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Electrophysiological Investigations of Retinogeniculate and Corticogeniculate Synapse Function
Published on: August 7, 2019
Experience-driven axon retraction in the pharmacologically inactivated visual cortex does not require synaptic
Kana Watanabe1, Yu Morishima, Masahito Toigawa
1Division of Integrative Bioscience, Institute of Regenerative Medicine and Biofunction, Tottori University Graduate School of Medical Sciences, Yonago, Japan.
Plos One
|January 15, 2009
Summary
Experience-driven axon retraction in the developing visual cortex can occur even when synaptic transmission is blocked. This highlights the critical role of presynaptic mechanisms in refining neural connections during early development.
Area of Science:
- Neuroscience
- Developmental Biology
- Visual System Research
Background:
- Postnatal development refines neural connections, particularly in the mammalian visual system.
- Altered visual experiences drive adaptive changes in visual cortical responses and axon rearrangements.
- Previous studies suggested presynaptic activity, not postsynaptic activity, causes geniculocortical axon retraction.
Purpose of the Study:
- To investigate if experience-driven axon retraction occurs in the visual cortex when synaptic inputs are blocked.
- To determine the role of synaptic transmission in experience-dependent axon refinement.
Main Methods:
- Inactivated the primary visual cortex in kittens using botulinum neurotoxin type E to block neurotransmitter release.
- Examined geniculocortical axon morphology in normally sighted and binocularly deprived kittens.
- Utilized SNAP-25 cleavage by botulinum neurotoxin type E to inhibit synaptic transmission.
Main Results:
- Significant axon retraction was observed in the inactivated cortex of normally sighted kittens.
- Axons in binocularly deprived kittens with inactivated cortex were preserved.
- Findings mirrored results from previous studies using muscimol to inhibit cortical neurons.
Conclusions:
- Experience-driven axon retraction in the visual cortex can occur independently of synaptic transmission.
- Presynaptic mechanisms are crucial for the experience-dependent refinement of geniculocortical axons.
- This suggests a presynaptic role in visual pathway development.
