Browsing by Author "San Martin, Rene"

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    Methodological considerations related to sleep paradigm using event related potentials
    (SOC BIOLGIA CHILE, 2008) Ibanez, Agustin M.; San Martin, Rene; Hurtado, Esteban; Lopez, Vladimir
    In the last few decades, several works on event related potentials (ERPs hereafter) during sleep have been reported. In Spite of numerous Studies, clear methodological rules for this kind Of Study are often missing, making it difficult to valorize the scope of these results. We propose here a description of methodological aspects to be considered when evaluating ERPs during sleep. The use of Rechtschaffen and Kales rules versus automatic methods is assessed, Plus the additional use of certain quantitative rneasures. Additionally, two topics are discussed which Must be controlled in ERPs sleep studies: the First Night Effect, and sleep disturbances. Better control of experimental paradigms is relevant for the growth of (lie neuroscience of sleep.
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    Size and probability of rewards modulate the feedback error-related negativity associated with wins but not losses in a monetarily rewarded gambling task
    (ACADEMIC PRESS INC ELSEVIER SCIENCE, 2010) San Martin, Rene; Manes, Facundo; Hurtado, Esteban; Isla, Pablo; Ibanez, Agustin
    Feedback error-related negativity (fERN) has been referred to as a negative deflection in the event related potential (ERP), which distinguishes between wins and losses in terms of expected and unexpected outcomes. Some studies refer to the "expected outcome" as the probability to win vs. to lose, and others as expected size of rewards. We still do not know much about whether these alternative interpretations of "expected outcome" affect the fERN in a different manner, nor do we know the effect of their interaction in an expected value fashion. We set a gambling task with four game categories; two had the same expected value, while the other two categories were equivalent to the first ones, but alternatively in the size or probability of the offered rewards. Results show that fERN preceded by a P200, and followed by a Pe-like wave differentiates between losing in the category with a higher expected value and the rest of the experimental conditions. fERN differentiates between wins and losses, but changes in the size and probability of rewards impact the fERN amplitude only in win conditions. Results also show greater positivity following win feedback when the size and/or probability of the outcome rewards were higher, so that the higher the expected value the greater the positivity following win feedback. Our findings support the notion that both the probability and size of the offered rewards modulate the motivational value for the win feedback, this being also true for their interaction in an expected value fashion. (C) 2010 Elsevier Inc. All rights reserved.