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Biomedical subjects

F Mercado

Publications and source records attributed to F Mercado.

9 recordsLinked to original sources
PubMed2001

Emotion and attention interaction studied through event-related potentials.

Several studies on hemodynamic brain activity indicate that emotional visual stimuli elicit greater activation than neutral stimuli in attention-related areas such as the anterior cingulate cortex (ACC) and the visual association cortex (VAC). In order to explore the temporo-spatial characteristics of the interaction between attention and emotion, two processes characterized by involving short and rapid phases, event-related potentials (ERPs) were measured in 29 subjects using a 60-electrode array and the LORETA source localization software. A cue/target paradigm was employed in order to investigate both expectancy-related and input processing-related attention. Four categories of stimuli were presented to subjects: positive arousing, negative arousing, relaxing, and neutral. Three attention-related components were finally analyzed: N280pre (from pretarget ERPs), P200post and P340post (both from posttarget ERPs). N280pre had a prefrontal focus (ACC and/or medial prefrontal cortex) and presented significantly lower amplitudes in response to cues announcing negative targets. This result suggests a greater capacity of nonaversive stimuli to generate expectancy-related attention. P200post and P340post were both elicited in the VAC, and showed their highest amplitudes in response to negative- and to positive-arousing stimuli, respectively. The origin of P200post appears to be located dorsally with respect to the clear ventral-stream origin of P340post. The conjunction of temporal and spatial characteristics of P200post and P340post leads to the deduction that input processing-related attention associated with emotional visual stimulation involves an initial, rapid, and brief "early" attentional response oriented to rapid motor action, being more prominent towards negative stimulation. This is followed by a slower but longer "late" attentional response oriented to deeper processing, elicited to a greater extent by appetitive stimulation.

Adult↗
PubMed2001

Emotion, attention, and the 'negativity bias', studied through event-related potentials.

Behavioral studies indicate that there exists a 'negativity bias' in the way surrounding events are processed. Particularly, it has been indicated that negative events elicit more rapid and more prominent responses than non-negative events. The objective of the present study was to explore the role of attention in relation to this negativity bias. Three groups of emotional pictures were used as stimuli: positive, negative and neutral. Event-related potentials were recorded from 35 subjects at F5, Fz, F6, C5, Cz, C6, P5, Pz and P6. Valence and arousal content of the stimulation was measured via a questionnaire. The experimental design ensured that subjects whose data were finally analyzed attended to the stimuli. ANOVAs showed that P200, an attention-related component, showed higher amplitudes and shorter latencies in response to negative stimuli than in response to positive stimuli. Additional partial correlation analyses indicated that P200 amplitude, but not latency, significantly associates (at frontal and central sites) with valence content of the stimulation. Therefore, due to the valence-related nature of the bias, it is concluded that intensity aspects (more than timing aspects) of the P200-related attentional processes are particularly involved in the negativity bias.

Adult↗
PubMed2000

Is there a relationship between rheumatoid arthritis and periodontal disease?

AIM: The aim of this study was to determine whether there is a relationship between disease experience of rheumatoid arthritis and periodontal disease. METHODS: 1,412 individuals attending the University of Queensland's School of Dentistry were assessed for the prevalence of periodontal disease and rheumatoid arthritis. Analysis of data obtained from a self-reported health questionnaire and dental records was carried out and included: number of individuals referred for advanced periodontal care (test group); number of individuals attending for routine dentistry; determination of rheumatoid arthritis, cardiovascular disease and diabetes mellitus through self-reporting and assessment of prescription medications; assessment of periodontal disease through assessment of existing oral radiographs. RESULTS: In patients referred for periodontal treatment, the prevalence of self-reported rheumatoid arthritis was 3.95% which is significantly higher than that seen in patients not referred for periodontal treatment (0.66%) and also that reported in the general population (1%). Of those referred patients with rheumatoid arthritis, 62.5% had advanced forms of periodontal disease. These results were mirrored in the results of the self-reported prevalence of cardiovascular disease and diabetes mellitus which was consistent with the published higher prevalence in periodontal patients. CONCLUSIONS: Based on data derived from self-reported health conditions, and not withstanding the limitations of such a study, we conclude that there is good evidence to suggest that individuals with moderate to severe periodontal disease are at higher risk of suffering from rheumatoid arthritis and vice versa.

