Article
Multidisciplinary Sciences
Juan Facundo Morici, Noelia Victoria Weisstaub, Camila Lidia Zold
Summary: Remembering life episodes is a complex process that requires interaction among multiple brain areas. The hippocampus activates the medial prefrontal cortex to trigger the recall of past events. Electrophysiological recordings showed increased synchronization between the ventral hippocampus and the medial prefrontal cortex during exploration of contextually mismatched objects.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Neurosciences
Zhenyu Xie, Shuxun Dong, Yiyao Zhang, Yi Yuan
Summary: The present study investigated the effectiveness of closed-loop transcranial ultrasound stimulation (closed-loop TUS) in modulating brain function to enhance memory. The researchers found that closed-loop TUS applied at the peak phase of theta cycles significantly improved memory performance in rats. The study also observed changes in neural activity and synaptic transmission patterns with closed-loop TUS.
Article
Neurosciences
Nancy C. Zepeda, Lindsey M. Crown, Sasha Medvidovic, Wooseong Choi, Megha Sheth, Matthew Bergosh, Raymond Gifford, Caroline Folz, Phillip Lam, Gengxi Lu, Robert Featherstone, Charles Y. Liu, Steven J. Siegel, Darrin J. Lee
Summary: This study found that acute administration of MK-801 leads to altered neural activity in the septohippocampal circuit and impaired spatial memory. Furthermore, theta-frequency stimulation of the medial septal nucleus may improve specific spatial memory deficits and could be a potential treatment for cognitive impairments caused by NMDA hypofunction.
NEUROBIOLOGY OF DISEASE
(2022)
Article
Neurosciences
Yixuan Wang, Jian Liu, Yanping Hui, Zhongheng Wu, Ling Wang, Xiang Wu, Yihua Bai, Qiaojun Zhang, Libo Li
Summary: This study found that multiple blocks of iTBS have dose and time-dependent effects on hippocampus-dependent memory in PD, which may be related to changes in hippocampal c-Fos expression and theta rhythm.
FRONTIERS IN NEUROSCIENCE
(2023)
Article
Neurosciences
Joseph H. Rudoler, Nora A. Herweg, Michael J. Kahana
Summary: Computational models suggest that hippocampal theta plays a crucial role in learning and memory, but human hippocampal recordings show divergent results. Decreases in memory-related broadband power mask narrowband theta increases. Theta oscillations appear prominently in memory retrieval processes and when aggregating signals across large brain regions. The study analyzed human hippocampal recordings from 162 neurosurgical patients performing a free recall task and found that broadband theta signals decrease while narrowband theta signals increase during successful encoding. Low-frequency theta oscillations increase before recall, but higher-frequency theta and alpha oscillations decrease, masking the positive effect of theta when aggregating across the full band. The effects of theta on memory encoding and retrieval are consistent regardless of the reference scheme used.
JOURNAL OF NEUROSCIENCE
(2023)
Article
Biology
Sarah M. Lurie, James E. Kragel, Stephan U. Schuele, Joel L. Voss
Summary: Through experimental studies on patients with epilepsy, it is found that the receptivity of the hippocampus to input changes with the phase of theta rhythms, further confirming the proposed mechanism of neural oscillations modulating human hippocampal function.
Article
Neurosciences
Brad E. Pfeiffer
Summary: The hippocampal network does not enhance representation of the goal location during rapid spatial learning, but instead shows increased global population activity rates. However, representation of a novel goal location rapidly emerges in hippocampal ripples during brief movement pauses. These findings suggest that the hippocampus facilitates active navigation without enhanced goal representation during movement, and that goal representation in hippocampal ripples supports subsequent navigation through activation of downstream cortical networks.
JOURNAL OF NEUROSCIENCE
(2022)
Article
Biology
Eloy Parra-Barrero, Kamran Diba, Sen Cheng
Summary: The study examines the relationships between theta phase, represented position, and true location in navigation through space in mammalian brains. Existing concepts of 'spatial' or 'temporal' theta sweeps are found to be inadequate in explaining how relevant variables change with running speed. A new concept of 'behavior-dependent' sweeps is introduced, where theta sweep length and place field properties vary based on running speed characteristics at different locations in the environment, providing essential structured heterogeneity for understanding the hippocampal code.
Article
Neurosciences
Umesh Vivekananda, Daniel Bush, James A. Bisby, Sallie Baxendale, Roman Rodionov, Beate Diehl, Fahmida A. Chowdhury, Andrew W. McEvoy, Anna Miserocchi, Matthew C. Walker, Neil Burgess
Summary: In a study involving presurgical epilepsy patients undergoing intracranial EEG recording, increased theta power in two discrete bands during cued retrieval was found to be associated with improved task performance in long-term spatial memory. Additionally, increased coupling between low theta phase and gamma amplitude during the same period was also correlated with better task performance. Furthermore, it was observed that low and high gamma amplitude peaked at different phases of the theta cycle, providing a novel connection between human hippocampal function and rodent data.
