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.
Research And Development
Medical Laboratory Technician100%
Manufacturer - Other33%