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Striatal asymmetry is a common feature in Parkinson's disease (PD), which changes with the progression of the disease. However, the correlation between the striatal asymmetry and severity of PD remains unclear. The present study aimed to investigate the characteristics of asymmetry in PD, and analyze the correlation between the striatal asymmetry index (SAI) and disease severity. This retrospective study enrolled 63 patients with idiopathic PD. The severity of PD was classified according to the Hoehn & Yahr (H&Y) staging system. The SAI in the subregions of the striatum was measured using 11C-N-2-carbomethoxy-3-(4-fluorophenyl)-tropane (11C-CFT) positron emission tomography (PET). There was a significant difference in the SAI of the posterior putamen among the three groups (H&Y stage I, H&Y stage II, and H&Y stage III-IV; p = 0.001). However, there was no difference in the SAI of the anterior putamen (p = 0.340) or SAI of the caudate nucleus (p = 0.342) among the three groups. The SAI of the posterior putamen in patients with PD was significantly higher than that in patients with multiple system atrophy or progressive supranuclear palsy (p = 0.008). The SAI of the posterior putamen is associated with the severity of PD, and may be correlated to the loss of dopamine cells in the pars compacta of the ventrolateral substantia nigra projecting to the posterior putamen. The SAI may be a potential indicator for evaluating the severity of PD, and distinguishing PD from other degenerative diseases. [ABSTRACT FROM AUTHOR]

Acute stress is associated with a shift from goal-directed to habitual behavior. This stress-induced preference for habitual behavior has been suggested as a potential mechanism by which binge eating disorder (BED) patients succumb to eating large amounts of high-caloric foods in an uncontrolled manner (i.e., binge episodes). While in healthy subjects the balance between goal-directed and habitual behavior is subserved by the anterior cingulate cortex (ACC), insular cortex, orbitofrontal cortex (OFC), anterior caudate nucleus, and posterior putamen, the brain mechanism that underlies this (possibly amplified) stress-induced behavioral shift in BED patients is currently unknown. In the current study, 76 participants (38 BED, 38 healthy controls (HCs)) learned six stimulus-response-outcome associations in a well-established instrumental learning task. Subsequently, three outcomes were selectively devalued, after which participants underwent either a stress induction procedure (Maastricht Acute Stress Test; MAST) or a no-stress control procedure. Next, the balance between goal-directed and habitual behavior was assessed during functional magnetic resonance imaging. Findings show that the balance between goal-directed and habitual behavior was associated with activity in the ACC, insula, and OFC in no-stress HCs. Although stress and BED did not modulate the balance between goal-directed and habitual behavior, BED participants displayed a smaller difference in putamen activation between trials probing goal-directed and habitual behavior compared with HCs when using a ROI approach. We conclude that putamen activity differences between BED and HC could reflect changes in monitoring of response accuracy or reward value, albeit perhaps not sufficiently to induce a measurable shift from goal-directed to habitual behavior. Future research could clarify potential boundary conditions of stress-induced shifts in instrumental behavior in BED patients. • Putamen activity differences in goal-directed action and habits was reduced in BED. • BED did not boost the shift in goal-directed to habitual responding. • Acute stress did not impact brain activity or behavior. [ABSTRACT FROM AUTHOR]

Objective: Previous studies revealed that 18F-FDOPA uptake was significantly decreased in the subregions of striatum contralateral to the side with predominant symptoms and was helpful for improving the early diagnostic accuracy of PD. However, in these studies, more than half of the PD patients already have bilateral motor symptoms (mH&Y stage≥2). This study was aimed to extend previous findings to a milder disease stage., Methods: Sixteen PD patients with only mild and unilateral motor symptoms (mH&Y stage=1 and disease duration≤2 years) and 22 healthy controls were involved. Striatal 18F-FDOPA uptake was analyzed using a ratio approach., Results: The SORs in the subregions of the contralateral striatum, including caudate, anterior putamen and posterior putamen were significantly decreased in the mild stage PD patients. The SOR for the contralateral posterior putamen had the largest area under the receiver operating characteristic curve (0.963) and separated mild stage PD patients from healthy controls with a sensitivity of 93.75% and a specificity of 95.45% when the cut-off value of <2.160 was selected., Conclusion: These data indicate that contralateral posterior putaminal 18F-FDOPA uptake may represent a potential marker for early diagnosis of PD, especially in patients with only mild and unilateral motor symptoms., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)