Abstract
The neural mechanism underlying object naming was studied using a patient with multimodal modality-specific aphasia due to an operation of an epidural left parietal haematoma, and a patient with aphasia complicated by semantic amnesia following evacuation of a left putaminal hemorrhage. Information on the form and material of an object analyzed in the sensory association cortices seems to be compared with the semantic memory stored in the inferior temporal lobes, resulting in recognition; the information from the semantic memory may be converted to a phonemic image by the lexical system and retained in the left superior temporal lobe; memory of the skilled movements stored in the left inferior parietal lobule may be retrieved for the articulation of the syllables, and based on this information, the left motor cortex seems to send commands to the articulatory apparatus. Corresponding to the location of the lesion, naming disturbances due to agnosia of a given modality (disconnection of the sensory association cortices and semantic memories), modality-specific aphasia (disconnection of the recognition system and the speech area), semantic amnesia (disruption of the semantic memory), and aphasia (disturbance of the lexical or phonemic system) seemed to occur. These symptoms can be complicated according to the extension of the lesion.