Adult↗
PubMed1988

Phytophotodermatitis mimicking jellyfish envenomation.

Two cases of citrus juice phytophotodermatoses with long hyperpigmented macular lesions are reported. These lesions simulated those resulting from jellyfish envenomation. The diagnosis can be established by the lack of local pain or signs of envenomation, and the absence of a serological response to jellyfish venom.

Adolescent↗
PubMed1979

Cold reactive antilymphocyte antibodies in neurological diseases.

Cold reactive (15 degrees C) antilymphocyte antibodies were detected in the sera of 33% of patients with multiple sclerosis, 50% with Guillain-Barré syndrome, 42% with myasthenia gravis, and 38% with polymyositis. We did not detect such antibodies against autologous cells in multiple sclerosis. In multiple sclerosis there was no correlation between the presence of antilymphocytic antibodies and disease activity or duration. In patients with multiple sclerosis, myasthenia gravis, and polymyositis there was no correlation between the presence of cold reactive antilymphocyte antibodies and abnormalities of T or B cell levels.

Antilymphocyte Serum↗
PubMedDate not supplied

[Human brain activity in response to emotional visual stimuli: open issues and recent data].

INTRODUCTION: The traditional circumplex model on the structure of emotion postulates that this process is organized in two basic dimensions: valence (positive negative) and activation (relaxing activating). This model assumes that the valence activates a single evaluative system. With regard to cerebral activity, two ideas are derived from this assumption: 1) a single set of mechanisms and neural circuits becomes activated in response to both positive and negative events, 2) the faculty of response to adverse and pleasant responses (i.e., latency and intensity with which the neural structures involved can respond) is potentially balanced. DEVELOPMENT: We describe the debates on these two issues and, subsequently, the current data regarding them are also described. These data indicate that, in response to aversive stimuli (often noxious), neural systems characterized by their ability to produce an immediate response are preferentially activated. On the other hand, pleasant stimuli (which lead to an approaching behavior towards the stimulus) preferentially activate systems associated with more intense and precise information processing. This is a slower but longer lasting type of activity. CONCLUSION: The data suggest that there are separate mechanisms for the evaluation and preparation of a response according to whether the stimulus is negative or positive.

Affect↗
PubMedDate not supplied

[Ion channels that are sensitive to the extracellular concentration of protons: their structure, function, pharmacology and pathophysiology].

AIM: Acid sensing ion channels (ASIC) members of the ENaC degenerine channel family, have been shown to participate in various sensorial pathways including nociception, also they have been shown to participate in synaptic transmission, learning and memory processes and in the physiopathology of the ischemic stroke. DEVELOPMENT: The proton concentration in the organism is strictly regulated by distinct buffer systems. Drastic changes of pH are generated only by pathological conditions as is the ischemia; however, some physiological processes may produce local changes in the extracellular pH. Recently, a new family of proton receptors known as ASIC has been cloned. These are ionic channels inactivated at physiological pH (7.4) and activated with a pH fall (increase in H+ concentration). ASICs are permeable to sodium ions and in a lesser degree to calcium ions, activation of these channels leads to an increase in cell excitability. The ASICs are distributed widely in the central and peripheral nervous system, and in specialized epithelia. In the past few years they have become a focus of interest due to its role in nociception, taste perception, long term potentation and the physiopathology of ischemic stroke. CONCLUSIONS: In this review we address the most relevant molecular, physiological and pharmacological aspects of the ASICs, its participation in some pathological process, and the perspectives of basic and clinic investigation in this arising research field.

Acid Sensing Ion Channels↗