Contrast ratio analysis of the SNc using 3D neuromelanin-sensitive MRI may serve as a quick and accurate tool to discern between patients with PD and healthy controls.

• Structural changes in early multiple system atrophy were evaluated using multi-modal neuroimaging. • White matter was more affected than grey matter in early MSA. • Clinical variables did not correlate with early structural changes.

BACKGROUND AND PURPOSE:The frequency of seizures is an important factor that can alter functional brain connectivity. Analysis of this factor in patients with epilepsy is complex because of disease-and medication-induced confounders. Because patients with hot-water epilepsy generally are not on long-term drug therapy, we used seed-based connectivity analysis in these patients to assess connectivity changes associated with seizure frequency without confounding from antiepileptic drugs.

It is concluded that WC is a network disorder with widespread dysfunction much larger than clinically evident and changes induced by rTMS probably act through subcortical and trans-hemispheric unaffected connections. Longitudinal studies with therapeutic rTMS will be required to ascertain whether such information could be used to select patients prior to rTMS therapy.

Psychosis, manifested through formed visual hallucinations or minor hallucinations, is a common non-motor symptom of Parkinson's disease (PD). The pathogenesis of psychosis in PD remains unclear; however, is possibly linked to structural and functional alterations in the hippocampus. To explore the role of hippocampus in psychosis, a detailed hippocampal subfield analysis was performed on PD patients with (PD-P) and without psychosis (PD-NP), and healthy controls (HC). An automated subfield parcellation was performed on T1 MRI images of 141 subjects (PD-P:42, PD-NP:51, and HC:48). The volumes of 12 subfields on each side were estimated and analyzed between the three groups and were corrected for multiple comparisons using false discovery rates. The volumes were also correlated to psychosis severity and specific neuropsychological tests and finally were employed to predict the psychosis severity in PD-P using a support vector regression (SVR) model. Compared to controls, PD-NP group did not demonstrate any significant differences; however, the PD-P group had significantly lower total hippocampal volume. Bilateral molecular layer, granule cell-dentate gyrus, left subiculum, and hippocampal tail and right CA3, CA4, and HATA illustrated significantly lower volumes, while bilateral hippocampal fissure demonstrated a significant widening. Compared to PD-NP, the PD-P group had higher volume of the bilateral hippocampal fissures. Finally, SVR could significantly predict the psychosis severity from all the subfield volumes. Our findings indicate a higher degeneration of specific hippocampal subfields in PD-P compared to controls and a trend of higher volume of hippocampal fissures in PD-P group than in PD-NP.