Browsing by Author "Bacigalupo, Felix"

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    Alpha-band EEG suppression as a neural marker of sustained attentional engagement to conditioned threat stimuli
    (2022) Bacigalupo, Felix; Luck, Steven J.
    Attention helps us to be aware of the external world, and this may be especially important when a threat stimulus predicts an aversive outcome. Electroencephalogram (EEG) alpha-band suppression has long been considered as a neural signature of attentional engagement. The present study was designed to test whether attentional engagement, as indexed by alpha-band suppression, is increased in a sustained manner following a conditioned stimulus (CS) that is paired with an aversive (CS+) vs neutral (CS-) outcome. We tested 70 healthy young adults in aversive conditioning and extinction paradigms. One of three colored circles served as the CS+, which was paired in 50% of the trials with a noise burst (unconditioned stimulus, US). The other colored circles (CS-) were never paired with the US. For conditioning, we found greater alpha-band suppression for the CS+ compared to the CS-; this suppression was sustained through the time of the predicted US. This effect was significantly reduced for extinction. These results indicate that conditioned threat stimuli trigger an increase in attentional engagement as subjects monitor the environment for the predicted aversive stimulus. Moreover, this alpha-band suppression effect may be valuable for future studies examining normal or pathological increases in attentional monitoring following threat stimuli.
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    The debate about death: an imperishable discussion?
    (SOC BIOLGIA CHILE, 2007) Bacigalupo, Felix; Huerta, Daniela; Montefusco Siegmund, Rodrigo
    In this concise review we discuss some of the complex edges of the concept of death that arose after the notorious advances in science and medicine over the last 50 years, in which the classical cardio-pulmonary criteria have led to the neurological criteria of death. New complicated questions like the definition of death and the operational criteria for diagnosing it have arisen and we think that they are far from being adequately and satisfactorily solved. A number of important issues -like the reliability and differences between cardiopulmonary versus brain based criteria of death, if death is an event or a process, the meaning of integration and irreversibility- have not yet received sufficient attention. Here we have approached the death problem from two (biological) complex system perspectives: the organism level and the cellular-molecular level. We also discuss issues from a third systemic approach, that is, the entire society, thus involving legal, religious, bioethical and political aspects of death. Our aim is to integrate new perspectives in order to promote further discussion on these critical yet frequently neglected issues.