Centre for Cognitive Sciences

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    8 th IBRO world congress of neuroscience
    ( 2012-01-01) Gautam, Akash
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    A few suggestions on broadening the cross-linguistic relevance of the Multilink model
    ( 2019-08-01) Mishra, Ramesh Kumar
    In their keynote article, Dijkstra, Wahl, Buytenhuijs, van Halem, Al-jibouri, De Korte & Rekke (2018) propose a new model that aims to integrate and take care of the possible shortcomings of both the Revised Hierarchical Model (RHM, Kroll & Stewart, 1994) and Bilingual Interactive Activation model (BIA and several of its later versions, Dijkstra & Van Heuven, 1998). They begin their proposal by examining the objections/issues raised by Brysbaert and Duyck (2010) on RHM. It is well known that RHM is a developmental, production-based model which mostly predicted performance on translation-based tasks albeit with different predictions for translation recognition vs. production with regard to second language proficiency; BIA being a connectionist model of bilingual word recognition majorly emphasized on language non-selective selection and parallel language activation. Having been developed in and around Dutch (English as the second language), it took cognate status and orthographic similarity between words very seriously. Cognate status and orthographic similarity as factors won't count much as theoretical constructs around which a hypothesis could be developed if we look round the diverse types of orthographies and phonologies we find around the world.
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    A mathematical model of capacious and efficient memory that survives trauma
    ( 2004-02-15) Srivastava, Vipin ; Edwards, S. F.
    The brain's memory system can store without any apparent constraint, it recalls stored information efficiently and it is robust against lesion. Existing models of memory do not fully account for all these features. The model due to Hopfield (Proc. Natl. Acad. Sci. USA 79 (1982) 2554) based on Hebbian learning (The Organization of Behaviour, Wiley, New York, 1949) shows an early saturation of memory with the retrieval from memory becoming slow and unreliable before collapsing at this limit. Our hypothesis (Physica A 276 (2000) 352) that the brain might store orthogonalized information improved the situation in many ways but was still constrained in that the information to be stored had to be linearly independent, i.e., signals that could be expressed as linear combinations of others had to be excluded. Here we present a model that attempts to address the problem quite comprehensively in the background of the above attributes of the brain. We demonstrate that if the brain devolves incoming signals in analogy with Fourier analysis, the noise created by interference of stored signals diminishes systematically (which yields prompt retrieval) and most importantly it can withstand partial damages to the brain. © 2003 Elsevier B.V. All rights reserved.
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    A nearly exact method of solving certain localisation problems
    ( 1989-12-01) Srivastava, V.
    The old theories of localisation of Anderson (1958) and Abou-Chacra et al (1973) are reexamined. It is argued that (a) the convergence properties of the renormalised perturbation series for the self-energy are predominantly governed by its first term; and (b) the localisation problem in a real lattice can be mapped on to the localisation problem in a Cayley tree lattice in which the non-contributing branches are trimmed off. The connectivity constant for the trimmed Cayley tree, which can be evaluated exactly, should be used in the Abou-Chacra et al method (1973-1974) to obtain results for a real lattice. Calculations for two-dimensional lattices show partial agreement with the well known result that all states should be localised at any disorder-the triangular lattice (coordination number C=6) appears to show complete localisation only above a critical value of disorder, the honeycomb lattice (C=3) shows complete localisation always, and the square lattice (C=4) is found to be the marginal case.
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    A unified view of the orthogonalization methods
    ( 2000-09-08) Srivastava, Vipin
    A geometrical view of all known orthogonalization procedures is taken in order to understand their distinctive features and the inter-connections between them. Useful new information is gained. Its possible application to certain cognitive phenomena is also indicated.
