Associate Faculty
A G Ramakrishnan
Professor, Dept. of Electrical EngineeringPhone: +91 80 2293 2256
E-Mail: agr[at]iisc.ac.in
Web : http://mile.ee.iisc.ac.in/
Research Areas
Brain functional connectivity in altered consciousness, machine learning in neuroscience, mechanisms behind pranayama
Research Details
Breathing is fundamental to our living; it continues autonomously even during deep sleep or most cases of disorders of consciousness (coma). Then, obviously there must be inhibitory networks active in the brain, when one voluntarily stops breathing for a short duration. We study the functional connectivity of the brain during slow breathing and breath hold by recording high-density EEG. In our experiments, we have found that sinus arrhythmia continues unabated even during breath hold, showing that there are mechanisms in the cardiorespiratory centres beyond respiratory sinus arrhythmia. We intend to study the neural mechanisms behind this phenomenon and seek research collaborators interested in this exploration.
We also study the dynamic functional connectivity patterns involved in different levels of altered consciousness – deep sleep, anaesthesia, and meditation. Purely based on the analysis of one or more of the recorded signals such as EEG, EOG, ECG, breathing signal, GSR and their variations (eg. heart rate variability), can we classify these different states of the brain using machine learning techniques?
We also have state-of-the-art results in decoding imagined speech using deep neural networks and transfer learning as well as in automated sleep staging on standard, open data.
Book Chapter
A G Ramakrishnan, “Cardiorespiratory and endocrine mechanisms behind the effectiveness of pranayama”, in the book “Evidence-based Perspectives on the Psychophysiology of Yoga and Its Applications,” published by IGI Global, edited by Dr. Shirley Telles, Sept. 2020.
Publications
TP Jerrin, AG Ramakrishnan,, (2021), Decoding Imagined Speech from EEG using Transfer Learning, IEEE Access
Jain Ritika, Angarai Ganesan Ramakrishnan,, (2021), Reliable sleep staging of unseen subjects with fusion of multiple EEG features and RUSBoost, Biomedical Signal Processing and Control,, Vol. 70
TP Jerrin, AG Ramakrishnan, , (2021), Decoding Covert Speech from EEG – A Comprehensive Review, Frontiers in Neuroscience, section Neuroprosthetics.
Amit Meghanani, Anoop C S, and A G Ramakrishnan,, (2021), Recognition of Alzheimer’s dementia from the transcriptions of spontaneous speech using fastText and CNN models, Frontiers in Computer Science, DOI: 10.3389/fcomp.2021.624558.
Thomas Panachakel Jerrin, A. G. Ramakrishnan,, (2021), Binary classification of meditative state from the resting state using EEG, accepted IEEE INDICON.
Pradeep, Kumar G.; Kanishka, Sharma; Ramakrishnan, A. G.; Adarsh, A., (2021), Increased Entropy of Gamma Oscillations in the Frontal Region during Meditation, accepted, 43rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society.
A. S. Anusha, A. G. Ramakrishnan,, (2021), Brain Functional Connectivity as Biomarker for Propofol-Induced Alterations of Consciousness, accepted, 43rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society.
Thomas Panachakel Jerrin, A. G. Ramakrishnan,, (2021), Classification of Phonological Categories in Imagined Speech using Phase Synchronization Measure, accepted, 43rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society.
Thomas Panachakel Jerrin, Sharma Kanishka, A. S. Anusha, A. G. Ramakrishnan, , (2021), Can we identify the category of imagined phoneme from EEG?, accepted, 43rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society.
A. S. Anusha, A. G. Ramakrishnan, , (2021), Midline EEG Functional Connectivity as Biomarker for Conscious States in Sleep and Wakefulness, accepted, 43rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society.
Jain Ritika, A. G. Ramakrishnan,, (2021), An efficient sleep scoring method using visibility graph and temporal features of single-channel EEG, accepted, 43rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society.
J. T. Panachakel, A. G. Ramakrishnan,, (2021), An Elegant Experimental Setup for Accurate Presentation of Dichoptic Stimuli, Proc, IEEE R10 Humanitarian Tech Conference 2021.
Kanishka Sharma, A G Ramakrishnan,, (2021), Factors behind higher COVID-19 recovery and lower fatality rates in India – need for a focused study, Proc, IEEE R10 Humanit. Tech Conf 2021.
TP Jerrin, AG Ramakrishnan, TV Ananthapadmanabha,, (2021), Common Spatial Pattern Based Data Augmentation Technique for Decoding Imagined Speech, Proc. International Conference on Electronics, Computing and Communication Technologies, IEEE CONECCT.
AG Ramakrishnan, S Kanishka, (2021), Redesign of the COVID-19 ICUs to save the Corona warriors, Proc. IEEE Bangalore Humanitarian Technology Conference (B-HTC 2020) (best paper award).
A G Ramakrishnan,, (2020), Cardiorespiratory and endocrine mechanisms behind the effectiveness of pranayama, in the book “Evidence-based Perspectives on the Psychophysiology of Yoga and Its Applications,” published by IGI Global, edited by Dr. Shirley Telles.
R Jain, AG Ramakrishnan,, (2020), Electrophysiological and neuroimaging studies – During resting state and sensory stimulation in disorders of consciousness: a review, Frontiers in Neuroscience, 14, 987.
