Alpha Oscillations Modulate Preparatory Activity in Marmoset Area 8Ad

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Primate Neurophysiology

Background:

• Cognitive control necessitates suppressing prepotent stimulus-driven responses.
• Proactive inhibition within the frontoparietal saccade network supports saccade suppression.
• Laminar neural mechanisms of inhibition are poorly understood due to anatomical constraints in macaques.

Purpose of the Study:

• To investigate the interlaminar neural basis of inhibitory saccade control.
• To leverage the lissencephalic cortex of the common marmoset for laminar recordings.
• To explore task-dependent neural activity in the marmoset frontal eye field (area 8Ad) and lateral intraparietal area.

Main Methods:

• Laminar recordings using linear electrode arrays in area 8Ad and the lateral intraparietal area of two male marmosets.
• Performance of a task requiring alternating blocks of saccade generation or inhibition.
• Analysis of local field potential (LFP) oscillations (alpha/gamma bands) and single-unit discharge rates.

Main Results:

• Prominent task-dependent activity observed in LFP alpha/gamma bands and single-neuron firing rates in area 8Ad during a prestimulus epoch.
• Rhythmic alpha-band activity was higher in deeper cortical layers, while spiking activity was lower in upper layers during instructed saccade suppression.
• These findings align with a model where deeper layer alpha activity inhibits upper layer spiking to support proactive inhibitory control.

Conclusions:

• The study elucidates laminar neural mechanisms supporting proactive inhibitory saccade control in the marmoset frontal eye field.
• Rhythmic alpha-band activity in deeper layers appears crucial for suppressing prepotent responses.
• Reduced alpha power during task preparation may underlie deficits in saccade suppression observed in neuropsychiatric disorders.