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    Activation of shape and semantic information during ambiguous homophone processing: eye tracking evidence from Hindi
    ( 2014-11-01) Mishra, Ramesh Kumar ; Singh, Siddharth
    In two visual world eye tracking studies, we examined the activation of subordinate meanings of ambiguous homophones in Hindi and particularly when the sentence context is biased towards the dominant meaning. Participants listened to sentences that were either neutral or biased towards the dominant meaning of the homophone and saw a display containing four pictures. In experiment 1, the display had a shape competitor of the subordinate meaning of the homophone in both neutral and biased conditions along with three unrelated distractors. Experiment 2 had semantic competitors of the subordinate meaning of the homophones along with three distractors. Proportion of fixations to different objects overtime suggested that participants activated the subordinate meanings and oriented their attention to the shape and semantic competitors even when the prior context was biased towards the dominant meaning. Overall, these data from Hindi provide further support to those models of lexical access that assume exhaustive access of both the meanings of an ambiguous homophone. These data suggest even a dominant bias does not eliminate the activation of perceptual and conceptual features of the subordinate meaning.
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    Alcoholic Extract of Ashwagandha Leaves Protects Against Amnesia by Regulation of Arc Function
    ( 2016-04-01) Gautam, Akash ; Kaul, Sunil C. ; Thakur, Mahendra K.
    Our earlier report on scopolamine-induced amnesia and its improvement by pre-treatment with i-Extract (alcoholic extract of Ashwagandha leaf) suggested that the i-Extract mediated nootropic effect may involve neuronal immediate early gene, Arc. With a hypothesis that the i-Extract induced expression of Arc protein may cause augmentation in Arc function, we examined the effect of i-extract on a major function of Arc protein, i.e. F-actin expansion, using Arc antisense oligodeoxynucleotides (ODN). Stereotaxic infusion of Arc antisense ODN in the CA1 region of hippocampus decreased the level of Arc protein as demonstrated by immunoblotting. However, this decrease was attenuated when treated with i-Extract prior to infusion of Arc antisense ODN. We noted a significant decrease in the polymerization of F-actin during scopolamine-induced amnesia as well as Arc antisense ODN infusion that was restored rather enhanced when pre-treated with i-Extract in both the cases. We also compared the corresponding changes between CA1 (the infusion site) and CA3 (neighbouring site of infusion) regions of hippocampus, and found more pronounced effects in CA1 than in the CA3 region. The extent of F-actin polymerization, as revealed by changes in the dendritic spine architecture through Golgi staining, showed that both scopolamine as well as Arc antisense ODN disrupted the spine density and mushroom-shaped morphology that was again regained if pre-treated with i-Extract. In conclusion, the findings reveal that the Arc helps in polymerization of F-actin and subsequent changes in the morphology of dendritic spines after pre-treatment with i-Extract in scopolamine-induced amnesic mice, suggesting an important role of Arc in scopolamine-induced amnesia and its recovery by i-Extract.
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    An updated insight into the molecular pathogenesis, secondary complications and potential therapeutics of COVID-19 pandemic
    ( 2020-09-15) Jamwal, Sumit ; Gautam, Akash ; Elsworth, John ; Kumar, Mandeep ; Chawla, Rakesh ; Kumar, Puneet
    Coronavirus disease 2019 (COVID-19) is an unprecedented disease caused by highly pathogenic SARS-CoV-2 and characterized by extreme respiratory deterrence, pneumonia and immune damage. The phylogenetic analysis demonstrated the sequence similarity of SARS-CoV-2 with other SARS-like bat viruses. The primary source and intermediate host are not yet confirmed, although transmission from human to human is universally confirmed. The new SARS-CoV-2 virus reaches cells via ACE-2 and subsequently down-regulates ACE-2, leaving angiotensin II unbalanced in affected organs primarily in the lungs, heart, brain, and kidneys. As reported recently, numerous secondary complications i.e., neurological, nephrological, cardiovascular, gastrointestinal, immune, and hepatic complications, are associated with COVID-19 infection along with prominent respiratory disease including pneumonia. Extensive research work on recently discovered SARS-CoV-2 is in the pipeline to clarify pathogenic mechanisms, epidemiological features, and identify new drug targets that will lead to the development of successful strategies for prevention and treatment. There are currently no appropriate scientifically approved vaccines/drugs for COVID-19. Nonetheless, few broad-spectrum antiviral drugs, azithromycin were tested against COVID-19 in clinical trials, and finally, FDA approved emergency use of remdesivir in hospitalized COVID-19 patients. Additionally, administration of convalescent plasma obtained from recovered COVID-19 patients to infected COVID-19 patients reduces the viral burden via immunomodulation. This review analysis therefore concentrates primarily on recent discoveries related to COVID-19 pathogenesis along with a full description of the structure, genome, and secondary complication associated with SARS-CoV-2. Finally, a short and brief clinical update has been provided concerning the development of therapeutic medications and vaccines to counter COVID-19.
