Topic: theta sequences

Humans and animals construct internal models linking actions with their likely outcomes, and use these models to guide behavior. Such model-based cognition is often referred to as planning, and its neural mechanisms remain poorly understood (Miller & Venditto, 2021). The hippocampus, known for its role in spatial learning and memory, is necessary for planning (Miller et al., 2017; Vikbladh et al., 2019). Specifically, hippocampal sequences, which “sweep out” nonlocal trajectories both during active behavior (“theta sequences”) and at rest (“sharp-wave ripple sequences”; SWR), have been pro

Two aspects of hippocampal temporal coding during behaviour have come to dominate theories of hippocampal function: phase precession at the single-cell level, and theta sequences at the population level. Both their significance for memory functions as much as their connection to specific network dynamics and to each other, remain matter for speculation. Here we address these questions by taking advantage of simultaneous recordings of population activity and layer-specific LFP dynamics in the CA1 region. What we find is that these two phenomena are largely segregated both at the spatial and at

Hippocampal replay, the sequential reactivation of place cells, is postulated to be a mechanism central to memory consolidation. Commonly studied using highly repeated stereotyped behaviours (e.g. running back and forth on a linear track), we don’t understand how such memories are formed in more naturalistic settings, with a single or limited exposure, and the effect on subsequent replay. To further investigate this, we trained rats to run back on forth on two novel linear tracks each day, each track limited to a fixed but different number of laps. Following a post-behaviour sleep session, rat

Memory-related computations must occur across various brain states, each characterized by distinct oscillatory patterns. Theta oscillations in the hippocampal CA1 region are prominent during movement and are thought to organize network computations during active exploration, such as the virtual spatial paths formed by the sequential activity of CA1 spatial-tuning neurons, or 'place cells,' known as theta sequences. However, it remains unclear how theta supports memory during periods of immobility, when CA1 theta oscillations dissipate. To address this, we recorded laminar neural activity using

Studies suggest that adaptive behaviors arise from multiple decision systems in the brain, and spatial complexity affects these processes. Three regions are hypothesized to make distinct contributions: hippocampus (HC) — encoding state-space and enabling flexible behaviors, dorsolateral striatum (DLS) — encoding action-chains and enabling automated behaviors, and prefrontal cortex (mPFC) — encoding task-space and strategy-setting. We simultaneously recorded across these regions, and in a separate cohort we chemogenetically inhibited mPFC on a rule-switch task, the left/right/alternation foragi