Development Of Spatial Memory Research Articles

Induced deficit in hippocampal‐dependent spatial memory development of pups from lithium treated pregnant rats

Lithium carbonate is routinely used in the treatment of patients suffering from bipolar disorder, but can decrease the availability of phosphatidylcholine and choline. Both nutrients are important during pregnancy and are required for foetal brain development. This study aims to assess the effect on memory development of pups from lithium treated dams (LTD). Pregnant Sprague‐Dawley rats were administered water (control) or lithium carbonate 30mg/kg/day by oral gavage throughout the course of pregnancy until birth and access to food and water ad libitum. Pups were given access to food and water ad libitum. After 4 months, offspring were tested in the cued and spatial version of the Morris water maze task, and their rate of acquisition and retention were compared. Pups from the LTD exhibited a cognitive deficit in hippocampal‐dependent spatial memory, however no significant difference was seen in the rate of acquisition of cued task. It can therefore be concluded that lithium therapy during pregnancy can impair the memory development in offspring, an effect that may be related to choline and phosphatidlycholine supply.Source of research support: Graduate Studies & Research U.W.I Mona.

Memory for object location: A span study in children.

The aim of the present study was to analyze the developmental changes in three spatial processes, namely, in positional reconstruction involving the retention of spatial locations per se (Positional encoding task), in the assignment of objects to positions (Object-to-position assignment task), and in the integration of these two (Combined task). A span procedure was used to assess the development of spatial memory in children aged 6, 8, and 10 years tested in these three tasks. The findings of the present study provide developmental spans for each relocation task. Results show an age-dependent improvement in all tasks, suggesting that spatial position is not automatically encoded. The results also show different developmental patterns for the relocation tasks considered, suggesting that spatial memory comprises a number of different component processes.

Development of spatial memory in occlusion-experienced domestic chicks

At around day 11 of life, domestic chicks show a tendency to move out of sight of their mother before returning and regaining social and visual contact. We conducted a series of experiments to investigate the role of this voluntary ‘out-of-sight’ behaviour on the development of spatial memory in young chicks. We compared the behaviour of chicks that were reared in environments that provided opportunities to move out of sight of an imprinting stimulus (occlusion-experienced chicks) with the behaviour of chicks that were given minimal occlusion experience (controls). As in natural conditions, out-of-sight behaviour peaked on day 11. When chicks were released into larger pens at 14 days of age, occlusion-experienced chicks walked more than control chicks, but otherwise showed similar degrees of dispersal. Occlusion-experienced chicks tended to show better (although not significant, P=0.09) retrieval of a visually displaced imprinting stimulus than control chicks. Time spent out of sight in the rearing pens was negatively related to the number of orientation errors in a detour test. Occlusion-experienced chicks also tended to make fewer orientation errors in the first trial ( P=0.07) and in subsequent trials ( P=0.05). In contrast, experimentally manipulating the amount of time that chicks were out of sight of an imprinting stimulus (by confining the chicks) had no effect on their performance in displacement or detour tests. The results presented here suggest that active experience of occlusion around day 11 improved egocentric orientation towards an out-of-sight goal, supporting the hypothesis that enrichment-induced behavioural changes are dependent on the interaction with objects.

The Nine Box Maze Test: A measure of spatial memory development in children

This study investigates the development of visuo-spatial memory in school-aged children, as measured by the Nine Box Maze Test Child Version (NBMT-CV). This task, originally developed for adults by Abrahams, Pickering, Polkey, and Morris (1997), utilises an allocentric framework to assess the complexities of spatial memory. Sixty children participated in this study (aged 5–12 years), which also involved administration of traditional ‘non-verbal’ memory tests. Results indicate that visuo-spatial memory develops across childhood and that the NBMT-CV taps distinct skills compared to other ‘non-verbal’ memory tasks. The theoretical, assessment and developmental issues raised by these findings are discussed.

Damage to the vestibular inner ear causes long-term changes in neuronal nitric oxide synthase expression in the rat hippocampus

The vestibular inner ear detects head acceleration and initiates compensatory eye movement and postural reflexes that help keep the visual image of the world stable on the retina, and maintain balance, during unexpected head movement. The most primitive vestibular systems are estimated to have evolved more than 500 million years ago and in mammalian and submammalian species the vestibular reflexes are mediated by basic brainstem pathways (see Wilson and Melvill Jones, 1979 for review). Although the contributions of the vestibular system to higher cognitive function have generally received less attention than its reflexive roles, vestibular sensory information is transmitted to higher centres in the brain and humans with vestibular damage are known to experience debilitating perceptual illusions (see Curthoys and Halmagyi, 1995; Berthoz, 1996 for reviews). Increasing behavioural and neurophysiological evidence suggests that the hippocampus uses information from the vestibular inner ear in order to build up maps of space that can be used in the development of spatial memory during learning tasks ( McNaughton et al., 1991; Chapuis et al., 1992; Wiener and Berthoz, 1993; O’Mara et al., 1994; Wiener et al., 1995; Gavrilov et al., 1995; Stackman and Taube, 1996; Vitte et al., 1996; Taube et al., 1996; Save et al., 1998; Peruch et al., 1999; Cuthbert et al., 2000; Russell et al., 2000). However, to date, there has been no indication of the long-term neurochemical effects of the loss of vestibular input on hippocampal function. Since nitric oxide has been implicated in the mechanisms of hippocampal synaptic plasticity associated with the development of short-term memory (e.g. Schuman and Madison, 1991; Schuman et al., 1994; Arancio et al., 1996; Wu et al., 1997; Lu et al., 1999), we examined whether changes occur in the activity and expression of the enzymes responsible for nitric oxide production (nitric oxide synthases) in subregions of the rat hippocampus at different times following unilateral peripheral vestibular lesions, using western blotting and radioenzymatic assays. We found a decreased expression of neuronal nitric oxide synthase in the ipsilateral dentate gyrus at 2 weeks following the vestibular damage and not before, that may be related to the long-term effects of the loss of vestibular input on hippocampal function. These results support the hypothesis that head movement and position information derived from the vestibular inner ear may be important for the normal function of the hippocampus.

