scholarly journals Processing of Degraded Speech in Brain Disorders

2021 ◽  
Vol 11 (3) ◽  
pp. 394
Author(s):  
Jessica Jiang ◽  
Elia Benhamou ◽  
Sheena Waters ◽  
Jeremy C. S. Johnson ◽  
Anna Volkmer ◽  
...  
Keyword(s):  
Neural Plasticity ◽  
Speech Processing ◽  
Neural Circuit ◽  
Predictive Coding ◽  
Brain Disorders ◽  
Healthy Individuals ◽  
Degraded Speech ◽  
The Brain ◽  
Sensitive Marker ◽  
Language Network

The speech we hear every day is typically “degraded” by competing sounds and the idiosyncratic vocal characteristics of individual speakers. While the comprehension of “degraded” speech is normally automatic, it depends on dynamic and adaptive processing across distributed neural networks. This presents the brain with an immense computational challenge, making degraded speech processing vulnerable to a range of brain disorders. Therefore, it is likely to be a sensitive marker of neural circuit dysfunction and an index of retained neural plasticity. Considering experimental methods for studying degraded speech and factors that affect its processing in healthy individuals, we review the evidence for altered degraded speech processing in major neurodegenerative diseases, traumatic brain injury and stroke. We develop a predictive coding framework for understanding deficits of degraded speech processing in these disorders, focussing on the “language-led dementias”—the primary progressive aphasias. We conclude by considering prospects for using degraded speech as a probe of language network pathophysiology, a diagnostic tool and a target for therapeutic intervention.

scholarly journals THE VISUAL SYSTEM: A "CHICKEN AND EGG" PROBLEM SOLVED

2009 ◽  
Vol 05 (01) ◽  
pp. 115-121
Author(s):  
ANDREW R. PARKER ◽  
H. JOHN CAULFIELD
Keyword(s):  
Visual System ◽  
Neural Plasticity ◽  
Neural Circuit ◽  
Process Data ◽  
System A ◽  
New Information ◽  
The Brain

"What comes first: the chicken or the egg?" Eyes and vision were a great concern for Darwin. Recently, religious fundamentalists have started to attack evolution on the grounds that this is a chicken and egg problem. How could eyes improve without the brain module to use the new information that eye provides? But how could the brain evolve a neural circuit to process data not available to it until a new eye capability emerges? We argue that neural plasticity in the brain allows it to make use of essentially any useful information the eye can produce. And it does so easily within the animal's lifetime. Richard Gregory suggested something like this 40 years ago. Our work resolves a problem with his otherwise-insightful work.

scholarly journals Neural Mechanisms and Psychology of Psychedelic Ego Dissolution

2021 ◽  
Author(s):  
Devon Stoliker ◽  
Gary F. Egan ◽  
Karl Friston ◽  
Adeel Razi
Keyword(s):  
Neural Plasticity ◽  
Message Passing ◽  
Functional Neuroimaging ◽  
Effective Connectivity ◽  
Predictive Coding ◽  
Therapeutic Effects ◽  
Long Term Effects ◽  
Cortical Hierarchy ◽  
The Brain

Neuroimaging studies of psychedelics have advanced our understanding of hierarchical brain organisation and the mechanisms underlying their subjective and therapeutic effects. The primary mechanism of action of classic psychedelics is binding to serotonergic 5HT2A receptors. Agonist activity at these receptors leads to neuromodulatory changes in synaptic efficacy that can have a profound effect on hierarchical message passing in the brain. Here, we review the cognitive and neuroimaging evidence for the effects of psychedelics; in particular, their influence on selfhood and subject-object boundaries—known as ego dissolution—surmised to underwrite their subjective and therapeutic effects. Agonist of 5HT2A receptors, located at the apex of the cortical hierarchy may have a particularly powerful effect on sentience and consciousness. These effects can endure well after the pharmacological half life, suggesting that psychedelics may have long-term effects on neural plasticity – that may play a role in their therapeutic efficacy. Psychologically, this may be accompanied by a surrender of ego resistance that increases the repertoire of perceptual hypotheses, including those that undergird selfhood. We consider the interaction between serotonergic neuromodulation and sentience through the lens of hierarchical predictive coding, which speaks to the value of psychedelics in understanding how we make sense of the world—and specific predictions about effective connectivity in cortical hierarchies that can be tested using functional neuroimaging.