G Pradeep Kumar, AG Ramakrishnan, S Kanishka,, (2020), Fuzzy Entropy as a Measure of EEG Complexity During Rajyoga Practice in Long-Term Meditators, Proc. IEEE INDICON.
AG Ramakrishnan, G Pradeep Kumar, S Kanishka,, (2020), Characterization of Meditation EEG Based on Consistency of Covariance Matrices over Time, Proc. IEEE INDICON.
J Ritika, AG Ramakrishnan, (2020), Sleep-Awake Classification Using EEG Band-Power-Ratios and Complexity Measures, Proc. IEEE INDICON.
AG Ramakrishnan, J Ritika, (2020), Binary State Prediction of Sleep or Wakefulness Using EEG and EOG Features, Proc. IEEE INDICON.
A G Ramakrishnan, A Adarsh,, (2020), R-wave Amplitude Changes and Atypical Heart Rate Changes Accompanying Breath Hold During Low Breathing Rates, Proc. IEEE EMBC 2020, Montreal, Canada.
Angarai Ganesan Ramakrishnan, A Adarsh, Kanishka Sharma, Kumar G Pradeep, (2020), Anomaly in respiratory sinus arrhythmia – multiple heart rate variability cycles within each breathing cycle at low breath rates with breath holds, Proc. International Conf. on Electronics, Computing and Communication Technologies (CONECCT 2020).
A. G. Ramakrishnan and J. V. Satyanarayana,, (2016), Reconstruction of EEG from limited channel acquisition using estimated signal correlation, Biomedical Signal processing & Control , 27, 164–173, doi:10.1016/j.bspc.2016.02.004.
A. G. Ramakrishnan, A.P. Prathosh and T. V. Ananthapadmanabha,, (2014), Threshold-independent QRS detection using the dynamic plosion index, IEEE Signal Processing Letters, 21(5),, 554-558.
A Ramesh, C Jagdish, M Nagapoorinima, PN Suman Rao, AG Ramakrishnan, GC Thomas, M Dominic, A Swarnarekha,, (2012), Low cost calibrated mechanical noisemaker for hearing screening of neonates in resource constrained settings, The Indian journal of medical research, 135(2),, 170.
Neelam Sinha and A. G. Ramakrishnan,, (2010), Quality assessment in magnetic resonance images, invited review article, Critical Reviews in Biomedical Engineering,, 38(2), 127-141.
Neelam Sinha, Manojkumar Saranathan and A. G. Ramakrishnan, (2010), Dynamic MR imaging using generalized series, International Journal of Magnetic Resonance Imaging, 2(1), 3-21.
Neelam Sinha, Manojkumar Saranathan and A. G. Ramakrishnan, (2010), Improved kt-BLAST for fast fMRI imaging, Journal of Magnetic Resonance,, 204, 273-280
Neelam Sinha, A. G. Ramakrishnan and Manojkumar Saranathan,, (2010), Composite MR image reconstruction and unaliasing for general trajectories using neural networks, Magnetic resonance imaging, 28(10), 1468-1484.
M D Livera, B Priya, A Ramesh, P N Suman Rao, V Srilaxmi, M Nagapoornima, A G Ramakrishnan, M Dominic and Swarnarekha,, (2008), Spectral analysis of noise in the neonatal intensive care unit, Indian Jl. of Paediatrics, 75(3), 217-222.
R Srikanth, A G Ramakrishnan,, (2006), Wavelet-based Estimation of Hemodynamic Response Function from fMRI data, International Journal of Neural Systems, World scientific publishing company,, 16(02), 125-138.
R. Srikanth, A.G.Ramakrishnan,, (2005), Contextual Encoding in Uniform and Adaptive Mesh-based Lossless Compression of MR Images, IEEE Trans. Medical Imaging, 24(9), 1199 – 1206.
Jagadisha, BN Gangadhar, N Janakiramiah, K Girish, AG Ramakrishnan, (2003), Post-seizure EEG fractal dimension and spectral power predict antidepressant response to unilateral ECT, Indian Journal of Psychiatry, 45(1), 16-20.
K. N. Bhanuprakash, A. G. Ramakrishnan, S. Suresh, and Teresa W. P. Chow,, (2002), Fetal lung maturity analysis using ultrasound image features, IEEE Trans. Inf. Tech. Biomedicine, 6(1), 38-45
K. N. Bhanuprakash, A. G. Ramakrishnan, S. Suresh, and Teresa W. P. Chow, (2001), An investigation into the feasibility of fetal lung maturity prediction using statistical textural features, Ultrasonic Imaging, 22(1), 39-54.
G Sita and AG Ramakrishnan, (2000), Wavelet domain nonlinear filtering for evoked potential signal enhancement, Computers and Biomed, 33, 431-446
P. Raghuraj, A. G. Ramakrishnan, H. R. Nagendra, and Shirley Teles,, (1998), Effect of two selected yogic breathing techniques on heart rate variability, Ind. J. Physiol. Pharmacol, 42(4) , 467-472.
I. Rajan, P. J. Naga Venkatesha Murthy, A. G. Ramakrishnan, B. N. Gangadhar and N. Janakiramaiah, , (1998), Heart rate variability as an index of cue reactivity in alcoholics, Biological Psychiatry, 43, 544-546.
A. G. Ramakrishnan and T. M. Srinivasan, (1995), Electrophysiological Correlates of Hanseniasis, International Journal of Leprosy, 63(3), 395-408
