scholarly journals The brain and its time: intrinsic neural timescales are key for input processing

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Mehrshad Golesorkhi ◽  
Javier Gomez-Pilar ◽  
Federico Zilio ◽  
Nareg Berberian ◽  
Annemarie Wolff ◽  
...  
Keyword(s):  
Neural Activity ◽  
Recent Literature ◽  
Neural Mechanisms ◽  
Temporal Organization ◽  
Multiple Timescales ◽  
Input Processing ◽  
Evolutionary Context ◽  
Input Sharing ◽  
The Brain

AbstractWe process and integrate multiple timescales into one meaningful whole. Recent evidence suggests that the brain displays a complex multiscale temporal organization. Different regions exhibit different timescales as described by the concept of intrinsic neural timescales (INT); however, their function and neural mechanisms remains unclear. We review recent literature on INT and propose that they are key for input processing. Specifically, they are shared across different species, i.e., input sharing. This suggests a role of INT in encoding inputs through matching the inputs’ stochastics with the ongoing temporal statistics of the brain’s neural activity, i.e., input encoding. Following simulation and empirical data, we point out input integration versus segregation and input sampling as key temporal mechanisms of input processing. This deeply grounds the brain within its environmental and evolutionary context. It carries major implications in understanding mental features and psychiatric disorders, as well as going beyond the brain in integrating timescales into artificial intelligence.

scholarly journals Exploring the role of expectations and stimulus relevance on stimulus-specific neural representations and conscious report

2019 ◽  
Vol 2019 (1) ◽  
Author(s):  
Erik L Meijs ◽  
Pim Mostert ◽  
Heleen A Slagter ◽  
Floris P de Lange ◽  
Simon van Gaal
Keyword(s):  
Attentional Blink ◽  
Neural Activity ◽  
Subjective Experience ◽  
Activity Patterns ◽  
Neural Mechanisms ◽  
Top Down ◽  
Neural Representations ◽  
Dependent Signal ◽  
Task Irrelevant

Abstract Subjective experience can be influenced by top-down factors, such as expectations and stimulus relevance. Recently, it has been shown that expectations can enhance the likelihood that a stimulus is consciously reported, but the neural mechanisms supporting this enhancement are still unclear. We manipulated stimulus expectations within the attentional blink (AB) paradigm using letters and combined visual psychophysics with magnetoencephalographic (MEG) recordings to investigate whether prior expectations may enhance conscious access by sharpening stimulus-specific neural representations. We further explored how stimulus-specific neural activity patterns are affected by the factors expectation, stimulus relevance and conscious report. First, we show that valid expectations about the identity of an upcoming stimulus increase the likelihood that it is consciously reported. Second, using a series of multivariate decoding analyses, we show that the identity of letters presented in and out of the AB can be reliably decoded from MEG data. Third, we show that early sensory stimulus-specific neural representations are similar for reported and missed target letters in the AB task (active report required) and an oddball task in which the letter was clearly presented but its identity was task-irrelevant. However, later sustained and stable stimulus-specific representations were uniquely observed when target letters were consciously reported (decision-dependent signal). Fourth, we show that global pre-stimulus neural activity biased perceptual decisions for a ‘seen’ response. Fifth and last, no evidence was obtained for the sharpening of sensory representations by top-down expectations. We discuss these findings in light of emerging models of perception and conscious report highlighting the role of expectations and stimulus relevance.

scholarly journals The Physiology of Fear: Reconceptualizing the Role of the Central Amygdala in Fear Learning

Physiology ◽  
2015 ◽  
Vol 30 (5) ◽  
pp. 389-401 ◽  
Author(s):  
Orion P. Keifer ◽  
Robert C. Hurt ◽  
Kerry J. Ressler ◽  
Paul J. Marvar
Keyword(s):  
Lateral Hypothalamus ◽  
Recent Literature ◽  
Brain Structures ◽  
Memory Formation ◽  
Fear Learning ◽  
Central Amygdala ◽  
A Site ◽  
The Brain ◽  
Human And Mouse

