The Role of Unimodal Feedback Pathways in Gender Perception During Activation of Voice and Face Areas.

Cross-modal effects provide a model framework for investigating hierarchical inter-areal processing, particularly, under conditions where unimodal cortical areas receive contextual feedback from other modalities. Here, using complementary behavioral and brain imaging techniques, we investigated the functional networks participating in face and voice processing during gender perception, a high-level feature of voice and face perception. Within the framework of a signal detection decision model, Maximum likelihood conjoint measurement (MLCM) was used to estimate the contributions of the face and voice to gender comparisons between pairs of audio-visual stimuli in which the face and voice were independently modulated.

Neural circuits for long-range color filling-in.

Surface color appearance depends on both local surface chromaticity and global context. How are these inter-dependencies supported by cortical networks? Combining functional imaging and psychophysics, we examined if color from long-range filling-in engages distinct pathways from responses caused by a field of uniform chromaticity. We find that color from filling-in is best classified and best correlated with appearance by two dorsal areas, V3A and V3B/KO.

Increasing Attentional Load Boosts Saccadic Adaptation.

Purpose: Visual exploration relies on saccadic eye movements and attention processes. Saccadic adaptation mechanisms, which calibrate the oculomotor commands to continuously maintain the accuracy of saccades, have been suggested to act at downstream (motor) and upstream (visuoattentional) levels of visuomotor transformation. Conversely, whether attention can directly affect saccadic adaptation remains unknown.

Contributions of contour frequency, amplitude, and luminance to the watercolor effect estimated by conjoint measurement.

The watercolor effect is a long-range, assimilative, filling-in phenomenon induced by a pair of distant, wavy contours of different chromaticities. Here, we measured joint influences of the contour frequency and amplitude and the luminance of the interior contour on the strength of the effect. Contour pairs, each enclosing a circular region, were presented with two of the dimensions varying independently across trials (luminance/frequency, luminance/amplitude, frequency/amplitude) in a conjoint measurement paradigm (Luce & Tukey, 1964).

Spatial selectivity of the watercolor effect.

The spatial selectivity of the watercolor effect (WCE) was assessed by measuring its strength as a function of the luminance contrast of its inducing contours for different spatial configurations, using a maximum likelihood scaling procedure. The approach has previously been demonstrated to provide an efficient method for investigating the WCE as well as other perceptual dimensions. We show that the strength is narrowly tuned to the width of the contour, that it is optimal when its pair of inducing contours are of equal width, and that the strength can be increased by varying the overall size of the stimulus when the width of the inducing contour is not optimal.

A role for the parietal cortex in sensorimotor adaptation of saccades.

Sensorimotor adaptation ensures movement accuracy despite continuously changing environment and body. Adaptation of saccadic eye movements is a classical model of sensorimotor adaptation. Beside the well-established role of the brainstem-cerebellum in the adaptation of reactive saccades (RSs), the cerebral cortex has been suggested to be involved in the adaptation of voluntary saccades (VSs).

Functional activation of the cerebral cortex related to sensorimotor adaptation of reactive and voluntary saccades.

Potentially dangerous events in the environment evoke automatic ocular responses, called reactive saccades. Adaptation processes, which maintain saccade accuracy against various events (e.g.

Integration of visual information for saccade production.

To foveate a visual target, subjects usually execute a primary hypometric saccade (S1) bringing the target in perifoveal vision, followed by a corrective saccade (S2) or by more than one S2. It is still debated to what extent these S2 are pre-programmed or dependent only on post-saccadic retinal error. To answer this question, we used a visually-triggered saccade task in which target position and target visibility were manipulated.

Prior knowledge of illumination for 3D perception in the human brain.

In perceiving 3D shape from ambiguous shading patterns, humans use the prior knowledge that the light is located above their head and slightly to the left. Although this observation has fascinated scientists and artists for a long time, the neural basis of this "light from above left" preference for the interpretation of 3D shape remains largely unexplored. Combining behavioral and functional MRI measurements coupled with multivoxel pattern analysis, we show that activations in early visual areas predict best the light source direction irrespective of the perceived shape, but activations in higher occipitotemporal and parietal areas predict better the perceived 3D shape irrespective of the light direction.

Effects of motion and configural complexity on color transparency perception.

We tested whether motion and configural complexity affect perceived transparency. A series of five coherent chromatic transformations in color space was applied across a figure: translation, convergence, shear, divergence and rotation. The stimuli consisted of a bipartite or a checkerboard configuration (10 x 10 degrees), with a central static or moving overlay (5 x 5 degrees).