GABAergic inhibition gates excitatory LTP in perirhinal cortex

Area of Science:

• Neuroscience
• Synaptic Plasticity
• Auditory Processing

Background:

• The perirhinal cortex (PRh) is crucial for familiarity-based memory.
• Auditory cortex (ACx) signals are modulated by GABAergic inhibition in the PRh.

Purpose of the Study:

• Investigate if inhibitory shunting in PRh neurons blocks excitatory long-term potentiation (e-LTP) induction.
• Determine the role of GABAergic transmission in regulating synaptic plasticity in the PRh.

Main Methods:

• Used brain slice electrophysiology in gerbils.
• Stimulated ACx-recipient PRh neurons with theta burst stimulation (TBS).
• Applied GABA receptor antagonists (bicuculline for GABA_A, and a GABA_B antagonist).

Main Results:

• Without GABA blockers, TBS induced long-term depression in most PRh neurons.
• Partial GABA_A blockade increased EPSP amplitude but did not induce e-LTP.
• Complete blockade of GABA_A and GABA_B receptors enabled reliable e-LTP induction by TBS.

Conclusions:

• GABAergic transmission critically regulates e-LTP induction in the perirhinal cortex.
• Inhibitory mechanisms in the PRh are vital for controlling synaptic plasticity.
• This regulation may be linked to auditory learning processes.