Examinando por Autor "Tapia, Manuel"
Mostrando 1 - 4 de 4
- Resultados por página
- Opciones de ordenación
Ítem Cortical response to subjectively unconscious danger(Neuroimage, 2005) Carretié, Luis; Hinojosa, José Antonio; Mercado, Francisco; Tapia, ManuelCortical involvement in the evolution-favored automatic reaction to danger was studied. Electrical neural activity was recorded from 31 subjects, reporting fear of spiders, at 60 scalp locations. Visual stimuli containing spiders (negative elements) or, alternatively, nonnegative elements were presented to subjects, though they were unaware of their presence: a concurrent visual detection task using consciously perceived targets was administered. Spatial and temporal principal component analyses were employed to define and quantify, in a reliable manner, the main components of the neuroelectrical response to unconscious stimuli, and a source localization algorithm provided information on their neural origin. Results indicated that around 150 ms after stimulus onset,ventromedial prefrontal areas previously reported as responding rapidly to danger-related (conscious) stimuli were activated by unconsciously perceived spiders more markedly than by nonnegative unconscious stimuli. Subsequently, around 500 ms after stimulus onset, activation of the posterior cingulate and visual association cortices increased in this same direction. These data support previous results indicating that the ventromedial prefrontal cortex is involved in the topdown regulation of attention (through its capability to modulate the activity of posterior cortices in charge of visual processing) and that it automatically facilitates danger processing.Ítem Incidental encoding of emotional pictures: Affective bias studied through(International journal of psychophysiology, 2008) Tapia, Manuel; Carretié, Luis; Sierra, Benjamín; Mercado, FranciscoEmotional stimuli are better remembered than neutral stimuli. Most of the studies taking into account this emotional bias refer to explicit memory, use behavioral measures of the recall and predict better recall of negative stimuli. The few studies taking into account implicit memory and the valence emotional dimension are inconclusive on the effect of the stimulus' emotional valence. In the present study, 120 pictures (30 positive, 30 negative, 30 relaxing and 30 neutral) were shown to, and assessed by, 28 participants (study phase). Subsequently, event related brain potentials (ERPs) were recorded during the presentation of 120 new (shown for the first time) and 120 old (already shown in the study phase)pictures (test phase). No explicit instructions or clues related to recovery were given to participants, and a distractor task was employed, in order to maintain implicit the memory assessment. As expected from other studies' data, our results showed that old stimuli elicited an enhanced late positive component 450 ms after stimulus onset (repetition effect). Moreover, this effect was modulated by the stimuli's emotional valence, since the most positively valenced stimuli were associated with a decreased repetition effect with respect to the most negatively valenced stimuli. This effect was located at ventromedial prefrontal cortex. These results suggest the existence of a valence-mediated bias in implicit memory.Ítem Neural activity associated with metaphor comprehension: spatial analysis(Neuroscience Letters, 2005) Sotillo, María; Carretié, Luis; Hinojosa, José Antonio; Tapia, Manuel; Mercado, Francisco; López, Sara; Albert, JacoboThough neuropsychological data indicate that the right hemisphere (RH) plays a major role in metaphor processing, other studies suggest that, at least during some phases of this processing, a RHadvantage may not exist. The present study explores, through a temporally agile neural signal¿the event-related potentials (ERPs)¿, and through source-localization algorithms applied to ERP recordings, whether the crucial phase of metaphor comprehension presents or not a RH advantage. Participants (n = 24) were submitted to a S1¿S2 experimental paradigm. S1 consisted of visually presented metaphoric sentences (e.g., ¿Green lung of the city¿), followed by S2, which consisted of words that could (i.e., ¿Park¿) or could not (i.e., ¿Semaphore¿) be defined by S1. ERPs elicited by S2 were analyzed using temporal principal component analysis (tPCA) and source-localization algorithms. These analyses revealed that metaphorically related S2 words showed significantly higher N400 amplitudes than non-related S2 words. Source-localization algorithms showed differential activity between the two S2 conditions in the right middle/superior temporal areas. These results support the existence of an important RH contribution to (at least) one phase of metaphor processing and, furthermore, implicate the temporal cortex with respect to that contribution.Ítem The influence of emotional context on attention in anxious subjects: neurophysiological correlates(Journal of Anxiety Disorders, 2006) Mercado, Francisco; Carretié, Luis; Tapia, Manuel; Gómez-Jarabo, GregorioSeveral studies have shown the influence of threatening context on level of attention to target environmental stimuli. The present experiment explored the possibility that this influence of aversive context is particularly strong in anxious subjects, due to their known attentional bias towards negative information. Event-related potentials, that provide a direct index of attention-related cerebral processing, were recorded in 27 participants selected from a larger sample of 250, as a function of their trait anxiety scores (14 high, 13 low). State anxiety was also measured in selected subjects. Several contexts were presented: positive, negative, relaxing and neutral, and participants were instructed to attend, within these contexts, to a series of auditory stimuli. Threatening context triggered an increase in attention to these auditory stimuli only in conditions of high state anxiety, this increase being reflected in the greater amplitude of the P2 component, which is related to attentional processes. There were no significant differences in relation to trait anxiety. Data show that threatening context and high level of state anxiety in combination increase the quantity of attentional resources directed to the environment.