Evidence for a threshold in experience-dependent long-term changes of kitten visual cortex.

Area of Science:

• Neuroscience
• Developmental Neuroscience
• Visual System Plasticity

Background:

• The visual cortex exhibits developmental plasticity, allowing its structure and function to be shaped by visual experience.
• Understanding the role of spontaneous versus visually evoked activity is crucial for deciphering plasticity mechanisms.

Purpose of the Study:

• To investigate the role of spontaneous neuronal activity in visual cortex plasticity.
• To determine if sub-threshold activity influences ocular dominance and orientation tuning.

Main Methods:

• Monocular inactivation of retinal activity using tetrodotoxin (TTX) injections in kittens.
• Monocular deprivation by lid suture in control littermates.
• Comparison of ocular dominance shifts and neuronal orientation tuning between experimental groups.

Main Results:

• No significant difference in ocular dominance shift between TTX-inactivated and lid-sutured kittens.
• A non-significant trend towards reduced orientation tuning in TTX-treated kittens.
• No ocular dominance shift observed when one eye was inactivated and the other sutured closed.

Conclusions:

• Activity-dependent ocular dominance changes in the visual cortex have a critical threshold.
• Afferent activity below this threshold does not significantly impact functional connection stability or disruption.
• Spontaneous activity below the threshold plays a minimal role in visual cortex developmental plasticity.