The correlation between the degree of psychopathology (assessed by the Minnesota Multiphasic Personality Inventory, MMPI) and sympathetic function (assessed by the skin potential response to ...somatosensory stimuli) was evaluated in 209 patients with affective disorders. A number of skin potential parameters (skin potential levels, negative fluctuations of first derivative of skin potential, negative areas in phase plane analysis, differences between last and initial average potentials and between the last average potential for the preceding stimulus and initial average potentials for a given stimulus) were correlated with the psychopathology index, calculated as the average of clinically relevant MMPI scales. Categorical classification of patients having or not having abnormally high psychopathology index scores also supported the differences in skin potential response between both groups of patients. The results further indicate the existence of a correlation between severity of mood disorders and increased sympathetic reactivity.
Electrodermal responses in the facial region of freely moving rats were recorded bilaterally. After a nociceptive stimulus (ammonia vapor exposure), the response (a transient negative potential ...followed by a longer-lasting positive potential) attained a similar amplitude on both sides. Surgical sympathetic denervation of facial skin by ipsilateral superior cervical ganglionectomy (SCGx) significantly decreased the electrodermal response. When an inferior cervical ganglionectomy was performed in addition to SCGx, a further decrease in electrodermal response was observed. Pretreatment of unilaterally SCGx rats with atropine blunted the electrical response in the control side to levels similar to those found in the SCGx side. Treatment with phenoxybenzamine or propranolol was ineffective. Skin potential responses were measured in adult rats administered with clomipramine from the 8th to the 21st day of life and exhibiting a long-lasting syndrome resembling human depression. Clomipramine-injected rats developed larger skin potential responses to sound stimulation than controls while responses to ammonia vapor were similar in both groups, as well as the habituation rate after repetitive exposure to ammonia vapor. The results indicate that some of the altered electrodermal responses found in depressed patients are detectable in the clomipramine animal model of endogenous depression.
To assess whether the anesthetic and anticonvulsant activities of alphaxalone display diurnal variability, groups of Syrian hamsters were studied at 4 h-intervals during a 24 h-cycle. The ...administration of alphaxalone (5 mg/kg) brought about a greater anesthetic activity (loss of righting reflex) at the middle of the photophase. When assessed in hamsters injected with 3-mercaptopropionic acid, alphaxalone displayed maximal anticonvulsant activity at the 4th of darkness. Evaluation of the time needed for first convulsive response indicated that alphaxalone did not show time-dependent effects, while in control hamsters seizure threshold was low during daylight and attained maximal values at night, showing a peak in seizure threshold at light-dark transition.
Social and environmental factors are known risk factors and modulators of mental health disorders. We here conducted a nonsystematic review of the neuroimaging literature studying the effects of ...poverty, urbanicity, and community violence, highlighting the opportunities of studying non-Western developing societies such as those in Latin America. Social and environmental factors in these communities are widespread and have a large magnitude, as well as an unequal distribution, providing a good opportunity for their characterization. Studying the effect of poverty in these settings could help to explore the brain effect of economic improvements, disentangle the effect of absolute and relative poverty, and characterize the modulating impact of poverty on the underlying biology of mental health disorders. Exploring urbanicity effects in highly unequal cities could help identify the specific factors that modulate this effect as well as examine a possible dose–response effect by studying megacities. Studying brain changes in those living among violence, which is particularly high in places such as Latin America, could help to characterize the interplay between brain predisposition and exposure to violence. Furthermore, exploring the brain in an adverse environment should shed light on the mechanisms underlying resilience. We finally provide examples of two methodological approaches that could contribute to this field, namely a big cohort study in the developing world and a consortium-based meta-analytic approach, and argue about the potential translational value of this research on the development of effective social policies and successful personalized medicine in disadvantaged societies.
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