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Published on: February 8, 2020
Subcortical auditory input to the primary visual cortex in anophthalmic mice
Nicole Chabot1, Valérie Charbonneau, Marie-Eve Laramée
1Université du Québec à Trois-Rivières, Groupe de Recherche en Neurosciences, Canada.
Neuroscience Letters
|February 16, 2008
Summary
In blind mice, auditory information does not directly reach the primary visual cortex (V1) via a novel pathway, despite previous suggestions. This study reinvestigated connections in anophthalmic mice, finding no direct auditory-to-V1 projections.
Area of Science:
- Neuroscience
- Sensory processing
- Neuroanatomy
Background:
- Early-onset blindness in humans and animals can lead to auditory activation of the visual cortex.
- Intermodal pathways between auditory and visual cortices, and connections between the inferior colliculus and visual thalamus, are known.
- A previous study suggested a direct reciprocal connection between the inferior colliculus and primary visual cortex (V1) in congenitally anophthalmic ZRDCT/An mice.
Purpose of the Study:
- To reinvestigate the presence of a direct connection between auditory subcortical structures and the primary visual cortex (V1) in the ZRDCT/An mouse model of congenital blindness.
- To clarify the neuroanatomical pathways involved in cross-modal plasticity in early-onset blindness.
Main Methods:
- Utilized highly sensitive neuronal tracers to trace connections in ZRDCT/An mice.
- Examined known anatomical connections, including those between the inferior colliculus and dorsal lateral geniculate nucleus, V1 and superior colliculus, lateral posterior nucleus and V1, and inferior colliculus and medial geniculate nucleus.
- Specifically investigated for direct projections from auditory mesencephalon to V1.
Main Results:
- Confirmed previously described connections in ZRDCT/An mice: inferior colliculus to dorsal lateral geniculate nucleus, V1 to superior colliculus, lateral posterior nucleus to V1, and inferior colliculus to medial geniculate nucleus.
- Unambiguously demonstrated that auditory subcortical structures do not connect to the primary visual cortex (V1) in this anophthalmic mouse model.
- Found no evidence of a direct projection from the auditory mesencephalon to the cortex.
Conclusions:
- The ZRDCT/An mouse does not possess a direct tectal connection with the primary visual cortex (V1) from auditory structures.
- The findings refute the hypothesis of a direct auditory-to-V1 pathway in this model of congenital blindness.
- Established neuroanatomical pathways in this model do not support direct cross-modal innervation of V1 by auditory pathways from the mesencephalon.
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