Biomedical subjects

Timothy Behrens

Publications and source records attributed to Timothy Behrens.

3 recordsLinked to original sources

PubMed2006

Lesion probability maps of white matter hyperintensities in elderly individuals: results of the Austrian stroke prevention study.

OBJECTIVE: White matter hyperintensities (WMH) are common on brain MRI of the elderly. Their size ranges from punctate to early confluent to confluent lesions. While this increase in extension is frequently seen as evidence for a continuum of changes, histological data and clinical follow-up suggest differences in underlying pathology and their progression. METHODS: We tested this hypothesis by exploring the distributions of punctuate and confluent lesions using lesion probability maps (LPM) generated from MRI scans of 189 participants (mean age 60.8+/-6.2 years) in the Austrian Stroke Prevention Study. We dichotomised WMH according to the classification by Fazekas et al. [punctate (n=143) vs. early confluent and confluent (n=33)] to run voxel-based t-tests using permutation-based nonparametric inference. To test alternative hypotheses, we created similar LPM for age and arterial hypertension. RESULTS: We observed significant differences in the spatial distribution of lesions for the two WMH groups (p<0.01). Punctate lesions were more diffusely distributed throughout the cerebral white matter (peak probability approximately 5%) relative to confluent lesions (peak probability 45%). Confluent lesions had greatest likelihood of being found in perfusion "watershed" regions. These differences in distribution could not be explained by differences in age or hypertension only, as both greater age and the diagnosis of hypertension were associated with WMH abutting the occipital horns. CONCLUSIONS: Punctate and early confluent to confluent WMH show distinguishable differences in their spatial distribution within a normal elderly population. The pattern of punctate WMH is probably a consequence of mixed etiologies. Preferential localization of the more confluent WMH with arterial watershed areas implies a stronger ischemic component in their development.

Age Factors↗

PubMed2004

Keys to unlocking the mysteries of rheumatic autoimmune disease.

Autoimmune diseases are thought to affect between 14 million and 22 million people in this country. Despite decades of research, the underlying mechanisms of disease are poorly understood, diagnosis is often difficult, and therapies that minimize systemic side effects are lacking. Major advances in our understanding of human genetic variation and remarkable new technologies are paving the way for dramatically improving our fundamental knowledge of autoimmune diseases. Gene mapping studies have clearly illustrated the complexity of these diseases, which appear to involve many genes. Very high-throughput microarray assays that can measure the expression levels of thousands of genes simultaneously are revealing important insights into key biological pathways that appear to be perturbed in autoimmune diseases. We review recent advances in genetic and genomic studies, focusing primarily on systemic lupus erythematosus and related rheumatic autoimmune diseases such as Sjögren's syndrome and rheumatoid arthritis. Identification of susceptibility genes and dysregulated biological pathways for these diseases is likely to foster development of novel diagnostic and therapeutic approaches that are increasingly tailored to the underlying pathological mechanisms.

Alleles↗

PubMed2003

Functional asymmetry for auditory processing in human primary auditory cortex.

Structural asymmetries in the supratemporal plane of the human brain are often cited as the anatomical basis for the lateralization of language predominantly to the left hemisphere. However, similar asymmetries are found for structures mediating earlier events in the auditory processing stream, suggesting that functional lateralization may occur even at the level of primary auditory cortex. We tested this hypothesis using functional magnetic resonance imaging to evaluate human auditory cortex responses to monaurally presented tones. Relative to silence, tones presented separately to either ear produced greater activation in left than right Heschl's gyrus, the location of primary auditory cortex. This functional lateralization for primary auditory cortex is distinct from the contralateral dominance reported for other mammals, including nonhuman primates, and may have contributed to the evolution of a unique role for the left hemisphere in language processing.

Adult↗