Robust training attenuates TBI-induced deficits in reference and working memory on the radial 8-arm maze

Abstract

Globally, it is estimated that nearly 10 million people sustain severe brain injuries leading to hospitalization and/or death every year. Amongst survivors, traumatic brain injury (TBI) results in a wide variety of physical, emotional and cognitive deficits. The most common cognitive deficit associated with TBI is memory loss, involving impairments in spatial reference and working memory. However, the majority of research thus far has characterized the deficits associated with TBI on either reference or working memory systems separately, without investigating how they interact within a single task. Thus, we examined the effects of TBI on short-term working and long-term reference memory using the radial 8-arm maze (RAM) with a sequence of four baited and four unbaited arms. Subjects were given 10 daily trials for 6 days followed by a memory retrieval test 2 weeks after training. Multiple training trials not only provide robust training, but also test the subjects' ability to frequently update short-term memory while learning the reference rules of the task. Our results show that TBI significantly impaired short-term working memory function on previously acquired spatial information but has little effect on long-term reference memory. Additionally, TBI significantly increased working memory errors during acquisition and reference memory errors during retention testing 2 weeks later. With a longer recovery period after TBI, the robust RAM training mitigated the reference memory deficit in retention but not the short-term working memory deficit during acquisition. These results identify the resiliency and vulnerabilities of short-term working and long-term reference memory to TBI in the context of robust training. The data highlight the role of cognitive training and other behavioral remediation strategies implicated in attenuating deficits associated with TBI.

Pathophysiology and Treatment of Memory Dysfunction After Traumatic Brain Injury

“…[33–35]. After LFPI, working memory dysfunction follows a temporal evolution that is dependent on injury severity.…”

“…A study with a radial arm maze showed impairment in memory retention after mild and moderate TBI up to 25 PID [35,37,56–59]. Interesting, no deficits were observed when given a brief reminding procedural prompt [35,55].…”

Validation and standardization of a new radial-arm water maze protocol using a murine model of mild closed head traumatic brain injury

“…Our results indicate that using a weaker training protocol, like reducing the number of trials, is more sensitive than a massive training to identify differences in cognition after a CHI [38]. Reduction in the number of training per day reduced fatigue and stress in the animals.…”

Wuzang Wenyang Huayu decoction regulates differentially expressed transcripts in the rats' hippocampus after cerebral hypoperfusion

“…Vascular dementia, including learning-memory impairment, is one of the most severe symptoms of brain injury and has attracted attentions of numerous doctors and researchers. 22,23 Water maze is widely used to evaluate the learning-memory function in many murine brain injury models. 24,25 Cognitive impairment after vascular dementia has been found the correspondingly pathological changes in brain, for examples increasing axon and myelin density in the corpus callosum and white matter bundles in the striatum, increasing oligodendrocyte and oligodendrocyte progenitor cell number in the corpus callosum, cortex and striatum and increasing synaptic protein expression in the cortex, striatum and hippocampus.…”