Percorrer por autor "Santos, Fernando Ferreira"
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- Does attention to cardiac sensations modulate heartbeat-evoked potentials even after controlling for cognitive demands?Publication . Braga, Patrícia Vilela; Vieira, Beatriz; Carina, Fernandes; Barbosa, Fernando; Santos, Fernando Ferreira; Pereira, Mariana R.; Rocha, Nuno Barbosa; Mazer, Prune; Pasion, Rita; Schütz-Bosbach, Simone; Paiva, Tiago Oliveira; Campos, Carlos; Campos, Carlos; Rocha, Nuno; Mazer, PruneHeartbeat-evoked potentials (HEP) have been shown to be modulated by attentional focus (cardiac vs. exteroceptive attention), suggesting that HEP are a neural correlate of interoceptive prediction errors. However, this effect has not been consistently replicated, and differences in cognitive effort when contrasting interoceptive vs. exteroceptive attention may be a confounding factor. We devised a modified Heartbeat Attention Task to examine whether cardiac attention can modulate HEP amplitude even when cognitive demands are matched across interoceptive and exteroceptive conditions. In exteroceptive blocks, subjects were required to count subtle bursts of volume increase embedded within a continuous white noise. The bursts’ volume was individually tailored for each participant (near absolute threshold) and were presented in a rhythmic pattern replicating a typical heart rate. In interoceptive blocks, participants were asked to count their heartbeats, whilst the white noise was still presented, ensuring that the neural effects were driven by the attention shift rather than sensory changes. The task was first completed by 50 participants (25F; 28.44y) during a 9-electrode EEG recording: frontal, central and parietal sites. No significant differences were found regarding counted heartbeats (M=122.00) vs white noise bursts (M=118.86) as well as on perceived attentional efforts (heart M=65.00 vs bursts M=67.00), indicating similar task demands across conditions. No significant differences between conditions were found on HEP amplitude across all electrodes (p > .137 for all), suggesting no attentional modulation of HEP amplitude after accounting for cognitive demands. Due to the reduced number of electrodes, a follow-up sample of 26 participants (13F; 21.73y) completed the task using a new EEG geodesic 64-channel sensor net. This dataset is currently under processing and will allow for a more comprehensive data-driven analytic approach (cluster-based permutation test) to ensure whether the attentional modulation of HEP amplitude is indeed absent when accounting for cognitive demands.
- Task demand effects on Visual and Auditory MMN across autistic and schizotypal traitsPublication . Mazer, Prune; Pasion, Rita; Rao, Zohra Kamran; Silveira, Celeste; Santos, Fernando Ferreira; Mazer, PruneMismatch negativity (MMN) is an event-related potential component automatically elicited by violations of sensory predictions and is widely interpreted, within the Predictive Processing framework, as a neural correlate of prediction error. Disruptions in prediction error signaling have been proposed as a potential mechanism underlying the diverse cognitive and perceptual profiles observed in autism and schizophrenia spectrum conditions. In this study, 122 community participants completed auditory and visual oddball tasks with two levels of target detection difficulty while undergoing EEG recording, alongside self-report measures of autistic and schizotypal traits. We found that increased task difficulty significantly reduced MMN amplitude in both modalities, with large effect sizes for auditory (d = 1.826) and visual (d = 1.005) MMN, indicating robust modulation by perceptual load. Although associations between MMN amplitude and trait dimensions were limited, emerging patterns suggest a potential dissociation between social and non-social autistic traits. These findings address key gaps in the literature, particularly the underrepresentation of visual MMN, and highlight the importance of multidimensional, cross-modal approaches to investigating prediction error mechanisms in neurodiverse populations.