Transcranial electrical brain stimulation modulates neuronal tuning curves in perception of numerosity and duration

Amir Homayoun Javadi, Iva K Brunec, Vincent Walsh, Will D. Penny, Hugo J Spiers

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)


Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation method with many putative applications and reported to effectively modulate behaviour. However, its effects have yet to be considered at a computational level. To address this we modelled the tuning curves underlying the behavioural effects of stimulation in a perceptual task. Participants judged which of the two serially presented images contained more items (numerosity judgement task) or was presented longer (duration judgement task). During presentation of the second image their posterior parietal cortices (PPCs) were stimulated bilaterally with opposite polarities for 1.6s. We also examined the impact of three stimulation conditions on behaviour: anodal right-PPC and cathodal left-PPC (rA-lC), reverse order (lA-rC) and no-stimulation condition. Behavioural results showed that participants were more accurate in numerosity and duration judgement tasks when they were stimulated with lA-rC and rA-lC stimulation conditions respectively. Simultaneously, a decrease in performance on numerosity and duration judgement tasks was observed when the stimulation condition favoured the other task. Thus, our results revealed a double-dissociation of laterality and task. Importantly, we were able to model the effects of stimulation on behaviour. Our computational modelling showed that participants' superior performance was attributable to a narrower tuning curve--smaller standard deviation of detection noise. We believe that this approach may prove useful in understanding the impact of brain stimulation on other cognitive domains.

Original languageEnglish
Pages (from-to)451-457
Number of pages7
Issue numberPart 2
Early online date15 Aug 2014
Publication statusPublished - 15 Nov 2014


  • Adult
  • Female
  • Functional Laterality
  • Humans
  • Judgment
  • Male
  • Mathematical Concepts
  • Neurological Models
  • Parietal Lobe
  • Time Perception
  • Transcranial Direct Current Stimulation
  • Visual Perception
  • Young Adult

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