A simplicial analysis of the fMRI data from human brain dynamics under functional cognitive tasks.

The topological analysis of fMRI time series data has recently been used to characterize the identification of patterns of brain activity seen during specific tasks carried out under experimentally controlled conditions. This study uses the methods of algebraic topology to characterize time series networks constructed from fMRI data measured for adult and children populations carrying out differentiated reading tasks. Our pilot study shows that our methods turn out to be capable of identifying distinct differences between the activity of adult and children populations carrying out identical reading tasks. We also see differences between activity patterns seen when subjects recognize word and nonword patterns. The results generalize across different populations, different languages and different active and inactive brain regions.

Structural connectivity predicts sequential processing differences in music perception ability.

To relate individual differences in music perception ability with whole brain white matter connectivity, we scanned a group of 27 individuals with varying degrees of musical training and assessed musical ability in sensory and sequential music perception domains using the Profile of Music Perception Skills-Short version (PROMS-S). Sequential processing ability was estimated by combining performance on tasks for Melody, Standard Rhythm, Embedded Rhythm, and Accent subscores while sensory processing ability was ascertained via tasks of Tempo, Pitch, Timbre, and Tuning. Controlling for musical training, gender, and years of training, network-based statistics revealed positive linear associations between total PROMS-S scores and increased interhemispheric fronto-temporal and parieto-frontal white matter connectivity, suggesting a distinct segregated structural network for music perception. Secondary analysis revealed two subnetworks for sequential processing ability, one comprising ventral fronto-temporal and subcortical regions and the other comprising dorsal fronto-temporo-parietal regions. A graph-theoretic analysis to characterize the structural network revealed a positive association of modularity of the whole brain structural connectome with the d' total score. In addition, the nodal degree of the right posterior cingulate cortex also showed a significant positive correlation with the total d' score. Our results suggest that a distinct structural network of connectivity across fronto-temporal, cerebellar, and cerebro-subcortical regions is associated with music processing abilities and the right posterior cingulate cortex mediates the connectivity of this network.

Development and standardization of the DALI-DAB (dyslexia assessment for languages of India - dyslexia assessment battery).

A majority of Indian schoolchildren are biliterate in that they acquire literacy in at least two language systems, necessitating dyslexia assessment in both. The DALI-DAB assesses risk for dyslexia by evaluating reading ability and literacy-learning potential through a battery including literacy tests (letter and word reading, spelling, nonword reading, reading comprehension), and mediator skills (phonological awareness, processing automaticity and executive fluency, oral language) in multiple languages. DALI-DAB was developed in three languages - English, Hindi, and Marathi - and standardized on a sample of 1013 children. Reliability analyses revealed high internal consistency (α > 0.8) in most tests in all three languages. Low standard error of measurement values supported DALI-DAB score stability over repeated testing. Construct validity was variously reinforced through, (i) selection of culture-referenced, research-based tests, (ii) approval of test materials by schoolteachers (face validity) and (iii) grade-correlated performance increases on all DALI-DAB tests, besides robust correlations between (iv) literacy and mediator skill test scores (p < .001, concurrent validity), (v) equivalent tests across languages (p < .01, convergent validity), and (vi) DALI-DAB and WJ III ACH literacy scores (p < .01, criterion validity), in contrast to (vii) low correlation between DALI-DAB and WJ III ACH math scores (p > .05, discriminant validity). Overall, the DALI-DAB represents the first standardized dyslexia assessment tool for bilingual-biliterate children.

Perceived Closeness and Autistic Traits Modulate Interpersonal Vocal Communication.

