scholarly journals Bridging sensory and language theories of dyslexia: towards a multifactorial model

2019 ◽  
Author(s):  
Gabrielle O’Brien ◽  
Jason Yeatman
Keyword(s):  
Decision Making ◽  
Phonological Processing ◽  
Visual Motion ◽  
Reading Skill ◽  
Motion Processing ◽  
List Type ◽  
Deficit Model ◽  
Visual Motion Processing ◽  
Core Deficit ◽  
Sensory Encoding

AbstractCompeting theories of dyslexia posit that reading disability arises from impaired sensory, phonological, or statistical learning mechanisms. Importantly, many theories posit that dyslexia reflects a cascade of impairments emanating from a “core deficit”. Here we collect a battery of psychophysical and language measures in 106 school-aged children to investigate whether dyslexia is best conceptualized under a core-deficit model, or as a disorder with heterogenous origins. Specifically, by capitalizing on the drift diffusion model to separate sensory encoding from task-related influences on performance in a visual motion discrimination experiment, we show that deficits in motion perception, decision making and phonological processing manifest largely independently. Based on statistical models of how variance in reading skill is parceled across measures of sensory encoding, phonological processing and decision-making, our results challenge the notion that a unifying deficit characterizes dyslexia. Instead, these findings indicate a model where reading skill is explained by several distinct, additive predictors, or risk factors, of reading (dis)ability.Research HighlightsOur research provides direct evidence that a single-mechanism, or core-deficit, model of dyslexia cannot account for the range of linguistic and sensory outcomes in children.Individual differences in visual motion processing, perceptual decision making, phonological awareness and rapid naming each account for unique variance in reading skill.Our data support an additive risk-factor model, in which multiple independent dimensions each confer risk for reading difficulties.

scholarly journals Visual motion and decision-making in dyslexia: Evidence of reduced accumulation of sensory evidence and related neural dynamics

2021 ◽  
Author(s):  
Catherine Manning ◽  
Cameron D Hassall ◽  
Laurence T Hunt ◽  
Anthony M Norcia ◽  
Eric-Jan Wagenmakers ◽  
...  
Keyword(s):  
Decision Making ◽  
Visual Information ◽  
Visual Motion ◽  
Motion Processing ◽  
Global Motion ◽  
Perceptual Decision Making ◽  
Behavioural Responses ◽  
Visual Motion Processing ◽  
Decision Making Processes ◽  
Sensory Evidence

Children with and without dyslexia differ in their behavioural responses to visual information, particularly when required to pool dynamic signals over space and time. Importantly, multiple processes contribute to behavioural responses. Here we investigated which processing stages are affected in children with dyslexia when performing visual motion processing tasks, by combining two methods that are sensitive to the dynamic processes leading to responses. We used a diffusion model which decomposes response time and accuracy into distinct cognitive constructs, and high-density EEG. 50 children with dyslexia and 50 typically developing children aged 6 to 14 years judged the direction of motion as quickly and accurately as possible in two global motion tasks, which varied in their requirements for segregating signal-from-noise. Following our pre-registered analyses, we fitted hierarchical Bayesian diffusion models to the data, blinded to group membership. Unblinding revealed reduced evidence accumulation in children with dyslexia compared to typical children for both tasks. We also identified a response-locked EEG component which was maximal over centro-parietal electrodes which indicated a neural correlate of reduced drift-rate in dyslexia, thereby linking brain and behaviour. We suggest that children with dyslexia are slower to extract sensory evidence from global motion displays, regardless of whether they are required to segregate signal-from-noise, thus furthering our understanding of atypical perceptual decision-making processes in dyslexia.

scholarly journals A Dynamic Efficient Sensory Encoding Approach to Adaptive Tuning in Neural Models of Visual Motion Processing

2021 ◽  
Author(s):  
Scott T. Steinmetz ◽  
Oliver W. Layton ◽  
Nate V. Powell ◽  
Brett Fajen
Keyword(s):  
Optic Flow ◽  
Visual Motion ◽  
Tuning Curve ◽  
Model Performance ◽  
Motion Processing ◽  
Neural Models ◽  
Motion Direction ◽  
Dynamic Tuning ◽  
Visual Motion Processing ◽  
Sensory Encoding

This paper introduces a self-tuning mechanism for capturing rapid adaptation to changing visual stimuli by a population of neurons. Building upon the principles of efficient sensory encoding, we show how neural tuning curve parameters can be continually updated to optimally encode a time-varying distribution of recently detected stimulus values. We implemented this mechanism in a neural model that produces human-like estimates of self-motion direction (i.e., heading) based on optic flow. The parameters of speed-sensitive units were dynamically tuned in accordance with efficient sensory encoding such that the network remained sensitive as the distribution of optic flow speeds varied. In two simulation experiments, we found that model performance with dynamic tuning yielded more accurate, shorter latency heading estimates compared to the model with static tuning. We conclude that dynamic efficient sensory encoding offers a plausible approach for capturing adaptation to varying visual environments in biological visual systems and neural models alike.

scholarly journals Memory and Decision Making in the Frontal Cortex during Visual Motion Processing for Smooth Pursuit Eye Movements

