Prolonged anesthesia alters brain synaptic architecture

Area of Science:

• Neuroscience
• Anesthesiology
• Cognitive Science

Background:

• Prolonged medically induced coma (pMIC) is a common intensive care procedure.
• Cognitive impairment is a known consequence of pMIC, but its neuromorphological basis remains unclear.
• Existing research on medically induced coma (MIC) effects on neural circuits is limited to durations of approximately 6 hours.

Purpose of the Study:

• To investigate the neuromorphological correlates of prolonged medically induced coma (pMIC) exceeding 6 hours.
• To assess the impact of pMIC on cognitive function and synaptic plasticity in the brain.
• To elucidate the structural changes in neural circuits following extended anesthesia.

Main Methods:

• Establishment of a pMIC model in adolescent and mature mice, with durations up to 24 hours.
• Longitudinal two-photon imaging of cortical synapses to track structural dynamics.
• Repeated behavioral assessments using object recognition tasks to evaluate cognitive performance.

Main Results:

• Prolonged medically induced coma (pMIC) was found to impair object recognition memory in mice.
• pMIC induced significant changes in synaptic turnover, characterized by increased synapse formation during anesthesia.
• The postanesthetic period was associated with substantial synaptic loss, indicating a disruption of neural circuit structure.

Conclusions:

• Prolonged anesthesia, as induced by pMIC, has demonstrable adverse effects on neural circuit structure.
• The observed synaptic alterations during and after pMIC correlate with cognitive deficits.
• This study provides direct evidence of the neuromorphological consequences of extended medically induced coma.