Brain : a journal of neurology
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Multiple sensory stimuli contribute to the conscious awareness of the body. It is well known that limb amputation can result in abnormal body awareness, but the manner in which the CNS constructs and updates a body schema after injury is largely unknown. The purpose of the present study was to systematically evaluate the effects of sensory inputs on phantom limb awareness (PLA) shortly after unilateral upper extremity amputation. ⋯ In eight cases, the visual illusion of the missing limb transiently enhanced the spontaneous conscious awareness of the phantom limb. However, the visual illusion did not change the capacity of a tactile stimulus to induce dual percepts. These findings demonstrate that (i) phantom awareness of an amputated body part is common within the 14 months after traumatic upper extremity amputation, (ii) evoked dual percepts are less common than spontaneous PLA, (iii) visual, tactile and sensorimotor systems contribute to PLA, (iv) subtle changes in congruence of sensory information affects both evoked dual percepts and spontaneous PLA, however, (v) sensorimotor information pertaining to the state of the motor system can strongly influence spontaneous PLA, whereas the visual system can predominantly influence evoked PLA.
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Neurofilament light chain polypeptide (NEFL) is one of the most abundant cytoskeletal components of the neuron. Mutations in the NEFL gene were recently reported as a cause for autosomal dominant Charcot-Marie-Tooth type 2E (CMT2E) linked to chromosome 8p21. In order to investigate the frequency and phenotypic consequences of NEFL mutations, we screened 323 patients with CMT or related peripheral neuropathies. ⋯ Electrophysiological examination shows moderately to severely slowed nerve conduction velocities. We report the first nerve biopsy of a CMT patient with a de novo missense mutation in NEFL, and found an axonal pathology with axonal regeneration clusters and onion bulb formations. Our findings provide further evidence that the clinical variation observed in CMT depends on the gene mutated and the specific type of mutation, and we also suggest that NEFL mutations need to be considered in the molecular evaluation of patients with sporadic or dominantly inherited CMT.
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A unique feature of Japanese language is that its written sentences consist of both morphograms (kanji) and syllabograms (kana). Despite extensive research by PET, functional MRI and magnetoencephalography, the issues of the difference (or the similarities) between the processing of kanji and kana, and between word reading and object/picture naming have not been resolved as yet. This study investigated the function of the posterior basal temporal area in the language dominant hemisphere in auditory and visual language processing, with special emphasis on semantic and phonological recognition. ⋯ The fact that the impairment of kanji reading and disturbance of object/picture naming were elicited by electric stimulation of the same area indicates that there is at least one anatomical area that is used commonly for kanji (but not kana) and object processing. The conceptual entity of the test items supposedly was recognized correctly, but the concept failed to be matched to correct phonological representation. The left posterior basal temporal area, therefore, has an important function of connecting visual semantic information into phonological representation.