Biomedical subjects

Hendrik Peuskens

Publications and source records attributed to Hendrik Peuskens.

4 recordsLinked to original sources

PubMed2005

Oral glucose tolerance tests in treated patients with schizophrenia. Data to support an adaptation of the proposed guidelines for monitoring of patients on second generation antipsychotics?

OBJECTIVE: A recent consensus conference has proposed guidelines for the monitoring for diabetes in patients with schizophrenia and also identifies the need of long-term prospective studies. METHOD: A large scale prospective study on metabolic risks of antipsychotic medication is currently ongoing. At baseline, patients get a full laboratory screening, ECG and an oral glucose tolerance test (OGTT). Baseline data on 100 non-diabetic patients at study inclusion and stable on medication for at least 6 months are presented. RESULTS: Glucose abnormalities are found in 22% of patients at baseline. A monitoring protocol based only on fasting glucose would not have detected 63.6% of these patients with classifiable glucose abnormalities in our sample. Fasting insulin and measures for insulin resistance have a high predictive value for abnormalities late in the OGTT. CONCLUSION: Already at baseline, metabolic problems are frequently present in patients with schizophrenia treated with antipsychotics. Adding assessment of fasting insulin in a monitoring protocol improves detection of glucose abnormalities late in an OGTT.

Adult↗

PubMed2004

The processing of visual shape in the cerebral cortex of human and nonhuman primates: a functional magnetic resonance imaging study.

We compared neural substrates of two-dimensional shape processing in human and nonhuman primates using functional magnetic resonance (MR) imaging in awake subjects. The comparison of MR activity evoked by viewing intact and scrambled images of objects revealed shape-sensitive regions in occipital, temporal, and parietal cortex of both humans and macaques. Intraparietal cortex in monkeys was relatively more two-dimensional shape sensitive than that of humans. In both species, there was an interaction between scrambling and type of stimuli (grayscale images and drawings), but the effect of stimulus type was much stronger in monkeys than in humans. Shape- and motion-sensitive regions overlapped to some degree. However, this overlap was much more marked in humans than in monkeys. The shape-sensitive regions can be used to constrain the warping of monkey to human cortex and suggest a large expansion of lateral parietal and superior temporal cortex in humans compared with monkeys.

Adult↗

PubMed2004

Attention to 3-D shape, 3-D motion, and texture in 3-D structure from motion displays.

We used fMRI to directly compare the neural substrates of three-dimensional (3-D) shape and motion processing for realistic textured objects rotating in depth. Subjects made judgments about several different attributes of these objects, including 3-D shape, the 3-D motion, and the scale of surface texture. For all of these tasks, we equated visual input, motor output, and task difficulty, and we controlled for differences in spatial attention. Judgments about 3-D shape from motion involve both parietal and occipito-temporal regions. The processing of 3-D shape is associated with the analysis of 3-D motion in parietal regions and the analysis of surface texture in occipito-temporal regions, which is consistent with the different behavioral roles that are typically attributed to the dorsal and ventral processing streams.

Adult↗

PubMed2003

Similarities and differences in motion processing between the human and macaque brain: evidence from fMRI.

The present report reviews a series of functional magnetic resonance imaging (fMRI) activation studies conducted in parallel in awake monkeys and humans using the same motion stimuli in both species. These studies reveal that motion stimuli engage largely similar cortical regions in the two species. These common regions include MT/V5 and its satellites, of which FST contributes more to the human motion complex than is generally assumed in human imaging. These results also establish a direct link between selectivity of MT/V5 neurons for speed gradients and functional activation of human MT/V5 by three-dimensional (3D) structure from motion stimuli. On the other hand, striking functional differences also emerged: in humans V3A and several regions in the intraparietal sulcus (IPS) are much more motion sensitive than their simian counterparts.

Adult↗