Neural plasticity without postsynaptic action potentials: less-active inputs become dominant when kitten visual...

Area of Science:

• Neuroscience
• Neuroplasticity
• Visual Cortex Function

Background:

• Conventional models of synaptic plasticity link postsynaptic activity to enhanced presynaptic input efficacy.
• The visual cortex exhibits rapid ocular dominance plasticity during a critical developmental period, responding to visual input changes.

Purpose of the Study:

• To investigate the role of postsynaptic activity in ocular dominance plasticity within the visual cortex.
• To determine if postsynaptic spike activity is essential for inducing and directing plasticity.

Main Methods:

• Monocular deprivation was performed during the critical period in the visual cortex.
• Cortical cell discharges were selectively inhibited using muscimol, an inhibitory neurotransmitter agonist, via intracortical infusion.
• Single-unit recordings were used to assess visual cortex responsiveness after the muscimol blockade.

Main Results:

• Inhibition of postsynaptic cell discharges resulted in a shift of visual cortex responsiveness favoring the deprived (closed) eye.
• This plasticity occurred in favor of the less-active eye, contrary to typical activity-dependent plasticity.
• Regions not affected by muscimol showed the expected plasticity favoring the more-active (open) eye.

Conclusions:

• Postsynaptic neuronal activity is a critical factor in visual cortex plasticity.
• The direction and expression of plasticity are influenced by postsynaptic membrane properties like conductance or polarization.
• Synaptic plasticity can be induced and expressed even in the absence of postsynaptic spiking activity.