A Framework to Diagnose Autism Spectrum Disorder Using Morphological Connectivity of sMRI and XGBoost.

In this study, we automated the diagnostic procedure of autism spectrum disorder (ASD) with the help of anatomical alterations found in structural magnetic resonance imaging (sMRI) data of the ASD brain and machine learning tools. Initially, the sMRI data was preprocessed using the FreeSurfer toolbox. Further, the brain regions were segmented into 148 regions of interest using the Destrieux atlas. Features such as volume, thickness, surface area, and mean curvature were extracted for each brain region, and the morphological connectivity was computed using Pearson correlation. These morphological connections were fed to XGBoost for feature reduction and to build the diagnostic model. The results showed an average accuracy of 94.16% for the top 18 features. The frontal and limbic regions contributed more features to the classification model. Our proposed method is thus effective for the classification of ASD and can also be useful for the screening of other similar neurological disorders.

Conflict monitoring and adaptation to affective stimuli as a function of ageing.

The current study investigated whether preference for positive affect would be observed in the context of a higher order control process with increasing age given the premise of affective prioritization with ageing. The study examined how affect interacted with cognitive control mechanisms across young, middle-aged and older adults. Conflict monitoring and adaptation for affective stimuli was examined with a face-word Stroop task using happy and fearful facial expressions. The participants' task was to detect the emotional expression (Happy or Fear) of the face shown with a distractor word (Happy or Fear) written across the face. Reaction time and accuracy data was analysed to compare adaptation effect and Stroop interference as a function of age, valence and previous trial congruence. The results demonstrated a stronger adaptation effect for negative affect in young adults and for positive affect in middle-aged adults and older adults. These results can be explained in terms of the socio-emotional selectivity theory of affective bias in the elderly and the involvement of attentional control mechanisms. This study empirically demonstrates shifts in affective bias towards positive affect with ageing through the implicit recruitment of cognitive control.

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.

Neurocognitive mechanisms of affective conflict adaptation: An event related fMRI study.

Control of conflict can be seen in reduced effects of conflict following incompatible trials known as conflict adaptation. Such control mechanisms have been shown to depend on emotional content present in stimuli, which could be a motivational force for control adjustments. We explored the neural mechanisms of the interaction between proactive control in terms of conflict adaptation effect and emotions through an event related fMRI study involving an emotional Stroop effect (facial expression-emotional word paradigm) involving happy and angry expressions. Conflict adaptation was measured in terms of the reduction in Stroop effect as a function of previous trial congruence and previous trial emotion. Participants responded to the facial expression while ignoring the distractor word written over the face. Behavioral results showed larger Stroop effect for angry faces compared to happy faces. Conflict adaptation effect was greater for angry faces and was also influenced by previous trial emotion. Both priming and adaptation effects were observed. Stroop effect was correlated with activations in dorsal anterior cingulate. Emotion effect was correlated with activations in amygdala, fusiform face area (FFA), and insula along with the expected hemispheric asymmetry for positive and negative emotions in left vs right FFA, respectively. Conflict adaptation effect was correlated with activations in amygdala. In addition, activations in striatum supported the three-way interaction between emotion, previous and current trial congruence. Activation in dorsal anterior cingulate was correlated only with the overall Stroop effect in the current trial. Activations in amygdala and striatum were also found with facial expressions. The results indicate that emotion specific processing areas themselves such as amygdala and striatum may self-regulate and contribute toward enhanced proactive control mechanisms for task-relevant emotional stimuli. These findings further confirm the strong relationship between cognition and affect in the context of conflict monitoring and adjustments in cognitive control.

Effect of language proficiency on proactive occulo-motor control among bilinguals.

We examined the effect of language proficiency on the status and dynamics of proactive inhibitory control in an occulo-motor cued go-no-go task. The first experiment was designed to demonstrate the effect of second language proficiency on proactive inhibitory cost and adjustments in control by evaluating previous trial effects. This was achieved by introducing uncertainty about the upcoming event (go or no-go stimulus). High- and low- proficiency Hindi-English bilingual adults participated in the study. Saccadic latencies and errors were taken as the measures of performance. The results demonstrate a significantly lower proactive inhibitory cost and better up-regulation of proactive control under uncertainty among high- proficiency bilinguals. An analysis based on previous trial effects suggests that high- proficiency bilinguals were found to be better at releasing inhibition and adjustments in control, in an ongoing response activity in the case of uncertainty. To further understand the dynamics of proactive inhibitory control as a function of proficiency, the second experiment was designed to test the default versus temporary state hypothesis of proactive inhibitory control. Certain manipulations were introduced in the cued go-no-go task in order to make the upcoming go or no-go trial difficult to predict, which increased the demands on the implementation and maintenance of proactive control. High- proficiency bilinguals were found to rely on a default state of proactive inhibitory control whereas low- proficiency bilinguals were found to rely on temporary/transient proactive inhibition. Language proficiency, as one of the measures of bilingualism, was found to influence proactive inhibitory control and appears to modulate the dynamics of proactive inhibitory control.

