Publications (15) View all
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Article: Brain Structural Abnormalities in Doberman Pinschers with Canine Compulsive Disorder.
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ABSTRACT: Obsessive compulsive disorder (OCD) is a debilitating condition, the etiology of which is poorly understood, in part because it often remains undiagnosed/untreated for a decade or more. Characterizing the etiology of compulsive disorders in animal models may facilitate earlier diagnosis and intervention. Doberman pinschers have a high prevalence of an analogous behavioral disorder termed canine compulsive disorder (CCD), which in many cases responds to treatments used for OCD. Thus, studies of CCD may help elucidate the etiology of compulsive disorders. We compared brain structure in Dobermans with CCD (N=8) and unaffected controls (N=8) to determine whether CCD is associated with structural abnormalities comparable to those reported in humans with OCD. We obtained 3 Tesla magnetic resonance structural and diffusion images from anesthetized Dobermans and subjected images to segmentation, voxel based morphometry, and diffusion tensor analyses. CCD dogs exhibited higher total brain and gray matter volumes and lower dorsal anterior cingulate cortex and right anterior insula gray matter densities. CCD dogs also had higher fractional anisotropy in the splenium of the corpus callosum, the degree of which correlated with the severity of the behavioral phenotype. Together, these findings suggest that CCD is associated with structural abnormalities paralleling those identified in humans with OCD. Accordingly, the CCD model, which has a number of advantages over other animal models of OCD, may assist in establishing the neuroanatomical basis for and etiology of compulsive disorders, which could lead to earlier diagnosis of and new treatments for humans and animals with these disorders.Progress in Neuro-Psychopharmacology and Biological Psychiatry 04/2013; · 3.25 Impact Factor -
Article: Positive Reinforcement Training in Squirrel Monkeys Using Clicker Training.
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ABSTRACT: Nonhuman primates in research environments experience regular stressors that have the potential to alter physiology and brain function, which in turn can confound some types of research studies. Operant conditioning techniques such as positive reinforcement training (PRT), which teaches animals to voluntarily perform desired behaviors, can be applied to improve behavior and reactivity. PRT has been used to train rhesus macaques, marmosets, and several other nonhuman primate species. To our knowledge, the method has yet to be used to train squirrel monkeys to perform complex tasks. Accordingly, we sought to establish whether PRT, utilizing a hand-box clicker (which emits a click sound that acts as the conditioned reinforcer), could be used to train adult male squirrel monkeys (Saimiri boliviensis, N = 14). We developed and implemented a training regimen to elicit voluntary participation in routine husbandry, animal transport, and injection procedures. Our secondary goal was to quantify the training time needed to achieve positive results. Squirrel monkeys readily learned the connection between the conditioned reinforcer (the clicker) and the positive reinforcer (food). They rapidly developed proficiency on four tasks of increasing difficulty: target touching, hand sitting, restraint training, and injection training. All subjects mastered target touching behavior within 2 weeks. Ten of 14 subjects (71%) mastered all tasks in 59.2 ± 2.6 days (range: 50-70 days). In trained subjects, it now takes about 1.25 min per monkey to weigh and administer an intramuscular injection, one-third of the time it took before training. From these data, we conclude that clicker box PRT can be successfully learned by a majority of squirrel monkeys within 2 months and that trained subjects can be managed more efficiently. These findings warrant future studies to determine whether PRT may be useful in reducing stress-induced experimental confounds in studies involving squirrel monkeys. Am. J. Primatol. 00:1-9, 2012. © 2012 Wiley Periodicals, Inc.American Journal of Primatology 05/2012; · 2.22 Impact Factor -
Article: A double-blind, placebo-controlled trial of the NMDA glycine site antagonist, GW468816, for prevention of relapse to smoking in females.