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    Anderson localization in a model binary alloy
    ( 1978-01-01) Srivastava, Vipin ; Weaire, D.
    The equation-of-motion method is applied to a random binary alloy represented by a simple tight-binding Hamiltonian in the split-band limit. The results suggest that Anderson localization occurs well above the percolation threshold, which was not predicted by previous analytic studies. © 1978 The American Physical Society.
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    Anderson localization on a d=2 triangular lattice
    ( 1992-12-01) Li, Qiming ; Phillips, P. ; Srivastava, V.
    The authors show in this article, by using finite size scaling that the d=2 triangular lattice does not exhibit an insulator-metal transition in contrast to the claim of Srivastava.
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    Arithmetic of the integer quantum hall effect
    ( 1998-01-01) Srivastava, Vipin
    The integer quantum Hall effect (IQHE) is analysed, considering the degeneracies of localized and extended states separately. Occupied localized and extended states are counted, and their variation is studied as a function of magnetic field. The number of current-carrying electrons is found to have a saw-tooth variation with magnetic field. The analysis addresses certain basic questions in the IQHE, particularly the one about floatation of extended states as the magnetic field tends to zero.
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    Assessment of cholinergic properties of Ashwagandha leaf-extract in the amnesic mouse brain
    ( 2016-07-01) Gautam, Akash ; Wadhwa, Renu ; Thakur, Mahendra K.
    Background: In our earlier study, we have shown the memory enhancing and scopolamine-induced amnesia recovery properties of Ashwagandha leaf extract using behavioral paradigm and expression analysis of synaptic plasticity genes. Purpose: However, the exact mechanism through which Ashwagandha demonstrates these effects is still unknown. Methods: In the present study, we hypothesized that the alcoholic extract of Ashwagandha leaves (i-Extract) possesses cholinergic properties, which in turn inhibit the anti-cholinergic nature of scopolamine. Therefore, the potential of i-Extract to recover from the scopolamine-induced cholinergic deficits was assessed by measuring acetylcholine (neurotransmitter) and Arc (synaptic activity-related gene) expression level in the mouse brain. Results: The enzymatic activity of acetyl cholinesterase and choline acetyltransferase was assessed through colorimetric assays, and expression level of Arc protein was examined by Western blotting. Furthermore, mRNA level of these genes was examined by semi-quantitative reverse-transcriptase PCR. We observed that the treatment of i-Extract in scopolamine-induced am nesic mouse attenuates scopolamine-induced detrimental alterations in the cholinergic system. Conclusion: Thus, our study provided biochemical and molecular evidence of cholinergic properties of Ashwagandha leaf extract during brain disorders associated with cholinergic dysfunction.
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    Attention and perception in the deaf: A case for plasticity in consciousness
    ( 2018-02-26) Prasad, Seema ; Mishra, Ramesh Kumar
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    Attention and vision in language processing
    ( 2015-01-01) Mishra, Ramesh Kumar ; Srinivasan, Narayanan ; Huettig, Falk
    This volume provides a comprehensive overview of the nature of attentional and visual processes involved in language comprehension. Key concerns include how linguistic and non-linguistic processes jointly determine language comprehension and production and how the linguistic system interfaces with perceptual systems and attention. Language scientists have traditionally considered language in isolation from other cognitive and perceptual systems such as attention, vision and memory. In recent years, however, it has become increasingly clear that language comprehension must be studied within interaction contexts. The study of multimodal interactions and attentional processes during language processing has thus become an important theoretical focus that guides many research programs in psycholinguistics and related fields.
