Effects of prolonged grounding-based transcranial coupling to earth potential on learning, memory, and hippocampal biochemical status in male Wistar rats.

Learning and memory are regulated by physiological processes involved in hippocampal plasticity. Grounding-based cranial coupling to Earth potential has been proposed; however, its effects on cognition remain unclear. This study investigated whether prolonged grounding-based cranial coupling affects learning, memory, and hippocampal biochemistry in male Wistar rats. Forty-eight rats were randomly assigned to Control, Sham, and grounding exposure groups (7, 14, 21, and 28 days; n = 8/group). Grounding was applied continuously (24 h/day) through a cranial electrode connected to an Earth grounding system. Cognitive performance was evaluated using the Morris Water Maze, Novel Object Recognition, Shuttle Box, and Open Field Test. Hippocampal levels of TNF-α, IL-1β, IL-6, malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH), and brain-derived neurotrophic factor (BDNF), together with serum corticosterone, were measured. Prolonged grounding exposure (21-28 days) was associated with improved learning and memory, reflected by enhanced spatial, recognition, and passive avoidance memory, while locomotor activity remained largely unchanged. Behavioral improvements occurred alongside reduced hippocampal IL-1β, IL-6, TNF-α, and MDA levels, increased SOD activity, elevated GSH and BDNF levels, and lower serum corticosterone. These findings provide preliminary evidence of an association between sustained grounding-based cranial coupling and physiological changes related to hippocampal function and cognitive performance. However, this study did not assess cortical or hippocampal electrical activity, membrane potential, or tissue-level current flow; therefore, the observed behavioral and biochemical changes should not be interpreted as evidence of a direct electrical neuromodulatory mechanism. Further studies are required to clarify pathways and determine causality.