Syndromes majeurs de l'hémisphère mineur

For more than 50 years, the right hemisphere is no longer considered the minor partner of the brain. Several syndromes that preferentially emerge after right hemisphere damage (such as unilateral spatial neglect, anosognosia, topographical disorientation and dysprosody) have shown its dominant role on the left hemisphere. Such contexts confirm that, in physiological conditions, the right hemisphere has a central role in those attention and polymodal sensorial integration processes that are necessary for self- and environment appraisal. The pathogenesis of the right hemisphere specific syndromes is an active domain of neurosciences research. The confabulatory phenomena that characterize the anosognosia, misidentification syndromes, or other neuropsychiatric conditions due to right brain damage, give further relevance to the role of right polymodal associative brain areas in the neural process that elaborates self and environment awareness. Another field of interest is the role of the right brain in emotional processes. Although lexical and linguistic abilities depend on the left hemisphere, the right hemisphere plays a central role in the affective aspects of communication such as prosody and comprehension of facial expressions, and in the understanding of abstractions and figurative aspects of language. The individual with extensive right brain damage almost always seems to adequately communicate in superficial conversations, without evident phonological impairment, but with a more detailed analysis he may appear less communicative, distracted or abrupt, verbose but less perspicacious and emotionally flat. Unlike aphasic syndromes due to left hemisphere damage, right brain communicative deficits may not be integrated in any cognitive or anatomo-functional model but they are the subject of very active neuropsychological and neurophysiological research.