Related Experiment Video
Updated: Jul 7, 2026

Measuring and Manipulating Functionally Specific Neural Pathways in the Human Motor System with Transcranial Magnetic Stimulation
Published on: February 23, 2020
Non-primary motor areas in the human frontal lobe are connected directly to hand muscles
S Teitti1, S Määttä, L Säisänen
1Clinical Neurophysiology, NBS Laboratory, Kuopio University Hospital, Finland. steitti@hytti.uku.fi
Abstract:
Structural studies in primates have shown that, in addition to the primary motor cortex (M1), premotor areas are a source of corticospinal tracts. The function of these putative corticospinal neuronal tracts in humans is still unclear. We found frontal non-primary motor areas (NPMAs), which react to targeted non-invasive magnetic pulses and activate peripheral muscles as fast as or even faster than those in M1. Hand muscle movements were observed in all our subjects about 20 ms after transcranial stimulation of the superior frontal gyrus (Brodmann areas 6 and 8). Stimulation of NPMA could activate both proximal and distal upper limb muscles with the same delay as a stimulation of the M1, indicating converging motor representations with direct functional connections to the hand. We suggest that these non-primary cortical motor representations provide additional capacity for the fast execution of movements. Such a capacity may play a role in motor learning and in recovery from motor deficits.
Related Concept Videos
Motor and Sensory Areas of the Cortex
Motor Areas
The motor areas located in the frontal lobe are central to controlling voluntary movements. This region is further subdivided into the primary motor cortex and the premotor cortex.
Association Areas of the Cortex
Prefrontal Association Area: This area is located in the frontal lobe and is involved in planning, decision-making, and moderating social behavior. It connects with primary motor areas,...
Direct Motor Pathways
The corticospinal tract is responsible for the voluntary movement of the limbs and trunk. It originates in the cerebral cortex of the brain and descends through the cerebrum's internal capsule and the...
Somatosensory, Motor, and Association Cortex
Somatosensation
Muscles of the Forearm that Move the Hand and Fingers
Anterior Compartment
The anterior compartment muscles originate from the humerus. They primarily function as flexors and are also known as flexor muscles. They typically insert on the carpals, metacarpals, and phalanges. The superficial layer includes the flexor carpi radialis,...

