries were common. Chart review of 17 subjects reporting TBI indicated that histories of TBI had not been noted in the medical record. Finally, 63% of TBI subjects reported that their injury predated the onset of their psychiatric symptoms. These results suggest a possible role of TBI in psychiatric symptomatology and have implications for psychiatric treatment in this population.     

Monogeusia for fructose,glucose, sucrose,and maltose

We investigated the ability of subjects to discriminate sugars with a whole-mouth forced-choice paradigm, in which a standard solution was compared with a test solution of varied concentration. Discrimination probabilities were U-shaped functions of test concentration: for 6 subjects and pairwise combinations of fructose, glucose, and sucrose, discriminability always declined to chance over a narrow range of test concentrations. At concentrations ≦ 100 mM, maltose was indiscriminable from fructose but discriminable at higher concentrations for 4 subjects. By analogy with themonochromacy of night vision, whereby any two lights are indiscriminable when their relative intensities are suitably adjusted, we call the gustatory indiscriminability of these sugarsmonogeusia. The simplest account of monogeusia is that all information about the indiscriminable sugars is represented by a single neural signal that varies only in magnitude. The discriminability of maltose from the other sugars at higher concentrations is consistent with the hypothesis that maltose also activates a second gustatory code.     

Active and passive avoidance following the administration of systemic DSP4, xylamine, or p-chloroamphetamine

Groups of rats were administered either DSP4 (50 mg/kg, ip), xylamine (50 mg/kg, ip), or p-chloroamphetamine (2 X 10 mg/kg, ip), either 2 weeks or 1 week before the testing of two-way active avoidance. DSP4 and xylamine, the selective noradrenaline (NA) neurotoxins, caused a two-way avoidance impairment but p-chloroamphetamine, the selective 5-hydroxytryptamine (5-HT) neurotoxin, did not do so. Pretreatment with desipramine (20 mg/kg, ip) blocked the avoidance impairment caused by DSP4 and xylamine treatment. Neither DSP4 nor xylamine caused any alteration of passive avoidance retention. The biochemical analyses indicated severe NA, but not 5-HT, depletions in the DSP4 and xylamine conditions and drastic 5-HT, but not NA, depletions in the p-chloroamphetamine conditions. These results confirm and extend earlier findings concerning the role of NA in avoidance behavior.     

Fetal brain tissue transplants reduce visual deficits in adult rats with bilateral lesions of the occipital cortex

Fetal brain tissue from the occipital or the frontal cortex was implanted into the damaged occipital cortex of adult rats. The animals receiving grafts of embryonic frontal cortex showed partial restoration of brightness discrimination while recipients given homologous implants of occipital cortex were as impaired as those animals with lesions alone. Neither frontal nor occipital grafts aided in the performance of a pattern discrimination problem; both groups of brain-damaged animals were unable to learn the task. Nonetheless, both groups of animals had viable and enlarged grafts with similar neuronal and glial profiles.