Koichi Hashikawa

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Humans and non-human animals learn associations of temporally contingent stimuli to better cope with the changing environment. In animal models of classical conditioning, a neutral conditioned stimulus (CS) predicts an aversive unconditioned stimulus (US). Several lines of indirect evidence indicate that this learning may rely on stimulus convergence in a(More)
Apoptosis signal-regulating kinase 1 (ASK1) is a mitogen-activated protein (MAP) kinase kinase kinase family member, which induces apoptosis in various cells through JNK and p38 MAP kinase cascades. In addition to apoptosis signaling, a number of recent in vitro studies have suggested that ASK1 may play roles in neural function. However, the behavioral(More)
Specific neuronal subpopulations within specific brain areas are responsible for learning and memory. A fear memory engages a subset of lateral amygdala neurons, but whether multiple contextual fear memories engage the same or different subsets of lateral amygdala neurons remains unclear. Here, we demonstrate the representation of multiple contextual fear(More)
The activity-regulated cytoskeleton-associated gene (Arc, also known as Arg3.1) is an effector immediate-early gene rapidly induced by strong neural activity. Although a number of studies have revealed significant functions of Arc and Arc has come into widespread use as a neural activity marker in behavioral studies, the mechanisms regulating Arc(More)
Information processing in the central nervous system (CNS) during periods of rest is crucial for lasting memories but the precise off-line neuronal population activity that contributes to long-term memory formation remains unclear. This pattern of neuronal activity during rest triggers transcription of immediate early genes such as activity regulated(More)
Neural activity and de novo protein synthesis during a rest period following memory retrieval in the amygdala is necessary for stabilization of reactivated fear memory. Arc/Arg3.1 (Arc) expression is regulated by neural activity and is a critical protein for memory reconsolidation. However, it remains unclear whether memory retrieval alters Arc(More)
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