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Discusses the advances made in understanding the brain structures responsible for language. Presents findings made using magnetic resonance imaging (MRI) and positron emission tomographic (PET) scans to study brain activity. These findings map the structures in the brain that manipulate concepts and those that turn concepts into words. (MCO)

Author(s): Ralph Adolphs (corresponding author) [1, 2]; Frederic Gosselin [3]; Tony W. Buchanan [1]; Daniel Tranel [1]; Philippe Schyns [4]; Antonio R. Damasio [1] Ten years ago, we reported that [...]

The human amygdala appears to be important in making accurate social judgements using facial appearance to assess individuals. Three subjects with bilateral damage to the amygdala were found to assess faces more positively than controls in terms of trustworthiness and approachability. The difference in assessment was greater when faces were seen by controls to be least trustworthy and approachable. The three subjects performed normally in assessing verbal descriptions of individuals. The amygdala seems to be a major part of neural systems involved in retrieving knowledge using facial appearance.

Neuropsychological studies using positron emission tomography show that multiple regions of the left cerebral hemisphere are necessary for the process of retrieving words denoting concrete entities. This portion is located outside the classic language areas of the brain. Regions that are anatomically separable process words for distinct kind of items. Impaired retrieval of words for actions are correlated with injury to the left prefrontal/premotor region.

Some patients with face agnosia (prosopagnosia) caused by occipitotemporal damage produce discriminatory covert responses to the familiar faces that they fail to identify overtly. For example, their average skin conductance responses (SCRs) to familiar faces are significantly larger than average SCRs to unfamiliar faces. In this study we describe the opposite dissociation in four patients with bilateral ventromedial frontal damage: The patients recognized the identity of familiar faces normally, yet failed to generate discriminatory SCRs to those same familiar faces. Taken together, the two sets of results constitute a double dissociation: bilateral occipitotemporal damage impairs recognition but allows SCR discrimination, whereas bilateral ventromedial damage causes the opposite. The findings suggest that the neural systems that process the somatic-based valence of stimuli are separate from and parallel to the neural systems that process the factual, nonsomatic information associated with the same stimuti., INTRODUCTION We and others have shown that patients with prosopagnosia caused by bilateral occipitotemporal lesions can produce discriminatory skin conductance responses (SCRs) to familiar faces that are otherwise unrecognized, a [...]

A patient with selective bilateral damage to the amygdala did not acquire conditioned autonomic responses to visual or auditory stimuli but did acquire the declarative facts about which visual or auditory stimuli were paired with the unconditioned stimulus. By contrast, a patient with selective bilateral damage to the hippocamous failed to acquire the facts but did acquire the conditioning. Finally, a patient with bilaterirdamage to both amygdala and hippocampal formation acquired neither the conditioning nor the facts. These findings demonstrate a double dissociation of conditioning and declarative knowledge relative to the human amygdala and hippocampus., Studies in animals have established that the amygdala is critical for emotional conditioning (1), whereas several human and nonhuman primate studies have established that the hippocampus and surrounding regions are [...]

Following bilateral damage to the entire medial temporal lobe and interconnected cortices in the anterior temporal and medial frontal regions, patient Boswell developed a severe learning defect for all types and levels of factual knowledge, including faces. In the experiments described here, however, we demonstrate that Boswell can acquire a nonconscious bond between entirely new persons and the affective valence they display. The finding is important on the following accounts. First, Boswell's lesions guarantee that the entorhinal and perirhinal cortices, hippocampus, amygdala, and higher-order neocortices in the anterior temporal region are not required to support this form of covert learning. Second, this demonstration is possible only in a patient such as Boswell, because in individuals with normal or only partially impaired factual learning, fact memory will contaminate the performance.