Neurofeedback training can modulate task-relevant memory replay rate in rats

Abstract

Hippocampal replay - the time-compressed, sequential reactivation of ensembles of neurons related to past experience - is a key neural mechanism of memory consolidation. Replay typically coincides with a characteristic pattern of local field potential activity, the sharp-wave ripple (SWR). Reduced SWR rates are associated with cognitive impairment in multiple models of neurodegenerative disease, suggesting that a clinically viable intervention to promote SWRs and replay would prove beneficial. We therefore developed a neurofeedback paradigm for rat subjects in which SWR detection triggered rapid positive feedback in the context of a memory-dependent task. This training protocol increased the prevalence of task-relevant replay during the targeted neurofeedback period by changing the temporal dynamics of SWR occurrence. This increase was also associated with neural and behavioral forms of compensation after the targeted period. These findings reveal short-timescale regulation of SWR generation and demonstrate that neurofeedback is an effective strategy for modulating hippocampal replay.

Paradoxical replay can protect contextual task representations from destructive interference when experience is unbalanced

“…Future work can address how these different components can be combined, and explore any interactions that can occur. In common with Sagiv et al, we do not provide a mechanistic explanation for how the hippocampus would "know" what to replay; however, the phenomenon of "rebound" in SWR events after closed-loop suppression in the hippocampus (Gillespie et al, 2024;Girardeau et al, 2014) shows that there is a SWR pressure that is under homeostatic control. Further experimental work can determine what the physiological basis of this pressure is, whether it is content-specific, and inform how it is best modeled.…”