Vocal modulation is a critical component of interpersonal communication. It not only serves as a dynamic and flexible tool for self-expression and linguistic information but also plays a key role in social behavior. Variation in vocal modulation can be driven by individual traits of interlocutors as well as factors relating to the dyad, such as the perceived closeness between interlocutors. In this study we examine both of these sources of variation. At an individual level, we examine the impact of autistic traits, since lack of appropriate vocal modulation has often been associated with Autism Spectrum Disorders. At a dyadic level, we examine the role of perceived closeness between interlocutors on vocal modulation. The study was conducted in three separate samples from India, Italy, and the UK. Articulatory features were extracted from recorded conversations between a total of 85 same-sex pairs of participants, and the articulation space calculated. A larger articulation space corresponds to greater number of spectro-temporal modulations (articulatory variations) sampled by the speaker. Articulation space showed a positive association with interpersonal closeness and a weak negative association with autistic traits. This study thus provides novel insights into individual and dyadic variation that can influence interpersonal vocal communication.

Cultural differences in the use of acoustic cues for musical emotion experience.

Does music penetrate cultural differences with its ability to evoke emotion? The ragas of Hindustani music are specific sequences of notes that elicit various emotions: happy, romantic, devotion, calm, angry, longing, tension and sad. They can be presented in two modes, alaap and gat, which differ in rhythm, but match in tonality. Participants from Indian and Non-Indian cultures (N = 144 and 112, respectively) rated twenty-four pieces of Hindustani ragas on eight dimensions of emotion, in a free response task. Of the 192 between-group comparisons, ratings differed in only 9% of the instances, showing universality across multiple musical emotions. Robust regression analyses and machine learning methods revealed tonality best explained emotion ratings for Indian participants whereas rhythm was the primary predictor in Non-Indian listeners. Our results provide compelling evidence for universality in emotions in the auditory domain in the realm of musical emotion, driven by distinct acoustic features that depend on listeners' cultural backgrounds.

Ancestral Variations of the PCDHG Gene Cluster Predispose to Dyslexia in a Multiplex Family.

Dyslexia is a heritable neurodevelopmental disorder characterized by difficulties in reading and writing. In this study, we describe the identification of a set of 17 polymorphisms located across 1.9Mb region on chromosome 5q31.3, encompassing genes of the PCDHG cluster, TAF7, PCDH1 and ARHGAP26, dominantly inherited with dyslexia in a multi-incident family. Strikingly, the non-risk form of seven variations of the PCDHG cluster, are preponderant in the human lineage, while risk alleles are ancestral and conserved across Neanderthals to non-human primates. Four of these seven ancestral variations (c.460A>C [p.Ile154Leu], c.541G>A [p.Ala181Thr], c.2036G>C [p.Arg679Pro] and c.2059A>G [p.Lys687Glu]) result in amino acid alterations. p.Ile154Leu and p.Ala181Thr are present at EC2: EC3 interacting interface of γA3-PCDH and γA4-PCDH respectively might affect trans-homophilic interaction and hence neuronal connectivity. p.Arg679Pro and p.Lys687Glu are present within the linker region connecting trans-membrane to extracellular domain. Sequence analysis indicated the importance of p.Ile154, p.Arg679 and p.Lys687 in maintaining class specificity. Thus the observed association of PCDHG genes encoding neural adhesion proteins reinforces the hypothesis of aberrant neuronal connectivity in the pathophysiology of dyslexia. Additionally, the striking conservation of the identified variants indicates a role of PCDHG in the evolution of highly specialized cognitive skills critical to reading.

Reading Research and Practice: Indian Perspective.

The authors outline the basic structure of akshara, the basic unit of writing in Indic writing systems used widely in South and Southeast Asia; present preliminary studies relating to reading, assessment, and instruction of akshara; and outline recommendations for future studies.

Brains of verbal memory specialists show anatomical differences in language, memory and visual systems.

