Those with damage to the right hemisphere lack insight into illness or even denial of it
The right hemisphere is more self-aware and realistic, while the left is more grandiose, optimistic, and unrealistic about itâs shortcomings. Also, Insight into illness generally is dependent on the right hemisphere, and those who have damage to the right hemisphere tend to deny their illnessâthe wellârecognized, and extraordinary phenomenon of anosognosia, in which patients deny or radically minimize the fact that they have, for example, a blatant loss of use of what may be one entire half of the body. A patient with a completely paralyzed (left) limb may pointedly refuse to accept that there is anything wrong with it, and will come up with the most preposterous explanations for why he is not actually able to move it on request (The left hemisphere will confabulate explanations for things it doesnât know and seems completely convinced of them). This happens to some degree in the majority of cases after a stroke affecting the left side of the body (involving right hemisphere damage), but practically never after a right-sided stroke (involving left hemisphere damage). The phenomenon of denial can be temporarily reversed by activating the affected right hemisphere. Equally, denial of illness (anosognosia) can be induced by anesthetizing the right hemisphere.
Note that it is not just a blindness, a failure to see â itâs a willful denial. Hoff and PĂśtzl describe a patient who demonstrates this beautifully: âOn examination, when she is shown her left hand in the right visual field, she looks away and says âI donât see it.â She spontaneously hides her left hand under the bedclothes or puts it behind her back. She never looks to the left, even when called from that side.â If forced to confront the affected limb, there is not infrequently a sense of revulsion from it, known as misoplegia: if the examiner puts the patientâs own left hand in her right hand, âshe takes hold of it only to drop it immediately with an expression of disgustâ.
References
- Mcgilchrist, Iain. (2010). The Master and His Emissary Chapter 2 What Do the Hemispheres Do (p. 169). London, UK: Yale University Press.
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Type:đ´ Tags: Biology / Neuroscience / Neuropsychology Status:âď¸