Papers by RENATO TEODORO RAMOS
Focusing in experimental study of human behavior, this article discusses the concepts of informat... more Focusing in experimental study of human behavior, this article discusses the concepts of information and mental representation aiming the integration of their biological, computational, and semantic aspects. Assuming that the objective of any communication process is ultimately to modify the receiver’s state, the term correlational information is proposed as a measure of how changes occurring in external world correlate with changes occurring inside an individual. Mental representations are conceptualized as a special case of information processing in which correlational information is received, recorded, but also modified by a complex emergent process of associating new elements. In humans, the acquisition of information and creation of mental representations occurs in a two-step process. First, a sufficiently complex brain structure is necessary to establishing internal states capable to co-vary with external events. Second, the validity or meaning of these representations must be gradually achieved by confronting them with the environment. This contextualization can be considered as part of the process of ascribing meaning to information and representations. The hypothesis introduced here is that the sophisticated psychological constructs classically associated with the concept of mental representation are essentially of the same nature of simple interactive behaviors. The capacity of generating elaborated mental phenomena like beliefs and desires emerges gradually during evolution and, in a given individual, by learning and social interaction.
International Journal of Psychophysiology, 2007
In this study, we analyzed the EEG oscillatory activity induced during a simple visual task, in s... more In this study, we analyzed the EEG oscillatory activity induced during a simple visual task, in search of spectral correlate(s) of attention. This task has been previously analyzed by conventional event-related potential (ERP) computation, and Slow Potentials (SPs) were seen to be highly variable across subjects in topography and generators [Basile LF, Brunetti EP, Pereira JF Jr, Ballester G, Amaro E Jr, Anghinah R, Ribeiro P, Piedade R, Gattaz WF. (2006) Complex slow potential generators in a simplified attention paradigm. Int J Psychophysiol. 61(2):149-57]. We obtained 124-channel EEG recordings from 12 individuals and computed latency-corrected peak averaging in oscillatory bursts. We used currentdensity reconstruction to model the generators of attention-related activity that would not be seen in ERPs, which are restricted to stimulus-locked activity. We intended to compare a possibly found spectral correlate of attention, in topographic variability, with stimulus-related activity. The main results were (1) the detection of two bands of attention-induced beta range oscillations (around 25 and 21 Hz), whose scalp topography and current density cortical distribution were complex multi-focal, and highly variable across subjects (topographic dispersion significantly higher than sensory-related visual theta induced band-power), including prefrontal and posterior cortical areas. Most interesting, however, was the observation that (2) the generators of task-induced oscillations are largely the same individual-specific sets of cortical areas active during the pre-stimulus baseline. We concluded that attention-related electrical cortical activity is highly individual-specific, and possibly, to a great extent already established during mere resting wakefulness. We discuss the critical implications of those results, in combination with results from other methods that present individual data, to functional mapping of cortical association areas.
Case Series: Increased Vulnerability to Obsessive-Compulsive Symptoms With Repeated Episodes of Sydenham Chorea
Journal of The American Academy of Child and Adolescent Psychiatry, 1999
The association between obsessive-compulsive symptoms (OCS) and Sydenham chorea (SC) supports the... more The association between obsessive-compulsive symptoms (OCS) and Sydenham chorea (SC) supports the hypothesis of a common neuroimmunological dysfunction in basal ganglia associated with group A beta-hemolytic streptococcal infection underlying both conditions. Four children with 2 distinct SC episodes were evaluated to assess the course of OCS. All patients developed OCS during their second episodes (3 met criteria for obsessive-compulsive disorder [OCD]), but not in their first episodes (2 developed OCS and met criteria for OCD). These data suggest that the recurrence of SC episodes may result in a cumulative effect, thus increasing the risk of appearance and intensification of OCS.
Serum levels of clomipramine and desmethylclomipramine and clinical improvement in panic disorder
Journal of Psychopharmacology, 1999
Several placebo-controlled trials have shown the efficacy of clomipramine (CMI) in panic disorder... more Several placebo-controlled trials have shown the efficacy of clomipramine (CMI) in panic disorder. However, none has investigated the relationship between CMI, and desmethylclomipramine (DCMI) plasma levels, and outcome. In this trial, 41 patients meeting the DSM-III-R criteria for panic disorder with/without agoraphobia received 50-200 mg of CMI daily in a single-blind, flexible dose regimen for 14 weeks. At the end of treatment, 97% of the patients were free of panic attacks. Patients were classified into two groups of improvement according to the panic symptom items of the 'Patient-Rated Anxiety Scale'. A repeated-measures analysis of variance suggested a significant association between outcome and serum DCMI level/daily dose ratio as well as total serum level/daily dose. Patients with intense improvement showed DCMI and total serum levels lower than those with moderate improvement. The results indicate the importance of monitoring clomipramine and desmethylclomipramine serum levels in this disorder.
