Potenciais evocados somatossensitivos e motores são modalidades de testes neurofisiológicos com capacidade para avaliar funcionalmente a integridade das vias sensoriais e motoras, respectivamente, podendo ser utilizados na avaliação neurológica, no estabelecimento de prognóstico e na monitoração da evolução de uma lesão na medula espinhal. Este trabalho visa descrever as técnicas de obtenção de potenciais evocados com estimulação elétrica em cães portadores de doença de disco intervertebral toracolombar, e verificar se há associação com os sinais clínicos e com os achados da tomografia computadorizada (TC). Cinco cães hígidos (grupo controle) e dez cães condrodistróficos com paralisia de membros pélvicos (grupo afetado) devido à extrusão de disco intervertebral toracolombar foram avaliados com relação à classificação neurológica, imagens por TC e potenciais evocados somatossensitivos e motores sob anestesia geral. Presença ou ausência de registros caudais à lesão, mensuração de latências e amplitudes foram efetuadas. Foram captados registros cranianos em todos os cães após estimulação dos membros torácicos, mas apenas em seis cães após estimulação dos membros pélvicos. Da mesma forma, todos os cães apresentaram registros em membros torácicos após estimulação transcraniana, mas apenas em seis cães nos membros pélvicos e esfíncter anal. Houve diferença significativa quanto à presença ou ausência de registros entre os grupos afetado e controle para os membros pélvicos. Os valores mensurados de latência e amplitudes entre os grupos também são discutidos. Potenciais evocados e motores são factíveis de serem produzidos em cães com e sem paralisia de membros pélvicos sob anestesia geral, e foram correlacionados aos sinais clínicos. / Somatosensory and motor evoked potentials are neurophysiologic tests that assesse the integrity of sensory and motor pathways, and may be used in the neurological assessment, prognosis establishment and spinal cord injury monitoration. This study aims to describe the technique for evoked potentials recording with electrical stimulation in healthy dogs and in dogs with thoracolumbar intervertebral disc disease, and determine whether there is any association with clinical signs and computed tomography (CT) findings. Five clinically normal dachshunds (control group) and ten chondrodystrophic dogs with hind limb paralysis (affected group) due to thoracolumbar intervertebral disc extrusions were evaluated according to their neurological status, CT scans and somatosensory and motor evoked potentials under general anesthesia. Recordings presence or absence caudal to lesion, onset latencies and peak-to-peak amplitudes were measured. Records were captured in the scalp in all dogs after front limb stimulation, but only in six dogs after hind limb stimulation. Likewise, in all dogs records were obtained in forelimbs after transcranial stimulation, but only in six dogs on pelvic limbs and on external anal sphincter muscle. There were significant differences in presence or absent recordings between affected and control groups related to pelvic limbs PESS and PEM. Latencies and amplitudes measured between groups are discussed. Somatosensory and motor evoked potentials are feasible to produce in dogs with or without hind limb paralysis under general anesthesia, and correlated with clinical signs.

Potenciais evocados somatossensitivos e motores são modalidades de testes neurofisiológicos com capacidade para avaliar funcionalmente a integridade das vias sensoriais e motoras, respectivamente, podendo ser utilizados na avaliação neurológica, no estabelecimento de prognóstico e na monitoração da evolução de uma lesão na medula espinhal. Este trabalho visa descrever as técnicas de obtenção de potenciais evocados com estimulação elétrica em cães portadores de doença de disco intervertebral toracolombar, e verificar se há associação com os sinais clínicos e com os achados da tomografia computadorizada (TC). Cinco cães hígidos (grupo controle) e dez cães condrodistróficos com paralisia de membros pélvicos (grupo afetado) devido à extrusão de disco intervertebral toracolombar foram avaliados com relação à classificação neurológica, imagens por TC e potenciais evocados somatossensitivos e motores sob anestesia geral. Presença ou ausência de registros caudais à lesão, mensuração de latências e amplitudes foram efetuadas. Foram captados registros cranianos em todos os cães após estimulação dos membros torácicos, mas apenas em seis cães após estimulação dos membros pélvicos. Da mesma forma, todos os cães apresentaram registros em membros torácicos após estimulação transcraniana, mas apenas em seis cães nos membros pélvicos e esfíncter anal. Houve diferença significativa quanto à presença ou ausência de registros entre os grupos afetado e controle para os membros pélvicos. Os valores mensurados de latência e amplitudes entre os grupos também são discutidos. Potenciais evocados e motores são factíveis de serem produzidos em cães com e sem paralisia de membros pélvicos sob anestesia geral, e foram correlacionados aos sinais clínicos. / Somatosensory and motor evoked potentials are neurophysiologic tests that assesse the integrity of sensory and motor pathways, and may be used in the neurological assessment, prognosis establishment and spinal cord injury monitoration. This study aims to describe the technique for evoked potentials recording with electrical stimulation in healthy dogs and in dogs with thoracolumbar