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Anosognosia (, ; from Ancient Greek ἀ- ''a-'', "without", νόσος ''nosos'', "disease" and γνῶσις ''gnōsis'', "knowledge") is a deficit of self-awareness, a condition in which a person who suffers a certain disability seems unaware of the existence of his or her disability. It was first named by the neurologist Joseph Babinski in 1914. Anosognosia results from physiological damage to brain structures, typically to the parietal lobe or a diffuse lesion on the fronto-temporal-parietal area in the right hemisphere. Whilst this distinguishes the condition from denial, which is a psychological defense mechanism, attempts have been made at a unified explanation. Both anosognosia and denial are almost always connected with damage in the right hemisphere. Split-brain research suggests that this asymmetry points to a neurological answer.〔Franks, D. D. (2010). Neurosociology: The nexus between neuroscience and social psychology. Springer.〕 Anosognosia is sometimes accompanied by asomatognosia, a form of neglect in which patients deny ownership of their limbs. ==Causes== Relatively little has been discovered about the cause of the condition since its initial identification. Recent studies from the empirical data are prone to consider anosognosia a multi-componential syndrome or multi-faceted phenomenon. That is it can be manifested by failure to be aware of a number of specific deficits, including motor (hemiplegia), sensory (hemianaesthesia, hemianopia), spatial (unilateral neglect), memory (dementia), and language (receptive aphasia) due to impairment of anatomo-functionally discrete monitoring systems.〔〔 Anosognosia is relatively common following different etiologies of brain injury, such as stroke and traumatic brain injury (e.g. 10%–18% in the case of anosognosia for hemiparesis with onset of acute stroke), but can appear to occur in conjunction with virtually any neurological impairment. It is more frequent in the acute than in the chronic phase and more prominent for assessment in the cases with right hemispheric lesions than with the left kinds. However, it is not related to global mental confusion, cognitive flexibility, other major intellectual disturbance, or mere sensory/perceptual deficits. Anosognosia can be selective in that an affected person with multiple impairments may seem unaware of only one handicap, while appearing to be fully aware of any others. For example, anosognosia for hemiplegia may occur with intact awareness of visuo-spatial unilateral neglect, or vice versa. This phenomenon of double dissociation can be an indicator of domain-specific disorders of awareness modules, meaning that brain damage can selectively impact the self-monitoring process of one specific physical or cognitive function.〔〔 The condition does not seem to be directly related to sensory loss and is thought to be caused by damage to higher level neurocognitive processes that are involved in integrating sensory information with processes that support spatial or bodily representations (including the somatosensory system). Anosognosia is thought to be related to unilateral neglect, a condition often found after damage to the non-dominant (usually the right) hemisphere of the cerebral cortex in which sufferers seem unable to attend to, or sometimes comprehend, anything on a certain side of their body (usually the left). There are also studies showing that the maneuver of vestibular stimulation could temporarily improve both the syndrome of spatial unilateral neglect and of anosognosia for left hemiplegia. Combining the findings of hemispheric asymmetry to the right, association to spatial unilateral neglect, and the temporal improvement on both syndromes, it is suggested there can be a spatial component underlying the mechanism of anosognosia for motor weakness and their neural processes could be modulated similarly.〔 There were some cases of anosognosia for right hemiplegia after left hemisphere damage, but the frequency of this type of anosognosia has not been estimated.〔 Those diagnosed with dementia of the Alzheimer's type, often display this lack of awareness and insist that nothing is wrong with them. Anosognosia may occur as part of receptive aphasia, a language disorder that causes poor comprehension of speech and the production of fluent but incomprehensible sentences. A patient with receptive aphasia cannot correct his own phonetic errors and shows "anger and disappointment with the person with whom s/he is speaking because that person fails to understand her/him." This may be a result of brain damage to the posterior portion of the superior temporal gyrus, believed to contain representations of word sounds. With those representations significantly distorted, patients with receptive aphasia are unable to monitor their mistakes.〔 Other patients with receptive aphasia are fully aware of their condition and speech inhibitions, but cannot monitor their condition, which is not the same as anosognosia and therefore cannot explain the occurrence of neologistic jargon. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Anosognosia」の詳細全文を読む スポンサード リンク
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