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ABSTRACT: Relapse to smoking is common after initial abstinence with pharmacotherapy and behavioral support and represents a major clinical challenge. Although mechanisms underlying relapse to smoking have not been elucidated, preclinical studies suggest that glutamate receptors may be involved. We sought to test a selective antagonist of the glycine coagonist site on the glutamate N-methyl-D-aspartate receptor, GW468816, for prevention of relapse in recently abstinent smokers. To do so, we enrolled 264 healthy female smokers in an open 8-week smoking cessation intervention with behavioral therapy and a standard dose of transdermal nicotine replacement therapy with taper and additional gum or lozenge as needed for nicotine withdrawal symptoms. Ninety-eight participants achieved 7-day point prevalence abstinence and were randomized into a 5-week double-blind, placebo-controlled, relapse-prevention trial of GW468816 (200 mg/d) and then followed for 60 days after randomization. There was no effect of treatment on abstinence rates at the end of treatment (χ² [1, n = 96] = 0.168, P = 0.838), on the rates of relapse (χ² [1, n = 98] = 0.031, P = 1.000) or lapse (χ² [1, n = 62] = 0.802, P = 0.423), or on time to relapse (χ² [1, n = 98) = 0.001, P = 0.972). No significant relationships were detected between plasma GW468816 concentrations and abstinence, time to relapse, or self-reported craving. In conclusion, despite promising preclinical data that support the use of a selective NMDA glycine site antagonist for prevention of relapse to smoking, we observed no effect of GW468816 on relapse or lapse rates, time to relapse, or craving compared to placebo.Journal of clinical psychopharmacology 08/2011; 31(5):597-602. · 5.09 Impact Factor -
Article: Association between CHRNA5 genetic variation at rs16969968 and brain reactivity to smoking images in nicotine dependent women.
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ABSTRACT: Tobacco smoking is the leading preventable cause of death in the developed world. Identifying risk factors for smoking may lead to more effective treatments. Genome wide association studies revealed a relationship between development of nicotine dependence and a single-nucleotide polymorphism (SNP, rs16969968) of the nicotine acetylcholine receptor (nAChR) alpha-5 subunit gene (CHRNA5). The relationship between this SNP and other factors contributing to smoking behavior such as smoking cue reactivity is unclear. We assessed the role of rs16969968 on brain functional MRI (fMRI) reactivity to smoking cues by studying nicotine dependent women with the nicotine dependence 'risk' allele (A allele, N=14) and without the 'risk' allele (G/G smokers, N=10). Nicotine dependence severity, as assessed with the Fagerstrom test for nicotine dependence, smoking pack-years, and expired carbon monoxide levels, were equivalent in these groups. We observed a group difference in fMRI reactivity; women without the A allele (G/G smokers) showed greater fMRI reactivity to smoking images in brain areas related to memory and habitual behavior such as the hippocampus and dorsal striatum. Our finding suggests that nicotine-dependent smokers lacking the rs16969968 A allele are more likely to recall smoking-related memories and engage in habitual responding to smoking cues than A allele smokers. Although more studies are necessary to determine the mechanism underlying and significance of this cue reactivity difference, these data suggest that smokers may develop and remain nicotine dependent due to different factors including genetics and cue reactivity. This finding may have implications for personalizing smoking treatment.Drug and alcohol dependence 07/2011; 120(1-3):7-13. · 3.60 Impact Factor -
Article: Anterior cingulate proton spectroscopy glutamate levels differ as a function of smoking cessation outcome.
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ABSTRACT: Cigarette smoking is the leading preventable cause of death. Unfortunately, the majority of smokers who attempt to quit smoking relapse within weeks. Abnormal dorsal anterior cingulate cortex (dACC) function may contribute to tobacco smoking relapse vulnerability. Growing evidence suggests that glutamate neurotransmission is involved in mediating nicotine dependence. We hypothesized that prior to a cessation attempt, dACC glutamate levels would be lower in relapse vulnerable smokers. Proton magnetic resonance spectra (MRS) were obtained from dACC and a control region, the parieto-occipital cortex (POC), using two-dimensional J-resolved MRS at 4T and analyzed using LCModel. Nine nicotine-dependent women were scanned prior to making a quit attempt. Subjects then were divided into two groups; those able to maintain subsequent abstinence aided by nicotine replacement therapy (NRT) and those who slipped while on NRT (smoked any part of a cigarette after attaining at least 24h of abstinence). Slip subjects exhibited significantly reduced dACC MRS glutamate (Glu/Cr) levels (p<0.03) compared to abstinent subjects. This effect was not observed in the POC control region. Our preliminary findings suggest that dACC Glu levels as measured with MRS may help identify and/or be a biomarker for relapse vulnerable smokers. Future research following up on these findings may help clarify the role of dACC Glu in smoking dependence that may lead to new treatment strategies.Progress in Neuro-Psychopharmacology and Biological Psychiatry 05/2011; 35(7):1709-13. · 3.25 Impact Factor