Development of spatial memory and spatial orientation in preschoolers and primary school children.

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.

Vestibular-hippocampal interactions.

Since the early 1960s, researchers have speculated that the vestibular system, the sensory system concerned with the perception of balance and self-motion, contributes to spatial information processing and the development of spatial memory in the hippocampus. Anatomical studies have suggested that various parts of the thalamus are likely to transmit vestibular information to the hippocampus, perhaps via the parietal cortex; however, more direct pathways are possible. Over the last 2-3 years there have been a number of direct electrophysiological demonstrations that vestibular stimulation affects head direction cells in the anterior thalamic nuclei and place cells in the hippocampus. These studies demonstrate the importance of vestibular-hippocampal interactions for hippocampal function but also raise the possibility that the hippocampus may be important for compensation of vestibular function following peripheral or central vestibular lesions.

A preliminary evaluation of the cognitive and motor effects on pediatric HIV infection in Zairian children.

Fourteen asymptomatic HIV-infected Zairian children under 2 years of age displayed social and motor developmental deficits on the Denver Developmental Screening Test when compared with 20 HIV-negative cohorts born to HIV-infected mothers and 16 control children. In a second study, 11 infected children over 2 years of age had sequential motor and visual-spatial memory deficits on the Kaufman Assessment Battery for Children and motor development deficits on the Early Childhood Screening Profiles. HIV infection affects central nervous system structures mediating motor and spatial memory development, even in seemingly asymptomatic children. Furthermore, maternal HIV infection compromises the labor-intensive provision of care in the African milieu and undermines global cognitive development in even uninfected children.Language and motor skill deficits have been noted for HIV-infected children when tested with Stanford-Binet. With the McCarthy Scales of Children's Abilities, quantitative, verbal, and memory ability deficits have also been documented with infected children and are particularly significant for those children with accompanying neurological impairment from the virus. Deficits of visual-spatial integrative ability and memory have also been identified with the Kaufman Assessment Battery for Children. This paper reports results from a direct comparison of differences in cognitive and motor skills development between HIV-1-seropositive and HIV-1-seronegative children born to infected African mothers. Both subgroups were subsequently compared to a third group of HIV-negative children born to noninfected mothers in order to better assess some of the second-order effects of the epidemic upon the development of children who are not themselves infected, but who bear the consequences of the disease in the form of illness of the primary caregiver, and the hardship which that imposes upon the entire family. Such factors are most likely especially severe for nonaffluent families in developing countries. 14 asymptomatic HIV-infected Zairian children under 2 years old displayed social and motor developmental deficits on the Denver Developmental Screening Test when compared with 20 HIV-negative cohorts born to HIV-infected mothers and 16 control children. In the second study, 11 infected children over 2 years old had sequential motor and visual-spatial memory deficits on the Kaufman Assessment Battery for Children and motor development deficits on the Early Childhood Screening Profiles. The authors conclude that HIV infection affects central nervous system structures mediating motor and spatial memory development, even in seemingly asymptomatic children. Moreover, maternal HIV infection compromises the labor-intensive provision of care in the African milieu and undermines global cognitive development in even uninfected children.

A preliminary evaluation of the cognitive and motor effects on pediatric HIV infection in Zairian children.

Fourteen asymptomatic HIV-infected Zairian children under 2 years of age displayed social and motor developmental deficits on the Denver Developmental Screening Test when compared with 20 HIV-negative cohorts born to HIV-infected mothers and 16 control children. In a second study, 11 infected children over 2 years of age had sequential motor and visual-spatial memory deficits on the Kaufman Assessment Battery for Children and motor development deficits on the Early Childhood Screening Profiles. HIV infection affects central nervous system structures mediating motor and spatial memory development, even in seemingly asymptomatic children. Furthermore, maternal HIV infection compromises the labor-intensive provision of care in the African milieu and undermines global cognitive development in even uninfected children.

Neonatal exogenous testosterone modifies sex difference in radial arm and morris water maze performance in prepubescent and adult rats

To study the involvement of testosterone in the development of spatial abilities, testosterone propionate (TP) was administered to male and female rats during the first week after birth. As adults, these rats were trained and tested on the radial arm maze (RAM) or the Morris water maze (MWM). Sex and neonatal TP treatment influenced number of trials to criterion, accuracy, and the use of an adjacent-arm strategy on the RAM, as well as the speed with which the rats learned the location of a hidden platform in the MWM. On both RAM and MWM, control males performed better than control females, but TP treatment reversed this pattern, producing better maze performance in females and worse in males. Neonatal TP effects on MWM performance were also examined in 21-day-old male and female rats. Performance paralleled that of the adults in all but the testosterone-treated male group, which did not differ from control males. The results of this study provide support for the hypothesis that circulating testosterone during brain development may play a role in the development of spatial memory, and suggest that, in the rat, both the sex difference and testosterone influence are present early in life.