Spontaneous activity in the developing gerbil auditory cortex in vivo involves GABAergic transmission.

Area of Science:

• Neuroscience
• Developmental Neuroscience
• Auditory Neuroscience

Background:

• Spontaneous oscillations (SOs) and waves are critical for synaptic development in the brain.
• GABAergic signaling has differential effects on SOs in developing rodent and gerbil auditory cortex (ACx).

Purpose of the Study:

• To investigate the existence and characteristics of in vivo SOs in the developing gerbil ACx.
• To explore the role and manipulability of GABAergic involvement in these SOs.

Main Methods:

• In vivo extracellular recordings in P3-5 gerbil ACx.
• Anatomical validation using gross features and dye tracing (NeuroVue Red).
• Chronic administration of GABA(A) receptor blocker (bicuculline) and subsequent slice electrophysiology.
• Acute application of gap junction blockers (mefloquine, carbenoxolone) during spontaneous inhibitory postsynaptic current (sIPSC) recordings in slices.

Main Results:

• In vivo recordings revealed SOs in P3-5 gerbil ACx with distinct burst durations and inter-event intervals compared to slice data.
• NeuroVue Red confirmed anatomical connections between ACx and the auditory thalamus (MG).
• Postnatal bicuculline administration led to persistent spontaneous action potentials in P14-17 ACx neurons, unlike controls.
• Mefloquine increased sIPSC amplitude and frequency, while carbenoxolone only decreased sIPSC amplitude in ACx slices.

Conclusions:

• Developing gerbil ACx generates endogenous SOs in vivo.
• Inhibitory GABAergic activity, modulated by gap junctions, plays a significant role in ACx maturation.
• These findings highlight the importance of early neural activity patterns for auditory cortex development.