You can alternatively create a temporary bash script using file operations (and - ofcourse - loops) of the following format:
python script1.py &
python script2.py &
python script3.py &
python script4.py &
That's the entire script. It will run the four Python scripts at the same time. The "&" shell operator tells each process to go into the background
Now use the system command to run this script inside the matlab script.
Dont forget to delete the temporary file.