Guide: Dr. Bindu M Kutty
Co-guide: Dr. John P John (Addl. Prof., Dept. of Psychiatry)
Neurophysiology @ NIMHANS |
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Arun Sasidharan (5th yr PhD Scholar) presented his PhD work titled "Aberrant neural synchrony in Schizophrenia: a multi-modal EEG, fMRI and Polysomnography study"
Guide: Dr. Bindu M Kutty Co-guide: Dr. John P John (Addl. Prof., Dept. of Psychiatry) Ratna Jyothi (3rd yr PhD Scholar) presented her PhD work presentation titled "Vipassana Meditation and Well-Being: A neuro-psycho-physiological Study"
Guide: Dr Bindu M Kutty Co-Guide: Dr Seema Mehrotra Co-Guide: Dr Ravindra Panth Arun Sasidharan (5th yr PhD Scholar and ICMR-SRF) presented his seminar titled "Fundamentals of EEG and LFP".
He spoke on:
Dr Jyothi Kakumanu (PhD Scholar) presented the paper from Biological Psychology by Keune et al., 2013 entitled "Approaching dysphoric mood: State-effects of mindfulness meditation on frontal brain asymmetry"
ABSTRACT Meditation-based interventions reduce the relapse risk in recurrently depressed patients. Randomized trials utilizing neurophysiologic outcome measures, however, have yielded inconsistent results with regard to a prophylactic effect. Although frontal brain asymmetry, assessed through electroencephalographic (EEG) alpha activity (8–13 Hz), is indicative of approach vs. withdrawal-related response dispositions and represents a vulnerability marker of depression, clinical trials have provided mixed results as to whether meditation has beneficial effects on alpha asymmetry. Inconsistencies might have arisen since such trials relied on resting-state recordings, instead of active paradigms under challenge, as suggested by contemporary notions of alpha asymmetry. We examined two groups of remitted, recurrently depressed females. In a “mindfulness support group”, EEG was recorded during neutral rest, and rest following a negative mood induction. Subsequently, participants received initial meditation instructions. EEG was then obtained during an active period of guided mindfulness meditation and rest following the active period. In a “rumination challenge group”, EEGwas obtained during the same resting conditions, whereas in the active period, initial meditation instructions were followed by a rumination challenge. A significant shift in mid-frontal asymmetry, yielding a pattern indicative of approach motivation, was observed in the mindfulness support group, specifically during the meditation period. This indicates that mindfulness meditation may have a transient beneficial effect, which enables patients to take an approach-related motivational stance, particularly under circumstances of risk. - - - This paper is in an important area of research but there seemed to be a number of lacunae in the methodology as well as interpretation of results. Dr Jyothi discussed the findings and the various limitations of the study during her presentation. Ajay Nair (3rd year PhD Scholar) presented the paper by MM Arnold etal from Journal of Sleep Research, 2013 entitled "Information content in cortical spike trains during brain state transitions"
SUMMARY Even in the absence of external stimuli there is ongoing activity in the cerebral cortex as a result of recurrent connectivity. This paper attempts to characterize one aspect of this ongoing activity by examining how the information content carried by specific neurons varies as a function of brain state. We recorded from rats chronically implanted with tetrodes in the primary visual cortex during awake and sleep periods. Electroencephalogram and spike trains were recorded during 30-min periods, and 2–4 neuronal spikes were isolated per tetrode off-line. All the activity included in the analysis was spontaneous, being recorded from the visual cortex in the absence of visual stimuli. The brain state was determined through a combination of behavior evaluation, electroencephalogram and electromyogram analysis. Information in the spike trains was determined by using Lempel–Ziv Complexity. Complexity was used to estimate the entropy of neural discharges and thus the information content (Amigo´ et al. Neural Comput., 2004, 16: 717–736). The information content in spike trains (range 4–70 bits s)1) was evaluated during different brain states and particularly during the transition periods. Transitions toward states of deeper sleep coincided with a decrease of information, while transitions to the awake state resulted in an increase in information. Changes in both directions were of the same magnitude, about 30%. Information in spike trains showed a high temporal correlation between neurons, reinforcing the idea of the impact of the brain state in the information content of spike trains. Dr Harsha HN successfully defended his PhD work entitled "Neurobiology of Auditory Verbal Hallucinations in Schizophrenia - An integrated fMRI, EEG and Genomics based approach".
Guide: Dr Bindu M Kutty (Prof, Neurophysiology) Co-Guides: Dr Sanjeev Jain (Prof, Psychiatry) and Dr John P John (Additional Prof, Psychiatry) Examiner: Dr K Srinivasan (Dean, St John's Research Institute and Professor of Psychiatry) Ajay Kumar Nair (2nd year PhD scholar) presented his seminar on "Microstates - the atoms of thought? Studies in EEG, fMRI... A Conceptual Overview".
This seminar introduced a breadth of topics moving from cognition and consciousness to global workspace theory, cerebral networks, self organized criticality and scale free systems... and narrowed down to how the microstates approach to EEG analysis seems to provide evidence for the brain's function as a scale free phenomenon. Dr Arun Sasidharan (3rd Year PhD Scholar) presented his seminar on Schizophrenia - what EEG and fMRI can tell us?
In this detailed and well spelt-out seminar, Arun started off with reviewing current research on Schizophrenia and the findings from EEG and fMRI studies in the field. He then described the classical view of Schizophrenia and then went for a deep dive into understanding how EEG, ERP, source localization and fMRI approaches work, the potential pitfalls to watchout for and the benefits of each approach in order to be able to interpret the results better. Adya (2nd year MPhil Scholar) presented his seminar on Neurophysiological basis of EEG, EP and ERP.
He gave a quick historical overview beginning from Ancient Greece, work by Richard Caton from Liverpool in 1875 and the work by Hans Berger in 1925 with the first EEG recording. He then explained the dipole formation due to changes in ionic concentration, impact due to volume conduction and challenges in source localization so far. He then spoke about the referential and bipolar montages and quantitative and qualitative analysis approaches. Signal amplification and artifacts during recording were also covered. Adya discussed the EPs and their corresponding anatomical landmarks and the ERP signals and testing paradigms with special focus on contingent negative variation. He also touched upon MEG functioning. Finally he mentioned about the current areas of EEG research from clinical (like epileptogenesis) to brain machine interfaces. There was much animated discussion during the seminar about predominance of gamma and delta signals and their implications. |
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August 2019
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