scholarly journals Different theta frameworks coexist in the hippocampus and are coordinated during memory-guided exploration and novelty detection

2018 ◽  
Author(s):  
Víctor J. Lopez-Madrona ◽  
Elena Pérez-Montoyo ◽  
Efrén Álvarez-Salvado ◽  
David Moratal ◽  
Oscar Herreras ◽  
...  
Keyword(s):  
Theta Rhythm ◽  
Novelty Detection ◽  
Molecular Layer ◽  
Sensory Information ◽  
Neuronal Firing ◽  
Theta Oscillations ◽  
Lower Phase ◽  
Guided Exploration ◽  
Memory Representations ◽  
Freely Behaving

SummaryHippocampal firing is organized in theta sequences controlled by internal memory-related processing and by external sensory cues. How these computations are segregated or integrated, depending on the cognitive needs, is not fully understood. Although theta activity in the hippocampus is most commonly studied as a unique coherent oscillation, it is the result of a complex interaction between different rhythm generators. Here we investigated the coordination between theta generators as a possible mechanism to couple or decouple internally and externally driven computations. We separated and quantified three different theta current generators from the hippocampus of freely behaving rats, one originating in CA3 with current sinks in CA1 str. radiatum and two with current sinks in CA1 str. lacunosum-moleculare and dentate molecular layer, mainly driven by entorhinal cortex (EC) layers 3 and 2, respectively. These theta generators followed non fully coherent dynamics and presented epochs of higher and lower phase coupling, suggesting a flexible interaction between them. Selective optogenetic inhibition in CA3 depressed the str. radiatum generator without affecting the EC-driven theta oscillations, indicating that theta rhythm generators can be modulated independently. In addition, band-specific gamma interactions with theta oscillations selectively occurred with the corresponding pathway-specific theta current generator, supporting the existence of different theta-gamma coding frameworks to organize neuronal firing in the hippocampus. Importantly, we found that epochs of highly synchronized theta rhythmicity across generators preferentially occurred during memory-guided exploration and mismatch novelty detection in familiar environments, two conditions in which internally generated memory representations need to be coordinated with the incoming sensory information about external cues. We propose a mechanism for segregating and integrating hippocampal computations based on the coexistence of different theta-gamma frameworks that flexibly couple or decouple accommodating the cognitive needs.

scholarly journals A robust model of Stimulus-Specific Adaptation validated on neuromorphic hardware

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Natacha Vanattou-Saïfoudine ◽  
Chao Han ◽  
Renate Krause ◽  
Eleni Vasilaki ◽  
Wolfger von der Behrens ◽  
...  
Keyword(s):  
Novelty Detection ◽  
Mean Field ◽  
Sensory Information ◽  
Neuronal Firing ◽  
Equivalent Model ◽  
Mean Field Model ◽  
Neuromorphic Circuits ◽  
Complete Control ◽  
Specific Adaptation ◽  
Neuromorphic Hardware

AbstractStimulus-Specific Adaptation (SSA) to repetitive stimulation is a phenomenon that has been observed across many different species and in several brain sensory areas. It has been proposed as a computational mechanism, responsible for separating behaviorally relevant information from the continuous stream of sensory information. Although SSA can be induced and measured reliably in a wide variety of conditions, the network details and intracellular mechanisms giving rise to SSA still remain unclear. Recent computational studies proposed that SSA could be associated with a fast and synchronous neuronal firing phenomenon called Population Spikes (PS). Here, we test this hypothesis using a mean-field rate model and corroborate it using a neuromorphic hardware. As the neuromorphic circuits used in this study operate in real-time with biologically realistic time constants, they can reproduce the same dynamics observed in biological systems, together with the exploration of different connectivity schemes, with complete control of the system parameter settings. Besides, the hardware permits the iteration of multiple experiments over many trials, for extended amounts of time and without losing the networks and individual neural processes being studied. Following this “neuromorphic engineering” approach, we therefore study the PS hypothesis in a biophysically inspired recurrent networks of spiking neurons and evaluate the role of different linear and non-linear dynamic computational primitives such as spike-frequency adaptation or short-term depression (STD). We compare both the theoretical mean-field model of SSA and PS to previously obtained experimental results in the area of novelty detection and observe its behavior on its neuromorphic physical equivalent model. We show how the approach proposed can be extended to other computational neuroscience modelling efforts for understanding high-level phenomena in mechanistic models.

scholarly journals Global sleep homeostasis reflects temporally and spatially integrated local cortical neuronal activity

