The effects of delta-9-tetrahydrocannabinol (delta-9-THC) on monosynaptic population responses in hippocampal CA1 pyramidal cells were examined in acute rats for several doses and at several post injection time periods. Delta-9-THC enhanced paired pulse inhibition in a dose-dependent manner; however biphasic dose effects were observed on cell responses during low frequency potentiation and on population spikes elicited by a conditioning stimulus. The biphasic responses were such that 2--4 mg/kg THC (IP) excited while 16 mg/kg depressed the stimulus elicited CA1 response. For low doses of THC slight biphasic time effects were observed. Evidence presented suggests that some of THC's actions on hippocampus may be due to direct or indirect actions on GABA-mediated activity.
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http://dx.doi.org/10.1016/0361-9230(82)90042-9 | DOI Listing |
Proc Natl Acad Sci U S A
February 2025
Zanvyl Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, MD 21218.
The hippocampal dentate gyrus (DG) is thought to orthogonalize inputs from the entorhinal cortex (pattern separation) and relay this information to the CA3 region. In turn, attractor dynamics in CA3 perform a pattern completion or error correction operation before sending its output to CA1. In a mouse model of congenital hypoplasia of the DG, a deficiency in the (Wls) gene, specifically in cells expressing , which targets neuronal progenitors, led to an almost total absence of dentate granule cells and modestly impaired performance in spatial tasks.
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January 2025
Department of Neuroscience, University of California, Berkeley, Berkeley, CA, USA.
The mechanisms by which the brain replays neural activity sequences remain unknown. Recording from large ensembles of hippocampal place cells in freely behaving rats, we observed that replay content is strictly organized over multiple timescales and governed by self-avoidance. After movement cessation, replays avoided the animal's previous path for 3 seconds.
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January 2025
Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel.
Social animals live in groups and interact volitionally in complex ways. However, little is known about neural responses under such natural conditions. Here, we investigated hippocampal CA1 neurons in a mixed-sex group of five to 10 freely behaving wild Egyptian fruit bats that lived continuously in a laboratory-based cave and formed a stable social network.
View Article and Find Full Text PDFFront Comput Neurosci
January 2025
Institute for Neural Computation, Faculty of Computer Science, Ruhr University Bochum, Bochum, Germany.
Introduction: The hippocampal formation exhibits complex and context-dependent activity patterns and dynamics, e.g., place cell activity during spatial navigation in rodents or remapping of place fields when the animal switches between contexts.
View Article and Find Full Text PDFHum Brain Mapp
February 2025
Research Center for Social Computing and Information Retrieval, Harbin Institute of Technology, Harbin, China.
Pattern separation and pattern completion in the hippocampus play a critical role in episodic learning and memory. However, there is limited empirical evidence supporting the role of the hippocampal circuit in these processes during complex continuous experiences. In this study, we analyzed high-resolution fMRI data from the "Forrest Gump" open-access dataset (16 participants) using a sliding-window temporal autocorrelation approach to investigate whether the canonical hippocampal circuit (DG-CA3-CA1-SUB) shows evidence consistent with the occurrence of pattern separation or pattern completion during a naturalistic audio movie task.
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