intervertebral disc disease, and determine whether there is any association with clinical signs and computed tomography (CT) findings. Five clinically normal dachshunds (control group) and ten chondrodystrophic dogs with hind limb paralysis (affected group) due to thoracolumbar intervertebral disc extrusions were evaluated according to their neurological status, CT scans and somatosensory and motor evoked potentials under general anesthesia. Recordings presence or absence caudal to lesion, onset latencies and peak-to-peak amplitudes were measured. Records were captured in the scalp in all dogs after front limb stimulation, but only in six dogs after hind limb stimulation. Likewise, in all dogs records were obtained in forelimbs after transcranial stimulation, but only in six dogs on pelvic limbs and on external anal sphincter muscle. There were significant differences in presence or absent recordings between affected and control groups related to pelvic limbs PESS and PEM. Latencies and amplitudes measured between groups are discussed. Somatosensory and motor evoked potentials are feasible to produce in dogs with or without hind limb paralysis under general anesthesia, and correlated with clinical signs.

No description available.

O potencial evocado motor facial (PEMF) tem-se mostrado um excelente método de monitorização do nervo facial, gerando resultados bastante confiáveis e reprodutíveis no que tange à predição da função facial pós-operatória. O critério eletrofisiológico mais utilizado até então para tanto tem sido a relação de amplitude do PEMF final-valor de base. Os objetivos deste trabalho foram avaliar as alterações intraoperatórias da amplitude e da complexidade do PEMF, correlacioná-las com o prognóstico facial no pós-operatório imediato e tardio e verificar se amplitude e complexidade constituem variáveis independentes de predição funcional. Os registros dos potenciais intraoperatórios dos músculos orbiculares do olho e da boca de 35 pacientes portadores de schwannoma vestibular (SV) foram coletados e analisados retrospectivamente de acordo com tempos cirúrgicos preestabelecidos: inicial, abertura da dura-máter, dissecação do tumor (TuDis), ressecção do tumor (TuRes) e final. No pós-operatório imediato, a função facial apresentou uma significativa correlação negativa com as relações de amplitude do PEMF durante a TuDis, a TuRes e ao final do procedimento nos músculos orbiculares do olho (p =0,003, 0,055 e 0,028, respectivamente) e da boca (p=0,002, 0,104 e 0,014, respectivamente). No último seguimento, entretanto, a correlação foi significativa apenas para o músculo orbicular da boca, durante a TuDis (p=0,005) e ao final do procedimento (p=0,102). As variações da complexidade dos potenciais alcançaram resultados mais significativos tanto no pós-operatório imediato, quanto no tardio, de forma que houve uma correlação negativa no músculo orbicular do olho apenas nas medidas finais (imediato, p=0;023; seguimento, p=0,116) e no músculo orbicular da boca durante a TuDis, a TuRes e a medida final (imediato, p=0,071, 0,000 e 0,001, respectivamente; seguimento, p=0,015, 0,001 e 0,01, respectivamente). As alterações intraoperatórias das relações de amplitude e de complexidade dos PEMFs parecem representar variáveis independentes, podendo ser utilizadas na predição da função facial pós-operatória durante cirurgias de ressecção de SV. Baseados nos resultados deste trabalho, a monitorização evento-valor de base é bastante útil, justificando mudanças imediatas da estratégia cirúrgica, com o intuito de reduzir as chances de uma lesão definitiva do nervo facial. / Facial motor evoked potential (FMEP) amplitude ratio reduction at the end of the surgery has been identified as a good predictor for postoperative facial nerve outcome. We sought to investigate variations in FMEP amplitude and waveform morphology during vestibular schwannoma (VS) resection and to correlate these measures with postoperative facial function immediately after surgery and at the last follow-up. Besides we analyzed the relationship between quantitative parameters. Intraoperative orbicularis oculi and oris muscles FMEP data from 35 patients undergoing surgery for VS resection were collected, then analyzed by surgical stage: initial, dural opening, tumor dissection (TuDis), tumor resection (TuRes) and final. Immediately after surgery, postoperative facial function correlated significantly with the FMEP amplitude ratio during TuDis, TuRes and final in both the orbicularis oculi (p´s=0.003, 0.055 and 0.028, respectively) and oris muscles (p´s=0.002, 0.104 and 0.014, respectively). At the last follow-up, however, facial function correlated significantly with the FMEP amplitude ratio only during TuDis (p=0.005) and final (p=0.102) for the orbicularis oris muscle. At both time points, postoperative facial paresis correlated significantly with FMEP waveform deterioration in orbicularis oculi during final (immediate, p=0.023; follow-up, p=0.116) and in orbicularis oris during TuDis, TuRes and final (immediate, p´s=0.071, 0.000 and 0.001, respectively; follow-up, p´s=0.015, 0.001 and 0.01, respectively). FMEP amplitude ratio and waveform morphology during VS resection seem to represent independent quantitative parameters that can be used to predict postoperative facial function. Event-to-baseline FMEP monitoring is quite useful to dictate when intraoperative changes in surgical strategy are warranted to reduce chances of facial nerve injury.

