The study investigates the causal link between local field potentials (LFPs) and phase precession, a phenomenon where neural spiking relative to LFPs gradually shifts over time. Phase precession is observed in various brain regions and is hypothesized to promote local neuroplasticity. However, causal evidence and neuroplastic mechanisms have been lacking. The research uses three experiments to modulate LFPs in humans, a non-human primate, and computational models using alternating current (AC) stimulation. Key findings include: 1. **Human Experiment**: AC stimulation in humans led to a gradual phase shift of maximal corticospinal excitability by -90°. 2. **Non-human Primate Experiment**: Exogenous AC stimulation induced phase precession in a subset of entrained neurons (~30%) in the non-human primate. 3. **Computational Modeling**: Multiscale modeling suggests that AC-induced phase precession is driven by NMDA-mediated synaptic plasticity. These results provide mechanistic and causal evidence for phase precession as a global neocortical process, highlighting its potential role in synaptic plasticity and therapeutic neuromodulation. The study also discusses the implications for understanding and treating neurological and psychiatric disorders.The study investigates the causal link between local field potentials (LFPs) and phase precession, a phenomenon where neural spiking relative to LFPs gradually shifts over time. Phase precession is observed in various brain regions and is hypothesized to promote local neuroplasticity. However, causal evidence and neuroplastic mechanisms have been lacking. The research uses three experiments to modulate LFPs in humans, a non-human primate, and computational models using alternating current (AC) stimulation. Key findings include: 1. **Human Experiment**: AC stimulation in humans led to a gradual phase shift of maximal corticospinal excitability by -90°. 2. **Non-human Primate Experiment**: Exogenous AC stimulation induced phase precession in a subset of entrained neurons (~30%) in the non-human primate. 3. **Computational Modeling**: Multiscale modeling suggests that AC-induced phase precession is driven by NMDA-mediated synaptic plasticity. These results provide mechanistic and causal evidence for phase precession as a global neocortical process, highlighting its potential role in synaptic plasticity and therapeutic neuromodulation. The study also discusses the implications for understanding and treating neurological and psychiatric disorders.