Research Summary

Neurobiological Correlates & Translational Implications of Neuromodulation in OCD: A High Definition Transcranial Direct Current Stimulation (HD-tDCS) Study

Obsessive compulsive disorder(OCD) is a common debilitating neuropsychiatric disorder. Nearly 40 to 60 % of patients do not respond satisfactorily to medications(SSRIs), which is the conventional method of treatment. Error monitoring and response inhibition, a critical cognitive function is deficient in OCD and it forms the basis of symptoms. Converging evidence suggests the role of cortico-striato-thalamo-cortical(CSTC) circuits in the neurobiological basis of OCD including the cognitive deficits. Targeted circuitry specific approaches such as high definition transcranial direct current stimulation(HD-tDCS) might be able to modify these cognitive functions. This manipulation of the “critical” cognitive functions could potentially result in clinical improvement in OCD. The present project proposes to examine the neurobiological effects of HD-tDCS on a pivotal cortical region - Pre-SMA (which regulates the striatal functions), using a neurobiologically informed approach. This would be examined through comprehensive assessment of neurohemodynamic changes(fMRI) and electrophysiological changes(EEG) pertaining to error monitoring and response inhibition coupled with the assessment of neurochemical alterations (MRS- NAA and glutamate) in pre-SMA before and after HD-tDCS sessions using a randomised sham controlled design. In addition, the translational implications of modulation of the cognitive function would be examined by assessing the clinical improvement with HD-tDCS.