Information sources: cerebrovascular accidents and functional imaging devices. Aphasia: difficulty in producing and comprehending speech, caused by brain damage. Not to be caused by lack of motivation or sensory motor deficits. Patient is aware of his or her environment and that people are tying to communicate. Most language disturbances occur after damage to the left side of the brain( for 90% of the population) Right side is involved in selecting, assembling elements of what we want to say, expression and recognition of the emotion in the tone of voice, control of prosody (rhythm and stress in speech) First, you need to talk about an occurring/imagined event which happens in posterior part of the cerebral hemispheres (since both is based on the knowledge of the world) Conversion of perception, memories and thought into speech occurs in frontal lobes. Damage to a region of the inferior frontal lobe (broca"s area), but multiple brain regions are involved.