The historically understood role of the central amygdala (CeA) in fear learning is to serve as a passive output station for processing and plasticity that occurs elsewhere in the brain. However, recent research has suggested that the CeA may play a more dynamic role in fear learning. In particular, there is growing evidence that the CeA is a site of plasticity and memory formation, and that its activity is subject to tight regulation. The following review examines the evidence for these three main roles of the CeA as they relate to fear learning. The classical role of the CeA as a routing station to fear effector brain structures like the periaqueductal gray, the lateral hypothalamus, and paraventricular nucleus of the hypothalamus will be briefly reviewed, but specific emphasis is placed on recent literature suggesting that the CeA 1) has an important role in the plasticity underlying fear learning, 2) is involved in regulation of other amygdala subnuclei, and 3) is itself regulated by intra- and extra-amygdalar input. Finally, we discuss the parallels of human and mouse CeA involvement in fear disorders and fear conditioning, respectively.

scholarly journals Dissociable Forms of Repetition Priming: A Computational Model

2014 ◽  
Vol 26 (4) ◽  
pp. 712-738 ◽  
Author(s):  
Kirill Makukhin ◽  
Scott Bolland
Keyword(s):  
Computational Model ◽  
Neural Activity ◽  
Repetition Priming ◽  
Hebbian Learning ◽  
Neural Mechanisms ◽  
Stimulus Repetition ◽  
Repetition Suppression ◽  
Opposite Trend ◽  
Proposed Model ◽  
The Brain

Nondeclarative memory and novelty processing in the brain is an actively studied field of neuroscience, and reducing neural activity with repetition of a stimulus (repetition suppression) is a commonly observed phenomenon. Recent findings of an opposite trend—specifically, rising activity for unfamiliar stimuli—question the generality of repetition suppression and stir debate over the underlying neural mechanisms. This letter introduces a theory and computational model that extend existing theories and suggests that both trends are, in principle, the rising and falling parts of an inverted U-shaped dependence of activity with respect to stimulus novelty that may naturally emerge in a neural network with Hebbian learning and lateral inhibition. We further demonstrate that the proposed model is sufficient for the simulation of dissociable forms of repetition priming using real-world stimuli. The results of our simulation also suggest that the novelty of stimuli used in neuroscientific research must be assessed in a particularly cautious way. The potential importance of the inverted-U in stimulus processing and its relationship to the acquisition of knowledge and competencies in humans is also discussed.

Neuromodulation of Brain State and Behavior

2020 ◽  
Vol 43 (1) ◽  
pp. 391-415 ◽  
Author(s):  
David A. McCormick ◽  
Dennis B. Nestvogel ◽  
Biyu J. He
Keyword(s):  
Neural Activity ◽  
Behavioral Responses ◽  
Neural Mechanisms ◽  
Brain State ◽  
Neural Pathways ◽  
Repeated Presentation ◽  
Waking State ◽  
And Behavior ◽  
Fast Acting ◽  
The Brain

Neural activity and behavior are both notoriously variable, with responses differing widely between repeated presentation of identical stimuli or trials. Recent results in humans and animals reveal that these variations are not random in their nature, but may in fact be due in large part to rapid shifts in neural, cognitive, and behavioral states. Here we review recent advances in the understanding of rapid variations in the waking state, how variations are generated, and how they modulate neural and behavioral responses in both mice and humans. We propose that the brain has an identifiable set of states through which it wanders continuously in a nonrandom fashion, owing to the activity of both ascending modulatory and fast-acting corticocortical and subcortical-cortical neural pathways. These state variations provide the backdrop upon which the brain operates, and understanding them is critical to making progress in revealing the neural mechanisms underlying cognition and behavior.

scholarly journals Effect of intracerebroventricular benzamil on cardiovascular and central autonomic responses to DOCA-salt treatment

