Srikantan Nagarajan, Ph.D.

Assistant Professor in Residence

Education and Training

Research and Professional Experience

Honors and Awards

Publications

Nagarajan, S.S., Durand, D., and Warman, E.N., "Effects of induced electric fields on finite neuronal structures: a simulation study," IEEE Trans. in Biomedical Engineering, 40(11), 1175-1188, 1993

Nagarajan, S.S., Roth B.J., Durand, D. and Wijesinghe, R. "Analysis of magnetic stimulation of axons in a nerve bundle: Effects of current redistribution in the nerve bundle", Annals of Biomedical Engineering, 23 (2), 116-126, 1995

Nagarajan, S.S. and Durand, D. "Analysis of magnetic stimulation of a concentric axon in a nerve bundle", IEEE Transactions in Biomedical Engineering, 42 (9), 926-933, 1995

Nagarajan S. S. and Durand, D. "A Generalized Cable equation for Magnetic stimulation of neuronal structures", IEEE Trans. in Biomedical Engineering, 43(3), 304-312, 1996

Tallal, P., Miller, S. L., Bedi, G., Byma, G., Wang, X., Nagarajan, S. S., Schreiner, C., Jenkins, W. M. and Merzenich, M. M., "Language comprehension in language-learning impaired children improved with acoustically modified speech", Science, 271: 81-83, 1996.

Byl, N.N., Merzenich, M.M., Cheung, S., Bedenbaugh, P., Nagarajan, S.S., Jenkins, W.M., "A primate model for studying focal dystonia and repetitive strain injury: effect on the primary somatosensory cortex", Physical Therapy, 77(3), 269-284, 1996

NagarajanS. S. and Durand, D. "Mapping the location of excitation during in-vitro magnetic stimulation", Annals of Biomedical Engineering, 25 (1), 112-125, 1997

Maccabee, P., Nagarajan, S.S., Amassian, V.E., Durand, D.M., Eberle, L., Cracco, R.Q. and Lai, K.S., "Optimal polarity sequence for exciting peripheral nerve with neuromagnetic stimuli:In-vitro studies and computer simulations", Journal of Physiology (London), Dec 1;513 ( Pt 2):571-85. 1998

Nagarajan S.S., Wang X., Schreiner C.S., Merzenich M.M., Johnston P.J., Miller S.L. and Tallal P., "Speech modification algorithms used for training language-learning impaired children", IEEE Transactions in Rehabilitation Engineering, Sep;6(3):257-68, 1998

Nagarajan, S.S., Blake, D.T., Wright, B.A., Byl, N. and Merzenich, M.M., "Practice-related improvements in somatosensory interval discrimination exhibits temporal specificity but generalizes across skin location, hemisphere and modality", J. Neuroscience, 18(4), 1559-70, 1998

Nagarajan, S.S., Mahncke, H.M., Salz, T, Tallal, P, Roberts, T.P.L., and Merzenich, M.M., "Cortical auditory signal processing in poor-readers", PNAS, May 25;96(11):6483-8. , 1999

Sekihara, K., Nagarajan, S.S., Poeppel, D., Miyashita, Y., "Time-frequency MEG-MUSIC Algorithm", IEEE Transactions in Medical Imaging, Jan;18(1):92-7, 1999

Sekihara, K., Nagarajan, S.S., Poeppel, D., Miyashita, Y., "Estimating neural sources from each time-frequency component of magnetoencephalographic data", IEEE Transactions in Biomedical Engineering, v47, 5, 642-53, 2000

Byl, N. N., A. McKenzie, Nagarajan, S.S., "Differences in somatosensory hand organization in a healthy flutist and a flutist with focal hand dystonia: a case report." J Hand Therapy 13(4): 302-9, 2000

Temple E., Gabrieli J. D. E., Protopapas A., Nagarajan S. S., Salz T., Tallal P., Merzenich M. M., & Poldrack R. A., "Disruption of the Neural Response to Rapidly Transient Acoustic Stimuli in Dyslexia: Evidence from fMRI", v97 (25), 13907-12, PNAS, 2000

Ahissar, E., Nagarajan S.S., Ahissar, M., Protopapas, A., Mahncke, H. and Merzenich, M.M. "Speech comprehension is correlated with temporal response patters from auditory cortex", Proc Natl Acad Sci U S A., Nov 6;98(23):13367-72, 2001

Sekihara, K., Nagarajan, S.S., Poeppel, D., Marantz, A., and Miyashita, Y., "Reconstructing spatiotemporal activities of neural sources using an MEG vector beamformer", IEEE Transactions in Biomedical Engineering, 48(7): 760-771, 2001 Cheung, S., Nagarajan, S.S., Bedenbaugh, P., Schreiner, C.S., Wang, X and Wong, A., "Auditory cortical neuron response differences under isoflurane versus pentobarbital anesthesia ", Hearing Research, 156:115-117, 2001

