Article

Diffusion tensor tractography in mesencephalic bundles: relation to mental flexibility in detoxified alcohol-dependent subjects.

INSERM, U797 Research Unit Neuroimaging and Psychiatry, IFR49, Orsay, France.
Neuropsychopharmacology: official publication of the American College of Neuropsychopharmacology (Impact Factor: 7.83). 08/2008; 34(5):1223-32. DOI: 10.1038/npp.2008.101
Source: PubMed

ABSTRACT Components of the corticocerebellar circuit and the midbrain individually play a central role in addictive processes and have been associated with altered volumes and impairment of cognitive flexibility in alcohol-dependent subjects. The microstructure of white matter bundles composing the corticocerebellar network and passing through the midbrain was studied using diffusion tensor imaging in a group of detoxified alcohol-dependent men (n=20) and a group of healthy men (n=24). The relationship between properties of these white matter bundles and cognitive flexibility performance was investigated in alcohol-dependent subjects. Bundles connecting two regions of interest were analyzed using a fiber-tracking quantitative approach, which provided estimates of the fractional anisotropy and the apparent diffusion coefficient, as well as the number of tracked fibers normalized by the volume of regions of interest. Within the bundles running between the midbrain and pons, a mean of 18% fewer fibers per unit volume were tracked in alcohol-dependent men than in healthy controls. In addition, the normalized number of these fibers correlated with the performance in the Trail-Making Test part-B. Even though the alcohol-dependent subjects were detoxified and apparently neurologically intact, their earlier excessive use of alcohol seems to be associated with altered neural microstructure of mesencephalic white matter bundles, which may contribute to their cognitive flexibility impairment.

Download full-text

Full-text

Available from: Nikoleta Kostogianni, Mar 21, 2014
0 Followers
 · 
95 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Cognitive flexibility has been associated with prefrontal white matter (WM) integrity in healthy controls (HCs), showing that lower WM integrity is associated with worse performance. Although both cognitive flexibility and WM integrity have been found to be aberrant in alcohol-dependent (AD) patients, the relationship between the two has never been tested. In this study, we investigated the association between WM tract density and cognitive flexibility in patients with AD (n = 26) and HCs (n = 22). In order to assess the influence of AD severity, we also included a group of problematic drinkers (PrDs; n = 23) who did not meet the AD criteria. Behavioral responses and brain activity during a cognitive flexibility task were measured during functional magnetic resonance imaging. Probabilistic fiber tracking was performed between the dorsolateral prefrontal cortex and the basal ganglia; two crucial regions for task switching. Finally, the task-related functional connectivity between these areas was assessed. There were no signifi-cant group differences in the task performance. However, compared with HCs, AD patients and PrDs showed decreased WM integrity and increased prefrontal brain activation during task switching. Evidence is presented for a compensatory mechanism, involving recruitment of additional prefrontal resources in order to compensate for WM and neural function impairments in AD patients and PrDs. Although present in both alcohol groups, the PrDs were more successful in invoking this compensatory mechanism when compared to the AD patients. We propose that this may therefore serve as a protective factor, precluding transition from problematic drinking into alcohol dependence.
    Addiction Biology 12/2014; DOI:10.1111/adb.12199 · 5.91 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Emotional visual perception deficits constitute a major problem in alcohol-dependence. Indeed, the ability to assess the affective content of external cues is a key adaptive function, as it allows on the one hand the processing of potentially threatening or advantageous stimuli, and on the other hand the establishment of appropriate social interactions (by enabling rapid decoding of the affective state of others from their facial expressions). While such deficits have been classically considered as reflecting a genuine emotion decoding impairment in alcohol-dependence, converging evidence suggests that underlying visual deficits might play a role in emotional alterations. This hypothesis appears to be relevant especially as data from healthy populations indicate that a coarse but fast analysis of visual inputs would allow emotional processing to arise from early stages of perception. After reviewing those findings and the associated models, the present paper underlines data showing that rapid interactions between emotion and vision could be impaired in alcohol-dependence and provides new research avenues that may ultimately offer a better understanding of the roots of emotional deficits in this pathological state.
    Frontiers in Human Neuroscience 03/2014; 8. DOI:10.3389/fnhum.2014.00128 · 2.90 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To date, there is no study that explored the correlation of microstructural changes in the whole brain white matter (WM) and decision-making in alcohol dependent patients (ADP). In the present study, we applied Tract Based Spatial Statistics (TBSS) to study WM changes in ADP compared with healthy controls. We also tested whether there was any relationship between WM integrity and decision-making in ADP. The study included 17 inpatient ADP who had been abstinent for at least 2 weeks before testing and scanning and 16 healthy control subjects. The Iowa Gambling Task (IGT) was used to measure decision-making. Results for the IGT showed a significant group (ADP vs. control) by block interaction. Follow-up univariate analyses of variance showed that the groups were significantly different in the last 20 trails. Four significant clusters were found in which fractional anisotropy was significantly lower in ADP than in control subjects, including the corpus callosum and parietal, occipital and frontal regions. We found significant correlations between impaired IGT performance in the last 20 trials and WM integrity in these regions. Together, these results might help to explain observed decision making deficits in ADP.
    09/2013; 214(3). DOI:10.1016/j.pscychresns.2013.06.014