Dorsolateral Prefrontal Cortex Groups Research Articles

Randomized, Sham Controlled Trial of Transcranial Direct Current Stimulation for Painful Diabetic Polyneuropathy

ObjectiveTo investigate the analgesic effect of transcranial direct current stimulation (tDCS) over the primary motor (M1), dorsolateral prefrontal cortex (DLPFC), and sham tDCS in patients with painful diabetic polyneuropathy (PDPN).MethodsPatients with PDPN (n=60) were divided randomly into the three groups (n=20 per group). Each group received anodal tDCS with the anode centered over the left M1, DLPFC, or sham stimulation for 20 minutes at intensity of 2 mA for 5 consecutive days. A blinded physician rated the patients' pain using a visual analog scale (VAS), Clinical Global Impression (CGI) score, anxiety score, sleep quality, Beck Depression Inventory (BDI), and the pain threshold (PT) to pressure.ResultsAfter the tDCS sessions, the M1 group showed a significantly greater reduction in VAS for pain and PT versus the sham and DLPFC groups (p<0.001). The reduction in VAS for pain was sustained after 2 and 4 weeks of follow-up in the M1 group compared with the sham group (p<0.001, p=0.007). Significant differences were observed among the three groups over time in VAS for pain (p<0.001), CGI score (p=0.01), and PT (p<0.001). No significant difference was observed among the groups in sleep quality, anxiety score, or BDI score immediately after tDCS.ConclusionFive daily sessions of tDCS over the M1 can produce immediate pain relief, and relief 2- and 4-week in duration in patients with PDPN. Our findings provide the first evidence of a beneficial effect of tDCS on PDPN.

Discourse production following injury to the dorsolateral prefrontal cortex

Individuals with damage to the prefrontal cortex, and the dorsolateral prefrontal cortex (DLPFC) in particular, often demonstrate difficulties with the formulation of complex language not attributable to aphasia. The present study employed a discourse analysis procedure to characterize the language of individuals with left (L) or right (R) DLPFC lesions. All participants were 30–35 years post-onset of injury and presented with persistent discourse impairments. The discourse performance of the R DLPFC group was not significantly different from either the L DLPFC group or the non-injured comparison group. Individuals from the L DLPFC group demonstrated specific difficulties with narrative coherence and inclusion of critical story components. Both measures were significantly different from the comparison group. The discourse ability of the DLPFC groups was significantly correlated with measures of working memory. Findings support the use of discourse analysis for examining language impairments in individuals with PFC lesions.