MAR 20, 2014 01:00 PM PDT

Cholinergic modulation of visual perception in rodents

Presented At Neuroscience
Speakers
  • Full professor Ecole doptomtrie, Universit de Montral, Qubec, Canada
    Biography
      Dr Vaucher obtained her PhD Neurosciences at Universit Paris VI. CNRS UA 641, Paris / Institut Neurologique de Montral, Qubec. She has completed two post-doctoral formations in the field of the involvement of the cholnergic deficit in Alzheimer's disease. The aim of her research group is to determine the role of neurotransmitters in the visual processing, especially the role of neuromodulators such as acetylcholine in modifying the cortical representation of specific stimuli and the cortical plasticity. This project will extend the basic knowledge of how the visual stimuli are integrated by the cortical networks (including learning, memory and attentional processes) and will permit to use pharmacological agents as cognitive and/or sensory enhancers to facilitate sight recovery and cortical plasticity.

    Abstract:

    The cholinergic system is a potent neuromodulatory system which plays a critical role in cortical plasticity, attention and learning. The cholinergic activation of the cortex increases the signal-to-noise ratio, cue detection ability and the strength of the thalamocortical afferences relative to cortico-cortical signaling. These changes facilitate the treatment of a novel stimulus.
    We are particularly interested in the role of the cholinergic system in visual processing and cortical plasticity of the visual cortex (V1). Our laboratory uses a large panel of techniques behaviour, neurophysiology, neuroanatomy and optical imaging - to examine this issue from a cellular to an integrated and behavioural level. We have recently demonstrated that acetylcholine (ACh) was released in V1 during a pattern visual activation. The cholinergic deficit impaired the visually-induced neuronal activity in the layer 4 of V1 and the performance of the rat in a visual learning task. Moreover, deletion of different subtypes of muscarinic receptors in KO mice selectively altered the intrinsic organization of V1 suggesting a strong involvement of the muscarinic transmission in the detectability of visual stimuli. The transient coupling of cholinergic and pattern visual stimulation induced a long-term enhancement of the visual evoked potentials mediated by muscarinic, nicotinic and NMDA receptors. This cholinergic-induced long-term modifications of the cortical functioning also improved visual perception. Activation of the cholinergic system paired with visual stimulation over two weeks induced a long-term increase of visual evoked potentials in V1 and of the visual acuity of the rats.
    Our results demonstrate that the pairing of the cholinergic system activation with visual training improved the visual performance of the animals and functional organization of V1. This study opens the possibility of boosting V1 plasticity and facilitating visual recovery.
    Supported by CIHR, NSERC, FRQS Vision Research Network.


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