Final answer:
St. Bonaventure, a Franciscan friar and philosopher, is likely the medieval scholar who wrote about the ventricular theory of the brain, a model that attributed different cognitive functions to the ventricles of the brain.
Step-by-step explanation:
The medieval scholar in question, who wrote about the ventricular theory of the brain, is likely to be St. Bonaventure, a Franciscan friar and medieval philosopher. Bonaventure was known for his contributions to philosophy and theology, which included the attempt to reconcile Aristotelian philosophy with Christian theology. His understandings of the mind and brain were reflective of the intellectual traditions of the time, which often combined the philosophical views of Aristotle with Christian doctrine. The ventricular theory, a historical model of brain function, suggested that the ventricles of the brain were responsible for different cognitive processes.