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Christopher W Thomas ◽  
Mathilde CC Guillaumin ◽  
Laura E McKillop ◽  
Peter Achermann ◽  
Vladyslav V Vyazovskiy
Keyword(s):  
Neuronal Activity ◽  
Wave Activity ◽  
Neuronal Firing ◽  
Daily Amount ◽  
Local Process ◽  
Sleep Homeostasis ◽  
Freely Behaving ◽  
Electroencephalogram Eeg ◽  
Activity Dependent ◽  
Wake State

Sleep homeostasis manifests as a relative constancy of its daily amount and intensity. Theoretical descriptions define ‘Process S’, a variable with dynamics dependent on global sleep-wake history, and reflected in electroencephalogram (EEG) slow wave activity (SWA, 0.5–4 Hz) during sleep. The notion of sleep as a local, activity-dependent process suggests that activity history must be integrated to determine the dynamics of global Process S. Here, we developed novel mathematical models of Process S based on cortical activity recorded in freely behaving mice, describing local Process S as a function of the deviation of neuronal firing rates from a locally defined set-point, independent of global sleep-wake state. Averaging locally derived Processes S and their rate parameters yielded values resembling those obtained from EEG SWA and global vigilance states. We conclude that local Process S dynamics reflects neuronal activity integrated over time, and global Process S reflects local processes integrated over space.

scholarly journals Goal-directed and stimulus-driven selection of internal representations

2020 ◽  
Vol 117 (39) ◽  
pp. 24590-24598
Author(s):  
Freek van Ede ◽  
Alexander G. Board ◽  
Anna C. Nobre
Keyword(s):  
Working Memory ◽  
Feature Matching ◽  
Memory Performance ◽  
Sensory Information ◽  
Internal Representations ◽  
Memory Representations ◽  
External Stimuli ◽  
Selection Of ◽  
Do So

Adaptive behavior relies on the selection of relevant sensory information from both the external environment and internal memory representations. In understanding external selection, a classic distinction is made between voluntary (goal-directed) and involuntary (stimulus-driven) guidance of attention. We have developed a task—the anti-retrocue task—to separate and examine voluntary and involuntary guidance of attention to internal representations in visual working memory. We show that both voluntary and involuntary factors influence memory performance but do so in distinct ways. Moreover, by tracking gaze biases linked to attentional focusing in memory, we provide direct evidence for an involuntary “retro-capture” effect whereby external stimuli involuntarily trigger the selection of feature-matching internal representations. We show that stimulus-driven and goal-directed influences compete for selection in memory, and that the balance of this competition—as reflected in oculomotor signatures of internal attention—predicts the quality of ensuing memory-guided behavior. Thus, goal-directed and stimulus-driven factors together determine the fate not only of perception, but also of internal representations in working memory.

Memory representations underlying motor commands used during manipulation of common and novel objects

1993 ◽  
Vol 69 (6) ◽  
pp. 1789-1796 ◽  
Author(s):  
A. M. Gordon ◽  
G. Westling ◽  
K. J. Cole ◽  
R. S. Johansson
Keyword(s):  
Isometric Force ◽  
Sensory Information ◽  
Target Object ◽  
Force Output ◽  
Visual Identification ◽  
Force Increase ◽  
Novel Objects ◽  
Memory Representations ◽  
Different Shapes ◽  
Lift Off

1. While subjects lifted a variety of commonly handled objects of different shapes, weights, and densities, the isometric vertical lifting force opposing the object's weight was recorded from an analog weight scale, which was instrumented with high-stiffness strain gauge transducers. 2. The force output was scaled differently for the various objects from the first lift, before sensory information related to the object's weight was available. The force output was successfully specified from information in memory related to the weight of common objects, because only small changes in the force-rate profiles occurred across 10 consecutive lifts. This information was retrieved during a process related to visual identification of the target object. 3. The amount of practice necessary to appropriately scale the vertical lifting and grip (pinch) force was also studied when novel objects (equipped with force transducers at the grip surfaces) of different densities were encountered. The mass of a test object that subjects had not seen previously was adjusted to either 300 or 1,000 g by inserting an appropriate mass in the object's base without altering its appearance. This resulted in either a density that was in the range of most common objects (1.2 kg/l) or a density that was unusually high (4.0 kg/l). 4. Low vertical-lifting and grip-force rates were used initially with the high-density object, as if a lighter object had been expected. However, within the first few trials, the duration of the loading phase (period of isometric force increase before lift-off) was reduced by nearly 50% and the employed force-rate profiles were targeted for the weight of the object.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of Propofol on the Dynamic Properties of Sensory Information Processing in the Mouse Cerebellar Cortical Molecular Layer in vivo

