Biomedical subjects

C de Labra

Publications and source records attributed to C de Labra.

3 recordsLinked to original sources

PubMed2001

Electrical activity in primary visual area due to interocular suppression.

Under binocular rivalry conditions, evoked potentials to lower hemifield stimulation are more positive for the dominant than for the suppressed eye between 100 and 300 ms. However, this pattern reverses when the upper hemifield is stimulated, suggesting a neural source in V1 for this endogenous potential (rivalry-related potential, RRP). Here we investigated the functional significance of the RRP using an interocular suppression procedure. We replicated the RRP polarity reversal for upper versus lower hemifield stimulation and showed that the RRP reflects differences in processing during dominance and suppression and not shifts in dominance.

Adult↗

PubMed2000

Psychophysiological studies of unattended information processing.

The article describes the general methods and some of the results obtained in the Psychophysiology Laboratory of the University of La Coruña. The paper covers our research on the Simon effect and accessory effect, although it is not a review of the literature. The research strategy we followed is built around the use of lateralized motor potentials recorded from scalp. These measures allow observing the way responses are selected and when they are selected, providing an invaluable tool to study response interference and to split reaction time into two halves. The research on the Simon effect concludes that interference during response selection is critical in the Simon effect but it is dubious whether this process should be considered as automatic and stimulus-driven, as is widely accepted. The experiments with the accessory effect indicate that facilitation is produced before response selection is over, which ends a long controversy about the locus of the accessory effect.

Contingent Negative Variation↗

PubMed1999

Early visual processing during binocular rivalry studied with visual evoked potentials.

Visual evoked potentials (VEPs) were recorded to probes presented to the dominant and suppressed eyes in a binocular rivalry paradigm. Probes presented to the suppressed eye interrupted the current dominance phase and produced a P300-like deflection (400-700 ms). Probes delivered to the dominant eye increased the duration of the current dominance phase. VEPs to these probes included an endogenous component that overlapped the early exogenous components. The early endogenous component (rivalry-related potential, RRP) started as early as 70 ms and had a broad centroparietooccipital distribution.

Adult↗