Network hubs supporting memory encoding: Implications for cognitive preservation in epilepsy surgery

22 Jan

Influence of hypokinetic dysarthria severity level on the long-term outcome of repetitive transcranial magnetic stimulation therapy

Introduction: Hypokinetic dysarthria (HD) is a common and disabling symptom of Parkinson's disease (PD) for which established pharmacological and surgical treatments bring only limited, often short-term improvement in speech. The aim of this study was to investigate whether the long-term acoustic effects of repetitive transcranial magnetic stimulation (rTMS) over the right superior temporal gyrus (STG) depend on the baseline severity of HD.

Methods: 26 PD patients were randomized to active STG-targeted rTMS (n = 15) or sham stimulation (n = 11) and followed across five recording sessions over 14 weeks, alongside one session of matched healthy controls. HD severity at baseline was quantified using 3F test subscores and used to stratify patients into milder (0) and more severe (1) subgroups. The STG 1 subgroup combined greater motor and speech impairment with shorter disease duration. Multiple acoustic features from sustained phonation and free monologue were extracted, normalized to controls, adjusted for sex, and analyzed using non-parametric statistics and descriptive visualisations.

Results: Patients with more severe HD receiving active stimulation (STG 1) showed consistent, long-lasting improvements in phonation-related parameters, whereas milder HD (STG 0) and sham groups (SHAM 0, SHAM 1) exhibited only limited or transient changes.

5 Jan

Functional Impact Score of Mitochondrial Variants and Its Relationship With Functional Connectivity of the Brain: Potential Origins of Premature Aging in Young Adulthood

Alterations in mitochondrial DNA (mtDNA) have been associated with worse cognitive abilities in older adults and premature epigenetic aging in young adulthood. However, it is not clear how mitochondrial dysfunction affects brain function in young adulthood and whether cognition-related networks might be most affected. We tested whether mtDNA functional impact (FI) score might map onto specific patterns of between-network functional connectivity in young adults from the European Longitudinal Study of Pregnancy and Childhood (ELSPAC). We also tested whether these relationships might be mediated by accelerated epigenetic aging, calculated using Horvath's epigenetic clock, CheekAge clock, and AltumAge clock. General connectivity method was used as a reliable marker of individual differences in brain function. We showed that a greater mtDNA FI score was associated with lower connectivity between the dorsal attention and language networks (beta = -0.41, p = 0.0007, AdjR² = 0.15) and that there was suggestive evidence that this relationship might be mediated by accelerated epigenetic aging calculated using Horvath's epigenetic clock in young adulthood (ab = -0.061, SE = 0.04, 95% CI [-0.163; 0.001], 90% CI [-0.142; -0.002]). These findings were independent of sex, current BMI, and current substance use.