scholarly journals Mechanisms of saccade suppression revealed in the anti-saccade task

2017 ◽  
Vol 372 (1718) ◽  
pp. 20160192 ◽  
Author(s):  
Brian C. Coe ◽  
Douglas P. Munoz
Keyword(s):  
Reaction Times ◽  
Complex Nature ◽  
Valuable Insight ◽  
Different Types ◽  
Natural Response ◽  
Saccade Task ◽  
Saccadic Reaction Times ◽  
Time Courses ◽  
The Brain ◽  
Insight Into

The anti-saccade task has emerged as an important tool for investigating the complex nature of voluntary behaviour. In this task, participants are instructed to suppress the natural response to look at a peripheral visual stimulus and look in the opposite direction instead. Analysis of saccadic reaction times (SRT: the time from stimulus appearance to the first saccade) and the frequency of direction errors (i.e. looking toward the stimulus) provide insight into saccade suppression mechanisms in the brain. Some direction errors are reflexive responses with very short SRTs (express latency saccades), while other direction errors are driven by automated responses and have longer SRTs. These different types of errors reveal that the anti-saccade task requires different forms of suppression, and neurophysiological experiments in macaques have revealed several potential mechanisms. At the start of an anti-saccade trial, pre-emptive top-down inhibition of saccade generating neurons in the frontal eye fields and superior colliculus must be present before the stimulus appears to prevent express latency direction errors. After the stimulus appears, voluntary anti-saccade commands must compete with, and override, automated visually initiated saccade commands to prevent longer latency direction errors. The frequencies of these types of direction errors, as well as SRTs, change throughout the lifespan and reveal time courses for development, maturation, and ageing. Additionally, patients diagnosed with a variety of neurological and/or psychiatric disorders affecting the frontal lobes and/or basal ganglia produce markedly different SRT distributions and types of direction errors, which highlight specific deficits in saccade suppression and inhibitory control. The anti-saccade task therefore provides valuable insight into the neural mechanisms of saccade suppression and is a valuable tool in a clinical setting. This article is part of the themed issue ‘Movement suppression: brain mechanisms for stopping and stillness’.

scholarly journals Giving Subjects the Eye and Showing Them the Finger: Socio-Biological Cues and Saccade Generation in the Anti-Saccade Task

Perception ◽  
10.1068/p7085 ◽  
2012 ◽  
Vol 41 (2) ◽  
pp. 131-147 ◽  
Author(s):  
Nicola J Gregory ◽  
Timothy L Hodgson
Keyword(s):  
Opposite Direction ◽  
Reaction Times ◽  
Oculomotor System ◽  
Short Soas ◽  
Stimulus Onset ◽  
Saccade Direction ◽  
Saccade Task ◽  
Saccadic Reaction Times ◽  
Saccadic Responses ◽  
Gaze Cues

Pointing with the eyes or the finger occurs frequently in social interaction to indicate direction of attention and one's intentions. Research with a voluntary saccade task (where saccade direction is instructed by the colour of a fixation point) suggested that gaze cues automatically activate the oculomotor system, but non-biological cues, like arrows, do not. However, other work has failed to support the claim that gaze cues are special. In the current research we introduced biological and non-biological cues into the anti-saccade task, using a range of stimulus onset asynchronies (SOAs). The anti-saccade task recruits both top–down and bottom–up attentional mechanisms, as occurs in naturalistic saccadic behaviour. In experiment 1 gaze, but not arrows, facilitated saccadic reaction times (SRTs) in the opposite direction to the cues over all SOAs, whereas in experiment 2 directional word cues had no effect on saccades. In experiment 3 finger pointing cues caused reduced SRTs in the opposite direction to the cues at short SOAs. These findings suggest that biological cues automatically recruit the oculomotor system whereas non-biological cues do not. Furthermore, the anti-saccade task set appears to facilitate saccadic responses in the opposite direction to the cues.

scholarly journals Neural signatures of vigilance decrements predict behavioural errors before they occur

2020 ◽  
Author(s):  
Hamid Karimi-Rouzbahani ◽  
Alexandra Woolgar ◽  
Anina N. Rich
Keyword(s):  
Reaction Times ◽  
Neural Correlates ◽  
Neural Representation ◽  
Neural Data ◽  
Active Condition ◽  
Behavioural Performance ◽  
Target Monitoring ◽  
The Brain ◽  
Insight Into ◽  
Over Time

