Table 2.

Imaging studies using a treatment-based study paradigm in patients with MDD.

Study authors	Population	Paradigm	Imaging results
ANTIDEPRESSANT TREATMENT RESPONSIVITY
Lui et al. (2011)	Un-medicated MDD patients, HAMD ≥ 18 on day of scan (n = 60) Mean age (±SD): Refractory (n = 28, 10 female, 18 male): 33 years ± 11 Non-refractory (n = 32, 11 female, 21 male): 32 years ± 10 Healthy controls (n = 48, 17 female, 31 male). Mean age (±SD): 35 years ± 12	Participants underwent a baseline resting scan (eyes closed) and MDD patients were placed in one of 3 antidepressant medication conditions (tricyclics, SSRIs, SNRIs)	Non-refractory patients had a more distributed ↓ connectivity among ACC, bilateral PFC, HPC, amygdala, and bilateral insula compared to controls ↓Connectivity within the left amygdala/ACC and right insula/precuneus circuits in non-refractory MDD patients compared to controls
TRANSCRANIAL BRAIN STIMULATION (TMS)
Kito et al. (2011)	Treatment resistant MDD patients (n = 26, 12 female, 14 male). Mean age (±SD): 46 years ± 14	A PET scan was taken before and after TMS treatment (eyes closed). TMS included stimulation of the right dorsolateral prefrontal cortex (12 sessions over 3 weeks)	↓ rCBF in anterior and posterior insula following low-frequency TMS ↓ rCBF in anterior insula correlated with therapeutic efficacy of low-frequency TMS
Martinot et al. (2011)	Treatment resistant MDD patients (n = 31). Mean age (±SD): Responders (n = 17, 11 female, 6 male): 49 years ± 6 Non-responders (n = 14, 9 female, 5 male): 46 years ± 9 Healthy controls (n = 39, 11 female, 8 male). Mean age (±SD): 45 years ± 11	Participants underwent a baseline resting scan (eyes closed) and were placed in one of 3 TMS conditions: PET-guided TMS Active standard Sham-standard TMS	Compared to healthy controls, non-responders to TMS treatment had ↓glucose reuptake in the left ACC, bilateral insula, and frontal regions (dorsolateral prefrontal cortex, orbitofrontal cortex)

Imaging results only include those relating to insular activity.