CNBC Alumni Lecture
Title: The Anterior Temporal-Lobes and Semantic Memory: Putting Everything Together
Presenter: Tinothy Rogers
Location: WPIC Auditorium
Abstract: Essentially all current theories about the neural basis of semantic knowledge agree that much of the content of our semantic memory is represented in brain regions that overlap with, or even correspond to, the regions responsible for perceiving and acting. The more global neuroanatomical organization of the semantic system remains,however, something of a mystery. I have argued that anterior temporal lobe (ATL) regions play a critical role in mapping between different sensory, motor, and linguistic representations distributed widely in cortex. Consequently these regions come to serve as an amodal and domain-general =93semantic hub=94 that is important for representing all kinds of concepts and for supporting performance on semantic tasks irrespective of the particular modality of testing. This view originated with studies of patients with semantic dementia (SD), a disorder in which progressive impairment to semantic knowledge across all modalities of reception and expression is accompanied by progressive gray-matter loss and hypometabolism localized within anterior temporal regions. The theory is challenged, however, by findings from functional neuroimaging studies of healthy individuals, which routinely report semantic activation in posterior temporal, temporo-parietal, and prefrontal regions, but only rarely in ATL regions. It is also challenged by behavioral studies of patients with other forms of pathology in ATL regions, who rarely show the same profound patterns of semantic impairment observed in SD. In this talk I will try to reconcile these apparent contradictions with reference to new data from patient studies, functional neuroimaging, and computer modeling.