We studied a group of verbal memory specialists to determine whether intensive oral text memory is associated with structural features of hippocampal and lateral-temporal regions implicated in language processing. Professional Vedic Sanskrit Pandits in India train from childhood for around 10years in an ancient, formalized tradition of oral Sanskrit text memorization and recitation, mastering the exact pronunciation and invariant content of multiple 40,000-100,000 word oral texts. We conducted structural analysis of gray matter density, cortical thickness, local gyrification, and white matter structure, relative to matched controls. We found massive gray matter density and cortical thickness increases in Pandit brains in language, memory and visual systems, including i) bilateral lateral temporal cortices and ii) the anterior cingulate cortex and the hippocampus, regions associated with long and short-term memory. Differences in hippocampal morphometry matched those previously documented for expert spatial navigators and individuals with good verbal working memory. The findings provide unique insight into the brain organization implementing formalized oral knowledge systems.

Reading in Devanagari: Insights from functional neuroimaging.

OBJECTIVES: The current study used functional MRI (fMRI) to obtain a comprehensive understanding of the neural network underlying visual word recognition in Hindi/Devanagari, an alphasyllabic - partly alphabetic and partly syllabic Indian writing system on which little research has hitherto been carried out. MATERIALS AND METHODS: Sixteen (5F, 11M) neurologically healthy, native Hindi/Devanagari readers aged 21 to 50 named aloud 240 Devanagari words which were either visually linear - had no diacritics or consonant ligatures above or below central plane of text, e.g. फल, वाहन, or nonlinear - had at least one diacritic and/or ligature, e.g. फूल, किरण, and which further included 120 words each of high and low frequency. Words were presented in alternating high and low frequency blocks of 10 words each at 2s/word in a block design, with linear and nonlinear words in separate runs. Word reading accuracy was manually coded, while fMRI images were acquired on a 3T scanner with an 8-channel head-coil, using a T2*-weighted EPI sequence (TR/TE = 2s/35ms). RESULTS: After ensuring high word naming accuracy (M = 97.6%, SD = 2.3), fMRI data analyses (at FDR P < 0.005) revealed that reading Devanagari words elicited robust activations in bilateral occipito-temporal, inferior frontal and precentral regions as well as both cerebellar hemispheres. Other common areas of activation included left inferior parietal and right superior temporal cortices. Primary differences seen between nonlinear and linear word reading networks were in the right temporal areas and cerebellum. CONCLUSION: Distinct from alphabetic scripts, which are linear in their spatial organization, and recruit a primarily left-lateralized network for word reading, our results revealed a bilateral reading network for Devanagari. We attribute the additional activations in Devanagari to increased visual processing demands arising from the complex visuospatial arrangement of symbols in this ancient script.

Picture-naming in patients with left frontal lobe tumor - a functional neuroimaging study.

The objective of this study was to investigate behavioral performance as well as cortical activation patterns while picture-naming, in patients with left frontal lobe tumor prior to surgery. Functional magnetic resonance imaging was used to compare behavior and brain activations while 10 patients with a tumor in the left frontal lobe and 9 controls, named aloud simple pictures presented in a block design inside a 3 T Philips Achieva scanner. Evaluations of task performance included naming accuracy and articulation time. Behaviorally, patients took significantly longer to articulate picture names but naming accuracy was preserved. Analysis of brain activations showed differences only in the frontal regions of the cortical network. In particular, while the frontal activations in the control population were focused and localized in the left inferior orbito-frontal gyrus, in patients the frontal network was distributed and included a significantly greater number of clusters that were distributed in homologous or near homologous areas of the (orbito-frontal gyrus) left and/or right hemisphere of the frontal lobe. Our results suggest that in patients with a left frontal lobe tumor the process of naming simple pictures is preserved but the cortical network of activation in the frontal region is altered and is distributed in the frontal regions of both hemispheres.

Categorization of environmental sounds.

Sounds in the natural environment are non-stationary, in that their spectral dynamics is time-dependent. We develop measures to analyze the spectral dynamics of environmental sound signals and find that they fall into two categories-simple sounds with slowly varying spectral dynamics and complex sounds with rapidly varying spectral dynamics. Based on our results and those from auditory processing we suggest rate of spectral dynamics as a possible scheme to categorize sound signals in the environment.