Ever since zack suffered a brain injury by falling from a ladder, his wife has continued to tell the doctor that his personality has changed. he used to be fun loving and carefree, but he is now more critical and yells at his children for seemingly little reason. zack is likely to have suffered damage to the of his cortex.

Zack is likely to have suffered damage to the "frontal lobe" of his cortex.

The frontal lobe is the piece of the cerebrum that controls vital psychological abilities in people, for example, emotional articulation, critical thinking, memory, dialect, judgment, and sexual conduct etc. It is, in simple words, the "control board" of our identity and our capacity to express ourselves. Hurting this could change the personality as in this case can be seen.

Frontal Lobe

Explanation:

Zack seems to has damaged the frontal lobe of his cortex. It is a piece of cerebrum of prime importance that controls all your emotional reactions and thinking abilities. Which means that damaging the frontal lobe can cause significant changes in your psychological condition, can alter your personality traits and your behavior with people around.