Multiple sessions of transcranial direct current stimulation to the intact hemisphere improves visual function after unilateral ablation of visual cortex

Abstract

Damage to cerebral systems is frequently followed by the emergence of compensatory mechanisms, which serve to reduce the effects of brain damage and allow recovery of function. Intrinsic recovery, however, is rarely complete. Non-invasive brain stimulation technologies have the potential to actively shape neural circuits and enhance recovery from brain damage. In this study, a stable deficit for detecting and orienting to visual stimuli presented in the contralesional visual hemifield was generated by producing unilateral brain damage of the right posterior parietal and contiguous visual cortical areas. A long regimen of inhibitory non-invasive transcranial direct-current stimulation (cathodal 2mA, 20 min) was applied to the contralateral (intact) posterior parietal cortex over 14 weeks (total of 70 sessions, one per day, five days per week) and behavioral outcomes were periodically assessed. In three out of four stimulated cats, lasting recovery of visuospatial function was observed. Recovery started after 2–3 weeks of stimulation, and recovered targets were located first in the periphery, and moved to more central visual field locations with the accrual of stimulation sessions. Recovery for moving tasks followed a biphasic pattern before reaching plateau levels. Recovery did not occur for more difficult visual tasks. These findings highlight the ability of multiple sessions of transcranial direct-current stimulation to produce recovery of visuospatial function after unilateral brain damage.

Using transcranial direct-current stimulation (tDCS) to understand cognitive processing

“…Repeated stimulation spaced across time is a method that many laboratories are examining as a way to instantiate long-lasting effects (Nitsche et al, 2008, Liu et al, 2016). Some work with animals suggests that multiple sessions can have a cummulative effect (Rueger et al, 2012, Rushmore et al, 2013). A considerable effort is being made with human participants to determine whether tDCS effects are more potent with multi-session tDCS (Galvez et al, 2013, Dumel et al, 2016).…”

Strategies for replacing non-invasive brain stimulation sessions: recommendations for designing neurostimulation clinical trials

“…As such, minimum adherence expectations should reflect an intervention's properties and trials' objectives. Under the assumption that tDCS and TMS efficacy follows Kravitz´s models, guaranteeing that the participant receives a sufficient treatment dose to maximize the outcome is relevant [40][41][42][43]. Therefore, based on the reviewed literature, in these populations, and in NIBS trials with at least 5 or more stimulation visits, it seems reasonable to allow up to 20% of neurostimulation visits to be missed.…”

Methods of Improving the Visual Functions in Patients with Stable Maculopathy – Pilot Results of a New Study

“…Pooperačně se zlepšila schopnost číst naturálně, druhý den dosáhli pacienti průměrně hodnoty J.č.9 a sedmý den J.č. 8 Třetí den po implantaci SML nebyli nemocní schopni při testování rychlosti čtení text přečíst, nicméně po první zrakové rehabilitaci, rychlost čtení byla 23, 60 a 127 sekund, jeden pacient testovanou velikost textu J.č.10 nemohl naturálně přečíst. Po jednom měsíci intenzivní rehabilitace zraku, RČ byla 8, 13 a 33 sekund, jeden z pacientů opět nemohl J.č.10 přečíst.…”

“…Oceňovali samotné zlepšení zraku i snahu personálu o jejich návrat do běžného života jako před nemocí. Náš projekt si klade za cíl zhodnotit, zda tES dokáže akcelerovat či podnítit zrakovou rehabilitaci, jak je popisováno v mnoha studiích [1,2,8,6]. Efekt této metody však nelze toho času zhodnotit, neboť studie zatím ještě není odslepena.…”

“…Slouží k urychlení zrakové rehabilitace, kdy pozitivní zkušenosti byly zaznamenány např. u pacientů s hemianopsií [1,4] nebo u pokusných zvířat [8].…”