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We found a high correlation between degree of contrast enhancement on dynamic contrast-enhanced images and rCBV values in whole tumors and in regions having the highest degree of contrast enhancement in this small study. Our findings, which suggest that relative permeability and rCBV values may be correlated in high-grade glial neoplasms, deserve further study in a larger patient population.

Impaired P50 gating is thought to reflect a core deficit in schizophrenia, but the relevant neural network is not well understood. The present study used EEG and MEG to assess sensory gating and volumetric MRI to measure hippocampal volume to investigate relationships between them in 22 normal controls and 22 patients with schizophrenia. In the schizophrenia group, anterior but not posterior hippocampal volume was smaller, and both the P50 and M50 gating ratios were larger (worse) than in controls. Independent of group, left-hemisphere M50 gating ratio correlated negatively with left anterior hippocampal volume, and right-hemisphere M50 gating ratio correlated negatively with right anterior hippocampal volume. Schizophrenia diagnosis predicted M50 gating independent of hippocampal volume. These results are consistent with the finding that hippocampus is a critical part of a fronto-temporal circuit involved in auditory gating. Copyright © 2008 Society for Psychophysiological ResearchAddress reprint requests to: Robert J. Thoma Hippocampal structure and function are abnormal in schizophrenia (for recent reviews, see Goldman & Mitchell, 2004;Harrison, 2004). The most conspicuous functional abnormalities associated with hippocampal damage are deficits in learning and memory (especially relational mnemonic ability; Cohen & Eichenbaum, 1993;Moses, Cole, Driscoll, & Ryan, 2005;Rudy & Sutherland, 1995;Rudy & Sutherland, 1989). However, hippocampus is also known to subserve cognition in other ways. For example, there is evidence that hippocampus serves as part of neural networks involved in novelty detection (Knight, 1996;Moses & Ryan, 2006), in orienting attention toward novel auditory stimuli (Knight, 1996), and in novel target detection in tasks such as dichotic listening (Pollmann, Lepsien, Hugdahl, & von Cramon, 2004) and the oddball paradigm (Crottaz-Herbette, Lau, Glover, & Menon, 2005;Paller, McCarthy, Roessler, Allison, & Wood, 1992;Tesche, Karhu, & Tissari, 1996). Hippocampus is also known to be critical for the gating of sensory responses to stimuli. It has been well established that hippocampus is involved in prepulse inhibition (PPI) of startle, sometimes known as sensorimotor gating (Bast & Feldon, 2003;Caine, Geyer, & Swerdlow, 1992;Swerdlow et al., 2001;Zhang, Bast, & Feldon, 2002a, 2002b. However, whether and how hippocampus is involved in gating of the auditory event-related brain potential (ERP) P50 component in a paired-click paradigm is an open question.Impaired P50 sensory gating has been described as the most robust physiological finding in schizophrenia research (Bramon, Rabe-Hesketh, Sham, Murray, & Frangou, 2004;Heinrichs, 2004) and is associated with sensory overload and disruption of higher-order cognitive processing. Gating is typically assessed in a paired-click paradigm, in which two identical click stimuli are played in succession and the P50 response following each is measured. Normally, individuals show a reduced P50 response following the second click, and this reduction of the ...

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Abstract:Composite measures of fluctuating asymmetry (FA) of skeletal features are commonly used to estimate developmental instability (DI), the imprecise expression of developmental design due to perturbations during an individual's growth and maturation. Though many studies have detailed important behavioral correlates of FA, very little is known about its possible neuroanatomical correlates. In this study we obtained structural brain MRI scans from 20 adults and utilized voxel-based morphometry (VBM) to identify specific regions linked to FA. Greater FA predicted greater whole brain white matter volume, and a trend in the same direction was noted for whole brain gray matter volume. Greater FA was associated with significantly greater gray and white matter volumes in discrete brain regions, most prominently in the frontal lobes and in the right cerebral hemisphere. Developmental studies are needed to identify when FA-related brain differences emerge and to elucidate the specific neurobiological mechanisms leading to these differences.