Atypicalities of Gesture Form and Function in Autistic Adults.

While well-represented on clinical measures, co-speech gesture production has never been formally studied in autistic adults. Twenty-one verbally fluent autistic adults and 21 typically developing controls engaged in a controlled conversational task. Group differences were observed in both semantic/pragmatic and motoric features of spontaneously produced co-speech gestures. Autistic adults prioritized different functions of co-speech gesture. Specifically, they used gesture more than controls to facilitate conversational turn-taking, demonstrating a novel nonverbal strategy for regulating conversational dynamics. Autistic adults were more likely to gesture unilaterally than bilaterally, a motoric feature of gesture that was individually associated with autism symptoms. Co-speech gestures may provide a link between nonverbal communication symptoms and known differences in motor performance in autism.

Genetic dissection of intermale aggressive behavior in BALB/cJ and A/J mice.

Aggressive behaviors are disabling, treatment refractory, and sometimes lethal symptoms of several neuropsychiatric disorders. However, currently available treatments for patients are inadequate, and the underlying genetics and neurobiology of aggression is only beginning to be elucidated. Inbred mouse strains are useful for identifying genomic regions, and ultimately the relevant gene variants (alleles) in these regions, that affect mammalian aggressive behaviors, which, in turn, may help to identify neurobiological pathways that mediate aggression. The BALB/cJ inbred mouse strain exhibits relatively high levels of intermale aggressive behaviors and shows multiple brain and behavioral phenotypes relevant to neuropsychiatric syndromes associated with aggression. The A/J strain shows very low levels of aggression. We hypothesized that a cross between BALB/cJ and A/J inbred strains would reveal genomic loci that influence the tendency to initiate intermale aggressive behavior. To identify such loci, we conducted a genomewide scan in an F2 population of 660 male mice bred from BALB/cJ and A/J inbred mouse strains. Three significant loci on chromosomes 5, 10 and 15 that influence aggression were identified. The chromosome 5 and 15 loci are completely novel, and the chromosome 10 locus overlaps an aggression locus mapped in our previous study that used NZB/B1NJ and A/J as progenitor strains. Haplotype analysis of BALB/cJ, NZB/B1NJ and A/J strains showed three positional candidate genes in the chromosome 10 locus. Future studies involving fine genetic mapping of these loci as well as additional candidate gene analysis may lead to an improved biological understanding of mammalian aggressive behaviors.

Assessment of NMDA receptor NR1 subunit hypofunction in mice as a model for schizophrenia.

N-methyl-D-aspartate receptors (NMDARs) play a pivotal role in excitatory neurotransmission, synaptic plasticity and brain development. Clinical and experimental evidence suggests a dysregulation of NMDAR function and glutamatergic pathways in the pathophysiology of schizophrenia. We evaluated electrophysiological and behavioral properties of NMDAR deficiency utilizing mice that express only 5-10% of the normal level of NMDAR NR1 subunit. Auditory and visual event related potentials yielded significantly increased amplitudes for the P20 and N40 components in NMDAR deficient (NR1(neo)-/-) mice suggesting decreased inhibitory tone. Compared to wild types, NR1(neo)-/- mice spent less time in social interactions and showed reduced nest building. NR1(neo)-/- mice displayed a preference for open arms of a zero maze and central zone of an open field, possibly reflecting decreased anxiety-related behavioral inhibition. However, locomotor activity did not differ between groups in either home cage environment or during behavioral testing. NR1(neo)-/- mice displayed hyperactivity only when placed in a large unfamiliar environment, suggesting that neither increased anxiety nor non-specific motor activation accounts for differential behavioral patterns. Data suggest that NMDAR NR1 deficiency causes disinhibition in sensory processing as well as reduced behavioral inhibition and impaired social interactions. The behavioral signature in NR1(neo)-/- mice supports the impact of impaired NMDAR function in a mouse model with possible relevance to negative symptoms in schizophrenia.

