The role of the right hemisphere in the interpretation of figurative aspects of language A positron emission tomography activation study

TLDR

The study used PET to investigate whether the right hemisphere plays a specific role in interpreting figurative language, such as metaphors, by examining cerebral activity in six healthy volunteers. Participants performed metaphorical comprehension, literal sentence comprehension, and a lexical‑decision task while regional cerebral blood flow was measured with PET. Metaphor comprehension activated the same left‑hemisphere regions as literal comprehension but also engaged additional right‑hemisphere sites, indicating a bilateral but right‑hemisphere‑specialized network for figurative language.

Abstract

We investigated cerebral activity in six normal volunteers using PET to explore the hypothesis that the right hemisphere has a specific role in the interpretation of figurative aspects of language such as metaphors. We also mapped the anatomical structures involved in sentence comprehension. During regional cerebral blood flow measurement subjects were asked to perform three different linguistic tasks: (i) metaphorical comprehension; (ii) literal comprehension of sentences; and (iii) a lexical-decision task. We found that comprehension of sentences compared with the lexical-decision task, induced extensive activation in several regions of the left hemisphere, including the prefrontal and basal frontal cortex, the middle and inferior temporal gyri and temporal pole, the parietal cortex and the precuneus. Comprehension of metaphors was associated with similar activations in the left hemisphere, but in addition, a number of sites were activated in the right hemisphere: the prefrontal cortex, the middle temporal gyrus, the precuneus and the posterior cingulate. We conclude that the interpretation of language involves widespread distributed systems bilaterally with the right hemisphere having a special role in the appreciation of metaphors.