Cheung, S., Bedenbaugh, P., Nagarajan S.S., and Schreiner, C.S. "Functional Organization of Squirrel Monkey Primary Auditory Cortex: Responses to Pure Tones ", J. Neurophysiology, 85(4): 1732-49, 2001

Poldrack, R. A., Temple, E., Protopapas, A., Nagarajan, S., Tallal, P., Merzenich, M. M., Gabrieli, J. D. E., " Relation between the neural bases of rapid acoustic comprehension, and phonological processes in reading: Evidence from fMRI", J Cogn Neurosci., Jul 1;13(5):687-97, 2001

Nagarajan, S.S., "Successive signal representation in noise in dyslexics", Clinical Neurophysiology, Apr;113(4):459-61, 2002

Sekihara, K., Nagarajan, S.S., Poeppel, D., Marantz, A., and Miyashita, Y., "Application of MEG Eigenspace beamformers to reconstructing spatiotemporal activities from neural sources", Human Brain Mapping, 15(4):199-215, 2002

Nagarajan, S.S., Cheung, S.W., Bedenbaugh, P., Beitel, R.E., Schreiner, C.E. and Merzenich, M.M., "Representation of spectral and temporal envelope degradations of twitter vocalizations in primary auditory cortex of the common marmoset", J Neurophysiology, 87(4):1723-37, 2002

Houde, J., Nagarajan, S.S. and Merzenich, M.M., "Modulation of auditory cortex during speech: an MEG study", in press, J. Cognitive Neuroscience (First two authors contributed equally to this work), Nov 15;14(8):1125-38, 2002

Sekihara, K., Nagarajan, S.S., Poeppel, D., and Marantz, A., "Performance of an MEG Adaptive-Beamformer Technique in the Presence of Correlated Neural Activities: Effects on Signal Intensity and Time-Course Estimates", vol 40, No. 10, 1534-1546, IEEE Transactions in Biomedical Engineering, 2002

Blake DT, Byl NN, Cheung S, Bedenbaugh P, Nagarajan SS, Lamb M, Merzenich M. Sensory representation abnormalities that parallel focal hand dystonia in a primate model. Somatosens Mot Res. 2002;19(4):347-57

Byl NN, Nagarajan SS, Merzenich MM, Roberts T, McKenzie A. Correlation of clinical neuromusculoskeletal and central somatosensory performance: variability in controls and patients with severe and mild focal hand dystonia. Neural Plast. 2002;9(3):177-203

McKenzie, A., Nagarajan, S.S., Roberts, T.P.L. and Merzenich, M.M., and Byl, N., “Somatosensory representation of digits and clinical performance in patients with Focal Hand Dystonia”, Am J Phys Med Rehabilitation v82:737-749, 2003

Kai-Hsiung Hsu, Nagarajan SS and Dominique M. Durand, “Analysis of efficiency of magnetic stimulation”, IEEE Transactions in Biomedical Engineering, 2003 Nov;50(11):1276-85

Sekihara, K., Nagarajan, SS., Poeppel, D., and Marantz, A., “Performance of an MEG Adaptive-Beamformer Source Reconstruction Technique in the Presence of Additive Low-Rank Interferences”, IEEE Trans Biomed Eng. 2004 Jan;51(1):90-9.

Blomgren, M., Nagarajan, S.S., Lee, J., Li, T., “Language lateralization in stutterers: an fMRI study”, J Fluency Disord. 2003 Winter;28(4):337-55

Byl NN, Nagarajan SS and McKenzie AL, Effects of Sensory Discrimination Training on Structure and Function in Patients with Focal Hand Dystonia: A case series, in press, Archives in Physical Medicine and Rehabilitation

Sekihara, K., Nagarajan, SS., Poeppel, D., and Marantz, A., “Asymptotic SNR of Scalar and Vector Minimum Variance Beaformers for Neuromagnetic Source Reconstruction”, in press, IEEE Transactions in Biomedical Engineering

Henry RG, Berman JI, Nagarajan SS, Mukherjee P, and Berger MS, “Sub-cortical pathways serving cortical language sites: Initial experience with diffusion tensor imaging fiber tracking combined with intraoperative language mapping”, Neuroimage. 2004 Feb;21(2):616-22

Sekihara, K., Nagarajan, S.S., Sahani M., “Location Bias and Spatial Resolution in Adaptive and Non-adaptive Spatial Filters for Magnetoencephalography”, in press, Neuroimage

Bénédicte P, Beitel RE, Nagarajan SS, Bonham B, Schreiner CE, Cheung SW, “Functional organization and hemispheric comparison of primary auditory cortex in the common marmoset (Callithrix jacchus)”, in press, J. Comparitive Neurology

Sekihara K, Sahani M, Nagarajan SS, “Bootstrap-Based Statistical Thresholding For Meg Source Reconstruction Images”, Proceedings of IEEE-EMBS, San Francisco, 2004.

