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Lionel G. NOWAK

Chargé de Recherche CR1, CNRS

tel : 05 62 17 28 31, from abroad : 33 562 172 831

fax : 05 62 17 28 09, from abroad : 33 562 172 809

Processing dynamics and cortical interactions (Dytic 2.0)

PRESENT RESEARCH INTERESTS

My aim is to determine what are the structural basis and cellular mechanisms of visual perception. It is now well established that spiking activity in individual cells can be directly linked to perception, memory, attention and action. On the perceptual side, the visual cortex has been the most studied of the sensory cortices and neuronal response selectivity, with respect to visual stimuli attributes, has been characterized at length. What remains poorly understood is how specific responses are generated. This understanding requires analyzing the visual cortex at different levels that are accessible by the use of different techniques, such as intracellular and extracellular recording, reversible inactivation, neuroanatomy, optical imaging, etc… My present research and research projects are centered on the genesis of visual response properties in areas V1 and V2 of the visual cortex. More specifically, I work on :

  • - the role of intrinsic neuronal properties and of synaptic mechanisms in contrast adaptation,
  • - the influences of fast and slow contrast gain control mechanisms on receptive fields extent and orientation selectivity,
  • - the role of corticocortical connections in the control of the gain of the contrast-response relationship,
  • - the role of corticocortical connections in center-surround interactions and in the response of cortical neurons to elaborate visual stimuli (illusory contours, form from motion, etc).

PUBLICATIONS

Cross-modal plasticity (auditory responses in visual cortex after visual deprivation)

  • * Sanchez-Vives, M. V., Nowak, L. G., Descalzo, V. F., Garcia-Velasco, V., Gallego, R., and Berbel, P. (2006) Cross modal audio-visual interactions in the primary visual cortex of the visually deprived cat : a physiological and anatomical study. In : Progress in Brain Research, vol. 155, part 2 : Visual Perception - Fundamentals of Awareness : Multi-Sensory Integration and High-Order Perception. S. Martinez-Conde, S.L. Macknik, L.M. Martinez, J.-M. Alonso and P.U. Tse (eds), pp. 287-311.

Cellular and synaptic mechanisms of contrast adaptation in the visual cortex :

  • * Reig, R. Gallego, R., Nowak, L. G., and Sanchez-Vives, M. V. (2006) Impact of cortical network activity on short-term synaptic depression. Cerebral Cortex 16, 688-695.
  • * Descalzo, V. F., Nowak, L. G., Brumberg, J. C., McCormick, D. A. and Sanchez-Vives, M. V. (2005) Slow adaptation in fast spiking neurons of visual cortex. Journal of Neurophysiology 93, 1111-1118.
  • * Nowak, L. G., Sanchez-Vives, M. V. and McCormick, D. A. (2005) Role of synaptic and intrinsic membrane properties in short term receptive field dynamics in cat area 17. Journal of Neuroscience 25, 1866-1880.
  • * Sanchez-Vives, M. V., Nowak, L. G. and McCormick, D. A. (2000) Membrane mechanisms underlying contrast adaptation in cat area 17 in vivo. Journal of Neuroscience 20, 4267-4285.
  • * Sanchez-Vives, M. V., Nowak, L. G. and McCormick, D. A. (2000) Cellular mechanisms of long lasting adaptation in visual cortical neurons in vitro. Journal of Neuroscience 20, 4286-4299.

Publications about different cell classes and their visual response properties in the visual cortex (in vivo and in vitro intracellular recording) :

  • * Nowak, L. G., Sanchez-Vives, M. V., Azouz, R., Gray, C. M. and McCormick, D. A. (2003) Electrophysiological classes of cat primary visual cortical neurons in vivo as revealed by quantitative analysis. Journal of Neurophysiology 89, 1541-1566.
  • * Brumberg, J. C., Nowak, L. G. and McCormick, D. A. (2000) Ionic mechanisms underlying repetitive high-frequency burst firing in supragranular cortical neurons.
  • Journal of Neuroscience 20, 4829-4843.
  • * Azouz, R., Gray, C. M., Nowak, L. G. and McCormick, D. A. (1997) Physiological properties of identified interneurons in cat striate cortex. Cerebral Cortex 7, 534-545.

