Memory impairment following status epilepticus in immature rats: time‐course and environmental effects

Abstract

Status epilepticus (SE) has a high mortality and morbidity rate in children. Disturbances in learning and memory are frequently associated with SE although it is not clear when the cognitive deficits occur. If cognitive dysfunction occurs immediately following the seizure, the window of opportunity for therapeutic intervention is limited. The first goal of this study was to determine the timing of cognitive dysfunction following SE in weanling rats. As there is evidence that enriching the environment can improve cognitive and motor deficits following brain injury, our second goal was to determine whether environmental enrichment improves cognitive function following SE. Rats underwent lithium-pilocarpine-induced SE at postnatal (P) day 20 and were then tested for visual-spatial memory in the water maze at P22, P25, P30, or P50. Rats with SE performed significantly worse in the water maze than control rats at all time points. Once the time-courses of visual-spatial memory deficits were determined, a second group of P20 rats were subjected to SE and were then placed in an enriched environment (enriched group) or remained in standard cages in the vivarium (nonenriched group) for 28 days. Following environmental manipulation, the animals were tested in the water maze. Rats housed in an enriched environment following the SE performed substantially better in the water maze than rats housed in standard cages. However, no differences were found between the enriched and nonenriched groups in EEG or histological evaluation. Although SE results in cognitive impairment within days of the seizure, housing in an enriched environment after SE has a beneficial effect on cognitive performance in rats.

Altered Phase Precession and Compression of Temporal Sequences by Place Cells in Epileptic Rats

“…Animals were then killed and the brain analyzed for cell loss and synaptic reorganization using previously described scales (Rutten et al, 2002). The nonparametric Mann-Whitney test was used to compare cell loss and Timm scores (ranging from 0 to 5, where 5 is the darkest possible staining) (see Materials and Methods).…”

Long‐term outcomes of status epilepticus: A critical assessment

“…Some studies have demonstrated that functional outcome and likely QoL may improve over time 15, 18, 22, 23. Promising research in animal models is in the process of identifying biomarkers that can be modulated to minimize long‐term functional impairment 89, 90. Additional comparative effectiveness and interventional trials are underway to provide additional data.…”

Exposure to Mozart music reduces cognitive impairment in pilocarpine-induced status epilepticus rats

“…Control group n = 10; Epilepsy group n = 10 impaired cognitive performance when compared with healthy controls (Meador 2002). Annemarieke Rutten et al (2002) reported that impairments in visual-spatial memory were present shortly after SE in immature rats and persisted until adulthood. Impairment of a variety of memory types has been extensively described in TLE patients, including verbal, episodic and spatial working memory (Wieser 2004).…”