Have you been there before? Decoding recognition of spatial scenes from fMRI signals in precuneus.

One potential application of forensic "brain reading" is to test whether a suspect has previously experienced a crime scene. Here, we investigated whether it is possible to decode real life autobiographic exposure to spatial locations using fMRI. In the first session, participants visited four out of eight possible rooms on a university campus. During a subsequent scanning session, subjects passively viewed pictures and videos from these eight possible rooms (four old, four novel) without giving any responses. A multivariate searchlight analysis was employed that trained a classifier to distinguish between "seen" versus "unseen" stimuli from a subset of six rooms. We found that bilateral precuneus encoded information that can be used to distinguish between previously seen and unseen rooms and that also generalized to the two stimuli left out from training. We conclude that activity in bilateral precuneus is associated with the memory of previously visited rooms, irrespective of the identity of the room, thus supporting a parietal contribution to episodic memory for spatial locations. Importantly, we could decode whether a room was visited in real life without the need of explicit judgments about the rooms. This suggests that recognition is an automatic response that can be decoded from fMRI data, thus potentially supporting forensic applications of concealed information tests for crime scene recognition.

A randomized controlled trial of pudendal nerve block for pain relief after episiotomy.

BACKGROUND: Pain from episiotomy or perineal tears during childbirth is associated with significant pain in the postpartum period. We performed this randomized, double-blind, controlled trial to investigate the efficacy of nerve stimulator-guided unilateral pudendal nerve block for pain relief after episiotomy. METHODS: Forty women who gave birth vaginally with mediolateral episiotomy were randomized to receive pudendal nerve block with 15 mL of either ropivacaine 7.5 mg/mL (pudendal group) or normal saline (control group) after repair of the episiotomy. Episiotomy pain was assessed with a visual analog scale at rest at 3, 6, 12, 24, and 48 h postepisiotomy and during activities (walking and sitting). Breakthrough pain (visual analog scale >30 mm) was treated with niflumic acid suppositories 700 mg every 12 h. The primary outcome variables were pain scores at rest and during activities over 48 h postpartum. RESULTS: Demographic and obstetric characteristics were not different between groups. Successful pudendal nerve stimulation was achieved in all patients. Patients in the pudendal group reported significantly lower pain scores at rest than those in the control group at 3, 6, 12, 24, and 48 h after delivery (P < 0.05). They also reported better analgesia while sitting and walking (P < 0.05). Additional analgesia was required by three patients (15%) in the pudendal group versus 17 patients (85%) in the placebo group (P < 0.001). CONCLUSION: This study demonstrates that nerve stimulator-guided unilateral pudendal nerve block with ropivacaine 7.5 mg/mL is associated with decreased pain and need for additional analgesics during the first 48 h postepisiotomy.