Clomipramine and initial worsening in panic disorder: beyond the 'jitteriness syndrome
Journal of Psychopharmacology, 1993
The time course and the phenomenology of the initial response to clomipramine (10-20 mg/day) was ... more The time course and the phenomenology of the initial response to clomipramine (10-20 mg/day) was investigated in 70 patients with panic disorder with or without agoraphobia. Nineteen (27.1%) patients reported worsening of their clinical state which, on average, began 28 h after the first dose and lasted for 5 days. Increase in the frequency and severity of panic attacks was the most frequent finding (14 patients), followed by psycho- stimulant (jitteriness; n=9), depressive (n=8) and tonic anxiety symptoms (n=7). This pattern of initial worsening is different from the 'jitteriness syndrome' described for other antidepressants. Its implications for the understanding of the pathophysiology of panic disorder are discussed.
Journal of Psychopharmacology, 1993
The present reference drugs for the treatment of panic disorder and agoraphobia are imipramine an... more The present reference drugs for the treatment of panic disorder and agoraphobia are imipramine and alprazolam. The latter decreases performance and cognitive functioning. No study of such functions in panic/agoraphobia is available. Fifty four out-patients meeting DSM-III-R criteria for panic disorder with or without agoraphobia (PAG), taking part in a parallel groups controlled trial of imipramine (mean dose ±SEM 114±9 mg), clomipramine (50±4 mg) and propanteline (active placebo) over 8 weeks, were studied. A test battery of psychomotor and memory tests was administered at baseline, and after 1, 4 and 8 weeks of treatment. Their results were compared (at baseline and at the end of the trial) with those of a control group of 57 normal untreated subjects. There was no difference between treatments, and no drug effect on any test at any time. No consistent difference between patients and controls was detected. Given its apparently higher potency, and the absence of deleterious effects on cognitive measures known to be affected by benzodiazepines, we conclude that clomipramine is better than imipramine or alprazolam as a reference drug for panic/agoraphobia.
Journal of Psychopharmacology, 2001
Journal of Psychiatric Research, 2002
Little is known about the intracellular mechanisms involved in the pathophysiology of panic disor... more Little is known about the intracellular mechanisms involved in the pathophysiology of panic disorder (PD). Abnormalities in the cyclic AMP system have been described in several psychiatric disorders but there are no studies in panic patients. We evaluated not only the levels of platelet cyclic AMP, but also cyclic GMP and nitric oxide synthase (NOS) activity in patients with PD at baseline and after treatment with clomipramine and in healthy volunteers. Platelet cyclic AMP was determined by enzymeimmunoassay, cyclic GMP by radioimmunoassay and NOS activity by the conversion of 3 H-arginine to 3 H-citruline in 17 PD patients before treatment with clomipramine, after remission of panic attacks and in 22 healthy volunteers. Average baseline cyclic AMP of PD patients was lower than after remission of panic attacks (P <0.005) and lower than in healthy volunteers (P< 0.005). Average cyclic AMP after remission of panic attacks was not significantly different than in healthy volunteers. There were no significant differences in cyclic GMP and NOS analysis. Our results suggest that PD patients without treatment have lower platelets cyclic AMP levels than healthy volunteers and that this decrease may be corrected by clomipramine. #
American Journal of Psychiatry, 2005
Objective: Converging evidence implicates prefrontal circuits in the pathophysiology of bipolar d... more Objective: Converging evidence implicates prefrontal circuits in the pathophysiology of bipolar disorder. Proton spectroscopy studies performed in adult bipolar patients assessing prefrontal regions have suggested decreased levels of N -acetylaspartate (NAA), a putative marker of neuronal integrity. In order to examine whether such abnormalities would also be found in younger patients, a 1 H spectroscopy study was conducted that focused on the dorsolateral prefrontal cortex of children and adolescents with bipolar disorder.
Acta Psychiatrica Scandinavica, 2005
Obsessive-compulsive symptoms in adults with history of rheumatic fever, Sydenham's chorea and ty... more Obsessive-compulsive symptoms in adults with history of rheumatic fever, Sydenham's chorea and type I diabetes mellitus: preliminary results Asbahr FR, Ramos RT, Costa AN, Sassi RB. Obsessive-compulsive symptoms in adults with history of rheumatic fever, Sydenham's chorea and type I diabetes mellitus: preliminary results. Acta Psychiatr Scand 2005: 111: 159-161. Ó Blackwell Munksgaard 2004.
Journal of Theoretical Biology, 1999
We developed a simple mathematical model based on power law fitting for describing the interactio... more We developed a simple mathematical model based on power law fitting for describing the interactions among patients from a psychiatric ward. First we defined a protocol in order to evaluate in a quantative way the state of the patient, measuring sociability/restlessness through a daily analysis of the behavior and attributing a grade for both parameters, per patient. The grades were checked by two different specialists and a table of incidence was constructed. This table generated power laws for the grades and their variations. We concluded that power laws, like Zipf's law, may be good to explain the data, showing a self-organizing process that indicates a strong interaction component determining the whole behavior. We would like to see more data being collected, in other centers and among normal populations, trying to quantify complex collective behavioral phenomena using self-organizing criticality laws.
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Papers by RENATO TEODORO RAMOS