Journal articles
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Kumar S, Riddoch MJ, Humphreys GW, 'Handgrip based action information modulates attentional selection: An ERP study'
Frontiers in Human Neuroscience 15 (2021)
ISSN: 1662-5161 eISSN: 1662-5161
Abstract Prior work shows that the possibility of action to an object (visual affordance) facilitates attentional deployment. We sought to investigate the neural mechanisms underlying this modulation of attention by examining ERPs to target objects that were either congruently or incongruently gripped for their use in the presence of a congruently or incongruently gripped distractor. Participants responded to the presence or absence of a target object matching a preceding action word with a distractor object presented in the opposite location. Participants were faster in responding to congruently gripped targets compared to incongruently gripped targets. There was a reduced N2pc potential when the target was congruently gripped, and the distractor was incongruently gripped compared to the conditions where targets were incongruently gripped or when the distractor, as well as target, was congruently gripped. The N2pc results indicate that target selection is easier when action information is congruent with an object’s use.
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Kumar S, Veldhuis A, Malhotra T, 'Neuropsychiatric and Cognitive Sequelae of COVID-19'
Frontiers in Psychology 12 (2021)
ISSN: 1664-1078
Abstract Coronavirus disease 2019 (COVID-19) is likely to have long-term mental health effects on individuals who have recovered from COVID-19. Rightly, there is a global response for recognition and planning on how to deal with mental health problems for everyone impacted by the global pandemic. This does not just include COVID-19 patients but the general public and health care workers as well. There is also a need to understand the role of the virus itself in the pathophysiology of mental health disorders and longer-term mental health sequelae. Emerging evidence suggests that COVID-19 patients develop neurological symptoms such as headache, altered consciousness, and paraesthesia. Brain tissue oedema and partial neurodegeneration have also been observed in an autopsy. In addition, there are reports that the virus has the potential to cause nervous system damage. Together, these findings point to a possible role of the virus in the development of acute psychiatric symptoms and long- term neuropsychiatric sequelae of COVID-19. The brain pathologies associated with COVID-19 infection is likely to have a long-term impact on cognitive processes. Evidence from other viral respiratory infections, such as SARS, suggests a potential development of psychiatric disorders, long-term neuropsychiatric disorders, and cognitive problems. In this paper, we will review and evaluate the available evidence of acute and possible long-term neuropsychiatric manifestations of COVID-19. We will discuss possible pathophysiological mechanisms and the implications this will have on preparing a long-term strategy to monitor and manage such patients.
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Anju Mishra, Shanu Sharma, Sanjay Kumar, Priya Ranjan, Amit Ujlayan, 'Effect of Hand Grip Actions on Object Recognition Process: A Machine Learning based approach for Improved Motor Rehabilitation'
Neural Computing and Applications 33 (2020) pp.2339-2350
ISSN: 0941-0643 eISSN: 1433-3058
Abstract Brain computer interface (BCI) is the current trend in technology expansion as it provides an easy interface between human brain and machine. The demand for BCI based applications is growing tremendously and efforts are in progress to deploy BCI devices for real world applications. One of the widely known applications of BCI technology is rehabilitation in which BCI devices can provide various types of assistance to specially-abled persons. In this paper the effect of hand actions on objects is analyzed for motor related mental task. The proposed approach analysis electroencephalogram (EEG) based brain activity which was captured for images shown with different gripping actions on objects. The EEG recordings are first pre-processed, followed by extraction of epochs and frequency bands using discrete wavelet transform (DWT), afterwards feature extraction followed by training and classification steps are performed for classifying the grip action into congruent (correct) and incongruent (incorrect) grip categories. The proposed work makes use of average power and relative wavelet energy as discriminating features which are then fed to train an artificial neural network for automatically classifying the incoming EEG patterns into correct or incorrect object hand grips. The performance evaluation of proposed system is done on real EEG data set obtained from 14 subjects. Experimental results have shown an accuracy of 75%. Also, to evaluate the effectiveness of our work, a comparison of our work with other state of art works reported by different authors is presented at the end. The results show the effectiveness of proposed approach and suggest further that the system can be used for analyse and train subjects having motor-related disabilities for perceiving correct or incorrect hand grips on objects.
