Motor command in the brain

• The frontal lobe part of the telencephalon is where most motor control neurons are found.
• Association cortices are responsible for carrying out voluntary movements from high-order thoughts from the the two main parts of the association cortices: prefrontal cortex and posterior parietal cortex.
• The prefrontal cortex initiates long-term planning or cognitive aspects of movements, determines whether an action is suitable for the given situation, and weighs consequences of motor actions, thereby updating how future motor actions will affect the outcome in a similar or different situation.
• The posterior parietal cortex is responsible for integrating somatosensory with visual information. The posterior parietal cortex analyses information about the body's position(somatosensory proprioceptive information) with visual information of the body's surroundings.
• The motor cortex is made up of 3 related brain structures: permotor area, supplemental motor area, and primary motor cortex.
• The premotor area modulates motor output and is generally activated before a motor activity. There are probably mirror neurons in the PM.
• The supplemental motor area is required for manual coordination tasks that require the communication between the 2 hemispheres.
• The primary motor cortex is required for deliberate, voluntary movements and is made in response to a command. The motor cortex cells(aka. upper motor neurons) influence motor neurons. The lower motor neurons are found at the brain stem/spinal cord areas and fire when they receive signal from the upper motor neurons.
• The Penfield study observations were made during brain surgery done on patients who were awake and conscious. Penfield observed:

  1. Stimulation caused contralateral activity
  2. Stimulating one side of the brain caused muscle activity in the opposite side of the body
  3. 2. Different populations of neurons are responsible for communicating with their own specific muscle groups
  4. For example, the dorsal M1 group of cells are responsible for controlling activity in the hip and trunk area, whereas the lateral M1 group of cells are responsible for facial muscles.