Victor Andrew Stenger

Resting-state synchrony in short-term versus long-term abstinent alcoholics.

BACKGROUND We previously reported that when compared with controls, long-term abstinent alcoholics (LTAA) have increased resting-state synchrony (RSS) of the inhibitory control network and reduced synchrony of the appetitive drive network, and hypothesized that these levels of synchrony are adaptive and support the behavioral changes required to maintain abstinence. In this study, we investigate whether these RSS patterns can be identified in short-term abstinent alcoholics (STAA). METHODS Resting-state functional magnetic resonance imaging data were collected from 27 STAA, 23 LTAA, and 23 nonsubstance abusing controls (NSAC). We examined baseline RSS using seed-based measures. RESULTS We found ordered RSS effects from NSAC to STAA and then to LTAA within both the appetitive drive and executive control networks: increasing RSS of the executive control network and decreasing RSS of the reward processing network. Finally, we found significant correlations between strength of RSS in these networks and (i) cognitive flexibility, and (ii) current antisocial behavior. CONCLUSIONS Findings are consistent with an adaptive progression of RSS from short- to long-term abstinence, so that, compared with normal controls, the synchrony (i) within the reward network progressively decreases, and (ii) within the executive control network progressively increases.

Resting state synchrony in long-term abstinent alcoholics with versus without comorbid drug dependence

BACKGROUND We previously reported that when long-term abstinent alcoholics (LTAA; with no drug comorbidity) are compared to controls, they show increased resting state synchrony (RSS) in the executive control network and reduced RSS in the appetitive drive network suggestive of compensatory mechanisms that may facilitate abstinence. The aim of the present study was to investigate whether long-term abstinent alcoholics with comorbid stimulants dependence (LTAAS) show similar RSS mechanisms. METHODS Resting-state functional MRI data were collected on 36 LTAAS (20 females, age: 47.85±7.30), 23 LTAA (8 females, age: M=47.91±6.76), and 23 non-substance abusing controls (NSAC; 8 females, age: M=47.99±6.70). Using seed-based measures, we examined RSS with the nucleus accumbens (NAcc) and the subgenual anterior cingulate cortex (sgACC). RESULTS Results showed commonalities in LTAA and LTAAS RSS (similar enhanced executive control RSS and left insula RSS) as well as differences (no attenuation of appetitive drive RSS in LTAAS and no enhancement of RSS in right insula in LTAA). CONCLUSIONS We believe these differences are adaptive mechanisms that support abstinence. These findings suggest common as well as specific targets for treatment in chronic alcoholics with vs without comorbid stimulant dependence.

Simultaneous multislice spectral‐spatial excitations for reduced signal loss susceptibility artifact in BOLD functional MRI

Simultaneous multislice (SMS) imaging can significantly increase image acquisition rates and improve temporal resolution and contrast in gradient‐echo blood oxygen level–dependent (BOLD) functional MRI (fMRI) experiments. Through‐plane signal loss due to B0 inhomogeneities at air–tissue interfaces limits fMRI of structures near the nasal cavity and ear canals. This study implemented spectral–spatial (SPSP) radiofrequency pulses for reduced through‐plane signal loss across multiple simultaneously excited slices.

Motion correction for diffusion weighted SMS imaging

• Prospective motion correction for simultaneous-multislice diffusion-weighted acquisitions is proposed.

Iterative projection onto convex sets for quantitative susceptibility mapping.

Quantitative susceptibility map (QSM) reconstruction is ill posed due to the zero values on the “magic angle cone” that make the maps prone to streaking artifacts. We propose projection onto convex sets (POCS) in the method of steepest descent (SD) for QSM reconstruction.