Reduced attention-related negative potentials in schizophrenic children

ERPs were recorded from normal and schizophrenic children during performance of a reaction time task (RT) followed by a complex visual discrimination, the span of apprehension task (Span), sensitive to vulnerability factors in schizophrenia. Subjects responded rapidly to the onset of the visual arrays in the RT condition and differentially to the presence of 1 of 2 target letters in the Span condition. The EEG was recorded at 19 scalp sites and ERPs included activity 1 sec before through 1 sec after Span array onset. Difference potentials (Span-RT) were computed to remove unvarying exogenous activity, thus isolating endogenous activity associated with the processing demands of the Span task. When RT and Span task ERPs are compared, schizophrenic children produced a significantly smaller than normal increment in endogenous negative activity. This endogenous negativity differed in its topography and time course from the exogenous components (P1, N1 and P2), and most likely reflects attentional effort associated with serial search, pattern recognition and stimulus identification. We believe that the current results support the position that schizophrenics are impaired in their ability to allocate adequate attentional resources for the processing of the Span stimuli. It is important to note that this deficit is apparent quite early in discriminative processing.

Modulatory influence of continuous tone, tone offset, and tone onset on the human acoustic startle response

Startle modulation in young adult men, by continuous background tone and its offset, a 2-s sustained tone and its offset, and the onset of a 25-ms tone pip were compared. Tone (75dB 1000 Hz) offset and onset occurred either 2000 ms or 100-120 ms before the startle stimuli (104dB (SPL), 50-ms white noise bursts). Blink amplitude and latency were unaffected by continuous background tone. Blink amplitude was reliably inhibited by 100-ms offset of both the continuous background tone and the 2-s sustained tone or 120-ms onset of the tone pip, whereas effects on latency were more variable. Facilitation of blink amplitude and latency was significant but weak and only following the 2-s sustained tone, and only with respect to one of two experimental contexts. These findings support those of others and suggest that startle inhibition results from activation of neurons responding to transient environmental changes. The degree of inhibition appears to be related to stimulus value. Startle amplitude facilitation following long sustained prestimulation intervals is dependent on experimental context. Overall latency and amplitude modulation tend to be concordant, leading to the conclusion that the mechanism(s) underlying both are context dependent and linked in the adult human.

Significance testing of difference potentials

This note provides a statistical-graphical method for the evaluation of the statistical significance of difference potentials from a group of subjects, and for the comparison of difference potentials between two groups. A table of the lengths of statistically significant intervals for various sampling interval lengths, numbers of subjects, and autocorrelation parameters is presented.

Maturation of prestimulation-induced startle modulation in girls

This study of the maturation of prestimulation-induced modulation of startle in 4- to 8-year-old girls and young women demonstrated significant effects of age on both startle amplitude and onset latency modulation. Prestimulation with nonstartling tones resulted in strong inhibition of both amplitude and latency of the startle blink reflex in adults when 25-ms tones preceded the startling stimuli by 120 ms or 250 ms. Following sustained prestimulation for 2000 ms, the adults showed weak nonsignificant response facilitation. Eight-year-old girls showed mature inhibitory startle amplitude modulation, but significantly less inhibition of onset latency compared to adults. Preschool girls showed significantly less amplitude and latency inhibition and more facilitation than 8-year-olds and adult women. These findings in female subjects were very similar to those obtained by Ornitz, Guthrie, Kaplan, Lane, and Norman (1986) in male subjects. Gender differences were limited to the 8-year-old age group. The 8-year-old girls showed significantly less startle amplitude inhibition than 8-year-old boys following the 120-ms and 250-ms prestimulation intervals and less latency facilitation following 2000 ms of sustained prestimulation. In general, these findings suggest that brainstem mechanisms that mediate startle response modulation undergo development during early childhood and do not mature until about 8 years of age in both male and female subjects. The results are discussed in relation to studies of gender effects on development of other neurophysiological variables and to maturation of the nervous system.

Sigma receptor ligands alter concentrations of corticosterone in plasma in the rat

