Biomedical subjects

Marieke van Asselen

Publications and source records attributed to Marieke van Asselen.

5 recordsLinked to original sources

PubMed2006

Are space and time automatically integrated in episodic memory?

The aim of the present study was to determine to what extent spatial and temporal features are automatically integrated during encoding in episodic memory. Both nameable and non-nameable stimuli were presented sequentially at different locations on a computer screen. Mixed and pure blocks of trials were used. In the mixed blocks participants were instructed to focus either on the spatial or the temporal order of the objects, as on the majority of the trials recall of this feature was tested (expected trials). However, on a few trials participants had to reproduce the other feature (unexpected trials). In the pure blocks either the spatial or the temporal order of the objects was tested on all trials. More errors were made on unexpected than on expected trials of the mixed blocks. Moreover, no primacy or recency effects were found when performance on the spatial task was plotted as a function of the temporal position. These results suggest that spatial information and temporal order information rely on separate encoding processes.

Adult↗

PubMed2005

Neural correlates of human wayfinding in stroke patients.

Wayfinding is a complex cognitive function involving different types of information, such as knowledge about landmarks and direction information. This variety of processes suggest that multiple neural mechanisms are involved, e.g., the hippocampal system, the posterior parietal and temporal cortical areas. Although patient studies and imaging studies have given important insights in the exact neural circuitry underlying wayfinding, many controversies remain. Therefore, the current study sets out to further examine the neuroanatomical correlates of wayfinding in a sample of 31 stroke patients with unilateral lesions, tested with a series of different wayfinding tasks, including landmark recognition, landmark ordering, route reversal and route drawing. For all patients, the exact location of their lesion was determined using CT or MRI scans. Based on existing literature, a number of relevant brain areas were demarcated, after which the extent of damage to these areas was determined for each patient separately. Performance on the landmark recognition task was impaired by damage to the right hippocampal formation, whereas a weak correlation was found between damage to the dorsolateral prefrontal cortex and processing the order of the landmarks. Several brain areas were found to be involved in retracing a route from the end to the beginning, including the right hippocampal formation, the right posterior parietal cortex, the right dorsolateral prefrontal cortex and the right temporal lobe. Finally, damage to the right temporal lobe impaired the ability to draw the route.

Brain↗

PubMed2005

Brain areas involved in spatial working memory.

Spatial working memory entails the ability to keep spatial information active in working memory over a short period of time. To study the areas of the brain that are involved in spatial working memory, a group of stroke patients was tested with a spatial search task. Patients and healthy controls were asked to search through a number of boxes shown at different locations on a touch-sensitive computer screen in order to find a target object. In subsequent trials, new target objects were hidden in boxes that were previously empty. Within-search errors were made if a participant returned to an already searched box; between-search errors occurred if a participant returned to a box that was already known to contain a target item. The use of a strategy to remember the locations of the target objects was calculated as well. Damage to the right posterior parietal and right dorsolateral prefrontal cortex impaired the ability to keep spatial information 'on-line', as was indicated by performance on the Corsi Block-Tapping task and the within-search errors. Moreover, patients with damage to the right posterior parietal cortex, the right dorsolateral prefrontal cortex and the hippocampal formation bilaterally made more between-search errors, indicating the importance of these areas in maintaining spatial information in working memory over an extended time period.

Brain↗

PubMed2005

The influence of intentional and incidental learning on acquiring spatial knowledge during navigation.

In order to study the influence of intentional and incidental learning conditions on route learning, young adults walked a route through a university building. Half of the participants focused their attention on the route (intentional learning condition), while the other half did not (incidental learning condition). Five tests of spatial knowledge were employed: a route-length-estimation, landmark recognition, landmark ordering, map-drawing and navigation task. The intentional group performed better than the incidental group on the map-drawing and navigation task. No difference between the intentional and incidental group was found on the landmark-recognition and landmark-ordering task. Moreover, the intentional group overestimated the walking distance, while the incidental group underestimated it. These results suggest that route knowledge (landmark recognition and landmark ordering) requires less effortful processing than survey knowledge (developing a map-like representation and actual navigation).

Adult↗

PubMed2005

Spatial working memory and contextual cueing in patients with Korsakoff amnesia.

The current study investigated the effect of Korsakoff syndrome on memory for spatial information and, in particular, the effect of contextual cueing on spatial memory retention. Twenty Korsakoff patients and a comparison group of 22 age- and education- matched participants were tested with a newly developed spatial search task (the Box task). Participants were asked to search through a number of boxes shown at different locations on a touch-sensitive computer screen to find a target object. In subsequent trials, new objects were hidden in boxes that were previously empty. Two conditions were used: the boxes were either completely identical or had different colors serving as a cue. Within-search errors were made if a participant returned to an already searched box; between-search errors occurred if a participant returned to a box that already contained a target item. Moreover, the use of a strategy to remember the locations of the target objects was calculated. The results show that Korsakoff patients make more within and between-search errors than the comparison group, and although they were able to apply a search strategy, it did not help them to remember the locations of the targets. Interestingly, whereas the comparison group benefited from color cues that were given to the boxes, Korsakoff patients failed to do so.

Adult↗