New research is uncovering mechanisms underlying brain-related diseases and functions. Studies revealed unique brain signaling differentiating Parkinson’s disease from essential tremor, links between REM sleep quality and locus coeruleus activity, and altered theta waves associated with social defeat stress. Additionally, discoveries include the influence of ovarian hormones on fear extinction via dopamine pathways and novel molecular insights into Alzheimer’s hippocampal sex differences. These advances deepen the understanding of neural circuits and cognitive health.