Differential effects of acute cardiovascular exercise on explicit and implicit motor memory: The moderating effects of fitness level

A single bout of cardiovascular exercise (CE) performed after practice can facilitate the consolidation of motor memory. However, the effect is variable and may be modulated by different factors such as the motor task's or participant's characteristics and level of awareness during encoding (implicit vs explicit learning). This study examines the effects of acute CE on the consolidation of motor sequences learned explicitly and implicitly, exploring the potential moderating effect of fitness level and awareness. Fifty-six healthy adults (24.1 ± 3.3 years, 32 female) were recruited. After practicing with either the implicit or explicit variant of the Serial Reaction Time Task (SRTT), participants either performed a bout of 16 min of vigorous CE or rested for the same amount of time. Consolidation was quantified as the change in SRTT performance from the end of practice to a 24 h retention test. Fitness level (V̇O2peak) was determined through a graded exercise test. Awareness (implicit vs explicit learning) was operationalized using a free recall test conducted immediately after retention. Our primary analysis indicated that CE had no statistically significant effects on consolidation, regardless of the SRTT's variant utilized during practice. However, an exploratory analysis, classifying participants based on the level of awareness gained during motor practice, showed that CE negatively influenced consolidation in unfit participants who explicitly acquired the motor sequence. Our findings indicate that fitness level and awareness in sequence acquisition can modulate the interaction between CE and motor memory consolidation. These factors should be taken into account when assessing the effects of CE on motor memory.

Thoracolumbar spinal fracture in children: Conservative or surgical treatment?

PURPOSE

Spinal thoracolumbar fractures represent 10-14% of pediatric fractures. Most children concerned by such fractures are above 10 years of age. No guidelines presently exist. Analysis of spine pathophysiology and of the various common therapeutic attitudes led us to conduct a review of the different therapeutic approaches in pediatric thoracolumbar fracture.

METHODS

A review of the literature was carried out using the Medline and Embase databases with the search-term "pediatric thoracic lumbar spine fractures".

RESULTS

The systematic review identified 44 studies, 24 of which were selected, and 19 were included for analysis. Physiological age was categorized on Risser's classification. In Risser 1 with Magerl A1 fracture, surgical treatment was not necessary and functional (rest and analgesics) or conservative treatment (bracing for 6 weeks) was sufficient. In Risser 1 with Magerl A2, A3 or B fracture, conservative treatment (bracing for 3 months) was the first-line option. In Risser 2-4, conservative treatment with bracing for 3 months was possible in the absence of instability, with kyphosis>20° and canal compression>33%; otherwise, treatment should be surgical. Subsequently, in case of onset of secondary instability, surgical treatment can be proposed. We highlight the importance of MRI assessment for diagnosis of thoracolumbar fracture and associated lesions of the intervertebral discs and posterior ligament complex. Children classified as Risser 5 can undergo the same treatment as adults.

CONCLUSION

Two main parameters should be assessed in treatment decision-making for thoracolumbar fracture: the Risser scale and the Magerl classification.

Efficient CNS targeting in adult mice by intrathecal infusion of single-stranded AAV9-GFP for gene therapy of neurological disorders

Adeno-associated virus (AAV) gene therapy constitutes a powerful tool for the treatment of neurodegenerative diseases. While AAVs are generally administered systemically to newborns in preclinical studies of neurological disorders, in adults the maturity of the blood-brain barrier (BBB) must be considered when selecting the route of administration. Delivery of AAVs into the cerebrospinal fluid (CSF) represents an attractive approach to target the central nervous system (CNS) and bypass the BBB. In this study, we investigated the efficacy of intra-CSF delivery of a single-stranded (ss) AAV9-CAG-GFP vector in adult mice via intracisternal (iCist) or intralumbar (it-Lumb) administration. It-Lumb ssAAV9 delivery resulted in greater diffusion throughout the entire spinal cord and green fluorescent protein (GFP) expression mainly in the cerebellum, cortex and olfactory bulb. By contrast, iCist delivery led to strong GFP expression throughout the entire brain. Comparison of the transduction efficiency of ssAAV9-CAG-GFP versus ssAAV9-SYN1-GFP following it-Lumb administration revealed widespread and specific GFP expression in neurons and motoneurons of the spinal cord and brain when the neuron-specific synapsin 1 (SYN1) promoter was used. Our findings demonstrate that it-Lumb ssAAV9 delivery is a safe and highly efficient means of targeting the CNS in adult mice.