Final answer:
Focal brain damage in the left hemisphere primarily causes aphasia, impairing language and speech abilities, and can also lead to motor function impairment on the right side, visual processing issues related to language and space, and memory and cognitive deficits.
Step-by-step explanation:
The effect of focal brain damage in the left hemisphere can include a range of issues. Foremost among these is aphasia, a condition characterized by the impairment of language and speech abilities. Damage in the left hemisphere often affects areas known as Broca's or Wernicke's areas, which are crucial for language processing, and also impacts the white matter connections between them. Moreover, since the left hemisphere controls the right half of the body, focal brain damage here can result in impaired motor function on the right side of the body. However, this damage may extend beyond motor control and language to affect cognitive functions and memory, as the left hemisphere is involved in multi-modal integration and language-dependent processing. Although visual processing is not typically associated with the left hemisphere, impaired visual processing can occur if the damage affects the pathways that process visual information related to language and space. Finally, the left hemisphere's involvement in various integration processes means that its damage can also lead to some degree of impaired memory and cognitive function.