Extinction training regulates tyrosine hydroxylase during withdrawal from cocaine self-administration.

Chronic exposure to drugs of abuse is known to modulate tyrosine hydroxylase (TH) levels in the mesolimbic dopamine system. In this study, 12 d of cocaine self-administration in rats (4 hr/d) reduced TH immunoreactivity by 29% in the nucleus accumbens (NAc) shell, but not core, after a 1 week withdrawal period. In contrast, TH immunoreactivity in the NAc was completely restored in animals that experienced extinction training (4 hr/d) during the same withdrawal period. Extinction training also increased TH levels in the ventral tegmental area (VTA) by 45%, whereas TH was not altered in the VTA by cocaine withdrawal alone. Thus, extinction-induced normalization of NAc TH levels could involve increased TH synthesis, stability, and/or transport from the VTA to the NAc. A similar extinction training regimen failed to alter TH levels in the NAc or VTA of rats trained to self-administer sucrose pellets, indicating that TH regulation in cocaine-trained animals is not a generalized effect of extinction learning per se. Rather, these data suggest that neuroadaptative responses during cocaine withdrawal ultimately are determined by a complex interaction between chronic drug exposure and drug-seeking experience. The ability of extinction training to restore NAc TH levels is hypothesized to accelerate recovery from dopamine depletion and anhedonia during cocaine withdrawal.

Dark Agouti and Fischer 344 rats: differential behavioral responses to morphine and biochemical differences in the ventral tegmental area.

We sought to identify behavioral and biochemical differences between Dark Agouti and Fischer 344 inbred rat strains to assess whether they could serve as a model of genetically determined differences in sensitivity to drugs of abuse. We compared the strains for the following traits: morphine-induced locomotor activity and sensitization; circadian variation in plasma levels of corticosterone, a hormone reported to affect sensitivity to drugs of abuse; and several biochemical parameters in the ventral tegmental area and nucleus accumbens, brain regions implicated in the locomotor activating and reinforcing actions of drugs of abuse. Fischer 344 rats exhibited greater initial locomotor responses to morphine but, unlike Dark Agouti rats, did not develop sensitization to a second morphine exposure. Fischer 344 rats displayed a marked rise in basal plasma corticosterone levels in the late light phase and early dark phase, whereas Dark Agouti rats showed no significant circadian variation in corticosterone levels. Relative to drug-naive Fischer 344 rats, drug-naive Dark Agouti rats showed higher levels of tyrosine hydroxylase and glial fibrillary acidic protein, and lower levels of neurofilament proteins, in the ventral tegmental area. In contrast, no strain differences were found in levels of tyrosine hydroxylase, specific G protein subunits or protein kinase A in the nucleus accumbens. Together, these results demonstrate that Dark Agouti rats and Fischer 344 rats exhibit differences in specific behavioral, endocrine and biochemical parameters related to sensitivity to drugs of abuse.

Regulation of cocaine reward by CREB.

Cocaine regulates the transcription factor CREB (adenosine 3', 5'-monophosphate response element binding protein) in rat nucleus accumbens, a brain region that is important for addiction. Overexpression of CREB in this region decreases the rewarding effects of cocaine and makes low doses of the drug aversive. Conversely, overexpression of a dominant-negative mutant CREB increases the rewarding effects of cocaine. Altered transcription of dynorphin likely contributes to these effects: Its expression is increased by overexpression of CREB and decreased by overexpression of mutant CREB. Moreover, blockade of kappa opioid receptors (on which dynorphin acts) antagonizes the negative effect of CREB on cocaine reward. These results identify an intracellular cascade-culminating in gene expression-through which exposure to cocaine modifies subsequent responsiveness to the drug.

Genetic analysis of behavioral, neuroendocrine, and biochemical parameters in inbred rodents: initial studies in Lewis and Fischer 344 rats and in A/J and C57BL/6J mice.

