scholarly journals Reading Increases the Compositionality of Visual Word Representations

2019 ◽  
Author(s):  
Aakash Agrawal ◽  
K.V.S. Hari ◽  
S. P. Arun
Keyword(s):  
Visual Search ◽  
Brain Imaging ◽  
Reading Fluency ◽  
Visual Processing ◽  
Visual Word ◽  
Occipital Region ◽  
Indian Languages ◽  
The Brain

ABSTRACTReading causes widespread changes in the brain but its effect on visual word representations is unknown. Reading may facilitate visual processing by forming specialized detectors for longer strings, or by making word responses more predictable from single letters, that is by increasing compositionality. We provide evidence for the latter hypothesis by comparing readers and nonreaders of two Indian languages, Telugu and Malayalam. Readers showed decreased interactions between letters during visual search, which predicted their overall reading fluency. Brain imaging revealed increased compositionality in readers, whereby responses to bigrams were more predictable from single letters. This effect was specific to the lateral occipital region, where activations best matched behavior. Thus, reading facilitates visual processing by increasing the compositionality of visual word representations.

scholarly journals Reading Increases the Compositionality of Visual Word Representations

2019 ◽  
Vol 30 (12) ◽  
pp. 1707-1723 ◽  
Author(s):  
Aakash Agrawal ◽  
K. V. S. Hari ◽  
S. P. Arun
Keyword(s):  
Visual Search ◽  
Reading Fluency ◽  
Visual Processing ◽  
Single Letter ◽  
Visual Word ◽  
Occipital Region ◽  
Indian Languages ◽  
Learning To Read ◽  
Imaging Experiment ◽  
The Brain

Reading causes widespread changes in the brain, but its effect on visual word representations is unknown. Learning to read may facilitate visual processing by forming specialized detectors for longer strings or by making word responses more predictable from single letters—that is, by increasing compositionality. We provided evidence for the latter hypothesis using experiments that compared nonoverlapping groups of readers of two Indian languages (Telugu and Malayalam). Readers showed increased single-letter discrimination and decreased letter interactions for bigrams during visual search. Importantly, these interactions predicted subjects’ overall reading fluency. In a separate brain-imaging experiment, we observed increased compositionality in readers, whereby responses to bigrams were more predictable from single letters. This effect was specific to the anterior lateral occipital region, where activations best matched behavior. Thus, learning to read facilitates visual processing by increasing the compositionality of visual word representations.

scholarly journals Visual search for upright bigrams predicts reading fluency in children

2021 ◽  
Author(s):  
Aakash Agrawal ◽  
Sonali Nag ◽  
K.V.S. Hari ◽  
S. P. Arun
Keyword(s):  
Visual Search ◽  
Language Processing ◽  
Reading Fluency ◽  
Visual Processing ◽  
Word Reading ◽  
Primary School Children ◽  
Rapid Automatized Naming ◽  
Clear Understanding ◽  
Related Factors ◽  
Large Letter

ABSTRACTFluent reading is an important milestone in education, but we lack a clear understanding of why children vary so widely in attaining this milestone. Language-related factors such as rapid automatized naming (RAN) and phonological awareness have been identified as important factors that influence reading fluency. Of theoretical interest is also, however, whether aspects of visual processing influence reading fluency. To investigate this issue, we tested primary school children (n = 68) on four tasks: two reading fluency tasks (word reading and passage reading), a RAN task to measure naming speed, and a visual search task using letters and bigrams to measure visual processing. As expected, the RAN score was strongly correlated with reading fluency. In addition, visual processing of bigrams was correlated with reading fluency. Importantly, this association was specific to upright but not inverted bigrams, and to bigrams with normal but not large letter spacing. Thus, reading fluency in children is accompanied by specialized changes in upright bigram processing. We propose that bigram processing during visual search could complement existing measures of language processing to understand individual differences in reading fluency.

scholarly journals The brain timewise: how timing shapes and supports brain function

2015 ◽  
Vol 370 (1668) ◽  
pp. 20140170 ◽  
Author(s):  
Riitta Hari ◽  
Lauri Parkkonen
Keyword(s):  
Human Brain ◽  
Brain Imaging ◽  
Brain Function ◽  
Temporal Dynamics ◽  
Generative Models ◽  
Network Activity ◽  
Brain Diseases ◽  
Specific Information ◽  
Non Invasive ◽  
The Brain

