Dopaminergic modulation of auditory cortex-dependent memory consolidation through mTOR.

Area of Science:

• Neuroscience
• Auditory Neuroscience
• Molecular Neuroscience

Background:

• Long-term memory formation in the auditory cortex involves dopamine, mammalian target of rapamycin (mTOR), and protein synthesis.
• The precise role of the dopaminergic system in modulating memory via mTOR requires further investigation.

Purpose of the Study:

• To investigate the hypothesis that the dopaminergic system regulates auditory memory formation through mTOR activation.
• To determine the effects of D1/D5 dopamine receptor agonists and antagonists on frequency-modulated tone (FM) discrimination learning in gerbils.

Main Methods:

• Gerbils were trained on FM discrimination tasks with systemic or local administration of D1/D5 dopamine receptor agonist (SKF-38393) or antagonist (SCH-23390).
• The impact of mTOR inhibitor (rapamycin) and protein synthesis blocker (anisomycin) on learning was assessed.
• Immunohistochemistry was used to localize D1 dopamine receptors in the auditory cortex.

Main Results:

• SKF-38393 administration significantly improved FM discrimination learning hours to days after conditioning.
• The enhancing effect of SKF-38393 was blocked by SCH-23390, rapamycin, and anisomycin.
• D1 dopamine receptors were found predominantly in the infragranular layers of the gerbil auditory cortex.

Conclusions:

• Dopaminergic inputs in the auditory cortex regulate memory consolidation via mTOR-mediated, protein synthesis-dependent mechanisms.
• This dopaminergic regulation controls the formation of long-term memory for complex auditory stimuli discrimination for extended periods.