Proactive and reactive control depends on emotional valence: a Stroop study with emotional expressions and words.

We examined proactive and reactive control effects in the context of task-relevant happy, sad, and angry facial expressions on a face-word Stroop task. Participants identified the emotion expressed by a face that contained a congruent or incongruent emotional word (happy/sad/angry). Proactive control effects were measured in terms of the reduction in Stroop interference (difference between incongruent and congruent trials) as a function of previous trial emotion and previous trial congruence. Reactive control effects were measured in terms of the reduction in Stroop interference as a function of current trial emotion and previous trial congruence. Previous trial negative emotions exert greater influence on proactive control than the positive emotion. Sad faces in the previous trial resulted in greater reduction in the Stroop interference for happy faces in the current trial. However, current trial angry faces showed stronger adaptation effects compared to happy faces. Thus, both proactive and reactive control mechanisms are dependent on emotional valence of task-relevant stimuli.

Bilingual language control and general purpose cognitive control among individuals with bilingual aphasia: evidence based on negative priming and flanker tasks.

BACKGROUND: Bilingualism results in an added advantage with respect to cognitive control. The interaction between bilingual language control and general purpose cognitive control systems can also be understood by studying executive control among individuals with bilingual aphasia. objectives: The current study examined the subcomponents of cognitive control in bilingual aphasia. A case study approach was used to investigate whether cognitive control and language control are two separate systems and how factors related to bilingualism interact with control processes. METHODS: Four individuals with bilingual aphasia performed a language background questionnaire, picture description task, and two experimental tasks (nonlinguistic negative priming task and linguistic and nonlinguistic versions of flanker task). RESULTS: A descriptive approach was used to analyse the data using reaction time and accuracy measures. The cumulative distribution function plots were used to visualize the variations in performance across conditions. The results highlight the distinction between general purpose cognitive control and bilingual language control mechanisms. CONCLUSION: All participants showed predominant use of the reactive control mechanism to compensate for the limited resources system. Independent yet interactive systems for bilingual language control and general purpose cognitive control were postulated based on the experimental data derived from individuals with bilingual aphasia.

Development of cognitive and affective control networks and decision making.

Cognitive control and decision making are two important research areas in the realm of higher-order cognition. Control processes such as interference control and monitoring in cognitive and affective contexts have been found to influence the process of decision making. Development of control processes follows a gradual growth pattern associated with the prolonged maturation of underlying neural circuits including the lateral prefrontal cortex, anterior cingulate, and the medial prefrontal cortex. These circuits are also involved in the control of processes that influences decision making, particularly with respect to choice behavior. Developmental studies on affective control have shown distinct patterns of brain activity with adolescents showing greater activation of amygdala whereas adults showing greater activity in ventral prefrontal cortex. Conflict detection, monitoring, and adaptation involve anticipation and subsequent performance adjustments which are also critical to complex decision making. We discuss the gradual developmental patterns observed in two of our studies on conflict monitoring and adaptation in affective and nonaffective contexts. Findings of these studies indicate the need to look at the differences in the effects of the development of cognitive and affective control on decision making in children and particularly adolescents. Neuroimaging studies have shown the involvement of separable neural networks for cognitive (medial prefrontal cortex and anterior cingulate) and affective control (amygdala, ventral medial prefrontal cortex) shows that one system can affect the other also at the neural level. Hence, an understanding of the interaction and balance between the cognitive and affective brain networks may be crucial for self-regulation and decision making during the developmental period, particularly late childhood and adolescence. The chapter highlights the need for empirical investigation on the interaction between the different aspects of cognitive control and decision making from a developmental perspective.

Bilingualism and the increased attentional blink effect: evidence that the difference between bilinguals and monolinguals generalizes to different levels of second language proficiency.

The attentional blink task involves rapid serial presentation of visual stimuli, two of which the participants have to report. The usual finding is that participants are impaired at reporting the second target if it appears in close temporal proximity to the first target. Previous research has shown that the effect is stronger in bilinguals than monolinguals. We investigated whether the difference between monolinguals and proficient bilinguals can be extended to bilinguals of different proficiency levels. Therefore, we replicated the paradigm in a large sample of Hindi-English bilinguals with different proficiency levels of English, as measured with a validated vocabulary test. We additionally measured the participants' intelligence with the raven progressive matrices. We found that the size of the attentional blink effect correlates with the degree of second language proficiency and not with the degree of intelligence. This indicates that research on executive control functions can be done with bilinguals of different proficiency levels. Our results are also in line with recent findings showing that the attentional blink effect is not primarily due to limited processing resources.