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    Attention capture by brief abrupt-onset cues in deaf individuals
    ( 2022-03-12) Prasad, Seema ; Patil, Gouri Shanker ; Somashekarappa, Vidya ; Mishra, Ramesh Kumar
    Auditory loss in deaf individuals has been associated with an enhancement in the visual modality. Visual attention is one domain where such plasticity-induced changes have been observed, although which specific attentional mechanisms are improved is still not clear. Using a modified spatial cueing paradigm, we examined attention capture in deaf and normal-hearing participants. Brief abrupt-onset cues were presented for 16 ms either in attended or ignored locations. The to-be-attended locations for each trial were indicated by a horizontal or a vertical bar at the centre of the screen. These were presented either in vertical- or horizontal-only blocks or mixed together. We observed greater negative cueing effects in the NH group compared to deaf. Additionally, people with deafness showed greater capture by cues at ignored locations in the slower responses. These findings shed further light on orienting mechanisms in deaf and help in understanding the specificity of the differences in visual processing between deaf and normal-hearing individuals.
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    Bacopa monniera (CDRI-08) Upregulates the Expression of Neuronal and Glial Plasticity Markers in the Brain of Scopolamine Induced Amnesic Mice
    ( 2015-01-01) Konar, Arpita ; Gautam, Akash ; Thakur, M. K.
    Preclinical studies on animal models have discerned the antiamnesic and memory-enhancing potential of Bacopa monniera (Brahmi) crude extract and standardized extracts. These studies primarily focus on behavioral consequences. However, lack of information on molecular underpinnings has limited the clinical trials of the potent herb in human subjects. In recent years, researchers highlight plasticity markers as molecular correlates of amnesia and being crucial to design therapeutic targets. In the present report, we have investigated the effect of a special extract of B. monniera (CDRI-08) on the expression of key neuronal (BDNF and Arc) and glial (GFAP) plasticity markers in the cerebrum of scopolamine induced amnesic mice. Pre- and postadministration of CDRI-08 ameliorated amnesic effect of scopolamine by decreasing acetyl cholinesterase activity and drastically upregulating the mRNA and protein expression of BDNF, Arc, and GFAP in mouse cerebrum. Interestingly, the plant extract per se elevated BDNF and Arc expression as compared to control but GFAP was unaltered. In conclusion, our findings provide the first molecular evidence for antiamnesic potential of CDRI-08 via enhancement of both neuronal and glial plasticity markers. Further investigations on detailed molecular pathways would encourage therapeutic application of the extract in memory disorders.
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    Brain aging: A critical reappraisal
    ( 2012-01-01) Thakur, Mahendra K. ; Konar, Arpita ; Gautam, Akash
    Despite remarkable scientific advancements in recent years, much about the human brain still remains a mystery, particularly in the context of brain aging and associated disorders. Understanding of the factors that influence brain integrity late in life will help to maintain healthy brain functions. This is indeed a difficult task because in several cases, normal brain aging switches to pathological aging associated with drastic deterioration in cognitive abilities, motor skills and mood resulting in neurological diseases, ranging from late onset neurodegenerative diseases such as Alzheimer’s and Parkinson’s to early onset neuropsychiatric disorders such as schizophrenia and bipolar disorder. Brain aging is accompanied by several anatomical, cellular and molecular alterations including reduction in brain volume, protein turnover, increase in protein aggregation, impairment in neural plasticity, perturbed calcium homeostasis, neuronal survival and neuroinflammation, eventually affecting brain functions with increased incidence of neurological disorders. Factors like stress, depression, hypertension as well as obesity accelerate the aging of brain contributing to neurodegeneration and associated cognitive deficits. During the past decades, technical advances including microarray, neuroimaging and behavioral paradigms have helped to get a holistic picture of age-associated alterations in the brain. Here we review the current understanding of age-related structural and functional changes in the brain and how these changes might contribute to vulnerability for developing age-related neurological diseases and designing potential therapeutic avenues. Taken together, the findings suggest that adoption of certain neuroprotective strategies like dietary restriction, antioxidant supplementation, low alcohol intake, less exposure to stressors, environmental enrichment and lifestyle modulations involving exercise and intellectual brain training programs can be beneficial to delay the loss of brain integrity during aging.
