Anticipating social incentives recruits alpha-beta oscillations in the human substantia nigra and invigorates behavior across the life span.

Anticipating social and non-social incentives recruits shared brain structures and promotes behavior. However, little is known about possible age-related behavioral changes, and how the human substantia nigra (SN) signals positive and negative social information. Therefore, we recorded intracranial electroencephalography (iEEG) from the SN of Parkinson's Disease (PD) patients (n = 12, intraoperative, OFF medication) in combination with a social incentive delay task including photos of neutral, positive or negative human gestures and mimics as feedback. We also tested a group of non-operated PD patients (n = 24, ON and OFF medication), and a sample of healthy young (n = 51) and older (n = 52) adults with behavioral readouts only. Behaviorally, the anticipation of both positive and negative social feedback equally accelerated response times in contrast to neutral social feedback in healthy young and older adults. Although this effect was not significant in the group of operated PD patients - most likely due to the small sample size - iEEG recordings in their SN showed a significant increase in alpha-beta power (9-20 Hz) from 300 to 600 ms after cue onset again for both positive and negative cues. Finally, in non-operated PD patients, the behavioral effect was not modulated by medication status (ON vs OFF medication) suggesting that other processes than dopaminergic neuromodulation play a role in driving invigoration by social incentives. Together, our findings provide novel and direct evidence for a role of the SN in processing positive and negative social information via specific oscillatory mechanisms in the alpha-beta range, and they suggest that anticipating social value in simple cue-outcome associations is intact in healthy aging and PD.

Pronounced Orthostatic Hypotension in GBA-Related Parkinson's Disease.

Patients with Parkinson's disease (PD) carrying variants in the Glucocerebrosidase (GBA) gene (GBA-PD) suffer from orthostatic symptoms more frequently than idiopathic PD patients (IPD). Systematic measurements of the blood pressure have not yet been performed. In the present study, a prospective analysis of 33 GBA-PD and 313 IPD patients was carried out. Systolic blood pressure upon changing from the supine to the upright position dropped more strongly in GBA-PD compared to IPD patients. Diastolic blood pressure and heart rate did not differ between groups. This study provides further evidence for a pronounced involvement of the autonomic nervous system in GBA-PD.

Gonadotropin-releasing hormone regulates spine density via its regulatory role in hippocampal estrogen synthesis.

Spine density in the hippocampus changes during the estrus cycle and is dependent on the activity of local aromatase, the final enzyme in estrogen synthesis. In view of the abundant gonadotropin-releasing hormone receptor (GnRH-R) messenger RNA expression in the hippocampus and the direct effect of GnRH on estradiol (E2) synthesis in gonadal cells, we asked whether GnRH serves as a regulator of hippocampal E2 synthesis. In hippocampal cultures, E2 synthesis, spine synapse density, and immunoreactivity of spinophilin, a reliable spine marker, are consistently up-regulated in a dose-dependent manner at low doses of GnRH but decrease at higher doses. GnRH is ineffective in the presence of GnRH antagonists or aromatase inhibitors. Conversely, GnRH-R expression increases after inhibition of hippocampal aromatase. As we found estrus cyclicity of spine density in the hippocampus but not in the neocortex and GnRH-R expression to be fivefold higher in the hippocampus compared with the neocortex, our data strongly suggest that estrus cycle-dependent synaptogenesis in the female hippocampus results from cyclic release of GnRH.