We discuss the importance of timing in brain function: how temporal dynamics of the world has left its traces in the brain during evolution and how we can monitor the dynamics of the human brain with non-invasive measurements. Accurate timing is important for the interplay of neurons, neuronal circuitries, brain areas and human individuals. In the human brain, multiple temporal integration windows are hierarchically organized, with temporal scales ranging from microseconds to tens and hundreds of milliseconds for perceptual, motor and cognitive functions, and up to minutes, hours and even months for hormonal and mood changes. Accurate timing is impaired in several brain diseases. From the current repertoire of non-invasive brain imaging methods, only magnetoencephalography (MEG) and scalp electroencephalography (EEG) provide millisecond time-resolution; our focus in this paper is on MEG. Since the introduction of high-density whole-scalp MEG/EEG coverage in the 1990s, the instrumentation has not changed drastically; yet, novel data analyses are advancing the field rapidly by shifting the focus from the mere pinpointing of activity hotspots to seeking stimulus- or task-specific information and to characterizing functional networks. During the next decades, we can expect increased spatial resolution and accuracy of the time-resolved brain imaging and better understanding of brain function, especially its temporal constraints, with the development of novel instrumentation and finer-grained, physiologically inspired generative models of local and network activity. Merging both spatial and temporal information with increasing accuracy and carrying out recordings in naturalistic conditions, including social interaction, will bring much new information about human brain function.

Abstract TP147: Central Post Stroke Pain: A Systematic Review

Stroke ◽  
2017 ◽  
Vol 48 (suppl_1) ◽  
Author(s):  
Jonathan Singer ◽  
Alyssa Conigliaro ◽  
Elizabeth Spina ◽  
Susan Law ◽  
Steven Levine
Keyword(s):  
Systematic Review ◽  
Brain Imaging ◽  
Pain Scale ◽  
Post Stroke ◽  
Underlying Causes ◽  
Single Question ◽  
Thalamic Region ◽  
The Brain ◽  
A Current

Background: Central Post Stroke Pain (CPSP) is reportedly due to strokes in the thalamic region (Dishinbition Theory); however, the Central Imbalance Theory states that CPSP is due to damage to the spinothalamic pathway (STP). Aims: 1) Clarify the role of thalamic strokes and STP damage in CPSP patients. 2) Gain a current understanding of anatomic substrates, brain imaging, and treatment of CPSP. Methods: Two independent reviewers systematically reviewed PUBMED, CINAHL and Web of Science for studies including original, clinical studies and randomized controlled trials (RCTs) using PRISMA guidelines. Studies had to assess CPSP, using a single question or pain scale. Results: Search from January – July 2016, identifying 731 publications. We extracted data from 23 studies and categorized the articles’ aims into 4 sections: somatosensory deficits (5 studies), STP (3 studies), brain imaging (7 studies), and RCTs (8 studies). Somatosensory studies showed high rates of CPSP; however, the underlying causes of these deficits were unclear. Most studies did not refer to stroke location as playing a role in CPSP, but that pathways may. STP studies displayed consistent evidence that the STP plays a major role in CPSP, delineating that CPSP can occur even when the stroke is not in the thalamic region but in other regions (e.g. cerebellum, basal ganglia, medulla). Four of the brain imaging studies found CPSP not related and 3 found it was related to thalamic strokes. All 7 studies had major limitations including sample size, no control groups, and selection bias. RCTs were mostly negative, but brain stem and motor cortex stimulation studies showed the most promise. Conclusions: While CPSP has been linked to the thalamic region since the early 1900’s, the peer-reviewed literature showed equivocal results when examining location of stroke. Our systematic review suggests damage to the STP is associated with CPSP and this could provide insights into mechanisms and treatment. Moreover, historical connection of strokes in the thalamic region and CPSP should be reevaluated as many studies noted that strokes in other regions of the brain also produce CPSP.

