Journal Ariticles by Arun Sasidharan
The present study describes the development of a neurocognitive paradigm: " Assessing Neurocognit... more The present study describes the development of a neurocognitive paradigm: " Assessing Neurocognition via Gamified Experimental Logic " (ANGEL), for performing the parametric evaluation of multiple neurocognitive functions simultaneously. ANGEL employs an audiovisual sensory motor design for the acquisition of multiple event related potentials (ERPs)—the C1, P50, MMN, N1, N170, P2, N2pc, LRP, P300, and ERN. The ANGEL paradigm allows assessment of 10 neurocognitive variables over the course of three " game " levels of increasing complexity ranging from simple passive observation to complex discrimination and response in the presence of multiple distractors. The paradigm allows assessment of several levels of rapid decision making: speeded up response vs. response-inhibition; responses to easy vs. difficult tasks; responses based on gestalt perception of clear vs. ambiguous stimuli; and finally, responses with set shifting during challenging tasks. The paradigm has been tested using 18 healthy participants from both sexes and the possibilities of varied data analyses have been presented in this paper. The ANGEL approach provides an ecologically valid assessment (as compared to existing tools) that quickly yields a very rich dataset and helps to assess multiple ERPs that can be studied extensively to assess cognitive functions in health and disease conditions.
Drowsiness, the state where a person's alertness is reduced, is one of the major causes of accide... more Drowsiness, the state where a person's alertness is reduced, is one of the major causes of accidents. Therefore, there is a need for the detection of this state of human brain, especially for the people working in industries and also for those involved in driving activities. Hence, drowsiness detection system is gaining more importance these days. In this paper, the authors have presented a drowsiness detection methodology using electroencephalogram (EEG) signals. The method used in the detection is fractal dimension (FD), which is a measure of irregularity of the curve. Three FD algorithms, Higuchi, Katz and Petrosian are tried along with logarithm of energy (log E), and Intrinsic dimension (ID) on a set of 15 alert and 15 drowsy signals. In addition, certain statistical features are extracted from the signals. The Support vector Machine (SVM) classifier used in this work yielded a sensitivity of 76 percentage, a specificity of 70 percentage, in distinguishing the drowsy and alert samples.
The modern concept of sleep and wakefulness has evolved from the landmark discovery of ascending ... more The modern concept of sleep and wakefulness has evolved from the landmark discovery of ascending reticular activating system
by Moruzzi and Magoun in 1949. The other major contributions have come from the electrophysiological studies of sleep–wake
states following the discovery of electroencephalogram by Hans Berger in 1929. Research studies over the past 60 years
have provided us an enormous understanding on the neural basis of sleep–wake states and their regulatory mechanisms. By
shuttling through the two behavioral states of sleep and wake, brain coordinates many complex functions essential for cellular
homeostasis and adaptation to environment. This review brie fl y summarizes the current awareness on the dynamicity of brain
mechanisms of sleep and wakefulness as well as the newer concepts of the biological functions of sleep.
Conference Papers by Arun Sasidharan
Title: Correlates and Predictors of Endogenous-Cue Prospective Memory in Schizophrenia Author nam... more Title: Correlates and Predictors of Endogenous-Cue Prospective Memory in Schizophrenia Author names and affiliations: Ammu Lukosea,b, Harsha N. Halahallia,#,Nithin Ambekara,b, Arun Sasidharana,c, Devvarta Kumard, Arun Kumar Guptae, John P. Johna,b,f aMultimodal Brain Image Analysis Laboratory (MBIAL); Departments ofbPsychiatry, cNeurophysiology, dClinical Psychology, eNeuroimaging and Interventional Radiology and fClinical Neuroscience, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India – 560029; #Department of Physiology, K.S. Hegde Medical Academy, Nitte University, Mangalore, Karnataka, India – 575018 Abstract Objective: In a recent fMRI study, we recently reported maximum activations of the right rostral prefrontal cortex (BA10) with additional activations of the left dorsal anterior insula during the PM condition of a novel ‘endogenous-cue prospective memory’ paradigm involving incremental updating of working memory (WM) (Halahalli et al 2014). Bo...
Proficient practice of Mindfulness Meditation helps establish proper sleep organization, enhanced... more Proficient practice of Mindfulness Meditation helps establish proper sleep organization, enhanced slow wave sleep, enhanced REM, more sleep cycles, reduced wake after sleep onset (WASO) and N2. We describe spindle-delta dynamics in ten healthy male (aged 30-60 years) long-term Vipassana Meditators (Theravada tradition). For this, we show the sleep architecture in conjunction with Neuro-loop gain which is a predictor of sleep-related delta & spindle repetition, irrespective of EEG amplitude changes. The findings of this preliminary study show that there is a complex delta-spindle dynamicity in non-rapid eye movement (NREM) sleep that describes the sleep architecture in spite of wide variation amongst the long term meditators. This needs further research. Acknowledgements We acknowledge funding from Indian Council for Medical Research (Grant No:55/2/2012-BMS to B.M.K., SRF to A.K.N.) and Department of Science and Technology Cognitive Science Initiative (Grant No: SR/CSI/63/2011 to B.M...
Assessment of neurocognitive functions is traditionally done by observation or experimental manip... more Assessment of neurocognitive functions is traditionally done by observation or experimental manipulation of a single variable (such as attention, perception etc.) while keeping other variables constant. The intention is to study each variable in isolation. However, this introduces systematic confounds. Firstly, assessment of performance of any isolated neurocognitive function is not realistic and representative of real world performance. Secondly, subjects often complain of boredom, fatigue and drowsiness, as most tasks are simple, repetitive and time consuming. This reduces the quality of task performance over time. Thirdly, this approach imposes severe constraints on the realistic study of main and interaction effects of neurocognitive functions. We present a novel and realistic approach that relies on presentation of a logical combination of stimuli in a way that addresses the above limitations. Simultaneous acquisition of multiple variables of interest has been studied before (s...
