Biomedical subjects

Elena Betta

Publications and source records attributed to Elena Betta.

5 recordsLinked to original sources

PubMed2006

Microsaccadic response during inhibition of return in a target-target paradigm.

This study examined the relationship between inhibition of return (IOR) in covert orienting and microsaccade statistics. Unlike a previous study [Galfano, G., Betta, E., & Turatto, M. (2004)], IOR was assessed by means of a target-target paradigm, and microsaccade dynamics were monitored as a function of both the first and the second visual event. In line with what has been reported with a cue-target paradigm, a significant directional modulation was observed opposite to the first visual event. Because participants were to respond to any stimulus, this rules out the possibility that the modulation resulted from a generic motor inhibition, showing instead that it is peculiarly coupled to the oculomotor system. Importantly, after the second visual event, a different response was observed in microsaccade orientation, whose direction critically depended of whether the second visual event appeared at the same location as the first visual event. The results are consistent with the notion that IOR is composed of both attentional and oculomotor components, and challenge the view that covert orienting paradigms engage the attentional component in isolation.

Adult↗

PubMed2006

Visual oddballs induce prolonged microsaccadic inhibition.

Eyes never stop moving. Even when asked to maintain the eyes at fixation, the oculomotor system produces small and rapid eye movements called microsaccades, at a frequency of about 1.5-2 s(-1). The frequency of microsaccades changes when a stimulus is presented in the visual field, showing a stereotyped response pattern consisting of an early inhibition of microsaccades followed by a rebound, before the baseline is reached again. Although this pattern of response has generally been considered as a sort of oculomotor reflex, directional biases in microsaccades have been recently linked to the orienting of spatial attention. In the present study, we show for the first time that regardless of any spatial bias, the pattern of absolute microsaccadic frequency is different for oddball stimuli compared to that elicited by standard stimuli. In a visual-oddball task, the oddball stimuli caused an initial prolonged inhibition of microsaccades, particularly when oddballs had to be explicitly recognized and remembered. The present findings suggest that high-order cognitive processes, other than spatial attention, can influence the frequency of microsaccades. Finally, we also introduce a new method for exploring the visual system response to oddball stimuli.

Adult↗

PubMed2006

Are you ready? I can tell by looking at your microsaccades.

The direction of microsaccades has been shown to be biased by the allocation of spatial attention. Here, we investigated whether the cognitive processes involved in preparing to respond to an upcoming target can modulate the microsaccadic response. Specifically, we found that optimal manual response preparation, reflected by faster response times, was associated with a reduction in the absolute frequency of microsaccades. The present results are consistent with previous studies suggesting a relationship between oculomotor activity and different sorts of motor responses. Our findings, however, surprisingly demonstrate that the effect of preparation and stimulus expectation extends to an automatic and unconscious oculomotor activity such as microsaccade execution.

Adult↗

PubMed2004

Inhibition of return in microsaccades.

Inhibition of return (IOR) is the term used to describe the phenomenon whereby stimuli appearing at recently attended locations are reacted to less efficiently than stimuli appearing at locations that have not yet been attended. In the present study, we employed a typical IOR paradigm with peripheral uninformative cues while participants maintained their eyes at fixation. Eye position was monitored at a high sampling rate (500 Hz) in order to detect miniature eye movements called microsaccades, which have been shown to be crucial for avoiding disappearance of visual image. However, recent studies have demonstrated a close relationship between covert endogenous attentional shifts and the direction of microsaccades. Here, we demonstrate that the direction of microsaccades can be biased away from the peripheral location occupied by a salient, although task-irrelevant, visual signal. Because microsaccades are known not to be under conscious control, our results suggest strong links between IOR and unconscious oculomotor programming.

Adult↗

PubMed2004

An EEG-driven brain-computer interface combined with functional magnetic resonance imaging (fMRI).

Self-regulation of slow cortical potentials (SCPs) has been successfully used to prevent epileptic seizures as well as to communicate with completely paralyzed patients. The thought translation device (TTD) is a brain-computer interface (BCI) that was developed for training and application of SCP self-regulation. To investigate the neurophysiological mechanisms of SCP regulation the TTD was combined with functional magnetic resonance imaging (fMRI). The technical aspects and pitfalls of combined fMRI data acquisition and EEG neurofeedback are discussed. First data of SCP feedback during fMRI are presented.

Biofeedback, Psychology↗