Biomedical subjects

Robert R Rawlings

Publications and source records attributed to Robert R Rawlings.

5 recordsLinked to original sources

PubMed2006

A model linking biology, behavior and psychiatric diagnoses in perpetrators of domestic violence.

Research indicates that perpetrators of domestic violence have abnormalities in central serotonin and testosterone metabolism, an increased sensitivity to anxiogenic stimuli, and an impaired neuro-connection between their cortex and the amygdala. Clinical evaluations show that perpetrators of domestic violence also have a distinguishing set of behaviors and diagnoses related to anxiety, depression, intermittent explosive disorder, and borderline personality disorder. In this paper we propose a model to understand how the biological abnormalities can potentially explain the behaviors and diagnoses exhibited by the perpetrators. Changes in the perpetrator's neurotransmitters lead to a heightened sensitivity to environmental stimuli, anxiety, and conditioned fear. Lack of cortical input to the amygdala impairs the perpetrator's ability to extinguish anxiety and/or conditioned fear and gives rise to either innate behaviors (e.g., fight, flight, and shut down) or learned fear avoidant behaviors designed to avoid anxiety (e.g., alcohol consumption, self-injurious acts, and obsessive behaviors). Linking conditioned fear and fear avoidance to the behaviors and psychiatric diagnoses will serve to change the way the medical community perceives and treats perpetrators of domestic violence.

Behavior↗

PubMed2006

Single subject image analysis using the complex general linear model--an application to functional magnetic resonance imaging with multiple inputs.

A linear time invariant model is applied to functional fMRI blood flow data. Based on traditional time series analysis, this model assumes that the fMRI stochastic output sequence can be determined by a constant plus a linear filter (hemodynamic response function) of several fixed deterministic inputs and an error term assumed stationary with zero mean. The input function consists of multiple exponential distributed (time delay between images) visual stimuli consisting of negative and erotic images. No a priori assumptions are made about the hemodynamic response function that, in essence, is calculated at each spatial position from the data. The sampling rate for the experiment is 400 ms in order to allow for filtering out higher frequencies associated with the cardiac rate. Since the statistical analysis is carried out in the Fourier domain, temporal correlation problems associated with inference in the time domain are avoided. This formal model easily lends itself to further development based on previously developed statistical techniques.

Adult↗

PubMed2004

A select group of perpetrators of domestic violence: evidence of decreased metabolism in the right hypothalamus and reduced relationships between cortical/subcortical brain structures in position emission tomography.

In an earlier study, we reported that some perpetrators of domestic violence evidenced exaggerated fear-related responses to the panicogenic agent sodium lactate. In the current study, we employed positron emission tomography (PET) to investigate our hypothesis that there are differences in the neural structures and/or pathways that mediate and control the expression of fear-induced aggression in perpetrators of domestic violence. Regional cerebral glucose metabolism was measured in eight male perpetrators of domestic violence who fulfilled DSM-III-R criteria for alcohol dependence (DV-ALC), 11 male participants who fulfilled DSM-III-R criteria for alcohol dependence and had no history of interpersonal aggression (ALC) and 10 healthy male participants who did not fulfill criteria for any DSM-III-R axis I diagnosis and had no history of interpersonal aggression (HCS). DV-ALC had a significantly lower mean glucose uptake in the right hypothalamus compared to ALC and HCS. Correlations were performed between measures of glucose utilization in the brain structures involved in fear-induced aggression. The comparison of DV-ALC to HCS and to ALC differed in six and seven comparisons, respectively, involving various cortical and subcortical structures. HCS and ALC differed between the left thalamus and the left posterior orbitofrontal cortex. These PET findings show that some perpetrators of domestic violence differ from control participants in showing lower metabolism in the right hypothalamus and decreased correlations between cortical and subcortical brain structures. A possible psychological covariate of these changes in regional activity might be fear-induced aggression, but this hypothesis should be examined in larger study groups that undergo provocation during imaging.

Adult↗

PubMed2003

CSF monoamine metabolites and MRI brain volumes in alcohol dependence.

Correlations between cerebrospinal fluid (CSF) concentrations of monoamine metabolites (MAM) and brain structure have been described in schizophrenia, but not in alcoholism. To investigate the relationship between monoaminergic transmission and brain structure in alcoholism, the metabolites of dopamine (homovanillic acid, HVA), norepinephrenine (3-methoxy-4-hydroxyphenylethyleneglycol, MHPG) and serotonin (5-hydroxyindoleacetic acid, 5-HIAA) were measured in lumbar CSF in 54 alcohol-dependent patients and 20 healthy subjects. The volumes of the cerebrum, total grey and white matter, total and ventricular CSF, left and right hippocampus, and corpus callosum area were measured with MRI. MHPG and age were positively correlated in alcoholic women. The MAM concentrations were not significantly correlated with the MRI volumes in the subject categories. There were no differences in MAM across subjects defined by diagnosis and gender, age of onset of alcoholism or comorbidity of psychiatric disorders. Total CSF, cerebrum, and white and grey matter tissue volumes differed between patients and healthy subjects. The greatest difference was the white matter reduction in alcoholic women. In alcoholic women and men, monoaminergic neurotransmission measured by the CSF MAM HVA, MHPG, and 5-HIAA is not significantly correlated with the size of different brain structures.

Adult↗

PubMed2002

Distinct molecular basis for differential sensitivity of the serotonin type 3A receptor to ethanol in the absence and presence of agonist.

Ethanol can potentiate serotonin type 3 (5-HT(3)) receptor-mediated responses in various neurons and in cells expressing 5-HT(3A) receptors. However, the molecular basis for alcohol modulation of 5-HT(3) receptor function has not been determined. Here we report that point mutations of the arginine at amino acid 222 in the N-terminal domain of the 5-HT(3A) receptor can alter the EC(50) value of the 5-HT concentration-response curve. Some point mutations at amino acid 222 resulted in spontaneous opening of the 5-HT(3A) receptor channel and an inward current activated by ethanol in the absence of agonist. Among these mutant receptors, the amplitude of the current activated by ethanol in the absence of agonist was correlated with the amplitude of the current resulting from spontaneous channel openings, suggesting that the sensitivity of the receptor to ethanol in the absence of agonist is, at least in part, dependent on the preexisting conformational equilibrium of the receptor protein. On the other hand, point mutations that conferred greater sensitivity to ethanol potentiation of agonist-activated responses were less sensitive or insensitive to ethanol in the absence of agonist. For these receptors, the magnitude of the potentiation of agonist-activated responses by ethanol was inversely correlated with the EC(50) values of the 5-HT concentration-response curves, suggesting that these mutations may modulate ethanol sensitivity of the receptor by altering the EC(50) value of the receptor. Thus, distinct molecular processes may determine the sensitivity of 5-HT(3A) receptors to ethanol in the absence and presence of agonist.

Amino Acid Sequence↗