[Organization of the nervous system after coagulation of the follicles of mystacial vibrissae in the newborn mouse: an example of neuronal plasticity].
In the mouse the vibrissae and the common fur of the head are a good model of the so called neural plasticity. The characteristics of this model are: the pattern of implantation of the vibrissae at the periphery and that of the arrangement of barrels in the contralateral cortical projection area of vibrissae as well as that of the "barreloïds" in the subcortical vibrissal relays (somato sensory thalamus and trigeminal nuclear complex) are homeomorphic with one another. Each barrel and "barreloïd" receives projections from one vibrissa. Moreover at the level of the cortex these projections are also in register with projections from ipsilateral vibrissae. Head fur hairs project to well defined but entirely distinct areas. Destruction of vibrissae follicles at birth beside preventing barrel and barreloïd formation in the CNS, leads to several morphological changes: degeneration of the primary sensory neurons innervating vibrissae in the trigeminal ganglion, thus degeneration of their central axons and the corresponding terminals in the trigeminal vibrissal relays changes in the distribution of the activity of succinate dehydrogenase in the IVth layer of the cortical vibrissal area and in the corresponding subcortical relays, from the normal discrete (barrel hollow) pattern--corresponding to the clustered vibrissal afferents--to a continuous band, keeping a normal level of activity, excepted in the trigeminal vibrissal relays and a remarkable preservation of cortical thickness but a notable atrophy in the trigeminal vibrissal projection areas. Beside upsetting the anatomy vibrissae follicle destruction causes marked functional changes an outstanding take-over of the deafferented cortical vibrissal area (still identifiable from projections of vibrissae ipsilateral to it) by the head fur hairs this take over exist also in the subcortical vibrissal relays a change in the thalamo-cortical connections. Modifications in the organization of connections are initiated by the loss of the primary sensory neurons innervating vibrissae, in the trigeminal ganglion and results only from early lesions. In mice lesioned when adults the loss of primary sensory neurons is less important and functional take over by the common fur is not observed.
D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D001921:Brain / Q000502:physiology*; D051379:Mice; D008959:Models, Neurological; D009473:Neuronal Plasticity; D009475:Neurons, Afferent / Q000502:physiology; D013003:Somatosensory Cortex / Q000502:physiology; D013787:Thalamic Nuclei / Q000502:physiology; D012668:Trigeminal Ganglion / Q000502:physiology; D014276:Trigeminal Nerve / Q000502:physiology*; D014738:Vibrissae / Q000502:physiology*
L'organisation du système nerveux après coagulation des follicules des vibrisses mystaciales chez la souris nouveau-née: un exemple de plasticité neuronale.