AbstractThere are many monitoring environments, such as railway control, in which lapses of attention can have tragic consequences. Problematically, sustained monitoring for rare targets is difficult, with more misses and longer reaction times over time. What changes in the brain underpin these “vigilance decrements”? We designed a multiple-object monitoring (MOM) paradigm to examine how the neural representation of information varied with target frequency and time performing the task. Behavioural performance decreased over time for the rare target (monitoring) condition, but not for a frequent target (active) condition. This was mirrored in the neural results: there was weaker coding of critical information during monitoring versus active conditions. We developed new analyses that can predict behavioural errors from the neural data more than a second before they occurred. This paves the way for pre-empting behavioural errors due to lapses in attention and provides new insight into the neural correlates of vigilance decrements.

scholarly journals Quantification and selection of ictogenic zones in epilepsy surgery

2019 ◽  
Author(s):  
Petroula Laiou ◽  
Eleftherios Avramidis ◽  
Marinho A. Lopes ◽  
Eugenio Abela ◽  
Michael Müller ◽  
...  
Keyword(s):  
Computational Models ◽  
Brain Networks ◽  
Network Models ◽  
Combinatorial Problem ◽  
Valuable Insight ◽  
Potential Applicability ◽  
Healthy Functioning ◽  
The Brain ◽  
Insight Into ◽  
Selection Of

AbstractNetwork models of brain dynamics provide valuable insight into the healthy functioning of the brain and how this breaks down in disease. A pertinent example is the use of network models to understand seizure generation (ictogenesis) in epilepsy. Recently, computational models have emerged to aid our understanding of seizures and to predict the outcome of surgical perturbations to brain networks. Such approaches provide the opportunity to quantify the effect of removing regions of tissue from brain networks and thereby search for the optimal resection strategy.Here, we use computational models to elucidate how sets of nodes contribute to the ictogenicity of networks. In small networks we fully elucidate the ictogenicity of all possible sets of nodes and demonstrate that the distribution of ictogenicity across sets depends on network topology. However, the full elucidation is a combinatorial problem that becomes intractable for large networks. Therefore, we develop a global optimisation approach to search for minimal sets of nodes that contribute significantly to ictogenesis. We demonstrate the potential applicability of these methods in practice by identifying optimal sets of nodes to resect in networks derived from 20 individuals who underwent resective surgery for epilepsy.

scholarly journals Global disruption in excitation-inhibition balance can cause localized network dysfunction and Schizophrenia-like context-integration deficits

2021 ◽  
Vol 17 (5) ◽  
pp. e1008985
Author(s):  
Olivia L. Calvin ◽  
A. David Redish
Keyword(s):  
Decision Making ◽  
Contextual Information ◽  
Reaction Times ◽  
Pyramidal Cells ◽  
Current Information ◽  
Different Types ◽  
Decision Making System ◽  
Memory Network ◽  
Context Integration ◽  
The Brain

Poor context integration, the process of incorporating both previous and current information in decision making, is a cognitive symptom of schizophrenia. The maintenance of the contextual information has been shown to be sensitive to changes in excitation-inhibition (EI) balance. Many regions of the brain are sensitive to EI imbalances, however, so it is unknown how systemic manipulations affect the specific regions that are important to context integration. We constructed a multi-structure, biophysically-realistic agent that could perform context-integration as is assessed by the dot pattern expectancy task. The agent included a perceptual network, a memory network, and a decision making system and was capable of successfully performing the dot pattern expectancy task. Systemic manipulation of the agent’s EI balance produced localized dysfunction of the memory structure, which resulted in schizophrenia-like deficits at context integration. When the agent’s pyramidal cells were less excitatory, the agent fixated upon the cue and initiated responding later than the default agent, which were like the deficits one would predict that individuals on the autistic spectrum would make. This modelling suggests that it may be possible to parse between different types of context integration deficits by adding distractors to context integration tasks and by closely examining a participant’s reaction times.

Language Theory, Phonology and Etymology in Buddhism and their relationship to Brahmanism

2017 ◽  
Vol 34 (1) ◽  
pp. 25-51
Author(s):  
Bryan Geoffrey Levman
Keyword(s):  
Classification System ◽  
First Language ◽  
Theoretical Framework ◽  
Language Theory ◽  
Valuable Insight ◽  
Ultimate Truth ◽  
Different Types ◽  
The Creation ◽  
The Buddha ◽  
Insight Into

