Investigating temporal pole function by functional imaging.

Although the role of the temporal lobe especially its mesial part is becoming clearer, that of the temporal pole remains more mysterious. Temporal pole function can be investigated in various ways: by comparing anatomical and clinical data; through experiments in animals; and by using functional imaging techniques. Anatomo-clinical studies have suggested that the temporal pole is important in autobiographical memory; and studies in monkeys (conditioning and lesional experiments) have revealed a role for the temporal pole in a variety of functions, including taste and olfaction, face recognition, visual discrimination of two-dimensional pictures, and the mnemonic functions of matching and learning. Functional imaging techniques, whether based on positron emission tomography (PET) or magnetic resonance imaging (MRI), make it possible to observe the functioning of the temporal pole in vivo in both healthy control subjects and patients. Initially, this type of approach was simply used to confirm observations made in animals. More recently it has shed light on other functions, especially with respect to processes associated with linguistic integration, which underlie the ability to make lexical and semantic links between different words and make it possible to understand a story in a general way without prior specific knowledge. Studies of epileptic, demented and schizophrenic patients have revealed that abnormal patterns of temporal pole function are typical in all these conditions.