2010 ◽  
Vol 299 (6) ◽  
pp. R1500-R1510 ◽  
Author(s):  
Joanna M. Abrams ◽  
William C. Engeland ◽  
John W. Osborn
Keyword(s):  
Neural Activity ◽  
Sympathetic Activity ◽  
Supraoptic Nucleus ◽  
Salt Treatment ◽  
Salt Hypertension ◽  
Premotor Neurons ◽  
Study Completion ◽  
The Brain ◽  
Regulatory Sites

DOCA-salt treatment increases mean arterial pressure (MAP), while central infusion of benzamil attenuates this effect. The present study used c-Fos immunoreactivity to assess the role of benzamil-sensitive proteins in the brain on neural activity following chronic DOCA-salt treatment. Uninephrectomized rats were instrumented with telemetry transmitters for measurement of MAP and with an intracerebroventricular (ICV) cannula for benzamil administration. Groups included rats receiving DOCA-salt treatment alone, rats receiving DOCA-salt treatment with ICV benzamil, and appropriate controls. At study completion, MAP in vehicle-treated DOCA-salt rats reached 142 ± 4 mmHg. In contrast DOCA-salt rats receiving ICV benzamil had lower MAP (124 ± 3 mmHg). MAP in normotensive controls was 102 ± 3 mmHg. c-Fos immunoreactivity was quantified in the supraoptic nucleus (SON) and across subnuclei of the hypothalamic paraventricular nucleus (PVN), as well as other cardiovascular regulatory sites. Compared with vehicle-treated normotensive controls, c-Fos expression was increased in the SON and all subnuclei of the PVN, but not in other key autonomic nuclei, such as the rostroventrolateral medulla. Moreover, benzamil treatment decreased c-Fos immunoreactivity in the SON and in medial parvocellular and posterior magnocellular neurons of the PVN in DOCA-salt rats but not areas associated with regulation of sympathetic activity. Our results do not support the hypothesis that DOCA-salt increases neuronal activity (as indicated by c-Fos immunoreactivity) of other key regions that regulate sympathetic activity. These results suggest that ICV benzamil attenuates DOCA-salt hypertension by modulation of neuroendocrine-related PVN nuclei rather than inhibition of PVN sympathetic premotor neurons in the PVN and rostroventrolateral medulla.

Loss of cholecystokinin and glucagon-like peptide-1-induced satiation in mice lacking serotonin 2C receptors

2009 ◽  
Vol 296 (1) ◽  
pp. R51-R56 ◽  
Author(s):  
Lori Asarian
Keyword(s):  
Neural Mechanisms ◽  
Wild Type ◽  
Gut Peptides ◽  
Serotonin Signaling ◽  
The Central Nervous System ◽  
Fos Expression ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1 ◽  
The Brain

To investigate the role of serotonin 2C receptors (2CR), which are expressed only in the central nervous system, in the satiating actions of the gut peptides CCK and glucagon-like peptide 1 (GLP-1), we examined 1) the effect of null mutations of serotonin 2CR (2CR KO) on the eating-inhibitory potencies of dark-onset intraperitoneal injections of 0.9, 1.7, or 3.5 nmol/kg (1, 2, or 4 μg/kg) CCK and 100, 200, and 400 nmol/kg (33, 66, or 132 μg/kg) GLP-1, and 2) the effects of intraperitoneal injections of 1.7 nmol//kg CCK and 100 nmol/kg GLP-1 on neuronal activation in the brain, as measured by c-Fos expression. All CCK and GLP-1 doses decreased 30-min food intake in wild-type (WT) mice, but none of them did in 2CR KO mice. CCK increased the number of cells expressing c-Fos in the nucleus tractus solitarii (NTS) of WT, but not 2CR KO mice. CCK induced similar degrees of c-Fos expression in the paraventricular (PVN) and arcuate (Arc) nuclei of the hypothalamus of both genotypes. GLP-1, on the other hand, increased c-Fos expression similarly in the NTS of both genotypes and increased c-Fos expression more in the PVN and Arc of 2CR KO mice, but not WT mice. These results indicate that serotonin signaling via serotonin 2CR is necessary for the full satiating effects of CCK and GLP-1. In addition, they suggest that the satiating effects of the two peptides are mediated by different neural mechanisms.