Publications about response latencies in primate visual cortex and what it implies concerning the hierarchical / parallel organization of the visual system :

  • * Nowak, L. G. and Bullier, J. (1997) The timing of information transfer in the visual system. In "Cerebral Cortex vol. 12 : Extrastriate cortex in primates", K. Rockland, J.H. Kaas and A. Peters (eds), pp. 205-241.
  • * Nowak, L. G., Munk, M. H. J., Girard, P. and Bullier, J. (1995) Visual latencies in areas V1 and V2 of the macaque monkey. Visual Neuroscience 12, 371-384.
  • * Munk, M. H. J., Nowak, L. G., Girard, P., Chounlamountri, N. and Bullier, J. (1995) Visual latencies in different cytochrome oxidase bands of macaque monkey area V2. Proceedings of the National Academy of Science of the USA 92, 988-992.
  • * Bullier, J. and Nowak, L. G. (1995) Parallel versus serial processing, new vistas on the distributed organization of the visual system. Current Opinion in Neurobiology 5, 497-503.

Publications about synchronization of neuronal activities in vivo and spike timing reliability in vitro :

  • * Nowak, L. G. and Bullier, J. (2000) Cross correlograms for neuronal spike trains. Different types of temporal correlation in neocortex, their origin and significance. In "Time and the Brain, Conceptual advances in Brain Research", R. Miller (ed), Harwood Academic Publishers, pp. 53-96.
  • * Nowak, L. G., Sanchez-Vives, M. V., and McCormick, D. A. (1997) Influence of low and high frequency fluctuations on spike timing in visual cortical neurons. Cerebral Cortex 7, 487-501.
  • * Nowak, L. G., Munk, M. H. J., James, A. C., Nelson, J. I. and Bullier, J. (1995) The structural basis of cortical synchronization. I. 3 types of interhemispheric coupling. Journal of Neurophysiology 74, 2379-2400.
  • * Munk, M. H. J., Nowak, L. G., Nelson, J. I. and Bullier, J. (1995) The structural basis of cortical synchronization. II. Localization of the common input. Journal of Neurophysiology 74, 2401-2414.
  • * Nowak, L. G., Munk, M. H. J., James, A. C., Girard, P, and Bullier, J (1999) Cross correlation study of the temporal interactions between areas V1 and V2 of the macaque monkey. Journal of Neurophysiology 81, 1057-1074.

Publications about neuronal elements activated by electrical stimulation and spread of stimulating current in the cortical gray matter :

  • * Nowak, L. G. and Bullier, J. (1998) Axons, but not cell bodies, are activated by electrical stimulation in the cortical gray matter. I. Evidence from chronaxie measurements. Experimental Brain Research 118, 477-488.
  • * Nowak, L. G. and Bullier, J. (1998) Axons, but not cell bodies, are activated by electrical stimulation in the cortical gray matter. II. Evidence from selective inactivation of cell bodies and axon initial segment. Experimental Brain Research 118, 489-500.
  • * Nowak, L. G. and Bullier, J. (1996) Spread of stimulating current in the cortical grey matter of rat visual cortex studied on a new in vitro slice preparation. Journal of Neuroscience Methods 67, 237-248.

Corticocortical connections in vitro :

  • * Nowak, L. G., James, A. C. and Bullier, J. (1997) Corticocortical connections between visual areas 17 and 18a of the rat studied in vitro : spatial and temporal organization of functional synaptic inputs. Experimental Brain Research 117, 219-241.

ALL PUBLICATIONS

 

MAIN PARTNERS in CerCo

  • Pascal Barone, Chargé de Recherche CR1, CNRS
  • Pascal Girard, Chargé de Recherche CR1, INSERM

COLLABORATIONS

  • David A. McCormick, Yale University Scool of Medicine, New Haven, Connecticut, USA.
  • Maria V. Sanchez-Vives, Universidad Miguel Hernandez-Consejo Superior de Investigaciones, San Juan de Alicante, Spain.
  • Niall McLoughlin and Ingo Schiessl, University of Manchester Institute of Science and Technology, Manchester, UK.
  • David Hansel, Carl van Vreeswijk and Erez Persi, Université René Descartes and Centre National de la Recherche Scientifique, Paris, France.

TEACHING

Master 2 de Neuroscience, Comportement et Cognition, Université Paul Sabatier, Toulouse.

Mise à jour 15/04/2011