Steve Ramirez

This paper introduces a drift diffusion model with hidden Markov states to analyze time-dependent decision-making in rats, revealing daily fluctuations in performance linked to circadian rhythms.

The paper introduces a state-dependent drift diffusion model to show mice switch between impulsive and deliberative decision states during tasks, revealing active exploration of the speed-accuracy trade-off.

The paper shows that hippocampal place field remapping and coordinated ensemble activity, dependent on protein synthesis, are critical for contextual fear memory consolidation.

This study identifies astrocytic calcium-event sequences in the dorsal hippocampus during learning and memory tasks, showing they encode time-compressed information similar to neuronal time cells.

This study shows that repeated activation of negative memory engrams in mice leads to lasting cellular and behavioral abnormalities, similar to chronic negative thinking in humans.

This study tracks CA1 engram cell dynamics before and after learning, showing they are influenced by intrinsic activity, behavior, and memory.

This study shows that optogenetic reactivation of fear memories in the hippocampus reproduces cellular activity patterns seen during natural memory recall, highlighting neuronal-astrocytic coupling in fear behavior.

This study shows that stimulating engram neurons during the trough of theta oscillations enhances memory recall more than fixed frequency or peak stimulation.

This study shows that basolateral amygdala astrocytes are responsive to fear memory acquisition and recall, with distinct calcium dynamics during fear conditioning and extinction.

The paper reactivates hippocampal fear engrams across different contexts and identifies brain-wide network changes associated with distinct defensive behaviors.

The paper introduces a method to record cellular physiological histories using self-assembling protein chains that can be optically read, demonstrating its use in neurons and mouse brain.

This study shows that sleep deprivation does not cause memory loss but suboptimal storage, which can be retrieved using optogenetics or roflumilast.

The paper investigates age-related changes in neuronal excitability in the hippocampus of mice, finding that aged mice show a deficit in ensemble-specific excitability after learning, linked to memory impairment.

The paper shows that reactivating positive memories during fear memory recall reduces conditioned fear in mice, suggesting a method to disrupt negative affective states through memory updating.

This study investigates how ethanol exposure affects fear memory processing in mice and shows that optogenetic inhibition of hippocampal engrams reduces maladaptive contextual generalization.

This study investigates how engram reactivation in the dentate gyrus varies based on maze traversal routes and environment, finding that route-specific ensembles are encoded and reactivated differently.

This study shows that social interactions can reactivate fear memories in male mice, enhancing memory recall through hippocampal engram reactivation.

The paper identifies distinct cell populations in the ventral hippocampus that encode appetitive and aversive memories, showing molecular, cellular, and projection-specific differences.

This study shows that optogenetic reactivation of fear engrams in ethanol-exposed mice reduces fear responses, mimicking extinction, despite impaired extinction learning.

This study shows chronic optogenetic stimulation of hippocampal engrams in male mice enhances specific social behaviors but not others, with no detectable changes in neural activity markers.

This study shows that odor can delay the de-contextualization of fear memories, maintaining hippocampal dependence even at remote time points.