Nucleus basalis of Meynert cell responses in awake monkeys

Extracellular cell activity was recorded in the intermediate and posterior subdivisions of the nucleus basalis of Meynert (NBM) of awake monkeys to determine cell characteristics and the motor and sensory participation. Animals were trained to move a lever by elbow flexion-extensions to receive a reward. Cell activity was recorded when the animal was at rest and executing the task. The electromyogram of the upper limb, contralateral to the recording site, was recorded simultaneously with NBM neuron activity. The effect of visual, auditory, and tactile stimuli were also studied after performance of the learned task. A moderate number of cells responded to the reward (16%), while a higher percentage of them was associated with unexpected, unspecific stimuli (22%). Firing rates correlated positively with limb movement (30%). Visual (34%) and auditory (15%) responses were also found. No NBM cell responded to tactile stimulation. Considering these findings and the anatomical projections over the cortex, the NBM role ion complex integrative processes in discussed.