Global aphasia is a severe form of nonfluent aphasia, caused by damage to the left side of the brain, that affects[1] receptive and expressive language skills (needed for both written and oral language) as well as auditory and visual comprehension.[2] Acquired impairments of communicative abilities are present across all language modalities, impacting language production, comprehension, and repetition.[3][1] Patients with global aphasia may be able to verbalize a few short utterances and use non-word neologisms,[4] but their overall production ability is limited.[1] Their ability to repeat words, utterances, or phrases is also affected.[1] Due to the preservation of the right hemisphere, an individual with global aphasia may still be able to express themselves through facial expressions, gestures, and intonation.[3][5][6] This type of aphasia often results from a large lesion of the left perisylvian cortex. The lesion is caused by an occlusion of the left middle cerebral artery[4][7] and is associated with damage to Broca's area, Wernicke's area, and insular regions which are associated with aspects of language.[8][9]
https://en.wikipedia.org/wiki/Global_aphasia
Semantic dementia (SD), also known as semantic variant primary progressive aphasia (svPPA), is a progressive neurodegenerative disorder characterized by loss of semantic memory in both the verbal and non-verbal domains. However, the most common presenting symptoms are in the verbal domain (with loss of word meaning).[1][2][3] Semantic dementia is a disorder of semantic memory that causes patients to lose the ability to match words or images to their meanings.[4] However, it is fairly rare for patients with semantic dementia to develop category specific impairments, though there have been documented cases of it occurring.[5] Typically, a more generalized semantic impairment results from dimmed semantic representations in the brain.[6]
https://en.wikipedia.org/wiki/Semantic_dementia
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