Both BMY-14802 (alpha-(4-fluorophenyl)-4-(5-fluoro-2-pyrimidinyl)-1-piperazine-butanol hydrochloride) and gevotroline (WY-47384; 8-fluoro-2,3,4,5-tetrahydro-2-[3-(3-pyridinyl)-propyl]-1H-pyrido[4,3-b] indole hydrochloride) are known to antagonize the psychotomimetic action of N-allyl-normetazocine (NAN; SKF-10047) and exhibit a high affinity for the sigma receptor. Unexpectedly, the putative antagonists BMY-14802 and gevotroline acted like the agonist NAN and increased activity in the hypothalamic-pituitary-adrenal axis to elevate levels of corticosterone in plasma. During the acrophase (peak) of the effects of the circadian rhythm on the hypothalamic-pituitary-adrenal axis, the ED50 was 6.5 mmol/kg for BMY-14802 and 9.6 mmol/kg for gevotroline. The ED50s for BMY-14802 and gevotroline during the low activity phase were 15.8 and 21.2 mmol/kg, respectively. The efficacies during both phases of the circadian rhythm were similar for each drug. Additive effects on the levels of corticosterone in plasma were observed when the animals were pretreated with doses above the respective ED50 values and then subjected to a rotational stress, but a small dose of BMY-14802 (0.5 mg/kg) had the opposite effect and completely inhibited the stress-related increases in corticosterone in plasma. Neither drug, at large doses, altered the increase in levels of corticosterone in plasma generated by the circadian rhythm, but at smaller doses BMY-14802 did lower circadian-related levels of corticosterone. Pretreatment with dexamethasone blocked the gevotroline-related increase in corticosterone in plasma, but not the BMY-14802-related increase. These data suggest that central sigma receptor mechanisms are involved in the regulation of the hypothalamic-pituitary-adrenal axis and that therapeutic agents that affect these receptors may alter the activity in this axis.

Symptom beliefs and actual blood glucose in type II diabetes

The relationships of blood glucose levels to symptoms and symptom beliefs were examined in this study of persons (N = 51) with Type II diabetes. Analyses revealed that 88% of the subjects had at least one symptom that was substantially correlated with blood glucose levels. However, subjects' symptom beliefs (symptoms subjects believe are the best indicators of high or low blood glucose levels) were largely unrelated to actual blood glucose levels. Thus, subjects were often mistaken about which of their symptoms were accurate indicators of blood glucose levels. Analyses also showed that the accuracy of symptom beliefs for low blood glucose was positively related to metabolic control.

Event-related potential correlates of impaired attention in schizophrenic children

Electrophysiological correlates of focused attention were studied in 13 schizophrenic and 19 age- and gender-matched children. Subjects performed a version of the Continuous Performance Task (CPT) in which a target was designated as any digit from 0 through 9 occurring on two successive stimulus presentations. Signal digits were surrounded by distractor digits which varied in position, value, and number. Event-related potentials (ERPs) elicited by each stimulus of a target pair were recorded from midline and homologous parietal, temporal, and occipital electrode placements. Schizophrenic children made significantly more errors of omission and commission than normal children. The amplitude and time course of the intertrial CNV was the same for both groups. There was a circumscribed amplitude asymmetry, left smaller than right, for the P1/N1 and P2 measures which was greater in normal than in schizophrenic children. The P3 component was significantly larger to the second stimulus of the target pair than to the first for both groups, and larger for the normal than the schizophrenic children to both stimuli.

Maturation of startle facilitation by sustained prestimulation

The startle response to a 104dB (SPL) 50-ms burst of white noise was facilitated by prestimulation with a nonstartling tone sustained for 2 s prior to the startling stimulus in 3, 4, 5, and 8 year old children and young adults. Both startle amplitude and onset latency showed significantly greater facilitation in the preschool children than in the 8-year-olds and adults. The results of this experiment, which used a fixed prestimulation interval, were compared to those of an earlier study in which the prestimulation interval was varied. The maturational changes in startle facilitation in response to the 2-s prestimulation interval were similar in the two experiments. Hence the maturational effect on startle facilitation was independent of the uncertainty (as to when the startling stimulus would be given), which might be associated with variable prestimulation intervals. These findings suggest that the neuronal mechanisms that mediate startle facilitation undergo development during early childhood and mature about 8 years of age, and that this maturational sequence is relatively independent of attentional effects.

Effects of hap mutations on heme and cytochrome formation in yeast

Simultaneous effects of mutations in the transcriptional regulatory genes, HAP1, HAP2 and HAP3, on all respiratory cytochromes of Saccharomyces cerevisiae were determined. Cytochrome behavior in hap mutants and in cyc4 and rhm1 mutants, altered in regulation of 5-aminolevulinate synthase, was compared. Although hap mutants were isolated as trans-acting, transcriptional regulators of the CYC1 (iso-1-cytochrome c) gene, each mutant exhibits partial deficiencies in all cytochrome types. In hap2 and hap3 strains all cytochromes were decreased proportionally to about 40-50% of wild type values. In contrast, hap1 caused a decrease in all cytochromes and an accumulation of a pigment, probably Zn porphyrin. Apparently apocytochrome and heme biosynthesis retain coordination in hap2 and hap3, but not in hap1, mutants. Unlike cyc4 and rhm1 mutants, hap mutants do not exhibit 5-aminolevulinate-dependent restoration of cytochromes. The hap1 mutant grew at near-normal rates on glycerol, whereas hap2 and hap3 mutants grew very slowly. The frequency of [rho-] was high (16-18%) in hap2 and hap3 strains. Results are consistent with generalized control of mitochondrial replication directed by the HAP1-HAP2 system and heme-directed control of formation of all apocytochromes mediated by HAP1. Neither system exerts all-or-nothing control.

