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Dissociation in Optokinetic Stimulation Sensitivity between Omission and Substitution Reading Errors in Neglect Dyslexia.

Daini R, Albonico A, Malaspina M, Martelli M, Primativo S, Arduino LS - Front Hum Neurosci (2013)

Bottom Line: MA also showed an impairment in oculo-motor behavior with a non-reading task, while EP did not.Our results confirm a dissociation between the two mechanisms underlying omission and substitution reading errors in ND patients.Moreover, they suggest that such a dissociation could possibly be extended to the effectiveness of rehabilitative procedures, and that patients who mainly omit contralesional-sided letters would benefit from OKS.

View Article: PubMed Central - PubMed

Affiliation: Psychology Department, University of Milano-Bicocca , Milano , Italy.

ABSTRACT
Although omission and substitution errors in neglect dyslexia (ND) patients have always been considered as different manifestations of the same acquired reading disorder, recently, we proposed a new dual mechanism model. While omissions are related to the exploratory disorder which characterizes unilateral spatial neglect (USN), substitutions are due to a perceptual integration mechanism. A consequence of this hypothesis is that specific training for omission-type ND patients would aim at restoring the oculo-motor scanning and should not improve reading in substitution-type ND. With this aim we administered an optokinetic stimulation (OKS) to two brain-damaged patients with both USN and ND, MA and EP, who showed ND mainly characterized by omissions and substitutions, respectively. MA also showed an impairment in oculo-motor behavior with a non-reading task, while EP did not. The two patients presented a dissociation with respect to their sensitivity to OKS, so that, as expected, MA was positively affected, while EP was not. Our results confirm a dissociation between the two mechanisms underlying omission and substitution reading errors in ND patients. Moreover, they suggest that such a dissociation could possibly be extended to the effectiveness of rehabilitative procedures, and that patients who mainly omit contralesional-sided letters would benefit from OKS.

No MeSH data available.


Related in: MedlinePlus

MA (A) and EP (B) ocular behavior in a non-verbal saccadic task. The green lines indicate the dot positions, the red lines indicate the y coordinate of the eye movements and the blue lines the x coordinate.
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Figure 4: MA (A) and EP (B) ocular behavior in a non-verbal saccadic task. The green lines indicate the dot positions, the red lines indicate the y coordinate of the eye movements and the blue lines the x coordinate.

Mentions: Figure 4 shows the ocular behaviour of MA and EP during the saccadic task. We excluded analysis of fixations made on the first dot in the sequence and analysis of anticipatory saccades (i.e., saccades starting before the appearance of the following dot). We also excluded analysis of fixations that were far from the target with respect to its vertical axis (i.e., over 2 SD calculated on the vertical fixation positions of a control group collected and described in Primativo et al., 2013). The remaining fixations were considered “accurate” if they fell no more than 1° of visual angle away from the target.


Dissociation in Optokinetic Stimulation Sensitivity between Omission and Substitution Reading Errors in Neglect Dyslexia.

Daini R, Albonico A, Malaspina M, Martelli M, Primativo S, Arduino LS - Front Hum Neurosci (2013)

MA (A) and EP (B) ocular behavior in a non-verbal saccadic task. The green lines indicate the dot positions, the red lines indicate the y coordinate of the eye movements and the blue lines the x coordinate.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3775017&req=5

Figure 4: MA (A) and EP (B) ocular behavior in a non-verbal saccadic task. The green lines indicate the dot positions, the red lines indicate the y coordinate of the eye movements and the blue lines the x coordinate.
Mentions: Figure 4 shows the ocular behaviour of MA and EP during the saccadic task. We excluded analysis of fixations made on the first dot in the sequence and analysis of anticipatory saccades (i.e., saccades starting before the appearance of the following dot). We also excluded analysis of fixations that were far from the target with respect to its vertical axis (i.e., over 2 SD calculated on the vertical fixation positions of a control group collected and described in Primativo et al., 2013). The remaining fixations were considered “accurate” if they fell no more than 1° of visual angle away from the target.

Bottom Line: MA also showed an impairment in oculo-motor behavior with a non-reading task, while EP did not.Our results confirm a dissociation between the two mechanisms underlying omission and substitution reading errors in ND patients.Moreover, they suggest that such a dissociation could possibly be extended to the effectiveness of rehabilitative procedures, and that patients who mainly omit contralesional-sided letters would benefit from OKS.

View Article: PubMed Central - PubMed

Affiliation: Psychology Department, University of Milano-Bicocca , Milano , Italy.

ABSTRACT
Although omission and substitution errors in neglect dyslexia (ND) patients have always been considered as different manifestations of the same acquired reading disorder, recently, we proposed a new dual mechanism model. While omissions are related to the exploratory disorder which characterizes unilateral spatial neglect (USN), substitutions are due to a perceptual integration mechanism. A consequence of this hypothesis is that specific training for omission-type ND patients would aim at restoring the oculo-motor scanning and should not improve reading in substitution-type ND. With this aim we administered an optokinetic stimulation (OKS) to two brain-damaged patients with both USN and ND, MA and EP, who showed ND mainly characterized by omissions and substitutions, respectively. MA also showed an impairment in oculo-motor behavior with a non-reading task, while EP did not. The two patients presented a dissociation with respect to their sensitivity to OKS, so that, as expected, MA was positively affected, while EP was not. Our results confirm a dissociation between the two mechanisms underlying omission and substitution reading errors in ND patients. Moreover, they suggest that such a dissociation could possibly be extended to the effectiveness of rehabilitative procedures, and that patients who mainly omit contralesional-sided letters would benefit from OKS.

No MeSH data available.


Related in: MedlinePlus