The effects of denervation and stimulation upon synaptic ultrastructure

Area of Science:

• Neuroscience
• Cellular Biology
• Synaptic Plasticity

Background:

• The adult nervous system exhibits plasticity, but the extent and mechanisms are not fully understood.
• Denervation can induce changes in synaptic structure, even without external stimuli.

Purpose of the Study:

• To investigate the synaptic ultrastructural changes in cat cerebral cortex following chronic denervation and electrical stimulation.
• To determine the role of electrical stimulation in promoting synaptic plasticity in adult mammalian cortex.

Main Methods:

• Quantitative ultrastructural analysis of synaptic morphology in the upper layers of cat cerebral cortex.
• Comparison of intact cortex with chronically undercut cortex, with and without electrical stimulation.

Main Results:

• Chronic electrical stimulation of denervated cortex led to increased symmetric membrane contacts, larger terminal areas, and increased dendritic shaft contacts.
• Denervated cortex without stimulation showed some synaptic plasticity, including increased bouton area and dendritic shaft contacts.
• Electrical stimulation resulted in significantly greater plasticity than denervation alone, with both structural and functional components (effective inhibition).

Conclusions:

• Chronic electrical stimulation significantly enhances synaptic plasticity in the adult denervated cerebral cortex.
• The observed plasticity involves structural remodeling and functional changes, such as effective inhibition.
• These findings highlight the potential of electrical stimulation to promote neural repair and adaptation.