Aims and objectives: Temporal lobe epilepsy (TLE) is the most common form of focal epilepsy and i... more Aims and objectives: Temporal lobe epilepsy (TLE) is the most common form of focal epilepsy and is often intractable. Cognitive impairments are hallmarks of TLE, but are often associated with other comorbid conditions like anxiety and depression. Accordingly, in the present study we have used a rat model of chronic TLE to assess the spatial learning and memory, and also to evaluate the impact of anxiety and depression-like behaviour. Methods: Male Wistar rats of 200-250g were used for the study. A chemiconvulsant model of TLE using lithium-pilocarpine was established and the animals that showed spontaneous recurrent seizures were included in the study. These animals were assessed for spatial learning and memory in Morris water maze; anxiety-like behaviour in elevated plus maze and open-field; and depressive-like behaviour using forced swim and sucrose preference tests. Results: Epileptic rats were hyperactive in open-field test and showed signs of anxiety-like behaviour in elevated-...
Aims and objectives: Temporal lobe epilepsy (TLE) is the most common form of focal epilepsy and i... more Aims and objectives: Temporal lobe epilepsy (TLE) is the most common form of focal epilepsy and is often intractable. Cognitive impairments are the hallmark of TLE, but are often associated with comorbid conditions like anxiety and depression. Accordingly, in the present study we have used a rat model of chronic TLE to assess the spatial learning and memory, and also to evaluate the impact of anxiety and depressive-like behaviour. Further, the role of enriched environment on epilepsy-induced behavioural deficits was evaluated. Methods: Male Wistar rats of 200-250g were used for the study. A chemiconvulsant model of TLE using lithium-pilocarpine was established and characterized the induction of status epilepticus (SE) by hippocampal and cortical electroencephalograhy, and behavioural grading of seizures. Those animals that showed spontaneous recurrent seizures by 35-40 days post SE were included in the study. The epileptic animals with respective controls were assessed for spatial l...
Aims and objectives: Temporal lobe epilepsy (TLE) is the most common form of focal epilepsy and i... more Aims and objectives: Temporal lobe epilepsy (TLE) is the most common form of focal epilepsy and is often intractable. Cognitive impairments are the hallmark of TLE, but are often associated with comorbid conditions like anxiety and depression. Accordingly, in the present study we have used a rat model of chronic TLE to assess the spatial learning and memory, and also to evaluate the impact of anxiety and depressive-like behaviour. Further, the role of enriched environment (EE) and anti-epileptic drug (AED), levetiracetam on epilepsy-induced behavioural deficits was evaluated. Methods: Male Wistar rats of 200-250g were used for the study. A chemoconvulsant model of TLE using lithium-pilocarpine was established and the induction of status epilepticus (SE) was characterized by hippocampal and cortical electroencephalography, and behavioural grading of seizures. Those animals that showed spontaneous recurrent seizures by 35-40 days post SE were included in the study. The epileptic anima...
Aims and objectives: Temporal lobe epilepsy (TLE) is a common and intractable form of focal epile... more Aims and objectives: Temporal lobe epilepsy (TLE) is a common and intractable form of focal epilepsy. Cognitive impairments are the hallmark of TLE and are often associated with increased frequency of spontaneous seizures. Accordingly in the present study we used a rat model of chronic TLE to assess spatial learning and depression-like behaviour, and correlate these with their seizure occurrence parameters. We hypothesised that anti-epileptic drug (AED) treatment would improve cognitive deficits in association with seizure frequency reduction. Methods: Male Wistar rats (200-250g) were used for the study. A chemoconvulsant model of TLE using lithium-pilocarpine was developed and characterized by hippocampal and cortical electroencephalography, and behavioural grading of seizures. Seizure induced rats were either AED-treated (Levetiracetam for 14 days, 54mg/kg), vehicle-treated or kept untreated. They were video monitored (15h/day for about 30-44 days) to analyse the frequency, total ...
Papers by Arun Sasidharan
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Journal Ariticles by Arun Sasidharan
by Moruzzi and Magoun in 1949. The other major contributions have come from the electrophysiological studies of sleep–wake
states following the discovery of electroencephalogram by Hans Berger in 1929. Research studies over the past 60 years
have provided us an enormous understanding on the neural basis of sleep–wake states and their regulatory mechanisms. By
shuttling through the two behavioral states of sleep and wake, brain coordinates many complex functions essential for cellular
homeostasis and adaptation to environment. This review brie fl y summarizes the current awareness on the dynamicity of brain
mechanisms of sleep and wakefulness as well as the newer concepts of the biological functions of sleep.
Conference Papers by Arun Sasidharan
Papers by Arun Sasidharan
by Moruzzi and Magoun in 1949. The other major contributions have come from the electrophysiological studies of sleep–wake
states following the discovery of electroencephalogram by Hans Berger in 1929. Research studies over the past 60 years
have provided us an enormous understanding on the neural basis of sleep–wake states and their regulatory mechanisms. By
shuttling through the two behavioral states of sleep and wake, brain coordinates many complex functions essential for cellular
homeostasis and adaptation to environment. This review brie fl y summarizes the current awareness on the dynamicity of brain
mechanisms of sleep and wakefulness as well as the newer concepts of the biological functions of sleep.