How cortical neuronal networks encode visual information
Dr Tom Mrsic-Flogel
|Wellcome Trust Career Development Fellow|
|Tel: +44 (0)20 7679 6335|
|Email: Dr Tom Mrsic-Flogel|
Department of Neuroscience, Physiology and Pharmacology
The Rockefeller Building (room 322) 21
University Street London
WC1E 6DE, UK
|Dr Tom Mrsic-Flogel||biography|
The vast majority of our knowledge about how the brain encodes information has been obtained from recordings of one or few neurons at a time or from global mapping methods such as fMRI. These approaches have left unexplored how neuronal activity is distributed in space and time within a cortical column and how hundreds of neurons interact to process sensory information. By taking advantage of the most recent advances in two-photon microscopy, the research in my lab addresses two broad aims, with a particular focus on the function and development of primary visual cortex: 1) to understand how cortical neuronal networks encode visual information, and 2) to understand how they become specialised for sensory processing during postnatal development.
We use in vivo two-photon calcium imaging to record activity simultaneously from hundreds of neurons in visual cortex while showing different visual stimuli. This approach enables us to characterise in detail how individual neurons and neuronal subsets interact within a large cortical network in response to visual stimuli. We investigate the maturation of cortical network function after the onset of vision and assess the role of visual experience in this process.
In vivo two-photon calcium imaging. A. Schematic of multi-cell bolus loading: a membrane-permeable acetoxymethyl (AM) ester of a calcium-sensitive fluorescent dye (e.g. Oregon Green 488 BAPTA 1) is ejected from a micropipette into the extracellular space of the cortex, from where it diffuses into cells. Intracellular esterases hydrolyze the ester bond, rendering the indicator dye membrane-impermeable. Activity-dependent changes in intracellular calcium concentration can be monitored using two-photon fluorescence microscopy in a depth of up to 500 μm. Additional labeling with genetically encoded fluorescent proteins enables identification of specific cell-types (e.g. interneurons). B. Reconstruction of a 3D volume in mouse V1 stained with OGB1- AM. Scale bars, 50 μm. C. Fluorescence image of V1 neurons. The colored regions of interest refer to the calcium time courses in D. D. Response of three neurons to the direction of a drifting grating stimuli. Traces of ΔF/F versus time reflect changes in calcium concentration.
- Hofer SB, Mrsic-Flogel TD, Bonhoeffer T, Hübener M (2009) Experience leaves a lasting structural trace in cortical circuits. Nature. 457(7227):313-7.
- Keck T, Mrsic-Flogel TD, Vaz Afonso M, Eysel UT, Bonhoeffer T, Hübener M (2008) Massive restructuring of neuronal circuits during functional reorganization of adult visual cortex. Nat Neurosci. 11(10):1162-7.
- Mank M, Santos AF, Direnberger S, Mrsic-Flogel TD, Hofer SB, Stein V, Hendel T, Reiff DF, Levelt C, Borst A, Bonhoeffer T, Hübener M, Griesbeck O (2009) A genetically encoded calcium indicator for chronic in vivo two-photon imaging. Nat Methods. 5(9):805-11.
- Chakravarthy S, Keck T, Roelandse M, Hartman R, Jeromin A, Perry S, Hofer SB, Mrsic-Flogel T, Levelt CN (2008) Cre-dependent expression of multiple transgenes in isolated neurons of the adult forebrain. PLoS ONE. 3(8):e3059.
- Mrsic-Flogel TD, Hofer SB, Ohki K, Reid RC, Bonhoeffer T, Hübener M (2007) Homeostatic regulation of eye-specific responses in visual cortex during ocular dominance plasticity. Neuron 54: 961-72
- Hofer SB, Mrsic-Flogel TD, Bonhoeffer T, Hübener M (2006) Lifelong learning: Ocular dominance plasticity in mouse visual cortex. Curr Opin Neurobiol 16: 451-9
- Hofer SB, Mrsic-Flogel TD, Bonhoeffer T, Hübener M (2006) Prior experience enhances plasticity in adult visual cortex. Nature Neurosci 9: 127-32.
- Mrsic-Flogel TD, Hofer SB, Creutzfeldt C, Cloëz-Tayarani I, Changeux JP, Bonhoeffer T, Hübener M (2005) Altered map of visual space in the superior colliculus of mice lacking early retinal waves. J Neurosci 25: 6921-8
- Mrsic-Flogel TD, King AJ, Schnupp JWH (2005) Encoding of virtual acoustic space stimuli by neurons in ferret primary auditory cortex. J Neurophysiol 93: 3489-3503
- Mrsic-Flogel TD, Schnupp JWH, King AJ (2003) Acoustic factors govern developmental sharpening of spatial tuning in the auditory cortex. Nature Neurosci 6: 981-988
- Mrsic-Flogel T, Hübener M, Bonhoeffer T (2003) Brain mapping: New wave optical imaging. Current Biology 13: R778-R780
- Mrsic-Flogel T, Hübener M (2002) Visual cortex: Suppression by depression. Current Biology 12: R547-R549
- Schnupp JWH, Mrsic-Flogel TD, King AJ (2001) Linear processing of spatial cues in primary auditory cortex. Nature 414: 200-4