Intergroup and intrasubject principal component analysis of event-related potentials

The purpose of this paper is to show that the familiar principal component analysis (PCA) of event-related potentials is identical to an easily formulated least squares method. This correspondence permits interpretation of several criticisms of PCA and clearer presentation of its strengths and shortcomings. Because data analysis based on PCA compares amplitudes of empirically derived components, it is necessary that the shape of the components be similar under the experimental conditions. We present and illustrate a statistical method for comparison of principal components across groups and between conditions within subjects.

The Kiddie Formal Thought Disorder Rating Scale: clinical assessment, reliability, and validity

The Kiddie Formal Thought Disorder Story Game and the Kiddie Formal Thought Disorder Scale were administered to schizophrenic, schizotypal, and normal children, aged 5 to 13 years. The story game elicited more elaborate speech samples than did a structural clinical interview focused on psychotic symptomatology. The sum of illogical thinking and loose associations was a reliable kappa = 0.77), sensitive (79%), and specific (90%) indicator of schizophrenia in this sample. It also demonstrated significant developmental changes in the schizophrenic and normal subjects. Incoherence and poverty of content of speech were infrequently rated in both schizophrenic and normal subjects.

The effects of gepirone and 1-(2-pyrimidinyl)-piperazine on levels of corticosterone in rat plasma

It was found that gepirone and 1-(2-pyrimidinyl)-piperazine (1-PP) increased levels of corticosterone in plasma in the intact rat. Gepirone was more potent and more efficacious than its metabolite, 1-PP. The ED50 was 6.4 mumol/kg for gepirone and 65.4 mumol/kg for 1-PP. Forty-five min after intraperitoneal administration, gepirone and 1-PP produced maximum increases in corticosterone of 283% and 211%, respectively, above control values. The amplitude and duration of the effects of the drugs were dependent on the ongoing activity in the hypothalamic-pituitary-adrenal axis. Consequently, the greatest absolute increases in corticosterone were produced during the afternoon when the activity in the hypothalamic-pituitary-adrenal axis was greatest. A single 10 mg/kg dose of gepirone significantly elevated levels of corticosterone in plasma (313% after 1 hr) above control values for 2 hr during afternoon trials and for 1 hr (244%) during morning trials. In addition, it was found that the effects of the administration of gepirone and of stress on the levels of corticosterone in plasma were additive. In the light of other work on the hypothalamic-pituitary-adrenal axis, these results suggest that the increased levels of corticosterone, elicited by gepirone, were mediated through a serotonergic action rather than through noradrenergic activity.

Long-term habituation and sensitization of the acoustic startle response in the normal adult human

The development and independence of short-term and long-term habituation (and short-term sensitization) of the acoustic startle response to repetitive stimuli has been repeatedly demonstrated in the experimental animal. Although short-term habituation (and sensitization) of acoustic startle has been studied in humans, neither long-term habituation nor sensitization has been demonstrated. In this study, long-term habituation (response amplitude decrement) of the blink component of the acoustic startle response occurred in normal men across five consecutive daily sessions of repetitive acoustic stimulation. Long-term sensitization (onset latency shortening) developed after the third day. Both the long-term habituation and sensitization were independent of the day. Both the long-term habituation and sensitization were independent of the short-term habituation, which developed within each daily session.

Fucosylated forms of alpha-1-antitrypsin that predict unresponsiveness to chemotherapy in ovarian cancer

We have discovered modified fucosylation of alpha 1-antitrypsin (F-AT) in the sera of ovarian cancer patients. This was detected by SDS/electrophoresis and silver-staining after extracting the sera with the fucose-binding lectin, Lotus tetragonolobus, and was identified as alpha 1-antitrypsin by Western blotting. Initially, high F-AT levels appeared to be related to the recurrence of cancer, but later measurements showed that elevated levels were also present in patients who did not respond to therapy. Using an arbitrary grading system, the level of F-AT was assessed in pairs of sera from 29 ovarian cancer patients undergoing therapy; one specimen collected just after the start of therapy and the other on a later occasion. In 75% of the 15 non-responders, F-AT was higher when measured on a second occasion; whereas in 86% of the 14 responders the second measurement was either unchanged or lower, being frequently undetectable. F-AT levels were also low or undetectable in sera from healthy women. Eight responders were monitored for F-AT throughout cyclophosphamide chemotherapy. Despite a high tumour burden at the start of therapy, all patients had relatively low levels of F-AT and this was maintained throughout remission; the levels only becoming elevated with the recurrence of tumour growth. Increased F-AT expression did not appear to be particularly associated with the presence of liver metastases and frequently predated any clinical signs of a recurrence. The interesting characteristics of these molecules could make them useful in the management of ovarian cancer.

