Abstract: It is always an important study area to reveal the patterns of the presentation and processes on kinds of lexical knowledge information (such as grammatical category information). The way of collecting data from patients begins to become an important technique in such study. Some brain-damaged patients present selective cognitive processing deficits for verbs or nouns. In other words, they suffer from verb specific deficit or noun specific deficit. Exploring the mechanism of causing the deficits will provide a good chance to understand the patterns regarding the presentation and processes on grammatical category information in human brain. In the present paper, we introduced the finding on verb specific deficit or noun specific deficit. Concretely, some brain-damaged patients showed the selective loss of knowledge of verbs compared to nouns, and others showed the reversed pattern. Furthermore, we also discussed three theoretical explanations based on it, i.e. grammatical, semantic-conceptual，and lexical explanations.

Key words: verb specific deficit, noun specific deficit, cognitive neuropsychology