Article
Multidisciplinary Sciences
Yiyao Zhang, Liang Cao, Viktor Varga, Miao Jing, Mursel Karadas, Yulong Li, Gyorgy Buzsaki
Summary: In mice, cholinergic signaling in the hippocampus increased in parallel with theta/gamma power during walking and REM sleep, while reaching its minimum during hippocampal sharp-wave ripples (SPW-R). Memory performance was impaired when medial septal cholinergic neurons were selectively optogenetically stimulated in a delay area. This stimulation also decreased the incidence of SPW-Rs.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2021)
Review
Biology
Jennifer C. Robinson, Mark P. Brandon
Summary: The passage discusses the connection between envisioning the future and remembering the past, explaining the roles of the prefrontal cortex and hippocampus in memory and future planning, as well as how brain regions support the temporal organization of information.
Article
Neurosciences
Nicholas Yeh, Jessica D. Payne, Sara Y. Kim, Elizabeth A. Kensinger, Joshua D. Koen, Nathan S. Rose
Summary: This study investigated the role of mPFC in emotional memory encoding using transcranial magnetic stimulation. The results showed that mPFC activity interacts with consolidation processes to enhance the preservation of negatively salient information.
JOURNAL OF NEUROSCIENCE
(2021)
Review
Biology
Alison E. Comrie, Loren M. Frank, Kenneth Kay
Summary: This article discusses the importance of imagination as a biological function and its relationship with the hippocampus in the brain. It highlights recent findings that suggest the hippocampus plays a fundamental role in generating hypothetical experiences and thoughts, beyond traditional views of its function in memory and spatial navigation. The article suggests that the hippocampus contributes to a wider range of cognitive abilities than previously thought.
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES
(2022)
Article
Neurosciences
Bethany E. Frost, Sean K. Martin, Matheus Cafalchio, Md Nurul Islam, John P. Aggleton, Shane M. O'Mara
Summary: Lesions affecting the anterior thalamic nuclei may be responsible for diencephalic amnesia, similar to how hippocampal lesions cause temporal lobe amnesia. The core element of diencephalic amnesia seems to be the loss of information in hippocampal output regions following anterior thalamic pathology, possibly due to the direct connections between the two areas.
JOURNAL OF NEUROSCIENCE
(2021)
Article
Multidisciplinary Sciences
Virginie Sterpenich, Mojca K. M. van Schie, Maximilien Catsiyannis, Avinash Ramyead, Stephen Perrig, Hee-Deok Yang, Dimitri Van De Ville, Sophie Schwartz
Summary: Sleep promotes memory consolidation, with neural representations of rewarded experiences undergoing privileged reactivation during sleep, favoring their consolidation.
NATURE COMMUNICATIONS
(2021)
Article
Clinical Neurology
Rhys W. Niedecker, Michelle L. Kloc, Gregory L. Holmes, Jeremy M. Barry
Summary: Early life seizures can impact cognitive function, with sex and dynamic brain states playing important roles in outcomes. In this study, male rats with early life seizures showed avoidance impairments, while females were unaffected. Coherence between the hippocampus and medial prefrontal cortex was related to cognitive outcomes in spatial tasks, highlighting the importance of analyzing sex and dynamic cognition in understanding seizure effects on the developing brain.
Article
Clinical Neurology
Michelle L. Kloc, Jennifer M. Daglian, Gregory L. Holmes, Tallie Z. Baram, Jeremy M. Barry
Summary: The study found that although recurrent febrile seizures did not lead to spatial cognitive deficits in the active avoidance task, they did alter the brain structure and resulted in long-lasting changes in the temporal organization of the hippocampus.
Article
Neurosciences
Michelle L. Kloc, Yuncai Chen, Jennifer M. Daglian, Gregory L. Holmes, Tallie Z. Baram, Jeremy M. Barry
Summary: This study aimed to investigate the effects of febrile status epilepticus (FSE) on neural circuitry governing learning and memory. The results show that FSE leads to physiological changes in the hippocampal circuit and cognitive impairment. Specifically, FSE induces decoupling of cortical synaptic pathways and altered signal phase coherence, and increased DG synaptic activity is predictive of poor cognitive outcomes. These alterations interfere with the ability of hippocampal dendrites to receive, decode, and propagate neocortical inputs, potentially contributing to FSE cognitive comorbidities.