Attention and memory biases as stable abnormalities among currently depressed and currently remitted individuals with unipolar depression.

BACKGROUND: In the present study, we explored the possibility of the stability of attention bias and memory bias in currently remitted individuals with unipolar depression compared to currently depressed individuals with unipolar depression and never-depressed individuals. METHODS: The Emotional Stroop and autobiographical memory task (AMT) were administered on 10 participants, who were currently depressed, currently remitted with unipolar depression, or never-depressed. In the emotional Stroop task (EST), the respondent's task was to indicate the color of the ink of the positive, negative, and neutral words by selecting one of a series of colored blocks. In the AMT, participants were presented with positive, negative, and neutral cue words. For each word, they were asked to report specific events from their life. RESULTS: Both the attention bias and memory bias exist in both the clinical groups. In EST, both currently depressed and currently remitted groups were slower to respond to negative words compared to neutral words. Unlike EST, in AMT both currently depressed and currently remitted groups were slower to respond to positive words compared to neutral words. Interestingly, the capacity to generate specific events for negative events was higher in both currently depressed and currently remitted groups. They were over-general in their memories of positive events. Importantly, the never-depressed group was specific in their memories of both positive and negative events of their life. CONCLUSION: Our findings provide evidence for the stable existence of attention and memory bias in currently remitted individuals. This study has implications for the cognitive behavior therapy for depression to include modules to resolve the attention and memory bias toward negative thought and content, and to build strategies to overcome such biases.

Growth patterns of neuropsychological functions in Indian children.

We investigated age-related differences in neuropsychological performance in 400 Indian school children (5-15 years of age). Functions of motor speed, attention, executive functions, visuospatial functions, comprehension, learning, and memory were examined. Growth curve analysis was performed. Different growth models fitted different cognitive functions. Neuropsychological task performance improved slowly between 5 and 7 years, moderately between 8 and 12 years and slowly between 13 and 15 years of age. The overall growth patterns of neuropsychological functions in Indian children have been discussed with the findings reported on American children. The present work describes non-linear, heterogeneous, and protracted age trends of neuropsychological functions in Indian children and adolescents.

Cognitive-motivational deficits in ADHD: development of a classification system.

The classification systems developed so far to detect attention deficit/hyperactivity disorder (ADHD) do not have high sensitivity and specificity. We have developed a classification system based on several neuropsychological tests that measure cognitive-motivational functions that are specifically impaired in ADHD children. A total of 240 (120 ADHD children and 120 healthy controls) children in the age range of 6-9 years and 32 Oppositional Defiant Disorder (ODD) children (aged 9 years) participated in the study. Stop-Signal, Task-Switching, Attentional Network, and Choice Delay tests were administered to all the participants. Receiver operating characteristic (ROC) analysis indicated that percentage choice of long-delay reward best classified the ADHD children from healthy controls. Single parameters were not helpful in making a differential classification of ADHD with ODD. Multinominal logistic regression (MLR) was performed with multiple parameters (data fusion) that produced improved overall classification accuracy. A combination of stop-signal reaction time, posterror-slowing, mean delay, switch cost, and percentage choice of long-delay reward produced an overall classification accuracy of 97.8%; with internal validation, the overall accuracy was 92.2%. Combining parameters from different tests of control functions not only enabled us to accurately classify ADHD children from healthy controls but also in making a differential classification with ODD. These results have implications for the theories of ADHD.

Neuropsychological lateralization of brain dysfunction in children with mesial temporal sclerosis: a presurgical evaluation.

Presurgical evaluation of children with mesial temporal sclerosis has shown severe neurocognitive impairments. There is debate about lateralized material-specific deficits in memory in children with mesial temporal sclerosis. The authors examined lateralization of brain dysfunction and age appropriate development of cognitive functions in 17 children (7-15 years) with mesial temporal sclerosis who had histories of uncontrolled epilepsy. The National Institute of Mental Health and Neurosciences (NIMHANS) neuropsychological battery for children was employed and each participant's performance was compared with the norms. Results showed that the battery was sensitive to deficits in learning and memory associated with mesial temporal sclerosis. However, a lack of clearly lateralized material-specific memory deficits in children with left/right mesial temporal sclerosis was also observed. Performance on tests that assess learning, attention, working memory, and visuospatial functions was found to be below the age appropriate level. Children with mesial temporal sclerosis showed widely distributed neuropsychological deficits.

Development of attentional processes in ADHD and normal children.