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Carey LF, Anderson GM, Kumar S, 'A Novel Attention Bias Modification Single Session Training Improves Eye Gaze Behaviour in Social Anxiety Disorder: A Pilot Study'
Global Psychiatry 3 (1) (2020)
ISSN: 2451-4950
Abstract Background. Attention Bias Modification (ABM) can reduce anxiety and attentional bias towards threatening stimuli, but evidence of its usefulness as a potential intervention for socially anxious individuals has been mixed. Eye contact avoidance, a maladaptive attentional strategy in social anxiety disorder (SAD), has yet to be targeted by ABM research. Aims. This study sought to establish whether a new ABM training paradigm could increase attentional deployment towards eyes, and what effect this would have on social and gaze-related anxiety. Method. Participants (n = 23), recruited through adverts calling for people who felt anxious in social situations, completed either a novel ABM training task designed to induce attentional bias towards images of eyes over images of noses, or control training. Data on response times (RTs), accuracy of responses, gaze behaviour (using an eye tracker), and scores on clinical measures of social and gazerelated anxiety were collected before and after both training tasks. Results. ABM training produced a greater number of initial saccades towards eye images than did the control task, indicating an induced shift in early attentional deployment. ABM training was also associated with a marginal increase in fixation durations on eye images. No effect was observed on RTs, or social and gaze-related anxiety. Conclusions. Our results indicate that ABM can alter the gaze behaviour of socially anxious individuals. They also highlight the importance of eye tracking to ABM research, as it was more sensitive than analyses of RTs to changes in early attentional deployment.
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McIvor L, Sui J, Malhotra T, Drury D, Kumar S, 'Self-Referential Processing and Emotion Context Insensitivity in Major Depressive Disorder'
European Journal of Neuroscience 53 (1) (2020) pp.311-329
ISSN: 0953-816X eISSN: 1460-9568
Abstract We examined whether differential self-perception influences the salience of emotional stimuli in depressive disorders, using a perceptual matching task in which geometric shapes were arbitrarily assigned to the self and an unknown other. Participants associated shapes with personal labels (e.g. ‘self’ or ‘other’). Each geometric shape additionally contained a happy, sad or neutral line drawing of a face. Participants then judged whether shape-label pairs were as originally shown or re-paired, whilst facial emotion was task-irrelevant. The results showed biased responses to self-relevant stimuli compared to other-relevant stimuli, regardless of facial emotion, for both control and depressed participants. This was reflected in sensitivity (d’) and drift rate (v) measures, suggesting that self-bias and a bias towards emotion may reflect different underlying processes. We further computed bias scores by subtracting the ‘neutral’ value of each measure (acting as baseline) from the ‘happy’ and ‘sad’ values of each measure, indexing an ‘emotional bias’ (EB) score for ‘self’ and ‘other’ separately. Compared to control participants, depressed participants exhibited reduced ‘happy’ and ‘sad’ emotional biases, regardless of the self-relevance of stimuli. This finding indicates that depressed participants may exhibit generalised Emotion Context Insensitivity (ECI), characterised by hyopoattention to both positive and negative information, at short stimulus presentations. The implications of this are discussed.
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Srivastava C, Bhardwaj A, Sharma M, Kumar S, 'Cognitive Deficits in Euthymic Patients with Bipolar Disorder: State or Trait Marker?'
Journal of Nervous and Mental Disease 207 (2) (2019) pp.100-105
ISSN: 0022-3018 eISSN: 1539-736X
Abstract Cognitive deficits have been demonstrated in people in the euthymic phase of bipolar disorder. This cross-sectional study compared euthymic bipolar disorder patients (N=30) with never psychiatrically ill controls (N=30) on a neuropsychological test battery containing tasks of executive function, the Wisconsin Card Sorting Test (WCST), attention and working memory, Digits Forward and Backward, and speed of information processing, Digit Symbol. Scores on the Mini Mental State Examination (MMSE) and Vocabulary Test did not differ between the groups. The bipolar group were significantly impaired compared to controls on various indices of executive function on the Wisconsin Card Sort Test and on the Digit tests. The impaired performance on the Digit tests, but not the WCST, was significantly associated with medication status, notably prescribed benzodiazepines. There was no significant effect of severity or course of illness on performance. The findings support the hypothesis that impairments in executive function are present between illness episodes in bipolar disorder, and so are not simply state markers.
