Egocentric and allocentric spatial memory in idiopathic cervical dystonia.

OBJECTIVE

To investigate whether impaired spatial memory contributes to cognitive deficits in idiopathic cervical dystonia (ICD).

METHODS

The authors tested 16 untreated patients with ICD and 16 healthy controls with four variants of a classic spatial memory task, in which subjects were requested to recall the locations of 16 toy objects either immediately after their presentation or after an unfilled delay of 10 minutes. By varying the spatial relationship between subject and toy object array, we tested encoding and memory of spatial relationships between subject and toy objects (egocentric tasks) and of spatial relationships between toy objects and environment (allocentric tasks).

RESULTS

In all four tasks, absolute performance of patients did not differ significantly from controls, suggesting that there are no significant spatial memory deficits in ICD. However, significant correlations between egocentric and allocentric task performance were found in patients but not in controls.

CONCLUSIONS

While control subjects flexibly used egocentric or allocentric spatial representations in memory tasks, patients with idiopathic cervical dystonia (ICD) solved both task types with a single allocentric strategy. Our findings point to the existence of compensatory mechanisms between distinct neural systems supporting egocentric and allocentric spatial representations in ICD.