The Buddha considered names of things and people to be arbitrary designations, with their meaning created by agreement. The early suttas show clearly that inter alia, names, perceptions, feelings, thinking, conceptions and mental proliferations were all conditioned dhammas which, when their nature is misunderstood, led to the creation of a sense of ‘I’, as well as craving, clinging and afflictions. Although names were potentially afflictive and ‘had everything under their power’ (N?ma Sutta), this did not mean that they were to be ignored or even neglected; words were to be penetrated and thoroughly understood, as an essential instrument for liberation. One of the problems of transmitting the Buddha’s teachings was the large number of disciples who did not speak an Indo-Aryan language as their first language or spoke a dialect different from that of the Teacher. This also led to altered transmission of the Vinaya and Suttas by disciples who could not hear certain phonological distinctions not present in their own language or dialect. Hundreds of these anomalies are preserved in the different editions of the canon, testifying to these transmission ambiguities. The passages dealing with this problem provide a valuable insight into the phonological issues that the early sa?gha had to deal with to try and preserve the integrity of the s?sana. At the same time the etymological practices of Brahmanism were imported into Buddhism very early, probably from the time of the Buddha himself, to demonstrate the intellectual superiority of the Buddha and his teachings. Despite the Buddha’s teachings on the arbitrary nature of language, the commentarial and grammatical traditions developed a sophisticated theoretical framework to analyse, explicate and reinforce some of the key Buddhist doctrinal terms. Also, an elaborate classification system of different types of names (n?man) was developed, to show that the language of the Buddha was firmly grounded in saccika??ha, the highest truth, and that some terms were spontaneously arisen (opap?tika), even though such a concept — that words by themselves could arise spontaneously and directly embody ultimate truth — was quite foreign to their Founder.

scholarly journals CT-Guided Placement of a Neuromonitoring Suite in Swine for Trauma and Resuscitation Research

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Janet Elise Bonin, BS ◽  
Hossam Abdou, MD ◽  
Joseph Edwards, MD ◽  
Neerav Patel, MD ◽  
Michael Richmond, BS ◽  
...  
Keyword(s):  
Cerebral Perfusion ◽  
Brain Perfusion ◽  
Brain Parenchyma ◽  
Burr Hole ◽  
Valuable Insight ◽  
Ct Guided ◽  
Laser Doppler Flow ◽  
The Brain ◽  
Insight Into ◽  
Pressure Catheter

Background: This manuscript aims to describe a standardized method for placement of a neuromonitoring suite into the brain of a porcine model using CT guidance for use in trauma and resuscitation research. Methods: A baseline CT allowed for precise planning of the placement of the neuromonitoring suite including measurement of skull thickness at the location of the intended burr hole. After the burr hole was drilled, three neuromonitoring probes (pressure catheter, temperature probe, and laser doppler flow probe) were advanced into the brain parenchyma of the swine. A subsequent CT confirmed appropriate placement of the neuromonitoring suite. Results: Effective placement of the neuromonitoring suite was accomplished successfully and without complication in 6 Yorkshire swine. Mean duration of the procedure was 49.6 minutes ± 6.3. Representative data from one animal includes the following presented as mean ± standard deviation: intracranial pressure of 10 ± 0 mmHg, cerebral perfusion pressure of 61 ± 1 mmHg, intracranial temperature of 34.8 ± 0 °C, and brain perfusion of 704 ± 13 relative perfusion units. Conclusions: This CT-guided method facilitates placement of a neuromonitoring suite in a safe and reliable manner. The use of a neuromonitoring suite using CT may offer valuable insight into cerebral perfusion in the context of endovascular resuscitation.

Development of conditional imperatives in Japanese: A diachronic constructional approach

2018 ◽  
Vol 29 (2) ◽  
pp. 235-273
Author(s):  
Chiharu Uda Kikuta
Keyword(s):  
Language Change ◽  
Construction Grammar ◽  
Effective Model ◽  
Valuable Insight ◽  
Multiple Inheritance ◽  
Inheritance Model ◽  
Different Types ◽  
New Type ◽  
Grammar Analysis ◽  
Insight Into

AbstractThis paper proposes a diachronic construction grammar analysis of the conditional imperative in Japanese to demonstrate that a constructional approach provides an effective model for language change. The Japanese conditional imperative comprises two types with distinct properties, but no study to date has successfully analyzed how the two types appeared and are related to each other. In diachronic construction grammar, language change is situated in the context of a construction as well as in relation to other constructions linked in a network. This perspective makes it a particularly beneficial model for accommodating the case in question. The construction developed in two steps, exemplifying different types of language change, both of which, however, are motivated by analogy between different constructions. Adopting the multiple inheritance analysis, I contend that the construction first emerged as a result of the reanalysis of a sequence of an imperative sentence and a subsequent sentence as a type of the conditional construction. A later development reflected another case of construction-based analogy: the daughter construction inherited the host-class expansion that occurred in the parent, and the new type emerged as a result of coercion to accommodate the expansion. Thus the development of the Japanese conditional imperative not only finds a consistent analysis in this framework, but provides valuable insight into the workings of the construction network. This paper also addresses the issues of the inheritance model, and suggests the present case argues for a model with default inheritance at the construction level, which runs counter to previous studies which have restricted the overrides of default inheritance to the level of construct.

