Distinct Temporal Coordination of Spontaneous Population Activity between Basal Forebrain and Auditory Cortex

Area of Science:

• Neuroscience
• Computational Neuroscience
• Systems Neuroscience

Background:

• The basal forebrain (BF) is crucial for attention, learning, and memory.
• Previous studies linked artificial BF activation to arousal, but its neural ensemble dynamics remain unclear.
• Understanding BF neural activity is key to elucidating brain state regulation mechanisms.

Purpose of the Study:

• To investigate and compare the spontaneous neural population activity in the basal forebrain (BF) and auditory cortex (AC) in mice.
• To elucidate the differences in temporal coordination and operational timescales between BF and AC neural ensembles.
• To gain insights into the neural mechanisms underlying brain state regulation by the BF.

Main Methods:

• Simultaneous recording of neural population activity in the BF and AC of mice.
• Comparison of activity under both anesthetized and unanesthetized conditions.
• Analysis of firing rate distributions, inter-spike intervals (ISIs), spike count correlations, and spike-field entrainment.

Main Results:

• Auditory cortex (AC) neuronal populations showed skewed firing rates, a high proportion of short ISIs, and rich rhythmic firing.
• Basal forebrain (BF) populations also had skewed firing rates, but shorter ISIs were partly explained by a Poisson model, and spike count correlations were lower than in AC.
• A subset of BF neurons exhibited slow rhythmic firing (≤6 Hz) with varied phase preferences, distinct from the consistent phase preference observed in AC populations; these slow rhythmic BF cells showed higher correlations.

Conclusions:

• The fundamental difference between BF and AC population activity lies in their temporal coordination and operational timescales.
• BF neurons appear to slowly modulate downstream populations, while cortical circuits transmit signals across multiple timescales.
• Characterizing BF neural ensemble dynamics provides crucial insights into the neural mechanisms governing brain state regulation.