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    Characterization of recruitment through tandem running in an indian queenless ant Diacamma indicum
    ( 2017-01-18) Kaur, Rajbir ; Joseph, Joby ; Anoop, Karunakaran ; Sumana, Annagiri
    Tandem running is a primitive recruitment method employed by many ant genera. This study characterizes this behaviour during the recruitment of colony mates to a new nest in an Indian ant Diacamma indicum. Tandem leaders who have knowledge of the new nest lead a single follower at a time, to the destination by maintaining physical contact. In order to characterize tandem running, we captured and analysed 621 invitations, 217 paths and 226 termination events. Remarkably, not a single colony member was lost. While invitations were stereotypic in behaviour, termination was not. Analysis of speed revealed that the average transport speed was 4.2 cm s−1. Coupled adult-brood transport was slower than other transports but was more efficient than individual trips. Comparing tandem running with other popular recruitment methods in ants allows us to postulate that even though tandem running is primitive it is probably just anothermeans to achieve the same end.
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    Characterization of the olfactory system of the giant honey bee, Apis dorsata
    ( 2020-01-01) Mogily, Sandhya ; VijayKumar, Meenakshi ; Sethy, Sunil Kumar ; Joseph, Joby
    Apis dorsata is an open-nesting, undomesticated, giant honey bee found in southern Asia. We characterized a number of aspects of olfactory system of Apis dorsata and compared it with the well-characterized, western honeybee, Apis mellifera, a domesticated, cavity-nesting species. A. dorsata differs from A. mellifera in nesting behavior, foraging activity, and defense mechanisms. Hence, there can be different demands on its olfactory system. We elucidated the glomerular organization of A. dorsata by creating a digital atlas for the antennal lobe and visualized the antennal lobe tracts and localized their innervations. We showed that the neurites of Kenyon cells with cell bodies located in a neighborhood in calyx retain their relative neighborhoods in the pedunculus and the vertical lobe forming a columnar organization in the mushroom body. The vertical lobe and the calyx of the mushroom body were found to be innervated by extrinsic neurons with cell bodies in the lateral protocerebrum. We found that the species was amenable to olfactory conditioning and showed good learning and memory retention at 24 h after training. It was also amenable to massed and spaced conditioning and could distinguish trained odor from an untrained novel odor. We found that all the above mentioned features in A. dorsata are very similar to those in A. mellifera. We thereby establish A. dorsata as a good model system, strikingly similar to A. mellifera despite the differences in their nesting and foraging behavior.
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    Cluster approaches to random alloys: An appraisal
    ( 1978-12-01) Srivastava, Vipin ; Chaturvedi, Meena ; Joshi, S. K.
    Some of the cluster extensions of the coherent potential approximation (CPA) based on the effective medium theory have been critically studied with respect to the decoupling schemes involved in them. Their computational tractability has been examined and it has been found that the self-consistent calculations in three-dimensional systems are immensely difficult to perform. A self-consistent calculation has been reported for simple cubic lattices with diagonal and off-diagonal disorder using a pair-CPA method. A significant finding of the paper is that it has been shown that non-analyticities are a general feature of extensions of CPA within multiple scattering framework. The non-analyticities were reported several times but a general proof of their existence was not noticed. It was also believed that the so-called molecular-CPA is analytic, this has been shown to be wrong here. The density of states results with off-diagonal randomness have been qualitatively understood to yield some information about the influence of off-diagonal randomness on Anderson localisation of an electron. © 1977 Indian Academy of Sciences.