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Lionel G NOWAK

Chargé de Recherche CR1, CNRS

tel : 05 62 74 61 48, from abroad : +33 562 746 148

fax : 05 62 74 61 17, from abroad : +33 562 746 117

Team : 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 in vivo and in vitro, reversible inactivation, neuroanatomy, optical imaging, etc…

My present research and research projects are centered on the genesis of visual response properties and their dynamics in the visual cortex (mostly area V1). More specifically, I currently study (or recently studied) :

  • The mechanisms of receptive field property generation (spatiotemporal features of the receptive field, orientation selectivity, size tuning, etc)
  • The role of intrinsic neuronal properties and synaptic mechanisms in contrast gain control and contrast adaptation
  • The consequences of contrast gain control and contrast adaptation on receptive fields properties
  • Synaptic noise and gamma-band fluctuations
  • The enzymatic control of synaptic transmission

PUBLICATIONS (by topics)

Mechanisms and consequences of contrast gain control and contrast adaptation in the visual cortex

  • Durand JB, Girard P, Barone P, Bullier J and Nowak LG (2012) Effects of contrast and contrast adaptation on static receptive field features in macaque area V1. Journal of Neurophysiology 108, 2033-2050.
  • Persi E, Hansel D, Nowak L, Barone P and van Vreeswijk C (2011) Power-law input-output transfer functions explain the contrast-response and tuning properties of neurons in visual cortex. PLoS Computational Biology 7 : e1001078.
  • Nowak LG and Barone P (2009) Contrast adaptation contributes to contrast-invariance of orientation tuning of primate V1 cells. PLoS one 4 : e4781.
  • Reig R, Gallego R, Nowak LG, and Sanchez-Vives MV (2006) Impact of cortical network activity on short-term synaptic depression. Cerebral Cortex 16, 688-695.
  • Descalzo VF, Nowak LG, Brumberg JC, McCormick DA and Sanchez-Vives MV (2005) Slow adaptation in fast spiking neurons of visual cortex. Journal of Neurophysiology 93, 1111-1118.
  • Nowak LG, Sanchez-Vives MV and McCormick DA (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 MV*, Nowak LG* and McCormick DA (2000) Membrane mechanisms underlying contrast adaptation in cat area 17 in vivo. Journal of Neuroscience 20, 4267-4285. (* : shared first authorship)
  • Sanchez-Vives MV, Nowak LG and McCormick DA (2000) Cellular mechanisms of long lasting adaptation in visual cortical neurons in vitro. Journal of Neuroscience 20, 4286-4299.

Electrophysiological cell classes and receptive field properties (and their subthreshold mechanisms) in the visual cortex

  • Nowak LG, Sanchez-Vives MV and McCormick DA (2010) Spatial and temporal features of synaptic to discharge receptive field transformation in cat area 17. Journal of Neurophysiology 103, 677-697.
  • Nowak LG, Sanchez-Vives MV and McCormick DA (2008) Lack of orientation and direction selectivity in a subgroup of fast-spiking inhibitory interneurons : cellular and synaptic mechanisms and comparison with other electrophysiological cell types. Cerebral Cortex 18, 1058-1078.
  • Nowak LG, Sanchez-Vives MV, Azouz R, Gray CM and McCormick DA (2003) Electrophysiological classes of cat primary visual cortical neurons in vivo as revealed by quantitative analysis. Journal of Neurophysiology 89, 1541-1566.
  • Brumberg JC, Nowak LG and McCormick DA (2000) Ionic mechanisms underlying repetitive high-frequency burst firing in supragranular cortical neurons. Journal of Neuroscience 20, 4829-4843.
  • Azouz R, Gray CM, Nowak LG and McCormick, DA (1997) Physiological properties of identified interneurons in cat striate cortex. Cerebral Cortex 7, 534-545.

Cross-modal plasticity (auditory responses in the visual cortex)

  • Sanchez-Vives MV, Nowak LG, Descalzo VF, 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, SL Macknik, LM Martinez, JM Alonso and PU Tse (eds), pp. 287-311.

Response latencies in primate visual cortex and what it implies concerning the hierarchical / parallel organization of the visual system

  • Nowak LG 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.
  • Bullier J and Nowak LG (1995) Parallel versus serial processing, new vistas on the distributed organization of the visual system. Current Opinion in Neurobiology 5, 497-503.
  • Munk MHJ, Nowak LG, 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.
  • Nowak LG, Munk MHJ, Girard P and Bullier J (1995) Visual latencies in areas V1 and V2 of the macaque monkey. Visual Neuroscience 12, 371-384.

Synchronization of neuronal activities in vivo and spike timing reliability in vitro

  • Nowak LG 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 LG, Munk MHJ, James AC, 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.
  • Nowak LG, Sanchez-Vives MV, and McCormick DA (1997) Influence of low and high frequency fluctuations on spike timing in visual cortical neurons. Cerebral Cortex 7, 487-501.
  • Nowak LG, Munk MHJ, James AC, Nelson JI and Bullier J (1995) The structural basis of cortical synchronization. I. 3 types of interhemispheric coupling. Journal of Neurophysiology 74, 2379-2400.
  • Munk MHJ, Nowak LG, Nelson JI and Bullier J (1995) The structural basis of cortical synchronization. II. Localization of the common input. Journal of Neurophysiology 74, 2401-2414.

Neuronal elements activated by electrical stimulation and spread of stimulating current in the cortical gray matter

  • Nowak LG 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 LG 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 LG 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 LG, James AC 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.

To sum up : my HDR

  • (Sorry, in french only) Dynamique et mécanismes des réponses neuronales dans le cortex visuel



ALL PUBLICATIONS

 


MAIN PARTNERS in CerCo

  • Pascal Barone, Dytic 2.0 team
  • Jean-Baptiste Durand, Eco3D team
  • Caroline Fonta, Dytic 2.0 team
  • Pascal Girard, Dytic 2.0 team

CURRENT COLLABORATIONS

  • Maria V. Sanchez-Vives, Institució Catalana de Recerca i Estudis Avançats – Institut d’Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain.
  • David A. McCormick, Yale University Scool of Medicine, New Haven, Connecticut, USA.
  • David Hansel & Carl van Vreeswijk, Université René Descartes and Centre National de la Recherche Scientifique, Paris, France.
  • Christian Bergaud, LAAS-CNRS, UPR 8001, Toulouse & Christophe Jouffrais, IRIT, Toulouse.

TEACHING

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


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Mise à jour 13/02/2013