DSCAM-mediated control of dendritic and axonal arbor outgrowth enforces tiling and inhibits synaptic plasticity

Area of Science:

• Neuroscience
• Retinal Biology
• Cell Adhesion Molecules

Background:

• Mature mammalian neurons exhibit limited plasticity, hindering neurite extension and new synaptic connections.
• Mechanisms inhibiting neuronal plasticity in mature brains are not well understood.

Purpose of the Study:

• Investigate the mechanisms limiting neuronal plasticity in the mature mammalian retina.
• Identify the role of Down syndrome cell-adhesion molecule (DSCAM) in regulating retinal circuit plasticity.

Main Methods:

• Utilized conditional gene deletion of DSCAM in mature mouse retinas.
• Performed anatomical analysis of dendritic fields and photoreceptor contacts.
• Conducted electrophysiological recordings to assess visual receptive fields.

Main Results:

• OFF-type retinal bipolar cells in mice form new anatomical connections post-maturity.
• Conditional deletion of DSCAM allowed dendrite and axon arbors to extend beyond normal boundaries.
• DSCAM deletion resulted in expanded dendritic fields, increased cone photoreceptor contacts, and enlarged visual receptive fields in OFF bipolar cells.

Conclusions:

• Down syndrome cell-adhesion molecule (DSCAM) actively inhibits circuit-level plasticity in the adult retina.
• DSCAM-mediated inhibition regulates neuronal plasticity by confining anatomical rearrangements within established fields.
• Expanded dendritic territories in DSCAM-deficient cells form functional synapses, indicating plasticity in mature retinal circuits.