Preserved stenography reading in a patient with pure alexia. A model for dissociated reading processes

An artificial nervous system to treat chronic stroke

Despite remarkable advances in the treatment of numerous medical conditions, neurological disease and injury remains an outstanding challenge and cause of disability worldwide. The decreased regenerative capacity and extreme complexity and heterogeneity of nervous tissue, in particular the brain, and the fact that the brain remains the least understood organ, have hampered our ability to provide definitive treatments for prevalent conditions such as stroke. Stroke is the second-leading cause of death worldwide, and the nervous system is intimately involved in other prevalent conditions including ischemic heart disease, diabetes mellitus, and hypertension. Advances in neuromodulation, electroceuticals, microsurgical techniques, optogenetics, brain-computer interfaces, and autologous constructs offer potential solutions to address the otherwise permanent neurological deficits of stroke and other conditions. Here we review these various approaches to build an "artificial nervous system" that could restore function and independence in people living with these conditions. We focus on stroke both because it is the leading cause of neurological disability worldwide and because we anticipate that advances in the reversal of stroke-related deficits will have ripple effects benefiting people with other neurological conditions including spinal cord injury, traumatic brain injury, ALS, and muscular dystrophy.

Number reading in pure alexia--a review

It is commonly assumed that number reading can be intact in patients with pure alexia, and that this dissociation between letter/word recognition and number reading strongly constrains theories of visual word processing. A truly selective deficit in letter/word processing would strongly support the hypothesis that there is a specialized system or area dedicated to the processing of written words. To date, however, there has not been a systematic review of studies investigating number reading in pure alexia and so the status of this assumed dissociation is unclear. We review the literature on pure alexia from 1892 to 2010, and find no well-documented classical dissociation between intact number reading and impaired letter identification in a patient with pure alexia. A few studies report strong dissociations, with number reading less impaired than letter reading, but when we apply rigorous statistical criteria to evaluate these dissociations, the difference in performance across domains is not statistically significant. There is a trend in many cases of pure alexia, however, for number reading to be less affected than letter identification and word reading. We shed new light on this asymmetry by showing that, under conditions of brief exposure, normal participants are also better at identifying digits than letters. We suggest that the difference observed in some pure alexic patients may possibly reflect an amplification of this normal difference in the processing of letters and digits, and we relate this asymmetry to intrinsic differences between the two types of symbols.

[An aphasic reader]

Nonsemantic reading is the capacity to read without understanding by impairment of the lexical-semantic pathway. We report the case of a female steno secretary with nonsemantic reading capacity associated with severe aphasia caused by a left hemisphere ischemic stroke in Broca's area. Arguments in favor of a right hemisphere contribution to the reading ability are presented.

Electrical neuroimaging reveals early generator modulation to emotional words

Functional electrical neuroimaging investigated incidental emotional word processing. Previous research suggests that the brain may differentially respond to the emotional content of linguistic stimuli pre-lexically (i.e., before distinguishing that these stimuli are words). We investigated the spatiotemporal brain mechanisms of this apparent paradox and in particular whether the initial differentiation of emotional stimuli is marked by different brain generator configurations using high-density, event-related potentials. Such would support the existence of specific cerebral resources dedicated to emotional word processing. A related issue concerns the possibility of right-hemispheric specialization in the processing of emotional stimuli. Thirteen healthy men performed a go/no-go lexical decision task with bilateral word/non-word or non-word/non-word stimulus pairs. Words included equal numbers of neutral and emotional stimuli, but subjects made no explicit discrimination along this dimension. Emotional words appearing in the right visual field (ERVF) yielded the best overall performance, although the difference between emotional and neutral words was larger for left than for right visual field presentations. Electrophysiologically, ERVF presentations were distinguished from all other conditions over the 100-140 ms period by a distinct scalp topography, indicative of different intracranial generator configurations. A distributed linear source estimation (LAURA) of this distinct scalp potential field revealed bilateral lateral-occipital sources with a right hemisphere current density maximum. These data support the existence of a specialized brain network triggered by the emotional connotation of words at a very early processing stage.

Acquired dysgraphia in alphabetic and stenographic handwriting

We report the unusual case of AZO, who professionally used handwritten shorthand writing, and became dysgraphic after a stroke. AZO suffered from a complex cognitive impairment, and part of her spelling errors resulted from damage to auditory input processing, to phonology-orthography conversion procedures and to the ortographic output lexicon. However, analysis of her writing performance showed that the same variables affected response accuracy in alphabetic and shorthand writing; and, that the same error types, including transpositions, were observed in all tasks in the two types of writing. These observations are consistent with damage to the graphemic buffer. They suggest that, in multiple-code writing systems (e.g., stenography, Japanese, or in the case of multilingual speakers of languages that use different spelling codes), the graphemic buffer is shared by all codes.

Childhood dysgraphia. Part 1. An illustrated clinical classification

In this paper we propose a clinical neurological classification of childhood dysgraphia (medical model). The subject is introduced by briefly considering the childhood learning disorders as a whole, and subsequently dysgraphia will be considered in particular with description and illustration of the different types. In our second paper we report a detailed neuropsychological study which we made of 66 children with dysgraphia. In view of the differing definitions used between professionals, this first paper is an attempt to define the terms used in our classification so that subsequent statistical analysis of individual factors in aetiology and neurology can be interpreted.

Dissociated hemispheric superiorities for reading stenography vs print

In two lateralized tachistoscopic lexical decision experiments at different exposure durations, we found for high-frequency function words written in stenography a shift from a RVF advantage at long exposures to a LVF advantage at short exposures, while for the same words written in print a strong RVF effect persisted. We suggest that a reduction of exposure duration, together with the strong visuo-spatial features in stenography, activate right-hemispheric word recognition. Stenography, a non-orthographic and syllabic-ideographic writing system, could be a model to investigate different hemispheric reading processes in Western subjects.