Neuron ◽  
2009 ◽  
Vol 62 (5) ◽  
pp. 717-732 ◽  
Author(s):  
Natsuko Shichinohe ◽  
Teppei Akao ◽  
Sergei Kurkin ◽  
Junko Fukushima ◽  
Chris R.S. Kaneko ◽  
...  
Keyword(s):  
Decision Making ◽  
Eye Movements ◽  
Frontal Cortex ◽  
Smooth Pursuit ◽  
Visual Motion ◽  
Motion Processing ◽  
Smooth Pursuit Eye Movements ◽  
Pursuit Eye Movements ◽  
Visual Motion Processing

scholarly journals Visual motion processing recruits regions selective for auditory motion in early deaf individuals

2020 ◽  
Author(s):  
Stefania Benetti ◽  
Joshua Zonca ◽  
Ambra Ferrari ◽  
Mohamed Rezk ◽  
Giuseppe Rabini ◽  
...  
Keyword(s):  
Auditory Cortex ◽  
Visual Processing ◽  
Large Scale ◽  
Visual Motion ◽  
Brain Regions ◽  
Motion Processing ◽  
Temporal Region ◽  
List Type ◽  
Auditory Motion ◽  
Visual Motion Processing

AbstractIn early deaf individuals, the auditory deprived temporal brain regions become engaged in visual processing. In our study we tested further the hypothesis that intrinsic functional specialization guides the expression of cross-modal responses in the deprived auditory cortex. We used functional MRI to characterize the brain response to horizontal, radial and stochastic visual motion in early deaf and hearing individuals matched for the use of oral or sign language. Visual motion showed enhanced response in the ‘deaf’ mid-lateral planum temporale, a region selective to auditory motion as demonstrated by a separate auditory motion localizer in hearing people. Moreover, multivariate pattern analysis revealed that this reorganized temporal region showed enhanced decoding of motion categories in the deaf group, while visual motion-selective region hMT+/V5 showed reduced decoding when compared to hearing people. Dynamic Causal Modelling revealed that the ‘deaf’ motion-selective temporal region shows a specific increase of its functional interactions with hMT+/V5 and is now part of a large-scale visual motion selective network. In addition, we observed preferential responses to radial, compared to horizontal, visual motion in the ‘deaf’ right superior temporal cortex region that also show preferential response to approaching/receding sounds in the hearing brain. Overall, our results suggest that the early experience of auditory deprivation interacts with intrinsic constraints and triggers a large-scale reallocation of computational load between auditory and visual brain regions that typically support the multisensory processing of motion information.HighlightsAuditory motion-sensitive regions respond to visual motion in the deafReorganized auditory cortex can discriminate between visual motion trajectoriesPart of the deaf auditory cortex shows preference for in-depth visual motionDeafness might lead to computational reallocation between auditory/visual regions.

Pursuit and optokinetic deficits following chemical lesions of cortical areas MT and MST

1988 ◽  
Vol 60 (3) ◽  
pp. 940-965 ◽  
Author(s):  
M. R. Dursteler ◽  
R. H. Wurtz
Keyword(s):  
Eye Movements ◽  
Visual Field ◽  
Visual Motion ◽  
Ibotenic Acid ◽  
Motion Processing ◽  
Temporal Area ◽  
Target Speed ◽  
Pursuit Eye Movements ◽  
Medial Superior Temporal ◽  
Visual Motion Processing

1. Previous experiments have shown that punctate chemical lesions within the middle temporal area (MT) of the superior temporal sulcus (STS) produce deficits in the initiation and maintenance of pursuit eye movements (10, 34). The present experiments were designed to test the effect of such chemical lesions in an area within the STS to which MT projects, the medial superior temporal area (MST). 2. We injected ibotenic acid into localized regions of MST, and we observed two deficits in pursuit eye movements, a retinotopic deficit and a directional deficit. 3. The retinotopic deficit in pursuit initiation was characterized by the monkey's inability to match eye speed to target speed or to adjust the amplitude of the saccade made to acquire the target to compensate for target motion. This deficit was related to the initiation of pursuit to targets moving in any direction in the visual field contralateral to the side of the brain with the lesion. This deficit was similar to the deficit we found following damage to extrafoveal MT except that the affected area of the visual field frequently extended throughout the entire contralateral visual field tested. 4. The directional deficit in pursuit maintenance was characterized by a failure to match eye speed to target speed once the fovea had been brought near the moving target. This deficit occurred only when the target was moving toward the side of the lesion, regardless of whether the target began to move in the ipsilateral or contralateral visual field. There was no deficit in the amplitude of saccades made to acquire the target, or in the amplitude of the catch-up saccades made to compensate for the slowed pursuit. The directional deficit is similar to the one we described previously following chemical lesions of the foveal representation in the STS. 5. Retinotopic deficits resulted from any of our injections in MST. Directional deficits resulted from lesions limited to subregions within MST, particularly lesions that invaded the floor of the STS and the posterior bank of the STS just lateral to MT. Extensive damage to the densely myelinated area of the anterior bank or to the posterior parietal area on the dorsal lip of the anterior bank produced minimal directional deficits. 6. We conclude that damage to visual motion processing in MST underlies the retinotopic pursuit deficit just as it does in MT. MST appears to be a sequential step in visual motion processing that occurs before all of the visual motion information is transmitted to the brainstem areas related to pursuit.(ABSTRACT TRUNCATED AT 400 WORDS)

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