|1||Bachelor of Engineering||Electronics and Communication Engineering|| ||1995||Madurai Kamaraj University||
|2||Master of Science||Electrical Engineering|| ||1997||Indian Institute of Science, Bangalore||
|3||Doctor of Philosphy||Electrical Engineering|| ||2002||Indian Institute of Science, Bangalore||
| || || || || || ||
Thesis and Guide details:
|SNO||Title of Ph.D. Thesis||Name of Guide
|1||A computational model for the development of simple-cell receptive fields spanning the regimes before and after eye-opening||Prof. Y. V. Venkatesh
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Details of CSIR Fellowship/ Associateship held, if any or from other sources/ agencies.
Significant foreign assignments:
(a) Significant contributions to science and/ or technology development by the nominee
based on the work done in India during most part of last 5 years:
The discovery of voltage-gated ion channels in neuronal dendrites constitutes an important
breakthrough in neuroscience research. Research in the nominee’s laboratory is focused on
understanding the physiological roles of these dendritically-expressed channels, employing a
combination of experimental (in vitro and in vivo electrophysiology) and computational techniques.
Work in the nominee’s laboratory has resulted in several novel and significant scientific
advancements, both at the conceptual and the technical levels:
Degeneracy in hippocampal physiology and plasticity: Although biological systems are known to
exhibit degeneracy, where disparate structural components can elicit analogous functions, the
existence of degeneracy in the mammalian nervous system has not been explored. Several studies
from the nominee’s laboratory have demonstrated the existence of degeneracy in hippocampal
physiology and plasticity, showing specifically that several disparate channel combinations could elicit
analogous dendritic physiology or synaptic plasticity profiles (14, 19, 22, 26). In demonstrating this,
the nominee’s laboratory has developed novel techniques to assess spatiotemporal interactions
among dendritic ion channels, and to quantify the specific contributions of ion channels to
physiological phenomena (12, 19, 20, 21).
Subthreshold ion channels critically regulate local-field potentials: Local field potentials (LFP),
the low frequency component of extracellularly recorded neural potentials, have been largely believed
to be a reflection of afferent synaptic drive. The nominee’s laboratory demonstrated that a
dendritically-expressed ion channel enhances spike phase coherence and regulates the phase of
spikes and LFPs. These results add a novel dimension to the presence and plasticity of dendritic ion
channels, extending their regulatory potential beyond single-neuron physiology (24).
Physiological interactions between the plasma membrane and the ER membrane: Along an
active dendritic membrane, the presence of the endoplasmic reticulum spanning the neuronal
morphology constitutes the presence of two continuous membranes that can propagate information
by recruiting channels on either of them. The nominee’s laboratory has unveiled novel bidirectional
interactions between these two membranes, showing that channels on the dendritic membrane can
modulate ER function (16) and that activation of channels on the ER membrane is sufficient to alter
plasma membrane channels (23).
Dendritic ion channels and neural coding: Neuronal spikes encode specific features, which can be
characterized using the spike-triggered average (STA). Work in the nominee’s laboratory, employing
novel analysis techniques, has revealed the inadequacy of the traditional proposition that a single
STA is sufficient to characterize the entire neuron. Specifically, they uncover the location dependence
of STA and coincidence detection, demonstrating their critical regulation by dendritic ion channels.
Based on this, they propose a novel dynamically reconfigurable multi-STA model to characterize
location-dependent input feature selectivity in neurons with plastic active dendrites (18, 25).
Synergistic plasticity interactions govern neuronal physiology: Neurons are dynamic entities,
with the density and properties of channels and receptors across the somatodendritic arbor changing
in response to learning paradigms or pathophysiological conditions. Several studies from the
nominee’s laboratory have explored novel forms of interactions between plasticity in different
channels and receptors (16), and have unveiled specific roles for such concurrent plasticity in robust
information transfer (15), activity homeostasis (15) and behavioral-state-dependent calcium
(b) Impact of the contributions in the field concerned:
Impact of conceptual advances: Conceptual advances from the nominees work have either
addressed outstanding questions in the field, or have provided novel perspectives that have revealed
inadequacies of established dogma. First, although the Bienenstock-Cooper-Munro (BCM) has been
a standard theoretical framework for understanding synaptic plasticity in the hippocampus, an open
question concerned the specific mechanism that is responsible for regulating the sliding modification
threshold. Work from the nominee’s laboratory showed that there are several non-unique ways of
regulating the sliding modification threshold, thereby arguing against the search for a single regulatory
mechanism that controls this threshold.
