Lesions involving the medial temporal lobe (e.g. herpes simplex encephalitis, medial temporal lobe tumors, infarctions, trauma, temporal lobe epilepsy, especially with left sided lesions) often produce in their early stages severe emotional symptoms of fear, aggression, anxiety, irritability, periods of apathy or restlessness, over-attention to external stimuli, distractibility, inappropriate sexual behavior and even paranoid symptoms, and hallucinations.[1112] At least in the initial stages, such organic brain diseases are frequently misdiagnosed as schizophrenia.[11]The STG is the temporal gyrus that is just ventral to the sylvian fissure. Along the superior surface of the STG is the Heschl's gyrus which contains the primary auditory cortex. More posterior and on the left is part of Wernicke's area (BA 41 and 42), which includes the planum temporale, a brain region thought to be a neurological substrate of language.[13] Studies of electrical stimulation to the anterior portions of the STG have resulted in complex auditory hallucinations and verbal memories.[13] Disordered thinking has been elicited in electrical stimulation studies of the posterior portion of STG in patients undergoing neurosurgery for epilepsy.[14]