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Kumar S, Higgs S, Rutters F, Humphreys GW, 'Biased towards food: Electrophysiological evidence for biased attention to food stimuli'
Brain and Cognition 110 (2016) pp.85-93
ISSN: 0278-2626 eISSN: 1090-2147
Abstract We investigated the neural mechanisms involved in bias for food stimuli in our visual environment using event related lateralized (ERL) responses. The participants were presented with a cue (food or non-food item) to either identify or hold in working memory. Subsequently, they had to search for a target in a 2-item display where target and distractor stimuli were each flanked by a picture of a food or a non-food item. The behavioural data showed that performance was strongly affected by food cues, especially when food was held in WM compared to when the cues were merely identified. The temporal dynamics of electrophysiological measures of attention (the N1pc and N2pc) showed that the orienting of attention towards food stimuli was associated with two different mechanisms; an early stage of attentional suppression followed by a later stage of attentional orienting towards food stimuli. In contrast, non-food cues were associated only with the guidance of attention to or away from cued stimuli on valid and invalid trials. The results demonstrate that food items, perhaps due to their motivational significance modulate the early orienting of attention, including an initial suppressive response to food items.
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Kumar S, Pilling M, 'The cauldron of the ethical review process in human participant research'
Cortex 71 (2015) pp.413-414
ISSN: 0010-9452
Abstract
Bioethics; Human participants
Baron (2015) in this issue nicely identifies some of the issues the scientist faces in gaining ethical approval for their research, as well as offering a credible alternative to address these problems. We have made a number of observations – both from our own experiences and from those of our colleagues at various institutions – on the ethical approval process. Ethics is often a source of frustration for the research scientist; it can be time consuming, it operates as a bottleneck in the research process – by extension – it is arguably an impediment to scientific progress. The process of obtaining ethical acceptance is often a wearisome one for scientists and a frequent source of complaint. The impression is given that ethical panels tend to tolerate rather than support research on human participants. Some seem to operate from a starting principle of research on human participants' being an exploitative one, i.e., one in which, without the guardianship provided by the panels, scientists would frequently, knowingly or unknowingly, infringe upon the welfare of individual participants. Indeed, in the UK the National Research Ethics Service of the National Health Service seems to explicitly pledge such a role in affirming its service exists to protect the ‘rights, safety, dignity and well-being of research participants’ as its primary concern. We believe that the other ethical committees of different institutions may espouse similar views. This starting point of apparent antagonism between the scientist and ethics review panel is not a helpful one and is a source of many of the frustrations that scientists experience. Baron further argues that ethics review board members often fail to apply the parameters to judge ethical components in any constant manner; even where consistency is evident this is never done in terms of any objective analysis of expected utility-loss. This problem has been recognised before in critiques of the ethical review process. In particular Zimbardo (1973) – after his Stanford Prison Experiment – noted how ethics reviewers tend to make decisions using a relative (contingent) ethical principle, one which has potential to be used arbitrarily. It is notable that in Universities at least, the application of ethical principle seems to be something uniquely applied to research activities. No such ethical principle or process applies to other contexts, for example teaching. Thus the same stimulus set and experimental task can be conducted for educational or demonstration purposes in the teaching room. If the same experiment is done as part of a research activity then it suddenly falls into the domain of the ethics board and requires a whole set of protocols to follow and approvals to be obtained. It is not clear how same intervention (same stimuli/experiment) requires the application of two different set of rules, nor what is special about research per se which makes it a unique source of formal ethical concern.
We agree with Baron's point that the ethics board reviewer may make systematic errors in exaggerating low probability risks. In our personal view and experience of working at various institutions, we conservatively estimate to have each tested well over 2000 participants, either directly as a researcher or indirectly through supervising students' research, but either of us has yet had any encounter of a situation where a participant displayed an unanticipated or unpleasant reaction to an experimental manipulation or stimulus presentation. It is ironic that in most cases the research scientist themselves is the one best placed to assess the most likely risks of an experiment they are conducting; the ethical review panellists are often making judgements on things which are outside of their field of experience and expertise.
Baron goes on to propose that ethics board members be trained in decision making and statistics and be taught to bring such rules of logic to the ethical review process. However, such approach has the danger of becoming too formalised. It could ultimately lead to board members being replaced with an automated computer algorithm or expert system to make ethical decisions. Probably, as researchers we won't like to see this and most would like to retain some level of human element in the ethical decision process even despite the flaws and frustrations we have highlighted.
