Frontal Motor Cortexes
Primary Motor Cortex (M1):
Some people think that the primary motor cortex is the final pathway to
movement as 50% of the neurons that go to the spinal cord arise from these
This part of the brain has direct control over how we move.
Hitzig: studied dogs and figured that if he poked a certain part of the brain, the dogs
hemorrhoid will twitch.
Jackson: British physician studied cortex as his wife has epilepsy and had over 100
seizures a day. He learned that the seizures would progress in a logical manner
flowing up her arm from her fingertips to her arm to her face etc. He concluded
there must be a systemic correlation but stopped there.
Penfeld: Father of modern surgical neuroscience. Before, is there was someone with
epilepsy, they would cut out part of brain causing it and ignore the functions lost by
that structure. Penfeld would probe different parts of brain and notice what he
affected such as structural function and memory. Found the Human Homunculus.
Found the Human Homunculus existing on Motor Cortex (M1) but it was pretty
much identical on somatosensory cortex. Important to take out that on the cortex
there are different areas of the brain. When Penfeld was doing research, he would
probe signal and see twitch because of this people believed the cortex was a relay
system. Turns out incorrect.
Jorjopolus: Was a monkey neurophysiologist interested in placing probes on the
neurons of monkeys and see what happened. Monkey would grab mechanical arm
and touch different areas of the manipulatdum Jorjopolus would watch the
rasterplot of the monkey Rasterplot depicts the activation of a signal neuron
over time. See picture on page 39 of notes each row is each try. He concluded that
there are certain neurons that will only fire at high frequencies in special cases.
Some neurons will only fire for upper movements/ lower movement etc. Concluded
there are certain M1 neurons that only tune to certain movements.
Colour of sphere is given to each digit.
Size of the sphere is the intensity of
Digits of the hands intermingle with one
another and there is no set area for digits.