scholarly journals Awake reactivation and suppression after brief task exposure depend on task novelty

2019 ◽  
Author(s):  
Ji Won Bang ◽  
Dobromir Rahnev
Keyword(s):  
Performance Improvement ◽  
Neural Activity ◽  
Memory Consolidation ◽  
The Novel ◽  
Exact Role ◽  
Visual Training ◽  
Early Visual Cortex ◽  
Task Processing ◽  
The Brain

AbstractPreviously learned information is known to be reactivated during periods of quiet wakefulness and such awake reactivation is considered to be a key mechanism for memory consolidation. We recently demonstrated that feature-specific awake reactivation occurs in early visual cortex immediately after extensive visual training on a novel task. To understand the exact role of awake reactivation, here we investigated whether such reactivation depends specifically on the task novelty. Subjects completed a brief visual task that was either novel or extensively trained on previous days. Replicating our previous results, we found that awake reactivation occurs for the novel task even after a brief learning period. Surprisingly, however, brief exposure to the extensively trained task led to “awake suppression” such that neural activity immediately after the exposure diverged from the pattern for the trained task. Further, subjects who had greater performance improvement showed stronger awake suppression. These results suggest that the brain operates different post-task processing depending on prior visual training.

Neural Oscillations Orchestrate Multisensory Processing

2018 ◽  
Vol 24 (6) ◽  
pp. 609-626 ◽  
Author(s):  
Julian Keil ◽  
Daniel Senkowski
Keyword(s):  
Information Needs ◽  
Recent Literature ◽  
Multisensory Processing ◽  
Neural Mechanisms ◽  
Multisensory Perception ◽  
Neural Oscillations ◽  
Top Down ◽  
Cortical Areas ◽  
Distinct Frequency

At any given moment, we receive input through our different sensory systems, and this information needs to be processed and integrated. Multisensory processing requires the coordinated activity of distinct cortical areas. Key mechanisms implicated in these processes include local neural oscillations and functional connectivity between distant cortical areas. Evidence is now emerging that neural oscillations in distinct frequency bands reflect different mechanisms of multisensory processing. Moreover, studies suggest that aberrant neural oscillations contribute to multisensory processing deficits in clinical populations, such as schizophrenia. In this article, we review recent literature on the neural mechanisms underlying multisensory processing, focusing on neural oscillations. We derive a framework that summarizes findings on (1) stimulus-driven multisensory processing, (2) the influence of top-down information on multisensory processing, and (3) the role of predictions for the formation of multisensory perception. We propose that different frequency band oscillations subserve complementary mechanisms of multisensory processing. These processes can act in parallel and are essential for multisensory processing.

Hierarchical learning of statistical regularities over multiple timescales of sound sequence processing: A dynamic causal modelling study

2019 ◽  
Author(s):  
Kaitlin Fitzgerald ◽  
Ryszard Auksztulewicz ◽  
Alexander Provost ◽  
Bryan Paton ◽  
Zachary Howard ◽  
...  
Keyword(s):  
Evoked Potentials ◽  
Auditory System ◽  
Neural Activity ◽  
Auditory Evoked Potentials ◽  
Pattern Learning ◽  
Multiple Timescales ◽  
Causal Modelling ◽  
Sound Sequence ◽  
The Brain ◽  
Dynamic Causal Modelling