O potencial evocado motor facial (PEMF) tem-se mostrado um excelente método de monitorização do nervo facial, gerando resultados bastante confiáveis e reprodutíveis no que tange à predição da função facial pós-operatória. O critério eletrofisiológico mais utilizado até então para tanto tem sido a relação de amplitude do PEMF final-valor de base. Os objetivos deste trabalho foram avaliar as alterações intraoperatórias da amplitude e da complexidade do PEMF, correlacioná-las com o prognóstico facial no pós-operatório imediato e tardio e verificar se amplitude e complexidade constituem variáveis independentes de predição funcional. Os registros dos potenciais intraoperatórios dos músculos orbiculares do olho e da boca de 35 pacientes portadores de schwannoma vestibular (SV) foram coletados e analisados retrospectivamente de acordo com tempos cirúrgicos preestabelecidos: inicial, abertura da dura-máter, dissecação do tumor (TuDis), ressecção do tumor (TuRes) e final. No pós-operatório imediato, a função facial apresentou uma significativa correlação negativa com as relações de amplitude do PEMF durante a TuDis, a TuRes e ao final do procedimento nos músculos orbiculares do olho (p =0,003, 0,055 e 0,028, respectivamente) e da boca (p=0,002, 0,104 e 0,014, respectivamente). No último seguimento, entretanto, a correlação foi significativa apenas para o músculo orbicular da boca, durante a TuDis (p=0,005) e ao final do procedimento (p=0,102). As variações da complexidade dos potenciais alcançaram resultados mais significativos tanto no pós-operatório imediato, quanto no tardio, de forma que houve uma correlação negativa no músculo orbicular do olho apenas nas medidas finais (imediato, p=0;023; seguimento, p=0,116) e no músculo orbicular da boca durante a TuDis, a TuRes e a medida final (imediato, p=0,071, 0,000 e 0,001, respectivamente; seguimento, p=0,015, 0,001 e 0,01, respectivamente). As alterações intraoperatórias das relações de amplitude e de complexidade dos PEMFs parecem representar variáveis independentes, podendo ser utilizadas na predição da função facial pós-operatória durante cirurgias de ressecção de SV. Baseados nos resultados deste trabalho, a monitorização evento-valor de base é bastante útil, justificando mudanças imediatas da estratégia cirúrgica, com o intuito de reduzir as chances de uma lesão definitiva do nervo facial. / Facial motor evoked potential (FMEP) amplitude ratio reduction at the end of the surgery has been identified as a good predictor for postoperative facial nerve outcome. We sought to investigate variations in FMEP amplitude and waveform morphology during vestibular schwannoma (VS) resection and to correlate these measures with postoperative facial function immediately after surgery and at the last follow-up. Besides we analyzed the relationship between quantitative parameters. Intraoperative orbicularis oculi and oris muscles FMEP data from 35 patients undergoing surgery for VS resection were collected, then analyzed by surgical stage: initial, dural opening, tumor dissection (TuDis), tumor resection (TuRes) and final. Immediately after surgery, postoperative facial function correlated significantly with the FMEP amplitude ratio during TuDis, TuRes and final in both the orbicularis oculi (p´s=0.003, 0.055 and 0.028, respectively) and oris muscles (p´s=0.002, 0.104 and 0.014, respectively). At the last follow-up, however, facial function correlated significantly with the FMEP amplitude ratio only during TuDis (p=0.005) and final (p=0.102) for the orbicularis oris muscle. At both time points, postoperative facial paresis correlated significantly with FMEP waveform deterioration in orbicularis oculi during final (immediate, p=0.023; follow-up, p=0.116) and in orbicularis oris during TuDis, TuRes and final (immediate, p´s=0.071, 0.000 and 0.001, respectively; follow-up, p´s=0.015, 0.001 and 0.01, respectively). FMEP amplitude ratio and waveform morphology during VS resection seem to represent independent quantitative parameters that can be used to predict postoperative facial function. Event-to-baseline FMEP monitoring is quite useful to dictate when intraoperative changes in surgical strategy are warranted to reduce chances of facial nerve injury.