Previous work has identified inherent behavioral, neuroendocrine, and biochemical differences among inbred rodent strains that have been related to the animals' differential responsiveness to drugs of abuse or stress. In the present study, we sought to determine (1) whether there are genetic correlations among particular phenotypic traits that differ between a pair of inbred rat strains (Lewis and Fischer 344) or a pair of inbred mouse strains (A/J and C57BL/6J); (2) which of these traits might be amenable to quantitative trait locus analysis; and (3) whether additional behavioral or biochemical differences relevant to drug- or stress-responsiveness could be identified in these strains. Specifically, we measured several behavioral, neuroendocrine, and biochemical traits in parental Lewis and Fischer 344 rats and in 298 members of an F2 intercross population, as well as in parental A/J and C57BL/6J mice and in 11 of the AXB/BXA recombinant inbred mouse strains. Traits measured included exploratory locomotor activity in a novel environment; amphetamine-induced locomotor activity; several specific protein levels in striatal regions, including inhibitory G protein subunits, the dopamine transporter, the Fos family member transcription factor DeltaFosB, and the protein phosphatase inhibitor DARPP-32; and late-afternoon plasma corticosterone concentrations. Each of the traits measured in F2 rats or recombinant inbred mice appears to be influenced by multiple genes, as well as by environmental factors. There were statistically significant, albeit relatively weak, correlations among several traits in an F2 intercross population bred from Lewis and Fischer rats. Among the traits studied in Lewis and Fischer rats, one seemed most amenable to quantitative trait locus analysis: the level of the inhibitory G-protein subunit, Galphai, in the nucleus accumbens. We also found a robust genetic correlation between levels of DeltaFosB and levels of the dopamine transporter in striatal regions in AXB/BXA recombinant inbred mouse strains. While these studies demonstrate the likely complexity of the genetic factors that influence the numerous phenotypes associated with altered responsiveness to drugs of abuse and stress, they represent an initial and necessary step toward identifying specific genetic factors involved.

Sertraline in adults with pervasive developmental disorders: a prospective open-label investigation.

The short-term efficacy and tolerability of sertraline for adults with pervasive developmental disorders (PDDs) were assessed in this investigation. Forty-two adults with PDDs (autistic disorder, N = 22; Asperger's disorder, N = 6; and PDD not otherwise specified [NOS], N = 14) participated in a 12-week, open-label, systematic trial of sertraline. Behavioral ratings of repetitive symptoms, aggression, and social relatedness were obtained at baseline and after 4, 8, and 12 weeks of sertraline administration. Twenty-four (57%) of 42 patients showed significant improvement, primarily in repetitive and aggressive symptoms. Statistically significant changes in measures of social relatedness did not occur. Patients with autistic disorder and PDD NOS did significantly better than those with Asperger's disorder. Based on global improvement item criteria from the Clinical Global Impression Scale, 15 of 22 (68%) patients with autistic disorder, none of six (0%) patients with Asperger's disorder, and 9 of 14 (64%) patients with PDD NOS were categorized as treatment responders. Sertraline was well tolerated; no adverse cardiovascular effects, extrapyramidal symptoms, or seizures were identified. These findings suggested that sertraline may be an effective treatment for interfering repetitive and aggressive symptoms in adults with PDDs. Definitive statements about the efficacy and tolerability of sertraline for treating adults with PDDs must await results from double-blind, placebo-controlled trials. These preliminary results should not be generalized to include children and adolescents with PDDs.

Clomipramine in adults with pervasive developmental disorders: a prospective open-label investigation.

