These refer to parts of the Cerebral Cortex that are the first / last sections of the brain to receive sensory input or send motor commands.
On key pivotal figure that led to the discovery of these primary cortices was Wilder Penfield and Brodmann
brain cerebralCortex telencephalon forebrain primaryMotorCortex primarySomatosensoryCortex primaryVisualCortex primaryAuditoryCortex