Ultrastructural alterations in caudate nucleus in aged cats

These studies provide information on the changes in the ultrastructure in the caudate nucleus of aged cats. The major finding was that there was a decrease in the density of synapses in caudate neuropil. This decrease occurred in animals after 3 years of age and remained relatively constant in older animals. In conjunction with this change a population of unusually long synapses also occurred. These larger synaptic appositions were associated with enlarged spine heads. The caudate also showed a number of qualitative ultrastructural alterations. Many neurons contained accumulations of lipofuscin or lipopigment granules in aged animals. These inclusions occurred in both soma and dendrites of neurons and all types of glial cells. A unique configuration of collapsed agranular cisterns also was observed in aged animals. The present results indicate that decreases in synaptic density may be one morphological event underlying functional alterations observed in caudate neurons in aged cats.

The use of primary sentence stress by normal, aphasic, and autistic children

Primary sentence stress is an important aspect of the English prosodic system. Its adequate use is a prerequisite in the development of normal intonation patterns. This study examined the use of primary sentence stress in autistic children with mean length of utterance (MLU) scores between 1.9 and 4.1 morphemes. Normal and aphasic subjects at similar MLU levels served as contrast groups. The primary sentence task required that the subjects verbally respond to a request for information and provide a description of a play situation. Toy manipulation was used to elicit the desired responses. Listener judgment served as the basis for analyzing results. Although all subjects were able to perform the task, differences were seen in the number of correct responses and in the pattern of stress misassignment. These results are at variance with a prediction of stress placement on grammatical grounds. An explanation is offered, based on pragmatic considerations and cognitive developmental trends in young children.

Family stress with chronic childhood illness: cystic fibrosis, neuromuscular disease, and renal disease

Parents of children with neuromuscular disease (N = 16), cystic fibrosis (N = 16), and renal disease (N = 11) were compared with parents of control subjects matched by age to the clinical cases; the instrument used was the Questionnaire on Resources and Stress (QRS). The three clinical groups exhibited different patterns of stressful response, consistent with the nature of their illnesses and the requirements for care imposed on the families. Parents of children with neuromuscular disease reported a wide spectrum of problems, both qualitatively and quantitatively different from those experienced in the other two clinical samples. Parents of children with cystic fibrosis also experienced extensive stress, but less than anticipated. Parents of children with renal disease reported stress in only a few areas, in keeping with the nature of the disease. The relationship between severity of functional impairment from cystic fibrosis and QRS scales was examined and found to be equivocal. The 285-item and 66-item versions of the QRS were compared and judged to be appropriate for different situations (research vs. clinical screening).

Lower Purkinje cell counts in the cerebella of four autistic subjects: initial findings of the UCLA-NSAC Autopsy Research Report

As part of an autopsy research project, the brains of four autistic subjects were examined and compared with those of three comparison subjects without CNS pathology and one with phenytoin toxicity. The cerebellum was selected for initial investigation because pathognomonic symptoms and neurophysiological measures suggest that pathology may exist in the cerebellar-vestibular axis in certain patients. Total Purkinje cell counts were significantly lower in the cerebellar hemisphere and vermis of each autistic subject than in the comparison subjects.

The retardation of aging in mice by dietary restriction: longevity, cancer, immunity and lifetime energy intake

We sought to clarify the impact of dietary restriction (undernutrition without malnutrition) on aging. Female mice from a long-lived strain were fed after weaning in one of six ways: group 1) a nonpurified diet ad libitum; 2) 85 kcal/wk of a purified diet (approximately 25% restriction); 3) 50 kcal/wk of a restricted purified diet enriched in protein, vitamin and mineral content to provide nearly equal intakes of these essentials as in group 2 (approximately 55% restriction); 4) as per group 3, but also restricted before weaning; 5) 50 kcal/wk of a vitamin- and mineral-enriched diet but with protein intake gradually reduced over the life span; 6) 40 kcal/wk of the diet fed to groups 3 and 4 (approximately 65% restriction). Mice from groups 3-6 exhibited mean and maximal life spans 35-65% greater than for group 1 and 20-40% greater than for group 2. Mice from group 6 lived longest of all. The longest lived 10% of mice from group 6 averaged 53.0 mo which, to our knowledge, exceeds reported values for any mice of any strain. Beneficial influences on tumor patterns and on declines with age in T-lymphocyte proliferation were most striking in group 6. Significant positive correlations between adult body weight and longevity occurred in groups 3-5 suggesting that increased metabolic efficiency may be related to longevity in restricted mice. Mice from groups 3-6 ate approximately 30% more calories per gram of mouse over the life span than did mice from group 2. These findings show the profound anti-aging effects of dietary restriction and provide new information for optimizing restriction regimes.