AbstractThe nervous system is endowed with predictive capabilities, updating neural activity to reflect recent stimulus statistics in a manner which optimises processing of expected future states. This process has previously been formulated within a predictive coding framework, where sensory input is either “explained away” by accurate top-down predictions, or leads to a salient prediction error which triggers an update to the existing prediction when inaccurate. However, exactly how the brain optimises predictive processes in the stochastic and multi-faceted real-world environment remains unclear. Auditory evoked potentials have proven a useful measure of monitoring unsupervised learning of patterning in sound sequences through modulations of the mismatch negativity component which is associated with “change detection” and widely used as a proxy for indexing learnt regularities. Here we used dynamic causal modelling to analyse scalp-recorded auditory evoked potentials collected during presentation of sound sequences consisting of multiple, nested regularities and extend on previous observations of pattern learning restricted to the scalp level or based on single-outcome events. Patterns included the regular characteristics of the two tones presented, consistency in their relative probabilities as either common standard (p = .875) or rare deviant (p = .125), and the regular rate at which these tone probabilities alternated. Significant changes in connectivity reflecting a drop in the precision of prediction errors based on learnt patterns were observed at three points in the sound sequence, corresponding to the three hierarchical levels of nested regularities: (1) when an unexpected “deviant” sound was encountered; (2) when the probabilities of the two tonal states altered; and (3) when there was a change in rate at which probabilities in tonal state changed. These observations provide further evidence of simultaneous pattern learning over multiple timescales, reflected through changes in neural activity below the scalp.Author summaryOur physical environment is comprised of regularities which give structure to our world. This consistency provides the basis for experiential learning, where we can increasingly master our interactions with our surroundings based on prior experience. This type of learning also guides how we sense and perceive the world. The sensory system is known to reduce responses to regular and predictable patterns of input, and conserve neural resources for processing input which is new and unexpected. Temporal pattern learning is particularly important for auditory processing, in disentangling overlapping sound streams and deciphering the information value of sound. For example, understanding human language requires an exquisite sensitivity to the rhythm and tempo of speech sounds. Here we elucidate the sensitivity of the auditory system to concurrent temporal patterning during a sound sequence consisting of nested patterns over three timescales. We used dynamic causal modelling to demonstrate that the auditory system monitors short, intermediate and longer-timescale patterns in sound simultaneously. We also show that these timescales are each represented by distinct connections between different brain areas. These findings support complex interactions between different areas of the brain as responsible for the ability to learn sophisticated patterns in sound even without conscious attention.

Dorsolateral Prefrontal Cortex Enables Updating of Established Memories

2018 ◽  
Vol 29 (10) ◽  
pp. 4154-4168 ◽  
Author(s):  
Lisa Marieke Kluen ◽  
Lisa Catherine Dandolo ◽  
Gerhard Jocham ◽  
Lars Schwabe
Keyword(s):  
Prefrontal Cortex ◽  
Dorsolateral Prefrontal Cortex ◽  
Neural Mechanisms ◽  
Related Activity ◽  
Future Behavior ◽  
New Information ◽  
Dorsolateral Prefrontal ◽  
Increased Activity ◽  
The Brain

Abstract Updating established memories in light of new information is fundamental for memory to guide future behavior. However, little is known about the brain mechanisms by which existing memories can be updated. Here, we combined functional magnetic resonance imaging and multivariate representational similarity analysis to elucidate the neural mechanisms underlying the updating of consolidated memories. To this end, participants first learned face–city name pairs. Twenty-four hours later, while lying in the MRI scanner, participants were required to update some of these associations, but not others, and to encode entirely new pairs. Updating success was tested again 24 h later. Our results showed increased activity of the dorsolateral prefrontal cortex (dlPFC) specifically during the updating of existing associations that was significantly stronger than when simple retrieval or new encoding was required. The updating-related activity of the dlPFC and its functional connectivity with the hippocampus were directly linked to updating success. Furthermore, neural similarity for updated items was markedly higher in the dlPFC and this increase in dlPFC neural similarity distinguished individuals with high updating performance from those with low updating performance. Together, these findings suggest a key role of the dlPFC, presumably in interaction with the hippocampus, in the updating of established memories.

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