In two prior studies, we investigated the neural mechanisms of spatial attention using a combined event-related potential (ERP) and positron emission tomography (PET) approach (Heinze et al. [1994]: Nature 392:543–546; Mangun [1997]: Hum Brain Mapp 5:273–279). Neural activations in extrastriate cortex were observed PET measures for attended stimuli, these effects related to attentional modulations ERPs at specific latencies. The present study used functional magnetic resonance imaging (fMRI)...

The present study represents an attempt to find electrophysiological correlate of the redundant targets effect, or RTE (i.e., speeding up reaction time, RT, for vs. single targets). Subjects made a speeded response either one small checkerboard presented left right fixation pair identical checkerboards simultaneously both hemifields. Both and double could appear in upper lower visual hemifield. task required detection but not discrimination stimuli. During performance, we recorded...

Motion information tends to be segregated from color and form in the visual system, both perceptually neuroanatomically, it is therefore possible that different mechanisms of attention are used select targets defined by these feature types during search. To test this hypothesis, we recorded N2pc component event-related potential waveform search tasks with color, orientation, motion targets. The has previously been shown reflect a specific attentional mechanism present for targets, sought...

Abstract The aim of this study was to investigate the neural correlates functional distinction underlying attentional mechanisms endogenous‐sustained and exogenous‐transient spatial selection. We recorded event related potentials (ERPs) used magnetic resonance imaging (fMRI) in separate experiments while subjects performed a simple reaction time (RT) same visual stimulus displayed one several field locations. Endogenous‐sustained or focusing attention onto target location were obtained by...

Abstract To study the electrophysiological correlates of conscious vision, we recorded event-related potentials (ERPs) in a patient with partial unilateral visual extinction as result right-hemisphere damage. When, following bilateral presentations, contralesional stimuli were not perceived, there was an absence early attention-sensitive P1 (80-120 msec) and N1 (140-180 components ERP response. In contrast, or those presentations which perceived (about 60%), these present. These results...

There is substantial evidence that subliminal stimuli, i.e. stimuli cannot be perceived consciously, may influence visually guided human behaviour. Two important points require further investigation, namely, the neural bases and functional capability of unconscious stimulus processing. In this study we aimed at studying one specific aspect latter question, whether vision can feed into an error-monitoring system in much same way as conscious vision. We therefore tested event-related potential...

Abstract In this study we provide evidence that unconscious priming can be obtained as a result of the processing salient region (SR) illusory figures and without contours (ICs). We used metacontrast masking paradigm where were masked by real figures. Experiment 1 found clear effect when participants asked to discriminate between square diamond masks preceded congruent or incongruent primes. It is likely impairs ICs but not SR; therefore above strongly suggests was specifically related SR. 2...

In two prior studies, we investigated the neural mechanisms of spatial attention using a combined event-related potential (ERP) and positron emission tomography (PET) approach (Heinze et al. [1994]: Nature 392:543–546; Mangun [1997]: Hum Brain Mapp 5:273–279). Neural activations in extrastriate cortex were observed PET measures for attended stimuli, these effects related to attentional modulations ERPs at specific latencies. The present study used functional magnetic resonance imaging (fMRI)...

Abstract The goal of this study was to cast light on the existence functional callosal channels for interhemispheric transfer ( IHT ) spatial and semantic information. To do so, we recorded event‐related potentials in healthy humans while performing a primed odd‐even discrimination task. Targets were visually presented numbers preceded by single‐letter primes signaling probable presentation an odd or even number. Primes targets could appear either same different visual fields, thus requiring...

Purpose: To define the evolution patterns of blunt pancreatic trauma, and to point out CT features most significant for diagnosis. Material Methods: Ten cases observed over a period about 10 years, were analyzed in retrospect. The divided into 3 groups according time that had elapsed between trauma first CT: early phase (within 72 h: n=3/10); late (after days: following drainage (n=4/10). Results: In phase, one case showed blood collection surrounding head duodenum, displacing mesenteric...

In the present study, Poggendorff illusion was tested with four types of stimuli: A moving dot, a bar parallel to inducing lines, collinear motion trajectory, and static bars as in classic illusion. Psychometric functions alignment task showed that bar, where orientation trajectory matched, yielded best performance almost eliminating illusion; vertical on contrary, worst alignment, finally dot led intermediate alignments. These results demonstrate interaction between likely takes place...

Detection of elongated objects in the visual scene can be improved by additional elements flanking object on collinear axis. This is context effect (CE) and represented long-range horizontal connection plexus V1. The aim this study was to test whether motion improve CE. In three experiments study, flank presented with different types motion. particular, aligned longitudinal axis to-be-detected object: toward or away from it, orthogonal a direction perpendicular Only target showed robust...

Six ordinary and one Siamese cat were tested for spatial frequency contrast sensitivity flicker discrimination thresholds. The was markedly impaired in the former task but performed normally latter. This result is consistent with single-cell physiological evidence showing an abnormally high Y/X cell ratio area centralis of cats. Under a more general perspective, this genetically related dissociation visual impairments confirms idea parallel pathways subserving temporal resolution,...