Related Experiment Video
Updated: Jun 1, 2026
09:48
Intracortical Inhibition Within the Primary Motor Cortex Can Be Modulated by Changing the Focus of Attention
Published on: September 11, 2017
Area 5 influences excitability within the primary motor cortex in humans
Azra Premji1, Navjot Rai, Aimee Nelson
1Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada.
Plos One
|May 24, 2011
Summary
Brodmann's area 5 (BA 5) stimulation modulates primary motor cortex (M1) hand representation excitability. Continuous theta-burst stimulation (cTBS) of BA 5 increased motor evoked potentials (MEPs) bilaterally, while intermittent theta-burst stimulation (iTBS) increased them contralaterally.
Area of Science:
- Neuroscience
- Motor Control
- Human Brain Mapping
Background:
- Brodmann's area 5 (BA 5) in primates connects to primary motor cortex (M1) and is crucial for hand representation and skilled movement.
- The role of human BA 5 in M1 neural circuits for hand control remains less understood.
- Investigating BA 5's influence on M1 is key to understanding hand dexterity and potential therapeutic interventions.
Purpose of the Study:
- To examine how BA 5 influences excitatory and inhibitory neural circuitry in M1 related to hand control.
- To assess the effects of continuous (cTBS) and intermittent (iTBS) theta-burst stimulation (TBS) over BA 5 on M1 excitability.
- To determine if BA 5 stimulation modulates intracortical inhibition and facilitation within M1.
Main Methods:
- Utilized single and paired-pulse transcranial magnetic stimulation (TMS) over left hemisphere BA 5.
- Measured motor evoked potentials (MEPs), short interval intracortical inhibition (SICI), and intracortical facilitation (ICF) in the first dorsal interosseous muscle.
- Applied continuous (cTBS), intermittent (iTBS), and sham TBS to BA 5, assessing effects bilaterally.
Main Results:
- cTBS over BA 5 increased MEP amplitudes bilaterally for up to one hour.
- iTBS over BA 5 increased contralateral MEP amplitude with a delayed onset, persisting for up to one hour.
- SICI, ICF, and F-wave parameters remained unaltered following TBS over BA 5.
Conclusions:
- BA 5 stimulation, particularly cTBS and iTBS, effectively modulates M1 output to the hand.
- The observed effects suggest BA 5 influences corticospinal neurons rather than interneurons mediating SICI or ICF.
- Targeting BA 5 offers a novel approach for investigating hand control and potentially treating impaired hand function.
Related Concept Videos
01:14Motor and Sensory Areas of the Cortex
The cerebral cortex, the brain's outermost layer, is pivotal in processing complex cognitive tasks, emotions, and various sensory inputs and executing voluntary motor activities. This intricate structure is divided into three primary functional areas: the motor areas, sensory areas, and association areas.
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.
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.
01:23Somatosensory, Motor, and Association Cortex
The somatosensory cortex in the parietal lobes is crucial for interpreting sensory data such as touch, temperature, and proprioception. The somatosensory cortex, situated in the parietal lobes, plays a vital role in interpreting sensory information like touch, temperature, and proprioception—awareness of body position. This specialized brain region features an organized structure wherein neurons at the top primarily process sensations originating from the lower body. In contrast, those at the...
01:21Association Areas of the Cortex
Association areas are regions of the cerebral cortex that do not have a specific sensory or motor function. Instead, they integrate and interpret information from various sources to enable higher cognitive processes such as memory, learning, and decision-making. Some key association areas include the following:
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,...
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,...
01:11Direct Motor Pathways
The direct motor pathways, also known as the pyramidal tracts, are a group of neural pathways that originate in the brain and descend through the spinal cord. They control the voluntary movement of the body. There are two major direct motor pathways: the corticospinal and the corticobulbar tracts.
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...
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...