Sensory Integration Deficits in Neurodegenerative Diseases: Implications for Apraxia.

OBJECTIVE: Apraxia is the inability to perform voluntary, skilled movements following brain lesions, in the absence of sensory integration deficits. Yet, patients with neurodegenerative diseases (ND) may have sensory integration deficits, so we tested the associations and dissociations between apraxia and sensory integration. METHODS: A total of 44 patients with ND and 20 healthy controls underwent extensive testing of sensory integration (i.e., localization of tactile, visual, and proprioceptive stimuli; agraphesthesia; astereognosis) and apraxia (i.e., finger dexterity, imitation, tool use). RESULTS: The results showed (i) that patients with Alzheimer's disease, corticobasal syndrome, or posterior cortical atrophy were impaired on both dimensions; (ii) An association between both dimensions; (iii) that when sensory integration was controlled for, the frequency of apraxia decreased dramatically in some clinical subgroups. CONCLUSION: In a non-negligible portion of patients, the hypothesis of a disruption of sensory integration can be more parsimonious than the hypothesis of apraxia in case of impaired skilled gestures. Clinicians and researchers are advised to integrate sensory integration measures along with their evaluation of apraxia.

Haptic identification of raised-line drawings: high visuospatial imagers outperform low visuospatial imagers.

It has been assumed (Lederman et al. 1990, Perception & psychophysics) that a visual imagery process is involved in the haptic identification of raised-line drawings of common objects. The finding of significant correlations between visual imagery ability and performance on picture-naming tasks was taken as experimental evidence in support of this assumption. However, visual imagery measures came from self-report procedures, which can be unreliable. The present study therefore used an objective measure of visuospatial imagery abilities in sighted participants and compared three groups of high, medium and low visuospatial imagers on their accuracy and response times in identifying raised-line drawings by touch. Results revealed between-group differences on accuracy, with high visuospatial imagers outperforming low visuospatial imagers, but not on response times. These findings lend support to the view that visuospatial imagery plays a role in the identification of raised-line drawings by sighted adults.

Haptic recognition of two-dimensional raised-line patterns by early-blind, late-blind, and blindfolded sighted adults.

We investigated the role of visual experience and visual imagery in the processing of two-dimensional (2-D) tactile patterns. The performance of early-blind (EB), late-blind (LB), and blindfolded sighted (S) adults in the recognition of 2-D raised-line patterns was compared. We also examined whether recognition of 2-D tactile patterns depends on the type of memory strategy (eg spatial, visuo-spatial, verbal, and kinesthetic) used by EB, LB, and S participants to perform the task. Significant between-group differences in the recognition performance have not been found despite significant between-group differences in self-reported memory strategies. Recognition performance does not vary significantly with the strategy, but correlates positively with visuo-spatial imagery abilities in the S participants. These findings may be taken to suggest that the difficulties some blind people experience with tactile pictures are not due to difficulties in processing 2-D tactile patterns.

Symbolic use of size and color in freehand drawing of the tree: myth or reality?

In this study, we tested whether children and young adults varied the size and color of their tree drawings based on hypotheses related to the emotional characterization of the drawn topic. We asked a sample of 80 5- to 11-year-old children and adults to draw a tree (baseline drawing) and then a happy versus sad tree from their imagination. Results indicate that size, but not color, is used to express emotion under free drawing conditions. We discuss implications for clinical psychologists and practitioners interpreting drawings of the tree.