Sahani M, and Nagarajan SS, “Reconstructing correlated sources from MEG data”, Neural Information Processing System, Vancouver, 2003 (Invited for a talk)

Sekihara K, Hild KE, Nagarajan SS, “Influence of High-Rank Background Interference on Adaptive Beamformer Source Reconstruction”, Proceeding of International Conference for Bioelectromagnetism and Brain Electromagnetic Tomography (Invited paper)

Dalal, SS, Zumer, JM, Agrawal, V, Sekihara, K, Nagarajan, SS, “NUTMEG: A Neuromagnetic Source Reconstruction Toolbox”, in press, Neurology and Clinical Neurophysiology.

Cheung, S., Nagarajan, S.S., Schreiner, C.S, Bedenbaugh, P., and.Wong A, "Plasticity in Primary Auditory Cortex of Monkeys with Altered Vocal Production", J. Neuroscience, 25(10):2490-503, 2004

Sekihara, K., Nagarajan, S.S., Sahani M., “A simple non-parametric methods for estimating statistical significance of MEG beamformer images”, Neuroimage, Aug 15;27(2):368-76, 2005

S.S. Nagarajan, H.T. Attias, K.E. Hild, K. Sekihara, A Graphical Model for 005 Aug 15;27(2):368-76 Estimating Stimulus-Evoked Brain Responses in Noisy MEG data with Large Background Brain Activity, accepted, Neuroimage

Nagarajan SS, Attias HT, Hild KE, and Sekihara K., “Stimulus Evoked Independent Factor Analysis of MEG Data”, Neural Information Processing System, Vancouver 2005 (Invited for a talk)

Robinson SE, Nagarajan SS, Mantle M, Gibbons V, Kirsch H., Localization of interictal spikes using SAM(g2) and dipole fit, Neurol Clin Neurophysiol. 2004 Nov 30;2004:74.

1. Methods and apparatus for assessing and improving processing of temporal information in humans", Patent # 6,422,869 , Issued on July 23, 2002
2. Method and apparatus for diagnosis and remediation language-based learning impairments", Patent #6457362 issued in October 1, 2002 and # 6,109,107 issued on August 29, 2000, # 6,349,598 issued on Feb 26, 2002
3. Apparatus and methods for treating motor control and somatosensory perception deficits, Patent # 6,267,733, Issued on July 31, 2001

Current Funding

1. NIH-R01 Title: (01A1-DC004855 ) “Cortical Spatiotemporal Plasticity in humans”
   • Role: Principal Investigator
   • Total Costs: 1,375,000, Dates: January 2001 – January 2006
   • Effort: 35%
   • The major goals of this grant are to develop paradigms and algorithms for imaging cortical plasticity using MEG and EEG. This grant is in its final year of funding and a competitive renewal is planned for this July. There will be no algorithm development proposed in the renewal.
   • Overlap: None
2. NIH-R01 Grant (01A1-DC006435) Title: “Neural mechanisms of auditory feedback during speech”
   • Role: Principal Investigator
   • Total Costs: $1,583,474, Dates: July 2004 – June 2009
   • Effort: 44%
   • The major goals of this grant are to image the neural processes underlying auditory feedback during speaking using MEG and fMRI
   • Overlap: None
3. NIH-R01 Title: “Linking neurophysiology, anatomy and fMRI”
   • Role: Co-Investigator, PI of Sub-contract
   • PI: Elizabeth Disbrow
   • Total Costs: Dates: April 2003 – March 2007
   • Effort: 15%
   • The major goals of this grant are to link neurophysiological and neuroanatomical data from somatosensory and auditory cortex with neuroimaging data (fMRI, MEG, DTI) about activation and connectivity in these areas.
   • Overlap: None
4. NSF Grant Title: “The role of auditory cortex during speech motor control”
   • Role: Co-Principal Investigator, PI: John Houde
   • Total Costs: $150,000, Dates: 9/1/04-8/31/06
   • Effort: 1%
   • The major goals of this grant are to imaging the activity in auditory cortex during feedback perturbations of continuous speech productions and to examine the relationship between such cortical activity and speech output
   • Overlap: None