Restorative Neurology and Neuroscience - Volume 40, issue 1

Authors: Awada, Asmara | Bakhtiari, Shahab | Legault, Catherine | Odier, Celine | Pack, Christopher C.

Article Type: Research Article

Abstract: Background: Cortical blindness is a form of severe vision loss that is caused by damage to the primary visual cortex (V1) or its afferents. This condition has devastating effects on quality of life and independence. While there are few treatments currently available, accumulating evidence shows that certain visual functions can be restored with appropriate perceptual training: Stimulus sensitivity can be increased within portions of the blind visual field. However, this increased sensitivity often remains highly specific to the trained stimulus, limiting the overall improvement in visual function. Objective: Recent advances in the field of perceptual learning show that …such specificity can be overcome with training paradigms that leverage the properties of higher-level visual cortical structures, which have greater capacity to generalize across stimulus positions and features. This targeting can be accomplished by using more complex training stimuli that elicit robust responses in these visual structures. Methods: We trained cortically blind subjects with a complex optic flow motion stimulus that was presented in a location of their blind field. Participants were instructed to train with the stimulus at home for approximately 30 minutes per day. Once performance plateaued, the stimulus was moved deeper into the blind field. A battery of pre- and post-training measures, with careful eye tracking, was performed to quantify the improvements. Results: We show that 1) optic flow motion discrimination can be relearned in cortically blind fields; 2) training with an optic flow stimulus can lead to improvements that transfer to different tasks and untrained locations; and 3) such training leads to a significant expansion of the visual field. The observed expansion of the visual field was present even when eye movements were carefully controlled. Finally, we show that regular training is critical for improved visual function, as sporadic training reduced the benefits of training, even when the total numbers of training sessions were equated. Conclusions: These findings are consistent with the hypothesis that complex training stimuli can improve outcomes in cortical blindness, provided that patients adhere to a regular training regimen. Nevertheless, such interventions remain limited in their ability to restore functional vision. Show more

Keywords: Cortical blindness, vision restoration, training-induced brain plasticity, perceptual learning, motion perception

DOI: 10.3233/RNN-211223

Citation: Restorative Neurology and Neuroscience, vol. 40, no. 1, pp. 1-16, 2022

Authors: Borrell, Jordan A. | Krizsan-Agbas, Dora | Nudo, Randolph J. | Frost, Shawn B.

Article Type: Research Article

Abstract: Background: Closed-loop neuromodulation systems have received increased attention in recent years as potential therapeutic approaches for treating neurological injury and disease. Objective: The purpose of this study was to assess the ability of intraspinal microstimulation (ISMS), triggered by action potentials (spikes) recorded in motor cortex, to alter synaptic efficacy in descending motor pathways in an anesthetized rat model of spinal cord injury (SCI). Methods: Experiments were carried out in adult, male, Sprague Dawley rats with a moderate contusion injury at T8. For activity-dependent stimulation (ADS) sessions, a recording microelectrode was used to detect neuronal spikes in …motor cortex that triggered ISMS in the spinal cord grey matter. SCI rats were randomly assigned to one of four experimental groups differing by: a) cortical spike-ISMS stimulus delay (10 or 25 ms) and b) number of ISMS pulses (1 or 3). Four weeks after SCI, ADS sessions were conducted in three consecutive 1-hour conditioning bouts for a total of 3 hours. At the end of each conditioning bout, changes in synaptic efficacy were assessed using intracortical microstimulation (ICMS) to examine the number of spikes evoked in spinal cord neurons during 5-minute test bouts. A multichannel microelectrode recording array was used to record cortically-evoked spike activity from multiple layers of the spinal cord. Results: The results showed that ADS resulted in an increase in cortically-evoked spikes in spinal cord neurons at specific combinations of spike-ISMS delays and numbers of pulses. Efficacy in descending motor pathways was increased throughout all dorsoventral depths of the hindlimb spinal cord. Conclusions: These results show that after an SCI, ADS can increase synaptic efficacy in spared pathways between motor cortex and spinal cord. This study provides further support for the potential of ADS therapy as an effective method for enhancing descending motor control after SCI. Show more

Keywords: Activity dependent stimulation, neuromodulation, spinal cord injury, extracellular electrophysiology, synaptic efficacy

DOI: 10.3233/RNN-211214

Citation: Restorative Neurology and Neuroscience, vol. 40, no. 1, pp. 17-33, 2022

Authors: Glasner, Paulina | Sabisz, Agnieszka | Chylińska, Magdalena | Komendziński, Jakub | Wyszomirski, Adam | Karaszewski, Bartosz