Perception without Inferences

2017 ◽  
Author(s):  
Shaun Gallagher
Keyword(s):  
Neural Plasticity ◽  
Cultural Practices ◽  
Predictive Coding ◽  
Cognitive Penetration ◽  
Inference Models ◽  
Neuronal Processes ◽  
Set Up ◽  
And Function ◽  
The Brain ◽  
Bodily Movements

This chapter examines inference models of perception, including predictive coding models, and offers an enactivist alternative. It explores how the enactivist approach can respond to issues related to cognitive penetration and the effects of culture on perception. The enactivist view appeals to an account of the co-variant coupling of brain–body–environment, structured by the physical aspects of neuronal processes, bodily movements, affects, anatomy and function, and environmental regularities. Changes in any of these factors mean that perception changes. Processes involved in neural plasticity (where the brain is ‘set up to be set off’), and metaplasticity, where material and cultural practices define environmental regularities, mitigate the need to think that subpersonal perceptual processes are inferential.

scholarly journals Endogenous activity modulates stimulus and circuit-specific neural tuning and perception

2019 ◽  
Author(s):  
Yuanning Li ◽  
Michael J. Ward ◽  
R. Mark Richardson ◽  
Max G’Sell ◽  
Avniel Singh Ghuman
Keyword(s):  
Reaction Time ◽  
Neural Circuits ◽  
Neural Circuit ◽  
Predictive Coding ◽  
Sensory Inputs ◽  
Specific Manner ◽  
Endogenous Activity ◽  
Intracranial Recordings ◽  
The Brain

AbstractPerception reflects not only input from the sensory periphery, but also the endogenous neural state when sensory inputs enter the brain. Whether endogenous neural states influence perception only through global mechanisms, such as arousal, or can also perception in a neural circuit and stimulus specific manner remains largely unknown. Intracranial recordings from 30 pre-surgical epilepsy patients showed that endogenous activity independently modulated the strength of trial-by-trial neural tuning of different visual category-selective neural circuits. Furthermore, the same aspect of the endogenous activity that influenced tuning in a particular neural circuit also correlated with reaction time only for trials with the category of image that circuit was selective for. These results suggest that endogenous activity may influence neural tuning and perception through circuit-specific predictive coding processes.

Adaptive and Maladaptive Neural Plasticity Due to Facial Nerve Palsy

2016 ◽  
Vol 224 (2) ◽  
pp. 102-111 ◽  
Author(s):  
Carsten M. Klingner ◽  
Stefan Brodoehl ◽  
Gerd F. Volk ◽  
Orlando Guntinas-Lichius ◽  
Otto W. Witte
Keyword(s):  
Facial Nerve ◽  
Neural Plasticity ◽  
Cortical Plasticity ◽  
Brain Plasticity ◽  
Motor Nerve ◽  
Predictive Coding ◽  
Theoretical Framework ◽  
Cortical Reorganization ◽  
Nerve Lesion ◽  
Peripheral Facial Palsy

Abstract. This paper reviews adaptive and maladaptive mechanisms of cortical plasticity in patients suffering from peripheral facial palsy. As the peripheral facial nerve is a pure motor nerve, a facial nerve lesion is causing an exclusive deefferentation without deafferentation. We focus on the question of how the investigation of pure deefferentation adds to our current understanding of brain plasticity which derives from studies on learning and studies on brain lesions. The importance of efference and afference as drivers for cortical plasticity is discussed in addition to the crossmodal influence of different competitive sensory inputs. We make the attempt to integrate the experimental findings of the effects of pure deefferentation within the theoretical framework of cortical responses and predictive coding. We show that the available experimental data can be explained within this theoretical framework which also clarifies the necessity for maladaptive plasticity. Finally, we propose rehabilitation approaches for directing cortical reorganization in the appropriate direction and highlight some challenging questions that are yet unexplored in the field.

scholarly journals Synergistic Effect of Several Neurotransmitters in PFC-NAc-VTA Neural Circuit for the Anti-Depression Effect of Shuganheweitang in a Chronic Unpredictable Mild Stress Model

2021 ◽  
Vol 16 (3) ◽  
pp. 1934578X2110024
Author(s):  
Xin Chen ◽  
Yuanchun Ma ◽  
Xiongjun Mou ◽  
Hao Liu ◽  
Hao Ming ◽  
...  
Keyword(s):  
Animal Behavior ◽  
Neural Circuit ◽  
Concentration Level ◽  
Brain Regions ◽  
Mild Stress ◽  
Depression Effect ◽  
Monoamine Neurotransmitters ◽  
Reward Circuitry ◽  
High Doses ◽  
The Brain