The purpose of this investigation was to determine the short-term efficacy and tolerability of clomipramine in a consecutive series of adults with pervasive developmental disorders (PDDs). Thirty-five adults with PDDs (DSM-IV), 16 of whom were nonverbal, entered a 12-week prospective open-label trial of clomipramine. The initial sample included 18 patients with autistic disorder, 6 patients with Asperger's disorder, and 11 patients with pervasive developmental disorder not otherwise specified (PDDNOS). Behavioral ratings were obtained at baseline and after 4, 8, and 12 weeks of clomipramine. Eighteen (55%) of the 33 patients who completed the trial were categorized as treatment responders based on scores of "much improved" or "very much improved" on the Clinical Global Impression (CGI) global improvement item (p < 0.001). Ten (63%) of 16 patients with autistic disorder, 2 (33%) of 6 patients with Asperger's disorder, and 6 (55%) of 11 patients with PDDNOS were considered responders to clomipramine treatment. In those 18 patients, clomipramine significantly reduced total repetitive thoughts and behavior (p < 0.001) and also aggression (p < 0.001), and improved some aspects of social relatedness, such as eye contact and verbal responsiveness (p < 0.001). Change in these specific symptom clusters over time was not related to DSM-IV subtype of PDD. The level of autistic behavior, as measured by the Autism Behavior Checklist (ABC) score, and full-scale intelligence quotient (IQ) were not significantly associated with global treatment response. Whereas clomipramine was well tolerated by most patients, 13 had clinically significant adverse effects. Three patients had seizures during clomipramine treatment, including 2 who had prior seizure disorders and were taking anticonvulsants. Of the 32 patients who had no history of prior seizures, only 1 had a seizure during clomipramine treatment. There were no adverse cardiovascular or extrapyramidal effects. All responders continued on clomipramine after completion of the study. The results of this open-label trial suggest that clomipramine may be an effective drug for reducing repetitive thoughts and actions and aggressive behavior and for improving some elements of social behavior, such as eye contact and verbal responsivity in adults with PDDs. Careful monitoring of adverse effects, particularly seizures, is warranted. Although an electroencephalogram (EEG) is not mandatory in patients with PDD prior to clomipramine treatment, we recommend that patients with PDD and a history of seizures be treated initially with a selective serotonin uptake inhibitor rather than with clomipramine. The findings of this study require replication in a double-blind placebo-controlled investigation before definitive statements of efficacy and tolerability can be made.

Molecular mechanisms of drug addiction: adaptations in signal transduction pathways.

Despite staggering advances in the neurosciences over the past decade, detailed knowledge of the pathophysiology and pathogenesis of psychiatric disorders remains severely limited. Similarly, the mechanisms by which long-term exposure to psychotropic drugs leads to their clinically relevant actions are not yet known. This relative lack of progress in psychiatric research is due in part to the extraordinary complexity of the brain and the difficulties inherent in studying central nervous system pathology. However, the lack of progress is also due to the limited scope of psychiatric neuroscience, which remains focused to a great extent on traditional neurotransmitters and their receptors as the site of pathophysiological lesions in a disease state and as the ultimate targets for pharmacological treatments of these disorders. This limited focus persists despite our current knowledge that such neurotransmitters and receptors are truly the tip of the iceberg of the brain's complex inter- and intraneuronal regulatory machinery. The goal of this review is to illustrate how our rapidly evolving knowledge of neuronal regulatory mechanisms can be used as a template within which to delineate more complete models of the molecular mechanisms of psychotropic drug action, as well as the role of genetic and environmental factors in determining individual differences in drug responsiveness. The focus of the review is on drug addiction. Repeated exposure to drugs of abuse has been shown to elicit long-term adaptations in post-receptor second messenger and protein phosphorylation pathways in specific brain regions. There is increasing evidence that these adaptations are part of the molecular basis of an addictive state. Individual differences in some of these same signaling proteins also may contribute to individual differences in vulnerability for drug addiction. More recent research has demonstrated that drug-induced adaptations occur in other, non-second messenger-related, post-receptor signaling pathways, specifically, those influenced by neurotrophic factors. Together, these studies provide insight into the complex mechanisms that must be considered in understanding the brain's adaptations to chronic perturbations in general as well as the formation of a neuropsychiatric disorder and its treatment.