Synchrony between neurons with similar muscle fields in monkey motor cortex

Area of Science:

• Neuroscience
• Motor Control
• Computational Neuroscience

Background:

• Motor cortex neurons exhibit post-spike effects like facilitation (PSF) and suppression (PSS) on muscle activity.
• Understanding the relationship between neural synchrony and output connectivity is crucial for deciphering motor control mechanisms.

Purpose of the Study:

• To investigate the relationship between the synchrony of motor cortex cell firing and their output connectivity to hand muscles.
• To determine if neuronal synchrony reflects direct functional connections within motor control networks.

Main Methods:

• Simultaneous recordings of 144 pairs of motor cortex neurons in macaque monkeys during a precision grip task.
• Cross-correlation histograms were used to assess neuronal synchronization.
• Spike-triggered averages of electromyography (EMG) were employed to define the muscle field of each recorded neuron.

Main Results:

• Cell pairs with overlapping muscle fields demonstrated significantly greater synchronization than those with non-overlapping fields.
• Neurons exhibiting opposing effects on the same muscles showed negative synchronization, indicating inhibitory relationships.
• Synchrony was positively correlated with shared muscle output.

Conclusions:

• Neuronal synchrony in the motor cortex is associated with direct functional connections to the same muscle sets.
• The findings suggest the presence of inhibitory connections between motor cortex neuronal populations that exert opposing influences on muscle activity.
• Synchrony analysis provides insights into the network architecture and functional organization of the motor cortex.