Article Type: Research Article

Abstract: Background: Multiple sclerosis (MS) is associated with progressive brain atrophy, which in turn correlates with disability, depression, and cognitive impairment. Relapsing-remitting multiple sclerosis (RRMS) is a type of MS in which relapses of the disease are followed by remission periods. This is the most common type of the disease. There is a significant need for easy and low-cost methods to these cerebral changes. Changes in retinal layer thickness may reflect alterations in brain white and gray matter volumes. Therefore, this paper aims to determine whether retinal layer thickness, measured using optical coherence tomography (OCT), correlates with volumetric brain assessments obtained …by magnetic resonance imaging (MRI). Methods: This retrospective cohort study recruited 53 patients with relapsing–remitting MS who underwent MRI and OCT examinations for evaluation of brain compartment volumes and thickness of retinal layers, respectively. OCT parameters, including central retinal thickness; retinal nerve fiber layer thickness (RNFL, peripapillary thickness); ganglion cell complex thickness (GCC, macular thickness); and Expanded Disability Status Scale (EDSS) results were compared with MRI parameters (cerebral cortex; cerebral cortex and basal ganglia combined; brain hemispheres without the ventricular system; and white matter plaques). We also checked whether there is a correlation between the number of RRMS and OCT parameters. Objective: Our primary objective was to identify whether these patients had retinal thickness changes, and our secondary objective was to check if those changes correlated with the MRI brain anatomical changes. Results: RNFL and GCC thicknesses were strongly (p -value < 0.05) associated with (i) cerebral cortex volume, (ii) combination of brain cortex and basal ganglia volumes, and (iii) the hemispheres but without the ventricular system. White matter plaques (combined) showed only weak or no correlation with RNFL and GCC. There was no correlation between central retinal thickness and brain compartment volumes, and there were weak or no correlations between the summary EDSS scores and OCT results. Conclusions: Retinal layer thickness measured by OCT correlates with select volumetric brain assessments on MRI. During the course of RRMS, the anatomo-pathological structure of the retina might serve as a surrogate marker of brain atrophy and clinical progression within selected domains. Show more

Keywords: Multiple sclerosis, optical coherence tomography, brain atrophy, cognitive impairment, optic neuritis

DOI: 10.3233/RNN-211176

Citation: Restorative Neurology and Neuroscience, vol. 40, no. 1, pp. 35-42, 2022

Authors: Mehrem, Elsayed S. | Fergany, Lamyaa A. | Mohamed, Said A. | Fares, Hany M. | Kamel, Roshdy M.

Article Type: Research Article

Abstract: Background: Childhood hearing impairment is a major disability associated with delayed motor development. The affected Fine motor performance in children with sensorineural hearing loss (SNHL) could be due to dynamic balance deficits and visual-motor incoordination. Objective: This study was designed to investigate the effects of fine motor exercises with or without balancing exercises on fine motor skills in children with SNHL. Methods: One hundred and eighty (180) children their age ranged from 8 to 18 years old diagnosed with SNHL were selected. They were divided into three groups, 60 children (control group) practiced …only their ordinary activities of daily living, 60 children (fine motor exercises group) practiced fine motor exercises, and 60 children (fine motor and balance exercise) group practiced fine motor and balance exercises. The outcomes were assessed by the Bruininks Oseretsky Test of the motor proficiency second edition scale (BOT-2). Results: Generally, there was a statistically significant difference between control group and fine motor exercises group where (p  < 0.05), besides, there was a statistically significant difference between control group and fine motor and balance exercises group where (p  < 0.05). But, there was no statistically significant difference between fine motor exercises group and fine motor and balance exercises group where (p  > 0.05). Conclusions: The Fine Motor performance of children with SNHL has been improved by Fine motor with or without balancing exercises according to (BOT-2). Show more

Keywords: Hearing loss, fine motor, balance exercises

DOI: 10.3233/RNN-211156

Citation: Restorative Neurology and Neuroscience, vol. 40, no. 1, pp. 43-52, 2022

Authors: Alzoubi, Karem H. | Al-Dekah, Arwa M. | Jaradat, Saied | Alrabadi, Nasr

Article Type: Research Article

Abstract: Background: Post-traumatic stress disorder (PTSD) is a genuine obstructing mental disorder. As indicated by the name, it is related to the patients’ stress augmented by life-threatening conditions or accidents. The PTSD has linked to oxidative stress that can result in neurodegeneration. L-carnitine (L-CAR) is known for its antioxidant properties, which can protect against neuronal damage. Objective: In the current study, we investigated the beneficial effects of L-CAR on the memory impairment induced by PTSD using a rat model. Methods: A model of single-prolonged stress (a cycle of restraining, forced swimming, rest, and finally …diethyl ether exposure for 2 h, 20 min, 15 min, and 1–2 min, respectively) was used to induce PTSD-like behavior. Intraperitoneal L-CAR treatment (300 mg/kg/day) was introduced for four weeks. Both memory and special learning were evaluated utilizing the radial arm water maze (RAWM). Moreover, the levels of glutathione peroxidase (GPx), glutathione reduced (GSH), and glutathione oxidized (GSSG) were assessed as biomarkers oxidative stress in the hippocampus. Results: The results demonstrated that both the short and long-term memories were impaired by PTSD/SPS model (P  < 0.05), while L-CAR treatment prevented this memory impairment in PTSD rats. Besides, L-CAR prevented the reduction in GPx activity and increase in GSSG, which were altered in the hippocampus of the PTSD/SPS rats (P  < 0.05). Levels of GSH were not changed in PTSD and/or L-CAR rats. Conclusions: L-CAR administration prevented short- and long-term memories’ impairments induced in the PTSD/SPS rat model. This is probably related to its antioxidant effects in the hippocampus. Show more

Keywords: Post-traumatic stress disorder, L-carnitine, memory impairment, oxidative stress, antioxidants, hippocampus

DOI: 10.3233/RNN-211191

Citation: Restorative Neurology and Neuroscience, vol. 40, no. 1, pp. 53-61, 2022