scholarly journals Multimodal determinants of phase-locked dynamics across deep-superficial hippocampal sublayers during theta oscillations

2020 ◽  
Author(s):  
Andrea Navas-Olive ◽  
Manuel Valero ◽  
Teresa Jurado-Parras ◽  
Adan de Salas-Quiroga ◽  
Robert G Averkin ◽  
...  
Keyword(s):  
Computational Models ◽  
Phase Locking ◽  
Memory Task ◽  
Pyramidal Cells ◽  
Theta Oscillations ◽  
Ca1 Pyramidal Cells ◽  
Cell Type Specific ◽  
High Level ◽  
Specific Phase ◽  
Phase Preference

Theta oscillations play a major role in temporarily defining the hippocampal rate code by translating behavioural sequences into neuronal representations. However, mechanisms constraining phase timing and cell-type specific phase preference are unknown. Here, we employ computational models tuned with evolutionary algorithms to evaluate phase preference of individual CA1 pyramidal cells recorded in mice and rats not engaged in any particular memory task. We applied unbiased and hypothesis-free approaches to identify effects of intrinsic and synaptic factors, as well as cell morphology, in determining phase preference. We found that perisomatic inhibition delivered by complementary populations of basket cells interacts with input pathways to shape phase-locked specificity of deep and superficial pyramidal cells. Somatodendritic integration of fluctuating glutamatergic inputs defined cycle-by-cycle by unsupervised methods demonstrated that firing selection is tuneable across sublayers. Our data identify different mechanisms of phase-locking selectivity that are instrumental for high-level flexible dynamical representations.

scholarly journals Hippocampal-Prefrontal cortex network dynamics predict performance during retrieval in a context-guided object memory task

2021 ◽  
Author(s):  
Juan Facundo Morici ◽  
Noelia Victoria Weisstaub ◽  
Camila Lidia Zold
Keyword(s):  
Prefrontal Cortex ◽  
Contextual Information ◽  
Phase Locking ◽  
Memory Task ◽  
Pyramidal Cells ◽  
Neuronal Ensembles ◽  
Electrophysiological Recordings ◽  
Specific Object ◽  
Underlying Mechanisms ◽  
Amplitude Correlation

Remembering life episodes is a complex process that requires the interaction between multiple brain areas. It is thought that contextual information provided by the hippocampus (HPC) can trigger the recall of a past event through the activation of medial prefrontal cortex (mPFC) neuronal ensembles, but the underlying mechanisms remain poorly understood. Indeed, little is known about how the vHPC and mPFC are coordinated during a contextual-guided recall of an object recognition memory. To address this, we performed electrophysiological recordings in behaving rats during the retrieval phase of the object-in-context memory task (OIC). Coherence, phase locking and theta amplitude correlation analysis showed an increase in vHPC-mPFC LFP synchronization in the theta range when animals explore contextually mismatched objects. Moreover, we identified ensembles of putative pyramidal cells in the mPFC that encode specific object-context associations. Interestingly, the increase of vHPC-mPFC synchronization during exploration of the contextually mismatched object and the preference of mPFC incongruent object neurons predicts the animal's performance during the resolution of the OIC task. Altogether, these results identify changes in vHPC-mPFC synchronization and mPFC ensembles encoding specific object-context associations likely involved in the recall of past events.

scholarly journals Hippocampal theta coordinates memory processing during visual exploration

2019 ◽  
Author(s):  
James E. Kragel ◽  
Stephen VanHaerents ◽  
Jessica W. Templer ◽  
Stephan Schuele ◽  
Joshua M. Rosenow ◽  
...  
Keyword(s):  
Eye Movements ◽  
Phase Locking ◽  
Memory Performance ◽  
Memory Task ◽  
Sensory Information ◽  
Visual Exploration ◽  
Theta Oscillations ◽  
Neurosurgical Patients ◽  
Phase Amplitude ◽  
Encoding And Retrieval

SummaryThe hippocampus supports memory encoding and retrieval, with distinct phases of theta oscillations modulating the amplitude of gamma-band activity during each process. Encoding and retrieval operations dynamically interact over rapid timescales, especially when sensory information conflicts with memory. The ability to link hippocampal dynamics to specific memory-guided behaviors has been limited by experiments that lack the temporal resolution to segregate when encoding and retrieval occur. To resolve this issue, we simultaneously tracked eye movements and hippocampal field potentials while neurosurgical patients performed a spatial memory task. Novelty-driven fixations increased phase-locking to the theta rhythm, which predicted successful memory performance. Theta to gamma phase amplitude coupling increased during these viewing behaviors and predicted forgetting of conflicting memories. In contrast, theta phase-locking preceded fixations initiated by memory retrieval, indicating that the hippocampus coordinates memory-guided eye movements. These findings suggest that theta oscillations in the hippocampus support learning through two interleaved processes: strengthening the encoding of novel information and guiding exploration based on prior experience.

12. Human hippocampal theta oscillations show performance-dependent phase-locking during a working memory task

2011 ◽  
Vol 122 (1) ◽  
pp. e5
Author(s):  
Jonathan Kleen ◽  
Barbara Jobst ◽  
Kandan Kulandaivel ◽  
Terrance Darcey ◽  
Gregory Holmes ◽  
...  
Keyword(s):  
Working Memory ◽  
Phase Locking ◽  
Memory Task ◽  
Theta Oscillations ◽  
Hippocampal Theta

scholarly journals The Entorhinal Cortical Alvear Pathway Differentially Excites Pyramidal Cells and Interneuron Subtypes in Hippocampal CA1

2020 ◽  
Author(s):  
Karen A Bell ◽  
Rayne Delong ◽  
Priyodarshan Goswamee ◽  
A Rory McQuiston
Keyword(s):  
Brain Slices ◽  
Pyramidal Cells ◽  
Excitatory Input ◽  
Theta Burst Stimulation ◽  
Ca1 Pyramidal Cells ◽  
Whole Cell Patch Clamp ◽  
Hippocampal Ca1 ◽  
Physiological Impact ◽  
Theta Burst ◽  
Synaptic Responses

Abstract The entorhinal cortex alvear pathway is a major excitatory input to hippocampal CA1, yet nothing is known about its physiological impact. We investigated the alvear pathway projection and innervation of neurons in CA1 using optogenetics and whole cell patch clamp methods in transgenic mouse brain slices. Using this approach, we show that the medial entorhinal cortical alvear inputs onto CA1 pyramidal cells (PCs) and interneurons with cell bodies located in stratum oriens were monosynaptic, had low release probability, and were mediated by glutamate receptors. Optogenetic theta burst stimulation was unable to elicit suprathreshold activation of CA1 PCs but was capable of activating CA1 interneurons. However, different subtypes of interneurons were not equally affected. Higher burst action potential frequencies were observed in parvalbumin-expressing interneurons relative to vasoactive-intestinal peptide-expressing or a subset of oriens lacunosum-moleculare (O-LM) interneurons. Furthermore, alvear excitatory synaptic responses were observed in greater than 70% of PV and VIP interneurons and less than 20% of O-LM cells. Finally, greater than 50% of theta burst-driven inhibitory postsynaptic current amplitudes in CA1 PCs were inhibited by optogenetic suppression of PV interneurons. Therefore, our data suggest that the alvear pathway primarily affects hippocampal CA1 function through feedforward inhibition of select interneuron subtypes.

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