Second, the role of subthreshold-activated channels in regulating local field potentials (LFP) were not
considered, with the standard dogma that LFPs merely reflect the afferent synaptic drive. Work from
the nominee’s laboratory demonstrates that these channels could critically alter LFPs and associated
measurements, thereby expanding the role of dendritic sub-threshold ion channels beyond singleneuron
Third, physiological analysis in hippocampal neurons tended to consider one-to-one relationships
between ion channels and specific physiological phenomena. Work from the nominee’s laboratory has
shown that several coexistent functional maps expressing on the same neuronal topograph could be
achieved through several non-unique combinations of channels, with significant variability in the
contribution of each channel to any given measurement (19). These results have significant
ramifications for rules on ion channel targeting and localization, where it is not necessary to maintain
each ion channel expression at specific levels for physiological robustness to be achieved.
Fourth, in characterizing single neurons, systems and cellular physiologists traditionally assign a
single input-output function (the spike-triggered average, STA) for an entire neuron. Work from the
nominee’s laboratory has shown that this is clearly inadequate in neurons with plastic active
dendrites, and has instead proposed a multi-STA model for a single neuron. This suggests that
different parts of a neuron are responsive to different features, and thereby encode different aspect of
the afferent inputs, in a manner that is critically reliant on the specific ion channels expressed (16, 22).
Finally, and importantly, work from the nominee’s laboratory clearly shows that neural coding and
homeostasis in single neurons should not be analyzed in a piecemeal fashion, where the focus is on
one receptor or one channel at a time, but should encompass all receptors/channels and the complex
interdependent interactions among them. These conclusions have significant ramifications for the
neural basis of learning and memory, where the coding and associated homeostasis would be
considered as emergent consequences of synergistic plasticity in multiple neural components (13).
Impact of techniques developed: The nominee has developed several new analysis techniques as
part of work done as an independent investigator. First, within the framework of degeneracy, where
several ion channel combinations could results in identical physiological phenomenon, it was difficult
to assess the specific contributions of individual ion channels. The nominee’s laboratory has developed “virtual knockout models” to specifically assess the contributions of individual channels to
different physiological measurements, within the framework of degeneracy (19). This analysis
technique has been used by others in the field for analyzing the role of ion channels in other
physiological phenomena observed in other neurons (e.g., Anderson et al., J. Comp Neurosci., 2016).
Places where work of last 5 years has been referred/ cited in Books, Reviews:
Names of the industries in which the technology (ies) has (have) been used :
The achievements already been recognised by Awards by any learned body:
The Awardee a fellow of the Indian National Science Academy/Indian Academy of Sciences/National
Academy of Sciences/Others:
The Awardee delivered invited lecture(s) in India/abroad and/or chaired any scientific
Internatiional Conference Symposium:
List of Awardee's 10 most significant publications.
List of Awardee's 5 most significant publications during the last 5 years
List of Awardee's 5 most significant publications from out of work done in India
during the last five years:
Complete list of publications in standard refereed journals:
Complete list of publications with foreign collaborators (indicating your status
List of papers published in Conferences /Symposia/ Seminars, etc:
List of the most outstanding Technical Reports/ Review Articles:
Statement regarding collaboration with scientists abroad:
The nominee’s laboratory has a long-standing collaboration with Prof. Daniel Johnston’s laboratory at
The University of Texas at Austin, USA. They were awarded a joint grant with DBT from India and
NIH in USA on the role of calcium stores in neuronal intrinsic plasticity.
Total number of patents granted in last five years.
Details of Books published: