Why are speech implants placed in the motor cortex rather than in Broca's area? · Grey Matter

Because the motor cortex is where the signal turned out to be.

Why are speech implants placed in the motor cortex rather than in Broca's area?

Because the motor cortex is where the signal turned out to be. The 2023 speech implant at Stanford put two arrays in the ventral motor cortex and two in area 44, part of Broca's area, and the arrays in area 44 carried almost no information about the movements, sounds or words the participant attempted (below 12 % accuracy in classifying them), so every result came from the motor arrays. Broca's area seems to work at a higher level of planning, spread over a wider network, while the strip of motor cortex that drives the lips, tongue and larynx gives a dense, local pattern for each sound that a few hundred electrodes can read.