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Biomedical subjects

Erik van den Boogert

Publications and source records attributed to Erik van den Boogert.

2 recordsLinked to original sources

Resistance-based high resolution recording of predefined 2-dimensional pen trajectories in an fMRI setting.

The recent advent of functional magnetic resonance imaging (fMRI) as a readily accessible neuroimaging method has led to exciting new insights into the functioning of the human motor system. However, technical complications related to the fMRI scanner environment often limit the ability to measure the desired behavioral data reflecting the subjects' movements. In order to perform kinematic registrations of predefined complex two-dimensional movement patterns while scanning, a new MR-compatible setup has been developed. The method presented here allows the recording of detailed pen tracing data during concurrent functional image acquisition. Essentially, temporally high resolved resistance measurements are used to keep track of the covered distance across time, as applied here to the tracing of various mazes. In this way, the current setup adds the close monitoring of continuous tracing movements to the spectrum of behavioral data which can be successfully obtained in an fMRI setting.

Algorithms↗

Human cortical object recognition from a visual motion flowfield.

Moving dots can evoke a percept of the spatial structure of a three-dimensional object in the absence of other visual cues. This phenomenon, called structure from motion (SFM), suggests that the motion flowfield represented in the dorsal stream can form the basis of object recognition performed in the ventral stream. SFM processing is likely to contribute to object perception whenever there is relative motion between the observer and the object viewed. Here we investigate the motion flowfield component of object recognition with functional magnetic resonance imaging. Our SFM stimuli encoded face surfaces and random three-dimensional control shapes with matched curvature properties. We used two different types of an SFM stimulus with the dots either fixed to the surface of the object or moving on it. Despite the radically different encoding of surface structure in the two types of SFM, both elicited strong surface percepts and involved the same network of cortical regions. From early visual areas, this network extends dorsally into the human motion complex and parietal regions and ventrally into object-related cortex. The SFM stimuli elicited a face-selective response in the fusiform face area. The human motion complex appears to have a central role in SFM object recognition, not merely representing the motion flowfield but also the surface structure of the motion-defined object. The motion complex and a region in the intraparietal sulcus reflected the motion state of the SFM-implicit object, responding more strongly when the implicit object was in motion than when it was stationary.

Adult↗