Pharmacology ◽  
2015 ◽  
Vol 96 (5-6) ◽  
pp. 271-277 ◽  
Author(s):  
Wen-Zhe Jin ◽  
Jin-Di Shi ◽  
Heng Liu ◽  
Yan Lan ◽  
Chun-Ping Chu ◽  
...  
Keyword(s):  
Information Processing ◽  
Dynamic Properties ◽  
Molecular Layer ◽  
Sensory Information ◽  
Sensory Information Processing

scholarly journals Categorical judgments do not modify sensory information in working memory

2020 ◽  
Author(s):  
Long Luu ◽  
Alan A. Stocker
Keyword(s):  
Working Memory ◽  
Model Comparison ◽  
Human Subjects ◽  
Sensory Information ◽  
Memory Recall ◽  
Stimulus Feature ◽  
Inference Process ◽  
Categorical Judgment ◽  
Memory Representations ◽  
Stimulus Features

AbstractCategorical judgments can systematically bias the perceptual interpretation of stimulus features. However, it remained unclear whether categorical judgments directly modify working memory representations or, alternatively, generate these biases via an inference process down-stream from working memory. To address this question we ran two novel psychophysical experiments in which human subjects had to revert their categorical judgments about a stimulus feature, if incorrect based on feedback, before providing an estimate of the feature. If categorical judgments indeed directly altered sensory representations in working memory, subjects’ estimates should reflect some aspects of their initial (incorrect) categorical judgment in those trials.We found no traces of the initial categorical judgment. Rather, subjects seem to be able to flexibly switch their categorical judgment if needed and use the correct corresponding categorical prior to properly perform feature inference. A cross-validated model comparison also revealed that feedback may lead to selective memory recall such that only memory samples that are consistent with the categorical judgment are accepted for the inference process. Our results suggest that categorical judgments do not modify sensory information in working memory but rather act as top-down expectation in the subsequent sensory recall and inference process down-stream from working memory.

scholarly journals Different theta frameworks coexist in the rat hippocampus and are coordinated during memory-guided and novelty tasks

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Víctor J López-Madrona ◽  
Elena Pérez-Montoyo ◽  
Efrén Álvarez-Salvado ◽  
David Moratal ◽  
Oscar Herreras ◽  
...  
Keyword(s):  
Sensory Information ◽  
Gamma Oscillations ◽  
Theta Activity ◽  
Coherent Oscillation ◽  
Phase Coupling ◽  
Internal Memory ◽  
Complex Interactions ◽  
Theta Frequency ◽  
Memory Representations ◽  
Hippocampal Theta

Hippocampal firing is organized in theta sequences controlled by internal memory processes and by external sensory cues, but how these computations are coordinated is not fully understood. Although theta activity is commonly studied as a unique coherent oscillation, it is the result of complex interactions between different rhythm generators. Here, by separating hippocampal theta activity in three different current generators, we found epochs with variable theta frequency and phase coupling, suggesting flexible interactions between theta generators. We found that epochs of highly synchronized theta rhythmicity preferentially occurred during behavioral tasks requiring coordination between internal memory representations and incoming sensory information. In addition, we found that gamma oscillations were associated with specific theta generators and the strength of theta-gamma coupling predicted the synchronization between theta generators. We propose a mechanism for segregating or integrating hippocampal computations based on the flexible coordination of different theta frameworks to accommodate the cognitive needs.

scholarly journals Hippocampal and neocortical oscillations are tuned to behavioral state in freely-behaving macaques

2019 ◽  
Author(s):  
Omid Talakoub ◽  
Patricia Sayegh ◽  
Thilo Womelsdorf ◽  
Wolf Zinke ◽  
Pascal Fries ◽  
...  
Keyword(s):  
Early Stage ◽  
Gamma Oscillations ◽  
Theta Oscillations ◽  
Behavioral State ◽  
Spectral Content ◽  
Freely Behaving ◽  
Behavioral States

AbstractWireless recordings in macaque neocortex and hippocampus showed stronger theta oscillations during early-stage sleep than during alert volitional movement including walking. In contrast, hippocampal beta and gamma oscillations were prominent during walking and other active behaviors. These relations between hippocampal rhythms and behavioral states in the primate differ markedly from those observed in rodents. Primate neocortex showed similar changes in spectral content across behavioral state as the hippocampus.

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