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Rutters F, Kumar S, Higgs S, Humphreys GW, 'Electrophysiological evidence for enhanced representation of food stimuli in working memory'
Experimental Brain Research 233 (2) (2014) pp.519-528
ISSN: 0014-4819 eISSN: 1432-1106
Abstract
Studies from our laboratory have shown that, relative to neutral objects, food-related 30 objects kept in
working memory (WM) are particularly effective in guiding attention to food stimuli (Higgs et al.
2012). Here, we used electrophysiological measurements to investigate the neural representation of
food vs. non-food items in WM. Subjects were presented with a cue (food or non-food item) to either
attend to or hold in WM. Subsequently, they had to search for a target, while the target and distractor
35 were each flanked by a picture of a food or non-food item. Behavioural data showed that a food cue
held in WM modulated the deployment of visual attention to a search target more than a non-food
cue, even though the cue was irrelevant for target selection. Electrophysiological measures of
attention, memory and retention of memory (the P3, LPP and SPCN components) were larger when
food was kept in WM, compared to non-food items. No such effect was observed in a priming task,
40 when the initial cue was merely identified. Overall, our electrophysiological data are consistent with
the suggestion that food stimuli are particularly strongly represented in the WM system.
Studies from our laboratory have shown that, relative to neutral objects, food-related 30 objects kept in working memory (WM) are particularly effective in guiding attention to food stimuli (Higgs et al. 2012). Here, we used electrophysiological measurements to investigate the neural representation of food vs. non-food items in WM. Subjects were presented with a cue (food or non-food item) to either attend to or hold in WM. Subsequently, they had to search for a target, while the target and distractor were each flanked by a picture of a food or non-food item. Behavioural data showed that a food cue held in WM modulated the deployment of visual attention to a search target more than a non-food cue, even though the cue was irrelevant for target selection. Electrophysiological measures of attention, memory and retention of memory (the P3, LPP and SPCN components) were larger when food was kept in WM, compared to non-food items. No such effect was observed in a priming task, when the initial cue was merely identified. Overall, our electrophysiological data are consistent with the suggestion that food stimuli are particularly strongly represented in the WM system.
Website
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Telling AL, Kumar S, Meyer AS, Humphreys GW, 'Electrophysiological Evidence of Semantic Interference in Visual Search'
Journal of Cognitive Neuroscience 22 (10) (2010) pp.2212-2225
ISSN: 0898-929X eISSN: 1530-8898
Abstract
Visual evoked responses were monitored while participants searched for a target (e.g., bird) in a four-object display that could include a semantically related distractor (e.g., fish). The occurrence of both the target and the semantically related distractor modulated the N2pc response to the search display: The N2pc amplitude was more pronounced when the target and the distractor appeared in the same visual field, and it was less pronounced when the target and the distractor were in opposite fields, relative to when the distractor was absent. Earlier components (P1, N1) did not show any differences in activity across the different distractor conditions. The data suggest that semantic distractors influence early stages of selecting stimuli in multielement displays.
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Conference papers
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Shanu Sharma, Anju Mishra, Sanjay Kumar, Priya Ranjan and Amit Ujlayan, 'Analysis of Action Oriented Effects on Perceptual Process of Object Recognition Using Physiological Responses'
(2018) pp.46-58
ISBN: 9783030040208 eISBN: 9783030040215
Abstract Action on any objects provides perceptual information about the environment. There is a significant evidence that human visual system responds to action possibilities in an image as perceiving any ones action stimulates human motor system. However very limited studies have been done to analyze the effect of object affordance during action perception and execution. To study the effect of object affordance on human perception, in this paper we have analyzed the human brain signals using EEG based oscillatory activity of brain. EEG responses corresponding to images of objects shown with correct, incorrect and without grips are examined. Exploration of different gripping effects has been done by extracting Alpha and Beta frequency bands using Discrete Wavelet Transform based band extraction method, then baseline normalized power of Alpha and Beta frequency bands at 24 positions of motor area of left and right side of brain are examined. The result shows that 12 pooled electrodes at central and central parietal region provides a clear discrimination among the three gripping cases in terms of calculated power. The presented research explores new applicabilities of object affordance to develop a variety of Brain Computer Interface (BCI) based devices and to improve motor imagery ability among motor disorder related patients.Website
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Mishra A, Ranjan P, Kumar S, Ujlayan A, 'From Cognitive Psychology to Image Segmentation: A Change of Perspective'
(2018) pp.61-67
ISSN: 2367-3370 eISSN: 2367-3389 ISBN: 9789811089107
Abstract Image segmentation is a complex and essential task used in many computer vision applications. The problem of image segmentation can essentially be formulated as a grouping problem which in its simplest form tries to group the pixels of image into distinguished regions of interest so that further processing of the extracted regions can be achieved. This work proposes an image segmentation model which is inspired by the findings in cognitive psychology theories to divide the image into separate coherent regions. The proposed work tries to correlate between human and machine cognition by studying the segmentation process under the light of psychology of human vision.Website
Other publications
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Kumar S, Pilling M, 'The cauldron of the ethical review process in human participant research.'
