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Master's Research For my master's degree in Molecular Biology, I worked in the laboratory of Dr.Krishnan at the Dept.of Biological Sciences, Tata Intstitute ofFundamental Research, Bombay My work concerned the isolation and characterization of novel temperature-sensitive paralytic mutants of Drosophila. The aim was to identify proteins involved in synaptic vesicle cycling at the neuromuscular synapse. A detailed genetic, behavioral and electrophysiological characterization of these mutants was carried out. Subsequent molecular characterization has revealed one of these mutations, Kumbhakarna to be in the gene for the Sarcoplasmic/endoplasmic reticulum calcium ATPase (SERCA). I also worked with previously isolated mutants shibire,comatose and paralytic (Drosophila homologs of dynamin, NSF and the voltage gated sodium channel, respectively).
I did my PhD thesis work in the laboratory of Dr. David Fitzpatrick. The lab is interested in studying the functional organization of central visual pathways that mediate visual perception by combining diverse techniques such as optical imaging of intrinsic signals, extracellular and intracellular physiology and anatomical tracer injections. My published work investigated population responses of V1 neurons to stimuli in which multiple stimulus features could be varied independently. Stimulus features, including edge orientation, direction of motion, and spatial frequency, are mapped in primary visual cortex (V1). Nested arrangements of these maps are thought to serve as the basis for a population code of stimulus features. However, map relationships have mostly been studied using grating stimuli that vary in luminance only in one dimension (1D stimuli). Responses to two-dimensional stimuli indicate that cortical neurons are better described as Fourier energy filters rather than as feature detectors for orientation etc. We used optical imaging of intrinsic signals and extracellular recordings to assess the population activity evoked by motion of a texture (a field of iso-oriented bars). By varying motion axis, bar length and speed, we showed that the same stimulus orientation can activate neurons whose preferred grating orientation differs radically from that dictated by the bars in the textures. These results force a significant revision of our current conception of cortical maps. We propose that rather than multiple feature maps the population activity in visual cortex is better understood as resulting from a systematic mapping of energy filters with varying preferences in three dimensional spatiotemporal frequency space. Please visit the Fitzpatrick Lab web site for images from my work. Here is the first chapter of my thesis in PDF format:
Publications Basole A, Kreft-Kerekes V, White LE and Fitzpatrick D (2006) Cortical Cartography Revisited: A Frequency Perspective on the Functional Architecture of Visual Cortex (book chapter). Prog Brain Res., 154:121-34 Basole A (2005) A Spatiotemporal Frequency Perspective on the Columnar Organization of Population Activity in Visual Cortex, PhD thesis, Duke University, Durham, North Carolina. Sanyal S, Consoulos C, Kuromi H, Basole A, Mukai L, Kidokoro Y, Krishnan KS and Ramaswami M (2005) Analysis of conditional paralytic mutants in Drosophila SERCA reveals novel mechanisms for regulating membrane excitability. Genetics, 169(2):737-50. Basole A, White LE and Fitzpatrick D (2003) Mapping multiple features in the population response of visual cortex. Nature, 423:986-990. Sanyal S, Basole A and Krishnan KS (1999) Phenotypic interaction between temperature sensitive paralytic mutants comatose and paralytic suggests a role for N- ethylmaleimide sensitive fusion factor in synaptic vesicle cycling in Drosophila, Journal of Neuroscience, 19:RC47 (1-5). Sanyal S and Basole A (1999) Neural complexity underlying simple behavior (review). Journal of Bioscience, 24:255-257. Basole A (1999) Genetic and behavioral studies on temperature sensitive
paralytic mutations in Drosophila melanogaster. MSc. Thesis, University
of Bombay, Bombay, India.
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