Attention Deficit Hyperactivity Disorder (ADHD) is a developmental disorder. Typical development of attentional processes is rapid during early childhood. ADHD results in impairment in response inhibition, error monitoring, attentional disengagement, executive attention, and delay aversion and may effect the ongoing development of these processes during childhood. We examined the development of attentional processes in children with ADHD and normal children. Two hundred forty children (120 in each group) in the age range of 6-9 years participated in the study. Four tasks: Stop-Signal, attentional disengagement, attention network, and choice delay task were administered. Stop signal reaction time, switch costs, conflict effect, and percentage choice of short delay reward was higher in ADHD group compared to normal group. Post error of slowing was less in ADHD children. Endogenous orienting effect was more in normal children compared to ADHD children. Different developmental trajectories were observed for control functions in normal children. Major development in response inhibition occurred in 7-8 years, error monitoring in 6-9 years, and attentional disengagement in 7-9 years. Late development in alerting network was observed in normal children at age 9 years. No developmental changes occurred on these control functions in ADHD children aged 6-9 years. Age related changes were observed on delay aversion between 6 and 9 years in normal children, while it changed between 6 and 7 years in ADHD children. Performance was not changed on orienting and conflict attentional networks in both the children except conflict effect reduced between 7 and 9 years in ADHD children under double cue condition. Conflict network was interacted with the alerting and orienting network in normal children; specifically conflict network interacted with the orienting network in younger children (age 6 years) and with alerting network in older children (age 9 years). In ADHD group interaction between alerting and conflict network was observed only in the double cue condition. Together these results indicated that the deficits in control processes accumulate with age in ADHD children Present study favors the conceptual view of ADHD as a stable deficit in cognitive control functions, which are implicated in the pathology of ADHD. These results have theoretical implication for the theories of executive control and ADHD.

Development of task switching and post-error-slowing in children.

BACKGROUND: Executive control processes such as task switching and error processing have been shown to change with age. The present study explored from a developmental perspective whether shared or different mechanisms underlie these processes. METHODS: The sample included 180 children (30 in each of the six age groups from 6-11 years) who were required to perform two different tasks: identification of a digit, or counting the number of digits. We computed switch costs as a function of response-repetition, stimulus-response (S-R) compatibility, and post-error-slowing. We also analyzed reaction time distributions. RESULTS AND DISCUSSION: The results showed a switch cost in the response-repetition condition, with a reduction in switch cost between 7 to 8 and 9 to 10 years of age, and an S-R compatibility effect in 6 to 9 years old children. Reaction time (RT) distributions showed that the decrement in the switch cost is due to the overall decrease in RTs in fast (5th percentile) trials in 9 to 11 year olds, and slow (95th percentile) trials in 7 to 8 and 9 to 11 years old children, in both the task switch and non-switch trials. A major reduction in RT was found between 9 to 11 years in both the response type and S-R compatibility type conditions. RT distributions for post-error trials revealed that the large decrement seen in 7 to 8 and 9 to 10 years old children is primarily due to the sudden decrease in RTs in the fast and slow trials respectively. The developmental pattern of error processing was similar to one component of task switching (switch cost of the response-repetition condition), indicating that inhibition could be a common mechanism underlying both the processes. However, the failure to maintain task set was found only with task switching. CONCLUSION: The development of task switching and error processing is not gradual. The developmental pattern of error processing is similar to that of the switch cost of the response-repetition condition in task switching, indicating that inhibition could be a common mechanism underlying both processes. The present results have implications for theories of executive control.

Cognitive development in children with chronic protein energy malnutrition.

BACKGROUND: Malnutrition is associated with both structural and functional pathology of the brain. A wide range of cognitive deficits has been reported in malnourished children. Effect of chronic protein energy malnutrition (PEM) causing stunting and wasting in children could also affect the ongoing development of higher cognitive processes during childhood (>5 years of age). The present study examined the effect of stunted growth on the rate of development of cognitive processes using neuropsychological measures. METHODS: Twenty children identified as malnourished and twenty as adequately nourished in the age groups of 5-7 years and 8-10 years were examined. NIMHANS neuropsychological battery for children sensitive to the effects of brain dysfunction and age related improvement was employed. The battery consisted of tests of motor speed, attention, visuospatial ability, executive functions, comprehension and learning and memory RESULTS: Development of cognitive processes appeared to be governed by both age and nutritional status. Malnourished children performed poor on tests of attention, working memory, learning and memory and visuospatial ability except on the test of motor speed and coordination. Age related improvement was not observed on tests of design fluency, working memory, visual construction, learning and memory in malnourished children. However, age related improvement was observed on tests of attention, visual perception, and verbal comprehension in malnourished children even though the performance was deficient as compared to the performance level of adequately nourished children. CONCLUSION: Chronic protein energy malnutrition (stunting) affects the ongoing development of higher cognitive processes during childhood years rather than merely showing a generalized cognitive impairment. Stunting could result in slowing in the age related improvement in certain and not all higher order cognitive processes and may also result in long lasting cognitive impairments.