Neuronal correlate of the higher-order semantic code in human prefrontal cortex in language tasks.

Recently, Posner et al. (Science, 1988, 240: 1627-1631) have shown by means of positron-emission tomography (PET) that the highest activation related to the higher-order semantic encoding in language tasks is revealed in the anterior inferior region of the left prefrontal cortex. We had a case where we explored the neuronal activity in this cerebral area in a patient with diagnostic intracerebral electrodes. Neurons of the left cortical areas 10 and 46 exhibited responses related to the processing of semantic and grammatic signs of the presented phrases. Specific responses in neuronal activity of the same cells in other higher-order language tasks, in discrimination of concrete and abstract words, and the absence of significant responses in other relatively simpler language tasks, such as object naming and lexical decision, supports the PET finding on the selective participation of this cerebral area in the higher-order semantic encoding and discovers new neuronal mechanisms of this encoding.