Depression, a major worldwide mental disorder, leads to massive disability and can result in death. The PFC-NAc-VTA neuro circuit is related to emotional, neurovegetative, and cognitive functions, which emerge as a circuit-level framework for understanding reward deficits in depression. Neurotransmitters, which are widely distributed in different brain regions, are important detected targets for the evaluation of depression. Shuganheweitang (SGHWT) is a popular prescription in clinical therapy for depression. In order to investigate its possible pharmacodynamics and anti-depressive mechanism, the complex plant material was separated into different fractions. These in low and high doses, along with low and high doses of SGHWT were tested in animal behavior tests. The low and high doses of SGHWT were more effective than the various fractions, which indicate the importance of synergistic function in traditional Chinese medicine. Furthermore, amino acid (GABA, Glu) and monoamine neurotransmitters (DA, 5-HT, NA, 5-HIAA) in the PFC-NAc-VTA neuro circuit were investigated by UPLC-MS/MS. The level trend of DA and 5-HT were consistent in the PFC-NAc-VTA neuro circuit, whereas 5-HIAA was decreased in the PFC, Glu was decreased in the PFC and VTA, and NA and GABA were decreased in the NAc. The results indicate that the pathogenesis of depression is associated with dysfunction of the PFC-NAc-VTA neural circuit, mainly through the neural projection effects of neurotransmitters associated with various brain regions in the neural circuit. PCA and OPLS-DA score plots demonstrated the similarities of individuals within each group and the differences among the groups. In this study, SGHWT could regulate the concentration level of different neurotransmitters in the PFC-NAc-VTA neuro circuit to improve the depression, which benefitted from the recognition of the brain reward circuitry in mood disorders.

scholarly journals Neural circuit function redundancy in brain disorders

2021 ◽  
Vol 70 ◽  
pp. 74-80
Author(s):  
Beatriz E.P. Mizusaki ◽  
Cian O'Donnell
Keyword(s):  
Neural Circuit ◽  
Brain Disorders ◽  
Circuit Function

9 When the spark goes out: the neurology of apathy and motivation

2021 ◽  
Vol 92 (8) ◽  
pp. A3.2-A3
Author(s):  
Masud Husain
Keyword(s):  
Cognitive Outcome ◽  
Healthy People ◽  
Brain Disorders ◽  
Healthy Individuals ◽  
Neurological Patient ◽  
Dopaminergic Medication ◽  
Basal Ganglia Involvement ◽  
Goal Directed Behavior ◽  
Lines Of Evidence

Disorders of motivation are common across brain disorders. Clinicians frequently encounter pathological apathy across a range of conditions, including many neurodegenerative conditions such as small cerebrovascular disease, Parkinsons and Alzheimers disease. It is now becoming understood that apathy has a poor prognosis for long-term functional and cognitive outcome. Unfortunately, we understand very little about the mechanisms underlying the syndrome.In this talk, I shall put forward a conceptual framework with which we can begin to understand apathy by considering the processes that normally underlie motivated, goal- directed behavior. In particular Ill focus on the ability to generate options for behavior and effort-based decision making for rewards. Recent studies of the latter have been particularly revealing in both healthy people and neurological patient populations.Several lines of evidence suggest that when we make decisions about how much effort we might invest in actions, we weigh up the costs involved for the potential rewards to be obtained. Functional imaging in healthy people reveals both medial frontal and basal ganglia involvement when individuals make such decisions. In patients with apathy, this evaluation is altered. Apathetic patients show blunted sensitivity to rewards and less inclination to invest effort for low rewards than healthy individuals. Some evidence shows that these factors can be improved by dopaminergic medication. The findings support the view that it might be possible to provide a mechanistic account of the syndrome of apathy which might lead to treatments for the disorder.

Striatal dopamine mediates hallucination-like perception in mice

Science ◽  
2021 ◽  
Vol 372 (6537) ◽  
pp. eabf4740
Author(s):  
K. Schmack ◽  
M. Bosc ◽  
T. Ott ◽  
J. F. Sturgill ◽  
A. Kepecs
Keyword(s):  
Psychotic Disorders ◽  
Neural Circuit ◽  
Dopamine Neurons ◽  
Striatal Dopamine ◽  
Model Organisms ◽  
High Confidence ◽  
Optogenetic Stimulation ◽  
The Brain ◽  
Central Symptom ◽  
Stimulation Of

Hallucinations, a central symptom of psychotic disorders, are attributed to excessive dopamine in the brain. However, the neural circuit mechanisms by which dopamine produces hallucinations remain elusive, largely because hallucinations have been challenging to study in model organisms. We developed a task to quantify hallucination-like perception in mice. Hallucination-like percepts, defined as high-confidence false detections, increased after hallucination-related manipulations in mice and correlated with self-reported hallucinations in humans. Hallucination-like percepts were preceded by elevated striatal dopamine levels, could be induced by optogenetic stimulation of mesostriatal dopamine neurons, and could be reversed by the antipsychotic drug haloperidol. These findings reveal a causal role for dopamine-dependent striatal circuits in hallucination-like perception and open new avenues to develop circuit-based treatments for psychotic disorders.

Sign in / Sign up

Export Citation Format

Share Document