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Author Spotlight: Unveiling Neural Coding and Mechanisms of Visual Processing in the Superior Colliculus
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Cortical projections to the superior colliculus in grey squirrels (Sciurus carolinensis)
Mary K L Baldwin1,2, Nicole A Young1,3, Denis Matrov1,4,5
1Department of Psychology, Vanderbilt University, 301 Wilson Hall, 111 21st Avenue South, Nashville, TN, 37203, USA.
The European Journal of Neuroscience
|February 17, 2018
Summary
The grey squirrel's superior colliculus receives input from visual, auditory, and somatosensory cortical areas. This midbrain structure
Area of Science:
- Neuroscience
- Comparative Anatomy
- Sensory Integration
Background:
- The superior colliculus (SC) is a midbrain structure crucial for integrating sensory information and guiding orienting movements.
- Grey squirrels possess a disproportionately large SC, suggesting its significant role in their behavior.
- Cortical connections to the SC in grey squirrels remain poorly understood, particularly regarding visual and somatosensory influences.
Purpose of the Study:
- To investigate the cortical projections to the superior colliculus in the grey squirrel (Sciurus carolinensis).
- To compare the pattern of corticotectal connections in grey squirrels with those in other mammals, including rodents, tree shrews, and primates.
Main Methods:
- Anatomical tracer injections were administered into the medial superior colliculus of five grey squirrels.
- Cortical areas with projecting cells were analyzed in flattened cortex.
- Visual area V1 projections to the SC were examined in two additional animals.
Main Results:
- The superior colliculus receives significant cortical input from visual, higher-order somatosensory, and higher-order auditory regions.
- Projections were also observed from limbic, retrosplenial, and anterior cingulate cortices.
- Minimal to no corticotectal projections originated from primary motor, primary somatosensory, or parietal cortical areas.
Conclusions:
- The pattern of corticotectal inputs in grey squirrels resembles that of rodents like rats and mice.
- The absence of primary somatosensory and motor cortex inputs is more akin to tree shrews and primates.
- This unique connectivity may reflect a behavioral adaptation towards visual navigation over somatosensory (vibrissae-based) navigation in grey squirrels.
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