Study: NCT02426983

Intervention type: DEVICE
Group type: ACTIVE_COMPARATOR
Intervention: Direct Current Stimulation
Description: Comparison between active Direct Current Stimulation (2 mA, 20 minutes) and Sham stimulation (the device is set up, but only turned on for 30 seconds).~Conductive saline-soaked rubber electrodes super-imposed on sponge plates will be placed on the scalp overlying the left auditory cortex (anodal electrode) and on the contralateral forehead above the orbit (reference/cathode). Stimulation will be applied using a battery-driven constant-current regulator (Oasis Pro, Edmonton). In active tDCS sessions, the DC current will be initially increased in a ramp-like fashion over 10 s until reaching 2 mA and will be similarly decreased at the end of stimulation. In active tDCS, stimulation will be maintained for a total of 20 minutes. This will occur in two separate sessions, occurring within weeks. For 'sham' stimulation, the device will only be turned on for 30 seconds. This will occur in two separate sessions, occurring within weeks.

Intervention type: DEVICE
Group type: SHAM_COMPARATOR
Intervention: Direct Current Stimulation
Description: Comparison between active Direct Current Stimulation (2 mA, 20 minutes) and Sham stimulation (the device is set up, but only turned on for 30 seconds).~Conductive saline-soaked rubber electrodes super-imposed on sponge plates will be placed on the scalp overlying the left auditory cortex (anodal electrode) and on the contralateral forehead above the orbit (reference/cathode). Stimulation will be applied using a battery-driven constant-current regulator (Oasis Pro, Edmonton). In active tDCS sessions, the DC current will be initially increased in a ramp-like fashion over 10 s until reaching 2 mA and will be similarly decreased at the end of stimulation. In active tDCS, stimulation will be maintained for a total of 20 minutes. This will occur in two separate sessions, occurring within weeks. For 'sham' stimulation, the device will only be turned on for 30 seconds. This will occur in two separate sessions, occurring within weeks.

Intervention type: DRUG
Group type: ACTIVE_COMPARATOR
Intervention: Dextromethorphan
Description: Comparison between Dextromethorphan and a no-sugar placebo. Dextromethorphan (DMO), a non-competitive NMDA antagonist, will be delivered in the form of generic Life Brand Clear Cough Syrup DM (Trillium Healthcare Products Inc, Brockville, ON), which has high dose of DMO (15 mg/5 ml) with no other major additives. Each subject will receive a dose of 50 ml DM with no-sugar cranberry juice (100 ml) to drink from a mug, while wearing a nose plug. This same dose will be delivered in two separate sessions, occurring within weeks. Each subject will receive a dose of a placebo (150 ml of no-sugar cranberry juice) to drink from a mug, while wearing a nose plug. This same dose will be delivered in two separate sessions, occurring within weeks.

Intervention type: DRUG
Group type: PLACEBO_COMPARATOR
Intervention: Dextromethorphan
Description: Comparison between Dextromethorphan and a no-sugar placebo. Dextromethorphan (DMO), a non-competitive NMDA antagonist, will be delivered in the form of generic Life Brand Clear Cough Syrup DM (Trillium Healthcare Products Inc, Brockville, ON), which has high dose of DMO (15 mg/5 ml) with no other major additives. Each subject will receive a dose of 50 ml DM with no-sugar cranberry juice (100 ml) to drink from a mug, while wearing a nose plug. This same dose will be delivered in two separate sessions, occurring within weeks. Each subject will receive a dose of a placebo (150 ml of no-sugar cranberry juice) to drink from a mug, while wearing a nose plug. This same dose will be delivered in two separate sessions, occurring within weeks.