Sequential variation in brain functional magnetic resonance imaging after peripheral nerve injury: A rat study

Area of Science:

• Neuroscience
• Medical Imaging

Background:

• Peripheral nerve injury can lead to acute and chronic neuropathic pain, including hyperalgesia and allodynia.
• Current treatment protocols do not fully alleviate these pain states.

Purpose of the Study:

• To identify brain regions activated after peripheral nerve injury using sequential functional magnetic resonance imaging (fMRI).
• To correlate fMRI findings with histological data to assess brain changes over time.

Main Methods:

• Peripheral nerve injury was induced in rats by crushing the sciatic nerve.
• fMRI was performed sequentially at 3, 6, and 9 weeks post-injury, with concurrent electrical foot sole stimulation.
• c-Fos immunohistochemistry was used for histological validation.

Main Results:

• One week post-injury, fMRI detected significant activation in the cingulate cortex, insular cortex, amygdala, and basal ganglia.
• By 6 weeks, the extent of significant signal changes in the brain contracted.
• At 9 weeks, the amygdala and hippocampus showed notable activation, supported by histological findings.

Conclusions:

• fMRI successfully identified sequential brain activation patterns after sciatic nerve injury in rats.
• Acute peripheral nerve injury triggers widespread brain region activation.
• Chronic-stage activation in the amygdala and hippocampus may correlate with persistent neuropathic pain, hyperalgesia, and allodynia.