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Assecondi S, Hu R, Kroeker J, Eskes G, Shapiro K. Older adults with lower working memory capacity benefit from transcranial direct current stimulation when combined with working memory training: A preliminary study. Front Aging Neurosci 2022; 14:1009262. [PMID: 36299611 PMCID: PMC9589058 DOI: 10.3389/fnagi.2022.1009262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 09/20/2022] [Indexed: 11/27/2022] Open
Abstract
Aging is a very diverse process: successful agers retain most cognitive functioning, while others experience mild to severe cognitive decline. This decline may eventually negatively impact one’s everyday activities. Therefore, scientists must develop approaches to counteract or, at least, slow down the negative change in cognitive performance of aging individuals. Combining cognitive training and transcranial direct current stimulation (tDCS) is a promising approach that capitalizes on the plasticity of brain networks. However, the efficacy of combined methods depends on individual characteristics, such as the cognitive and emotional state of the individual entering the training program. In this report, we explored the effectiveness of working memory training, combined with tDCS to the right dorsolateral prefrontal cortex (DLPFC), to manipulate working memory performance in older individuals. We hypothesized that individuals with lower working memory capacity would benefit the most from the combined regimen. Thirty older adults took part in a 5-day combined regimen. Before and after the training, we evaluated participants’ working memory performance with five working memory tasks. We found that individual characteristics influenced the outcome of combined cognitive training and tDCS regimens, with the intervention selectively benefiting old-old adults with lower working memory capacity. Future work should consider developing individualized treatments by considering individual differences in cognitive profiles.
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Affiliation(s)
- Sara Assecondi
- Center for Mind/Brain Sciences—CIMeC, University of Trento, Rovereto, Italy
- Visual Experience Laboratory, School of Psychology, University of Birmingham, Birmingham, United Kingdom
- Center for Human Brain Health (CHBH), University of Birmingham, Birmingham, United Kingdom
- *Correspondence: Sara Assecondi, ,
| | - Rong Hu
- Visual Experience Laboratory, School of Psychology, University of Birmingham, Birmingham, United Kingdom
- Department of Neurology, School of Medicine, Guangzhou First People’s Hospital, South China University of Technology, Guangzhou, China
| | - Jacob Kroeker
- Departments of Psychiatry and Psychology and Neuroscience, Dalhousie University, Halifax, NS, Canada
| | - Gail Eskes
- Departments of Psychiatry and Psychology and Neuroscience, Dalhousie University, Halifax, NS, Canada
| | - Kim Shapiro
- Visual Experience Laboratory, School of Psychology, University of Birmingham, Birmingham, United Kingdom
- Center for Human Brain Health (CHBH), University of Birmingham, Birmingham, United Kingdom
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Esposito M, Ferrari C, Fracassi C, Miniussi C, Brignani D. Responsiveness to left-prefrontal tDCS varies according to arousal levels. Eur J Neurosci 2022; 55:762-777. [PMID: 34978110 PMCID: PMC9302688 DOI: 10.1111/ejn.15584] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 12/03/2021] [Accepted: 12/21/2021] [Indexed: 12/01/2022]
Abstract
Over the past two decades, the postulated modulatory effects of transcranial direct current stimulation (tDCS) on the human brain have been extensively investigated. However, recent concerns on reliability of tDCS effects have been raised, principally due to reduced replicability and to interindividual variability in response to tDCS. These inconsistencies are likely due to the interplay between the level of induced cortical excitability and unaccounted structural and state‐dependent functional factors. On these grounds, we aimed at verifying whether the behavioural effects induced by a common tDCS montage (F3‐rSOA) were influenced by the participants' arousal levels, as part of a broader mechanism of state‐dependency. Pupillary dynamics were recorded during an auditory oddball task while applying either a sham or real tDCS. The tDCS effects were evaluated as a function of subjective and physiological arousal predictors (STAI‐Y State scores and pre‐stimulus pupil size, respectively). We showed that prefrontal tDCS hindered task learning effects on response speed such that performance improvement occurred during sham, but not real stimulation. Moreover, both subjective and physiological arousal predictors significantly explained performance during real tDCS, with interaction effects showing performance improvement only with moderate arousal levels; likewise, pupil response was affected by real tDCS according to the ongoing levels of arousal, with reduced dilation during higher arousal trials. These findings highlight the potential role of arousal in shaping the neuromodulatory outcome, thus emphasizing a more careful interpretation of null or negative results while also encouraging more individually tailored tDCS applications based on arousal levels, especially in clinical populations.
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Affiliation(s)
- Marco Esposito
- Neurophysiology Lab, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
| | - Clarissa Ferrari
- Unit of Statistics, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
| | - Claudia Fracassi
- Neurophysiology Lab, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
| | - Carlo Miniussi
- Center for Mind/Brain Sciences CIMeC, University of Trento, Rovereto, Italy
| | - Debora Brignani
- Neurophysiology Lab, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy.,Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy
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