Benefit of multiple sessions of perilesional repetitive transcranial magnetic stimulation for an effective rehabilitation of visuospatial function

Abstract

Non-invasive neurostimulation techniques have been used alone or in conjunction with rehabilitation therapy to treat the neurological sequelae of brain damage with rather variable therapeutic outcomes. One potential factor limiting a consistent success for such techniques may be the few sessions carried out in patients, despite reports that their accrual may play a key role in alleviating neurological deficits long-term. In this study, we tested the effects of seventy consecutive sessions of perilesional high frequency (10 Hz) repetitive transcranial magnetic stimulation (rTMS) in the treatment of chronic neglect deficits in a well-established feline model of visuo-spatial neglect. Under identical rTMS parameters and visuo-spatial testing regimes, half of the subjects improved in visuo-spatial orienting performance. The other half experienced either none or extremely moderate ameliorations in the neglected hemispace and displayed transient patterns of maladaptive visuo-spatial behavior. Detailed analyses suggest that lesion location and extent did not account for the behavioral differences observed between these two groups of animals. We conclude that multi-session perilesional rTMS regimes have the potential to induce functional ameliorations following focal chronic brain injury, and that behavioral performance prior to the onset of the rTMS treatment is the factor that best predicts positive outcomes for non-invasive neurostimulation treatments in visuo-spatial neglect.

Low-Intensity Repetitive Transcranial Magnetic Stimulation Improves Abnormal Visual Cortical Circuit Topography and Upregulates BDNF in Mice

“…Our findings linking LI-rTMSinduced structural reorganization to BDNF expression are compatible with long-term behavioral modifications in healthy (Valero-Cabré et al, 2008) and parietally injured (Afifi et al, 2013) cats. In addition, our findings suggest a mechanism to explain the clinical efficacy of low-intensity magnetic stimulation, as well as rTMS, in disorders associated with plasticity and BDNF abnormalities (Thickbroom and Mastaglia, 2009; Autry Ϫ/Ϫ mice, with wild-types and the least disordered and most disordered TZ pairs within ephrin-A2A5 Ϫ/Ϫ mice shown separately.…”

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

“…). One task was performed in low ambient light conditions and required animals orient to a small laser light stimulus at the same eccentricities as in the standard task (laser task; Afifi et al ., ). The other task was a variant of the Hardy & Stein () task in which targets were presented while the animal was in motion towards a central target (runway perimetry task).…”

“…The importance of multiple sessions on the efficacy and magnitude of non‐invasive neurostimulation effects have been noted in intact animals and human participants (Valero‐Cabré et al ., ; Reis et al ., ; Monte‐Silva et al ., ), in human subjects with depression (Boggio et al ., ; Alonzo et al ., ; Brunoni et al ., ; Loo et al ., ), and in similar animals models of focal brain damage (Afifi et al ., ). Increasing sessions of cathodal tDCS also progressively elevates the number of neural stem cells labeled by bromodeoxyuridine and Hes3 antibodies (Rueger et al ., ).…”

“…The lighting in the room was brought from 85 to 1.3 cd/m 2 . After fixation, a laser was projected onto one of the 13 target eccentricities at the bottom of the arena and was moved (Afifi et al ., ). If the cat redirected its attention to the laser they would receive a high‐incentive food reward and the trial was scored as correct.…”

“…While the precise neural effects of tDCS are highly complex and likely to depend on factors such as the orientation of somatodendritic and axonal axes relative to the electric field as well as non‐linear effects of stimulation intensity (Bikson et al ., ; Radman et al ., ; Kabakov et al ., ; Batsikadze et al ., ), placing the anodal tDCS electrode over a brain area is generally thought to induce a lasting increase in brain activity under the electrode, while cathodal tDCS generally reduces neural excitability (Bindman et al ., ; Purpura & McMurtry, ; Nitsche & Paulus, ; Stagg & Nitsche, ). TDCS effects outlast the period of stimulation and, as with other neurostimulation techniques, a greater number of stimulation sessions is thought to increase the efficacy and size of the effect (Valero‐Cabré et al ., ; Reis et al ., ; Afifi et al ., ; Monte‐Silva et al ., ). This characteristic could be utilised to promote neuroplastic mechanisms and restore function after cerebral damage.…”