No abstract

A critical role in place learning has been attributed to place cells within the cornu ammonis 1 (CA1) sector of the hippocampus in rodents. The role of CA1 cells in the human hippocampus with regard to place learning remains elusive. Using a virtual Morris water maze, we investigated patients with acute transient global amnesia (TGA), a rare self-limiting dysfunction of the hippocampal system. Fourteen individuals with selective and focal lesions in the CA1 sector of the hippocampus showed a profound impairment in place learning. The size of the lesions and the duration of the TGA correlated with the deficit in the performance.

The present study addresses the question of what kind of information children use when orientating in new environments, if given proximal and distal landmarks, and how spatial memory develops in the investigated age groups. Ten 5-year-old, ten 7-year-old and ten 10-year-old children were presented with the 'Kiel Locomotor Maze', containing features of the Radial Arm Maze and the Morris Water Maze, in order to assess spatial memory and orientation. Children had to learn to approach baited locations only. Task difficulty was equated with respect to the children's age. Training was given until the children reached criterion. During testing, the maze configuration and response requirements were systematically altered, including response rotation, cue rotation, cue deletion and response rotation with cue deletion in order to assess the spatial strategies used by the children. During training and testing, working-memory errors (WM), reference-memory errors (RM) and working-reference memory errors (WR) were recorded. As expected, no difference between age groups appeared during training, thus confirming comparable task difficulty across age groups. During testing, age groups differed significantly with regard to the orientation strategy used. The 5-year-olds were bound to a cue strategy, orientating towards local, proximal cues. The 10-year-olds mastered all tasks, thus displaying a place strategy, being able to use distal cues for orientation, and were even able to do so after being rotated 180 degrees. The 7-year-olds proved to be at an age of transition: five of them were bound to a cue strategy, five children were able to adopt a place strategy. The differences in the orientation strategies used by children of different age groups was reflected by the sum of errors they made, also by RM. WM were found to be rare, especially in older children. We conclude that preschoolers use a cue strategy, that the development of place strategies occurs during primary school age and seems to be complete by the age of 10 years.

Spatial behaviour was investigated using a spatial learning task based on the Radial Arm Maze, the Morris Water Maze, and open-field search-task procedures. Ninety-six healthy children from six age groups (3, 4, 5, 7, 10 and 12 years) with no history of CNS disorders were studied with respect to the emergence of position-, cue- and place responses. Participants were to detect x out of n hidden locations, frames of reference could be varied systematically, and three spatial memory errors and speed of navigation were recorded automatically. Task difficulties were equivalent for each age group. Results showed that navigational place learning was fully developed by the age of 10, whereas participants relied on cue orientation up to age 7. Even in the youngest group, the task could be achieved without relying on egocentric orientation, provided that proximal cues were presented. Most of the errors were of the reference memory type, whereas working memory errors were extremely rare. Speed of navigation markedly improved between age 5 and 7. An additional experiment showed that navigational place-learning behaviour was clearly dependent on distal cues. A third study showed that in young adults, learning of the spatial layout improved, but performance on the place task did not improve any further. No sex differences were observed.

The acquisition of conditional associations using neutral and individually threatening verbal stimuli was assessed in 16 females with anorexia nervosa (AN), obsessive-compulsive disorder (OCD), bulimia nervosa and normal controls, respectively. Groups did not differ in terms of age, sex, intelligence, depression, verbal memory and verbal fluency measures. Patients and controls were widely comparable on tests assessing neuropsychological functioning. In the conditional-associative learning (CAL)-task only anorectic and OCD-patients displayed an impaired performance with neutral material but not with individually threatening material. Such a deficit was not evident in bulimics or in normal controls. These findings support the assumptions from functional neuroimaging investigations in AN and OCD and provide evidence that obsessive and compulsive behavior could have its origin within common neurobiological dysfunctions. The CAL possibly serves as a functional correlate of a neurophysiological dysfunction in obsessive-compulsive spectrum disorders.