scholarly journals Neural signatures of vigilance decrements predict behavioural errors before they occur

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Hamid Karimi-Rouzbahani ◽  
Alexandra Woolgar ◽  
Anina N Rich
Keyword(s):  
Reaction Times ◽  
Neural Representation ◽  
Neural Decoding ◽  
Neural Data ◽  
Active Condition ◽  
Behavioural Performance ◽  
Target Monitoring ◽  
The Brain ◽  
Insight Into ◽  
Over Time

There are many monitoring environments, such as railway control, in which lapses of attention can have tragic consequences. Problematically, sustained monitoring for rare targets is difficult, with more misses and longer reaction times over time. What changes in the brain underpin these ‘vigilance decrements’? We designed a multiple-object monitoring (MOM) paradigm to examine how the neural representation of information varied with target frequency and time performing the task. Behavioural performance decreased over time for the rare target (monitoring) condition, but not for a frequent target (active) condition. This was mirrored in neural decoding using magnetoencephalography: coding of critical information declined more during monitoring versus active conditions along the experiment. We developed new analyses that can predict behavioural errors from the neural data more than a second before they occurred. This facilitates pre-empting behavioural errors due to lapses in attention and provides new insight into the neural correlates of vigilance decrements.

Study of the resistor material of an automotive spark plug by use of the charge-up effect along with elemental mapping in an electron microprobe

1991 ◽  
Vol 49 ◽  
pp. 742-743
Author(s):  
D. R. Liu ◽  
S. S. Shinozaki ◽  
J. S. Park ◽  
B. N. Juterbock
Keyword(s):  
Electron Microprobe ◽  
Present Report ◽  
Coated Sample ◽  
Valuable Insight ◽  
Elemental Mapping ◽  
Spark Plug ◽  
Carbon Coated ◽  
Electron Image ◽  
Electron Imaging ◽  
Insight Into

The electric and thermal properties of the resistor material in an automotive spark plug should be stable during its service lifetime. Containing many elements and many phases, this material has a very complex microstructure. Elemental mapping with an electron microprobe can reveal the distribution of all relevant elements throughout the sample. In this work, it is demonstrated that the charge-up effect, which would distort an electron image and, therefore, is normally to be avoided in an electron imaging work, could be used to advantage to reveal conductive and resistive zones in a sample. Its combination with elemental mapping can provide valuable insight into the underlying conductivity mechanism of the resistor.This work was performed in a CAMECA SX-50 microprobe. The spark plug used in the present report was a commercial product taken from the shelf. It was sectioned to expose the cross section of the resistor. The resistor was known not to contain the precious metal Au as checked on the carbon coated sample. The sample was then stripped of carbon coating and re-coated with Au.

“Where is Dementia?” A Systematic Literature Review Exploring Neuroanatomical Aspects of Dementia

2017 ◽  
Vol 2 (15) ◽  
pp. 9-23 ◽  
Author(s):  
Chorong Oh ◽  
Leonard LaPointe
Keyword(s):  
English Language ◽  
Signs And Symptoms ◽  
Behavioral Symptoms ◽  
Journal Articles ◽  
People With Dementia ◽  
Different Types ◽  
Precise Diagnosis ◽  
Physical Changes ◽  
The Brain ◽  
Language Literature

Dementia is a condition caused by and associated with separate physical changes in the brain. The signs and symptoms of dementia are very similar across the diverse types, and it is difficult to diagnose the category by behavioral symptoms alone. Diagnostic criteria have relied on a constellation of signs and symptoms, but it is critical to understand the neuroanatomical differences among the dementias for a more precise diagnosis and subsequent management. With this regard, this review aims to explore the neuroanatomical aspects of dementia to better understand the nature of distinctive subtypes, signs, and symptoms. This is a review of English language literature published from 1996 to the present day of peer-reviewed academic and medical journal articles that report on older people with dementia. This review examines typical neuroanatomical aspects of dementia and reinforces the importance of a thorough understanding of the neuroanatomical characteristics of the different types of dementia and the differential diagnosis of them.

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