Cortex 71 (2015) pp.413-414ISSN: 0010-9452 eISSN: 1973-8102
Abstract Discussion forumWebsite
Glyn W Humphreys, Sanjay Kumar, Eun Young Yoon, Melanie Wulff, Katherine Roberts, & M J Riddoch. Attending to the possibilities of action. Philosophical Transactions of the Royal Society :B 368:20130059; doi:10.1098/rstb.2013.0059
Sanjay Kumar, Shobini L. Rao, B.A. Chandramouli & Shibu Pillai Reduced Contribution of Executive Functions in impaired Working Memory Performance in Mild Traumatic Brain Injury Patients. (2013). Clinical Neurology and Neurosurgery. doi: 10.1016/j.clineuro.2012.12.038.
Sanjay Kumar, M J Riddoch, & Glyn W Humphreys. (2013). Mu rhythm desynchronization reveals motoric influences of hand action on object recognition. Frontiers in Human Neuroscience, doi: 10.3389/fnhum.2013.00066
Eun Young Yoon, Glyn W Humphreys, Sanjay Kumar, & Pia Rotshtein. (2012). The neural selection and integration of actions and objects: An fMRI study. Journal of Cognitive Neuroscience, 24, 2268-2279.
Sanjay Kumar, Eun Young Yoon, & Glyn W Humphreys. (2012). Perceptual and motor based responses to actions on objects. Experimental Brain Research, 220, 153-164.
Anna L. Telling, Sanjay Kumar, Antje S. Meyer, & Glyn W Humphreys (2010). Electrophysiological evidence of semantic interference in visual search, Journal of Cognitve Neuroscience, 22, 2212-2225.
Glyn W Humphreys, Eun Young Yoon, Sanjay Kumar, Vaia Lestou, Keiko Kitadono, Katherine L. Roberst, & M. Jane Riddoch. (2010). The Interaction of attention and action: from seeing action to acting on perception. British Journal of Psychology, 101, 185-206.
Glyn W Humphreys, Eun Young Yoon, Sanjay Kumar, Vaia Lestou, Keiko Kitadono, Katherine L. Roberst, & M. Jane Riddoch. (2010). Attention and its coupling to action. British Journal of Psychology, 101, 217-219.
Tej B. Singh, Gauri S. Kaloiya, Sanjay Kumar, & Rakesh K. Chadda. Rehabilitation need assessment of severely mentally ill and effect of intervention. Delhi Psychiatry Journal, 13, 109-116.
Sanjay Kumar, David Soto, Glyn W. Humphreys (2009). Electrophysiological evidence for attentional guidance by the contents of working memory. European Journal of Neuroscience, 30, 307-317. Graphics from the study featured as the cover of the issue.
Sanjay Kumar, Shobini L. Rao, B.A. Chandramouli & Shibu Pillai (2009). Reduction of Functional Brain Connectivity in Mild Traumatic Brain Injury Patients during Working Memory, Journal of Neurotrauma, 26, 665-675.
Sanjay Kumar, Shobini L. Rao, Biju Sunny, & B. N. Gangadhar. (2007).Wide spread cognitive deficits associated with anterograde psychogenic amnesia. Psychiatry and Clinical Neurosciences, 61,583-586.
Sanjay Kumar, Shobini L. Rao, Ragesh G. Nair, Shibu Pillai, B.A.Chandra Mouli & D.K. Subbakrishna (2005). Sensory gating deficits in development of post concussive symptoms in mild head injury. Psychiatry and Clinical Neurosciences, 59, 466-472.