Poster B102, Sunday, March 25, 8:00-10:00 am, Exhibit Hall C
The effects of tDCS on orientation discrimination task performance
Abdullah Bin Dawood1, Abigail Dickinson2, Ali Aytemur1, Clare Howarth1, Elizabeth Milne1, Myles Jones1; 1The University of Sheffield, Sheffield, UK, 2University of California, Los Angeles, CA, USA
Cortical excitation-inhibition (E-I) balance plays a critical role in cognition and behaviour and has been hypothesized to underlie neurodevelopmental disorders such as epilepsy and autism. In the case of Autistic Spectrum Conditions (ASC) differences in E-I balance ratio have been inferred from performance of psychophysical tasks such as the visual Orientation Discrimination Task (ODT). A superior performance of ODT in ASC is thought to be due to increased levels of inhibition in the occipital cortex but studies linking ODT to E-I balance are equivocal. Thus, the current study investigates the putative association between ODT performance and occipital E-I balance by manipulating E-I balance using transcranial Direct Current Stimulation (tDCS). tDCS is a non-invasive brain-stimulation technique that modulates neural excitability: Anodal-tDCS increases excitability, while Cathodal-tDCS increases neural inhibition. 19 neurotypical human participants completed two tDCS-ODT sessions. In each session, participants received 10-minutes ‘off-line’ occipital tDCS (1st session: Sham, 2nd session: Anode or Cathode, 2mA) followed by the ODT. Orientation discrimination thresholds were measured using a two alternative forced choice adaptive staircase procedure. On each trial a reference grating and a target grating were presented sequentially. Participants were asked to judge whether the target grating has been rotated clockwise or anti-clockwise compared to the reference grating using keyboard keys. For oblique ODT performance there was a significant increase in performance following Cathodal tDCS and but no difference following anodal TDCs. As such, this data provides some further evidence that higher neural inhibition may be related to superior performance of the ODT.
Topic Area: PERCEPTION & ACTION: Vision