Il lavoro di tesi si è focalizzato sullo studio dell’arousal come indice psicofisiologico di attivazione e sull’applicazione della metodica di stimolazione elettrica transcranica (tES) non invasiva con lo scopo di modulare tale indice. L’obiettivo è stato quello di indagare se, applicando la tES, fosse possibile migliorare la performance di soggetti giovani sani in compiti di tipo cognitivo. Il progetto di ricerca si è sviluppato in 2 studi principali per un totale di 4 esperimenti. Tali studi hanno previsto l’acquisizione e la successiva analisi sia di dati comportamentali (tempi di reazione, accuratezza), che di indici psicofisiologici (conduttanza cutanea, diametro pupillare). I risultati hanno evidenziato che è possibile modulare l’arousal con dei “bursts” di stimolazione elettrica transcranica, somministrati in concomitanza di stimoli salienti per il soggetto. Tale modulazione si è manifestata con una riduzione dei tempi di reazione ed un contemporaneo aumento della risposta di conduttanza cutanea. Questi dati supportano la possibilità di utilizzare questo protocollo in pazienti con difficoltà di attenzione o altri problemi cognitivi per aumentare l’efficacia di interventi di riabilitazione. / The thesis analyzed the role of the arousal as a psychophysiological index of activation, and the application of non-invasive transcranial electrical stimulation (tES) technique with the aim to modulate this index. In this work we investigated if the application of tES could increase the performance of healthy young subjects during cognitive tasks. The thesis is based on 2 main studies for a total of 4 experiments with the recording of behavioural (reaction times, accuracy) and psychophysiological (skin conductance, pupil diameter) indeces. The results showed that it is possible to modulate arousal with bursts of tES, administered during the presentation of salient stimuli for the subject. This modulation resulted in a reduction of reaction times and an increase of the skin conductance response. These data support the possibility to use this protocol of stimulation with patients with attentional and other cognitive deficits in a rehabilitative context.

La schizophrénie (SZ) est une pathologie psychiatrique chronique et invalidante dont les conséquences fonctionnelles sont principalement liées à des déficits cognitifs. Ceux-ci sont étroitement associés à des déficits de perception auditive précoce d’informations de bas niveaux telle que la hauteur sonore. La perception auditive précoce peut s’évaluer avec un paradigme comportemental simple appelé « tone-matching » (appariement tonal AT), dans le lequel les sujets doivent discriminer activement entre deux sons courts (300-ms) d’une même paire séparés par un intervalle bref (500-ms). Les performances d’AT reflètent un processus cognitif de comparaison préattentionnelle se déroulant au sein du système auditif central (SAC). Le SAC est constitué du noyau géniculé médian du thalamus (MGN), de l’aire corticale auditive précoce (EA) et de l’aire corticale auditive associative (AA). Cependant, les dysfonctionnements du SAC sous-tendant les déficits d’AT dans la SZ restent mal connus. De plus, ces déficits sont élevés mais hétérogènes selon les cohortes. Ce travail de thèse propose de caractériser le fonctionnement du SAC associé aux performances d’AT chez les sujets SZ afin de mieux comprendre la physiopathologie du trouble et de développer des traitements ciblés. L’hypothèse guidant les 4 études expérimentales de ce travail est que des altérations psychophysiques et neurophysiologiques spécifiques du SAC sont impliquées dans les déficits d’AT dans la SZ. Nos études psychophysiques utilisant différents paradigmes de « tone-matching » ont montré 1) un déficit d’AT de magnitude croissante pour l’intensité, la hauteur et la longueur des stimuli auditifs chez les sujets SZ (n=29), 2) un déficit d’appariement de trios de sons médiant une corrélation entre les déficits d’appariement de paires de sons (AT proprement dit) et l’identification de phrases émotionnelles (n=27). Ces résultats démontrent que les sujets SZ présentent différents niveaux de déficits d’AT selon le type de caractéristique acoustique, ainsi que des niveaux de déficits hiérarchiquement organisés entre les types de complexité des stimuli auditifs perçus. 