Context-Dependent Modulation of Early Visual Cortical Responses to Numerical and Nonnumerical Magnitudes

2021 ◽  
pp. 1-12
Author(s):  
Joonkoo Park ◽  
Sonia Godbole ◽  
Marty G. Woldorff ◽  
Elizabeth M. Brannon
Keyword(s):  
Visual Processing ◽  
Context Dependency ◽  
Numerical Magnitude ◽  
Continuous Variables ◽  
Processing Stream ◽  
Cortical Responses ◽  
Early Visual Cortex ◽  
Context Dependent ◽  
Visual Cortical ◽  
The Brain

Abstract Whether and how the brain encodes discrete numerical magnitude differently from continuous nonnumerical magnitude is hotly debated. In a previous set of studies, we orthogonally varied numerical (numerosity) and nonnumerical (size and spacing) dimensions of dot arrays and demonstrated a strong modulation of early visual evoked potentials (VEPs) by numerosity and not by nonnumerical dimensions. Although very little is known about the brain's response to systematic changes in continuous dimensions of a dot array, some authors intuit that the visual processing stream must be more sensitive to continuous magnitude information than to numerosity. To address this possibility, we measured VEPs of participants viewing dot arrays that changed exclusively in one nonnumerical magnitude dimension at a time (size or spacing) while holding numerosity constant and compared this to a condition where numerosity was changed while holding size and spacing constant. We found reliable but small neural sensitivity to exclusive changes in size and spacing; however, changing numerosity elicited a much more robust modulation of the VEPs. Together with previous work, these findings suggest that sensitivity to magnitude dimensions in early visual cortex is context dependent: The brain is moderately sensitive to changes in size and spacing when numerosity is held constant, but sensitivity to these continuous variables diminishes to a negligible level when numerosity is allowed to vary at the same time. Neurophysiological explanations for the encoding and context dependency of numerical and nonnumerical magnitudes are proposed within the framework of neuronal normalization.

Converging Evidence That Neural Plasticity Underlies Transcranial Direct-Current Stimulation

2021 ◽  
Vol 33 (1) ◽  
pp. 146-157
Author(s):  
Chong Zhao ◽  
Geoffrey F. Woodman
Keyword(s):  
Visual Search ◽  
Direct Current ◽  
Neural Plasticity ◽  
Transcranial Direct Current Stimulation ◽  
Time Course ◽  
Memory Task ◽  
Long Term Memory ◽  
Visual Stream ◽  
Direct Current Stimulation ◽  
The Brain

It is not definitely known how direct-current stimulation causes its long-lasting effects. Here, we tested the hypothesis that the long time course of transcranial direct-current stimulation (tDCS) is because of the electrical field increasing the plasticity of the brain tissue. If this is the case, then we should see tDCS effects when humans need to encode information into long-term memory, but not at other times. We tested this hypothesis by delivering tDCS to the ventral visual stream of human participants during different tasks (i.e., recognition memory vs. visual search) and at different times during a memory task. We found that tDCS improved memory encoding, and the neural correlates thereof, but not retrieval. We also found that tDCS did not change the efficiency of information processing during visual search for a certain target object, a task that does not require the formation of new connections in the brain but instead relies on attention and object recognition mechanisms. Thus, our findings support the hypothesis that direct-current stimulation modulates brain activity by changing the underlying plasticity of the tissue.

scholarly journals Visual Navigation in Nocturnal Insects

Physiology ◽  
2016 ◽  
Vol 31 (3) ◽  
pp. 182-192 ◽  
Author(s):  
Eric Warrant ◽  
Marie Dacke
Keyword(s):  
Visual Processing ◽  
Visual Navigation ◽  
Compound Eyes ◽  
Visual Landmarks ◽  
Processing Strategies ◽  
Straight Line ◽  
Highly Sensitive ◽  
Celestial Compass ◽  
The Brain

Despite their tiny eyes and brains, nocturnal insects have evolved a remarkable capacity to visually navigate at night. Whereas some use moonlight or the stars as celestial compass cues to maintain a straight-line course, others use visual landmarks to navigate to and from their nest. These impressive abilities rely on highly sensitive compound eyes and specialized visual processing strategies in the brain.

scholarly journals Temporal Lobe Malformations in Achondroplasia: Expanding the Brain Imaging Phenotype Associated withFGFR3-Related Skeletal Dysplasias

2017 ◽  
Vol 39 (2) ◽  
pp. 380-384 ◽  
Author(s):  
S.A. Manikkam ◽  
K. Chetcuti ◽  
K.B. Howell ◽  
R. Savarirayan ◽  
A.M. Fink ◽  
...  
Keyword(s):  
Brain Imaging ◽  
Temporal Lobe ◽  
Skeletal Dysplasias ◽  
The Brain
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