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Spatio-temporal features of visual exploration in unilaterally brain-damaged subjects with or without neglect: results from a touchscreen test.

Rabuffetti M, Farina E, Alberoni M, Pellegatta D, Appollonio I, Affanni P, Forni M, Ferrarin M - PLoS ONE (2012)

Bottom Line: Classic outcome scores were computed as well.Results show statistically significant differences among groups (assumed p<0.05).Left-brain-damaged patients without USN were significantly slower and less efficient than controls (latency 1.19 s, about 7 crossings), preserving a normal preferred search direction (93.7% downward).

View Article: PubMed Central - PubMed

Affiliation: Fondazione Don Carlo Gnocchi ONLUS, Falconara Marittima, Ancona, Italy.

ABSTRACT
Cognitive assessment in a clinical setting is generally made by pencil-and-paper tests, while computer-based tests enable the measurement and the extraction of additional performance indexes. Previous studies have demonstrated that in a research context exploration deficits occur also in patients without evidence of unilateral neglect at pencil-and-paper tests. The objective of this study is to apply a touchscreen-based cancellation test, feasible also in a clinical context, to large groups of control subjects and unilaterally brain-damaged patients, with and without unilateral spatial neglect (USN), in order to assess disturbances of the exploratory skills. A computerized cancellation test on a touchscreen interface was used for assessing the performance of 119 neurologically unimpaired control subjects and 193 patients with unilateral right or left hemispheric brain damage, either with or without USN. A set of performance indexes were defined including Latency, Proximity, Crossings and their spatial lateral gradients, and Preferred Search Direction. Classic outcome scores were computed as well. Results show statistically significant differences among groups (assumed p<0.05). Right-brain-damaged patients with USN were significantly slower (median latency per detected item was 1.18 s) and less efficient (about 13 search-path crossings) in the search than controls (median latency 0.64 s; about 3 crossings). Their preferred search direction (53.6% downward, 36.7% leftward) was different from the one in control patients (88.2% downward, 2.1% leftward). Right-brain-damaged patients without USN showed a significantly abnormal behavior (median latency 0.84 s, about 5 crossings, 83.3% downward and 9.1% leftward direction) situated half way between controls and right-brain-damaged patients with USN. Left-brain-damaged patients without USN were significantly slower and less efficient than controls (latency 1.19 s, about 7 crossings), preserving a normal preferred search direction (93.7% downward). Therefore, the proposed touchscreen-based assessment had evidenced disorders in spatial exploration also in patients without clinically diagnosed USN.

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Related in: MedlinePlus

Result box plots (reporting median, quartiles and extreme values) of scores NS (5a, neglect score), NT (5b, target cancelled), ND (5c, distracters cancelled), and NP (5d, perseverations).Kruskall-Wallis ANOVA test is always positive, across-group statistically significant differences (post-hoc analysis, p<0.05) are marked by horizontal segments.
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pone-0031511-g005: Result box plots (reporting median, quartiles and extreme values) of scores NS (5a, neglect score), NT (5b, target cancelled), ND (5c, distracters cancelled), and NP (5d, perseverations).Kruskall-Wallis ANOVA test is always positive, across-group statistically significant differences (post-hoc analysis, p<0.05) are marked by horizontal segments.

Mentions: Control subjects evidenced performances whose global scores (NS, ND, NT, NP) were close to ceiling/floor values characterizing a “best” performance (i.e. all targets detected, no distracter cancelled, no perseverations observed) and, particularly, the neglect score NS was substantially (see figure 5). The performance indexes (LI, LG, PI, PG, NC) expressed the following normal pattern (figure 6): generally, it took less than one second for each target detection (median LI was 0.64 s), between 2 subsequentially touched targets there was at least one closer target to the initial touched one that was undetected (median PI was 1.8, 95th percentile was about 5) and rarely search path crossings were observed (median NC accounted for 2 to 3 crossing in the search for 40 targets with a maximum of 15 crossings). As no USN was shown by neurologically unimpaired subjects, even gradient indexes concerning latencies (LG) and proximities (PG) did not show any unbalance between right and left, and their values included the value as a central one.