3) Nos approches neurophysiologiques ont montré une distribution bimodale des performances d’AT chez les sujets atteints de SZ (n=310) avec un 1er groupe présentant une réduction significative de ces performances associée à une réduction de la connectivité fonctionnelle de repos à l’IRM entre les différentes régions du SAC (MGN-EA, MGN-AA et EA-AA impliquant particulièrement des sous-régions AA adjacentes à l’EA) et un 2nd ne présentant pas de déficits d’AT mais une réduction plus modérée de la connectivité uniquement entre EA-AA. Ces résultats démontrent que les performances d’AT permettent de séparer deux sous-types de SZ présentant des patterns topographiques spécifiques de dysconnectivité fonctionnelle de repos au sein du SAC. 4) Les résultats préliminaires de l’étude de l’effet d’une procédure de stimulation électrique transcrânienne non invasive (tES) ciblant le SAC gauche (2mA, 10x20min) montrent une modulation significative des performances d’AT après la procédure de stimulation chez les sujets SZ (n=2). Cela suggère que les déficits d’AT pourraient être dépendants de mécanismes d’excitabilité et de plasticité des neurones du SAC modulables par tES. Pris ensembles, ces résultats confirment l’influence d’altérations mécanistiques du SAC sur les déficits d’AT dans la SZ, dont les spécificités anatomo-fonctionnelles seront à confirmer par des études de validation et des explorations neurophysiologiques « temps réel » du SAC en situation d’AT. En perspective, comme les paradigmes de « tone-matching » peuvent être implémentés facilement en pratique clinique, ces nouvelles donnés pourront permettre de différencier facilement des sous-types physiopathologiques de patients, et de développer des approches thérapeutiques ciblées sur le SAC à la fois en tES et en entraînement cognitif sensoriel / Schizophrenia (SZ) is a chronic brain disorder with outcome primarily driven by deficits in cognition. These have been related to impaired discrimination of basic auditory information such as pitch, as assessed in tone-matching behavioral paradigms in which subjects are asked to actively discriminate between two short pure tones (300-ms) following a brief delay (500-ms). More specifically, tone-matching indexes early, pre-attentive comparison mechanisms occurring in the central auditory system (CAS, divided into thalamic medial geniculate nucleus (MGN), early auditory (EA) and association auditory (AA) cortical areas). Therefore, characterisations of the CAS functioning associated with tone-matching abilities in SZ individuals may be useful drivers for pathophysiology understanding and therapeutic development. First, we aimed at exploring tone-matching abilities in SZ across major acoustic features (length, pitch, intensity) and different levels of complexity (2-tones, 3-tones, emotional sentences) using psychophysical testing. We predicted that patients would display differential deficits across acoustic features, and present a mediated relationship between tone-matching levels of complexity. Second, we investigated the CAS functioning associated with tone-matching at a neurophysiological level, using resting-state functional connectivity MRI (rsFC-MRI) and CAS-targeted transcranial electrical stimulation (left fronto-temporal tES, 2mA, random noise current, ten 20-min twice-daily sessions). We predicted that functional dysconnectivity within the CAS would be associated with tone-matching impairments, and that tES would significantly modulate these impairments in patients. As complementary, we reviewed historical aspects of basic auditory explorations in SZ and studies investigating basic auditory-training approaches as a potential remediative treatment. Psychophysical studies demonstrated more prominent deficits for length than pitch and, in turn, than intensity (n=29), and showed that 3-tones discrimination mediates the correlation between 2-tones and auditory emotion recognition deficits (n=27). Neurophysiological approaches showed that tone-matching performances are bimodally distributed across SZ subjects (n=310), with one group (SZ-) showing significant reductions in both tone-matching and rsFC-MRI in regions of the bilateral CAS (i.e., between MGN and both EA and AA, as well as reductions between EA and AA, particularly involving parcels which are immediately adjacent to EA), and one group (SZ+) showing intact tone-matching and significant reductions only in EA-AA connectivity. The investigation of CAS-targeted tES impact on tone-matching abilities in patients is still ongoing, but preliminary results demonstrated significant modulations of tone-matching scores after the tES procedure (n=2). Our results demonstrate that SZ individuals present with different patterns of tone-matching deficits across acoustic features, but similar yet hierarchical levels of impairments for processing of simple vs. more complex auditory stimuli. Nevertheless, both feature- and complexity- dependant tone-matching deficits might be associated with different types of anatomo-functional underpinnings in the CAS. In addition, we showed that tone-matching measure segregates between discrete SZ subgroups presenting distinct topographic patterns of functional dysconnectivity in the CAS. Finally, tone-matching deficits might be related to neuronal excitability and plasticity mechanisms in the SAC that are modulated by tES. As tone-matching paradigms can be readily implemented within routine clinical settings, these experimental results may be useful to permit differentiation of discrete subtypes of SZ and to develop both non-invasive brain stimulation and remediative approaches

No description available.

