None listed
Conditions
Brief summary
A profusion of imaging and lesion based research now indicates that the dorsolateral prefrontal cortex (DLPFC) is a vital substrate for a number of important cognitive functions, particularly working memory (WM). Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique which applies a very weak current to the scalp which can transiently alter underlying brain function as well as behaviour. When applied over the DLPFC, tDCS has been shown to both enhance WM performance in healthy individuals and ameliorate its dysfunction in clinical cohorts. These changes are hypothesised to be due the ability for tDCS to alter the excitability of neurons within the brain, which in tern leads to neuroplasticity-related changes in cognitive function. Nevertheless, to date, the level with which tDCS can modulate cognition remains relatively modest and, as such, research is needed to explore ways of improving the clinical efficacy of this technology. There is currently some limited evidence to suggest that combining tDCS delivery with a cognitive task may have a synergistic effect, leading to greater subsequent improvements in cognition. However, this finding has yet to be systematically explored. The current project, therefore, aims to investigate this potential task-dependency effect in detail in a cohort of healthy adult participants utilising both behavioural and neurophysiological outcome measures.
Interventions
Transcranial direct current stimulation (tDCS) is a safe, non-invasive and painless neuromodulatory technology which has the capacity to temporarily alter cortical excitability and has been shown to improve working memory performance in previous trials. In this study it is delivered to the left dorsolateral prefrontal cortex (DLPFC).
This study employs a randomised, crossover design in which participants take part in three seperate testing sessions held on different days. A washout period of a
Transcranial direct current stimulation (tDCS) is a safe, non-invasive and painless neuromodulatory technology which has the capacity to temporarily alter cortical excitability and has been shown to improve working memory performance in previous trials. In this study it is delivered to the left dorsolateral prefrontal cortex (DLPFC). This study employs a randomised, crossover design in which participants take part in three seperate testing sessions held on different days. A washout period of at least 72 hours between sessions will be employed to reduce any carry over effects of stimulation. Each session involves the administration of either an active or sham (placebo) form of anodal tDCS (a-tDCS). Active a-tDCS will be administered at a stimulation strength of 1.5 mA for 15 minutes. Sham stimulation will involve 30 seconds of stimulation before the stimulator is ramped down to 0 mA. Specifically, in each testing session participants will receive. 1) a-tDCS delivered alone 2) a-tDCS combined with a cognitive task 3) sham tDCS combined with a cognitive task The cognitive task administered will be a computerised version of the the Adjusting Paced Auditory Serial Addition Test (A-PASAT) which measures both speed of information processing and working memory. In this test, single digits are presented aurally to the participant, who is required to add the two most recently presented numbers and give a response. The duration of the interval between the presented numbers is dependent on the participant's level of correctness in responding, with a correct response decreasing and an incorrect response increasing the time interval between presented digits. The test will be administered for a period of approximately 10 minutes.
Sponsors
Monash University
Study design
Allocation
Randomised controlled trial
Intervention model
Crossover
Primary purpose
Treatment
Masking
Blinded (masking used) (Subject)
Eligibility
Sex/Gender
All
Age
18 Years to 60 Years
Healthy volunteers
Yes
Inclusion criteria
1) Healthy right-handed adults who have the capacity to provide informed consent. 2) Have no personal history of psychiatric or neurological illness
Exclusion criteria
1) Anyone suffering from an unstable medical condition, neurological or psychiatric disorder or any history of a seizure disorder or who are currently pregnant or breastfeeding. 2) Anyone with any metallic implants in the head, a pacemaker, cochlear implant medication pump or other electronic device. 3) Anyone currently taking any psychoactive medications. 4) Professional drivers are not able to participate due to the, albeit relatively low, risk of seizure as this could affect their employment.
Outcome results
None listed