Spatio-temporal features of visual exploration in unilaterally brain-damaged subjects with or without neglect: results from a touchscreen test.

Rabuffetti M, Farina E, Alberoni M, Pellegatta D, Appollonio I, Affanni P, Forni M, Ferrarin M - PLoS ONE (2012)

Result box plots (reporting median, quartiles and extreme values) of scores NS (5a, neglect score), NT (5b, target cancelled), ND (5c, distracters cancelled), and NP (5d, perseverations).Kruskall-Wallis ANOVA test is always positive, across-group statistically significant differences (post-hoc analysis, p<0.05) are marked by horizontal segments.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3275551&req=5

pone-0031511-g005: Result box plots (reporting median, quartiles and extreme values) of scores NS (5a, neglect score), NT (5b, target cancelled), ND (5c, distracters cancelled), and NP (5d, perseverations).Kruskall-Wallis ANOVA test is always positive, across-group statistically significant differences (post-hoc analysis, p<0.05) are marked by horizontal segments.
Mentions: Control subjects evidenced performances whose global scores (NS, ND, NT, NP) were close to ceiling/floor values characterizing a “best” performance (i.e. all targets detected, no distracter cancelled, no perseverations observed) and, particularly, the neglect score NS was substantially (see figure 5). The performance indexes (LI, LG, PI, PG, NC) expressed the following normal pattern (figure 6): generally, it took less than one second for each target detection (median LI was 0.64 s), between 2 subsequentially touched targets there was at least one closer target to the initial touched one that was undetected (median PI was 1.8, 95th percentile was about 5) and rarely search path crossings were observed (median NC accounted for 2 to 3 crossing in the search for 40 targets with a maximum of 15 crossings). As no USN was shown by neurologically unimpaired subjects, even gradient indexes concerning latencies (LG) and proximities (PG) did not show any unbalance between right and left, and their values included the value as a central one.

Bottom Line: Classic outcome scores were computed as well.Results show statistically significant differences among groups (assumed p<0.05).Left-brain-damaged patients without USN were significantly slower and less efficient than controls (latency 1.19 s, about 7 crossings), preserving a normal preferred search direction (93.7% downward).

View Article: PubMed Central - PubMed

Affiliation: Fondazione Don Carlo Gnocchi ONLUS, Falconara Marittima, Ancona, Italy.

ABSTRACT
Cognitive assessment in a clinical setting is generally made by pencil-and-paper tests, while computer-based tests enable the measurement and the extraction of additional performance indexes. Previous studies have demonstrated that in a research context exploration deficits occur also in patients without evidence of unilateral neglect at pencil-and-paper tests. The objective of this study is to apply a touchscreen-based cancellation test, feasible also in a clinical context, to large groups of control subjects and unilaterally brain-damaged patients, with and without unilateral spatial neglect (USN), in order to assess disturbances of the exploratory skills. A computerized cancellation test on a touchscreen interface was used for assessing the performance of 119 neurologically unimpaired control subjects and 193 patients with unilateral right or left hemispheric brain damage, either with or without USN. A set of performance indexes were defined including Latency, Proximity, Crossings and their spatial lateral gradients, and Preferred Search Direction. Classic outcome scores were computed as well. Results show statistically significant differences among groups (assumed p<0.05). Right-brain-damaged patients with USN were significantly slower (median latency per detected item was 1.18 s) and less efficient (about 13 search-path crossings) in the search than controls (median latency 0.64 s; about 3 crossings). Their preferred search direction (53.6% downward, 36.7% leftward) was different from the one in control patients (88.2% downward, 2.1% leftward). Right-brain-damaged patients without USN showed a significantly abnormal behavior (median latency 0.84 s, about 5 crossings, 83.3% downward and 9.1% leftward direction) situated half way between controls and right-brain-damaged patients with USN. Left-brain-damaged patients without USN were significantly slower and less efficient than controls (latency 1.19 s, about 7 crossings), preserving a normal preferred search direction (93.7% downward). Therefore, the proposed touchscreen-based assessment had evidenced disorders in spatial exploration also in patients without clinically diagnosed USN.

Show MeSH
Related in: MedlinePlus