Working memory training improves performance on trained and untrained working memory tasks, but there is little consistent evidence that these gains benefit everyday tasks that rely on working memory. Evidence has shown that transcranial electrical stimulation (tES) may be an effective tool for enhancing cognitive training and promoting transfer. In the first study, participants completed Cogmed working memory training with either active or sham transcranial random noise stimulation (tRNS). Training was associated with substantial gains on the training activities and on transfer measures of working memory with common processing and storage demands to the training tasks. tRNS did not enhance gains on trained or untrained activities. The second study systematically investigated the boundary conditions to training transfer by testing whether gains following backward digit recall (BDR) training transferred within- and across-paradigm to untrained backward recall and n-back tasks with varying degrees of overlap with the training activity. A further aim was to test whether transcranial direct current stimulation (tDCS) enhanced training and transfer. Participants were allocated to one of three conditions: (i) BDR training with active tDCS, (ii) BDR training with sham tDCS, or (iii) visual search control training with sham tDCS. The results indicated that training transfer is constrained by paradigm, but not by stimuli domain or stimuli materials. There was no evidence that tDCS enhanced performance on the training or transfer tasks. The results of Study 1 and Study 2 provide no evidence that tES enhances the benefits of working memory training. The absence of transfer between backward recall training and n-back in Study 2 suggested the tasks might tap into distinct aspects of working memory. Consequently, the final study used a latent variable approach to explore the degree of overlap between different forms of backward recall and n-back tasks containing digits, letters, or spatial locations as stimuli. The best-fitting factor model included two distinct but related (r = .68) constructs corresponding to backward recall and n-back. Both categories of task were linked to a separate fluid reasoning construct, providing evidence that both are valid measures of higher-order complex cognition. Overall, the experiments in this thesis suggest that working memory tasks tap into separate processes and that training may be targeting and improving these distinct processes, explaining the absence of cross-paradigm transfer.

Existing neurocomputational and empirical data link deficient neuromodulation of the fronto-parietal and hippocampal-striatal circuitries with aging-related increase in processing noise and declines in various cognitive functions. Specifically, the theory of aging neuronal gain control postulates that aging-related suboptimal neuromodulation may attenuate neuronal gain control, which yields computational consequences on reducing the signal-to-noise-ratio of synaptic signal transmission and hampering information processing within and between cortical networks. Intervention methods such as cognitive training and non-invasive brain stimulation, e.g., transcranial direct current stimulation (tDCS), have been considered as means to buffer cognitive functions or delay cognitive decline in old age. However, to date the reported effect sizes of immediate training gains and maintenance effects of a variety of cognitive trainings are small to moderate at best; moreover, training-related transfer effects to non-trained but closely related (i.e., near-transfer) or other (i.e., far-transfer) cognitive functions are inconsistent or lacking. Similarly, although applying different tDCS protocols to reduce aging-related cognitive impairments by inducing temporary changes in cortical excitability seem somewhat promising, evidence of effects on short- and long-term plasticity is still equivocal. In this article, we will review and critically discuss existing findings of cognitive training- and stimulation-related behavioral and neural plasticity effects in the context of cognitive aging, focusing specifically on working memory and episodic memory functions, which are subserved by the fronto-parietal and hippocampal-striatal networks, respectively. Furthermore, in line with the theory of aging neuronal gain control we will highlight that developing age-specific brain stimulation protocols and the concurrent applications of tDCS during cognitive training may potentially facilitate short- and long-term cognitive and brain plasticity in old age.