Clinical Evaluation of Cingulum Bundle Connectivity for Neurosurgical Hypothesis Development.

BACKGROUND: The cingulum bundle (CB) has long been a target for psychiatric neurosurgical procedures, but with limited understanding of the brain networks being impacted. Recent advances in human tractography could provide a foundation to better understand the effects of neurosurgical interventions on the CB; however, the reliability of tractography remains in question. OBJECTIVE: To evaluate the ability of different tractography techniques, derived from typical, human diffusion-weighted imaging (DWI) data, to characterize CB connectivity described in animal models. This will help validate the clinical applicability of tractography, and generate insight on current and future neurosurgical targets for psychiatric disorders. METHODS: Connectivity of the CB in 15 healthy human subjects was evaluated using DWI-based tractography, and compared to tract-tracing findings from nonhuman primates. Brain regions of interest were defined to coincide with the animal model. Tractography was performed using 3 techniques (FSL probabilistic, Camino probabilistic, and Camino deterministic). Differences in connectivity were assessed, and the CB segment with the greatest connectivity was determined. RESULTS: Each tractography technique successfully reproduced the animal tracing model with a mean accuracy of 72% (68-75%, P < .05). Additionally, one region of the CB, the rostral dorsal segment, had significantly greater connectivity to associated brain structures than all other CB segments (P < .05). CONCLUSION: Noninvasive, in vivo human analysis of the CB, using clinically available DWI for tractography, consistently reproduced the results of an animal tract-tracing model. This suggests that tractography of the CB can be used for clinical applications, which may aid in neurosurgical targeting for psychiatric disorders.

Instructions to suppress semantic memory enhances or has no effect on P300 in a concealed information test (CIT).

The present study investigated the extent to which people can suppress semantic memory as indexed with the P300 ERP and the autobiographical implicit association test (aIAT). In EXP 1, participants (22) were run in a counterbalanced repeated measures study in both simply knowledgeable (SK) and knowledgeable with suppression (SP) conditions. A P300-based, concealed information test ("Complex Trial Protocol"; CTP) with a 50/50 Target/Nontarget (T/NT) ratio was given both with and without instructions to suppress semantic memories. The results showed increased P300s to probe name stimuli, reduced (but still high positive) aIAT d-scores, and increased simple reaction times to all stimuli used in ERP tests in the SP condition. EXP 2 was similar, but with SP and SK in two separate groups, and a 20/80 T/NT ratio. Again, ERP and aIAT results failed to show a suppression effect for semantic memory. The behavioral data suggest some task demand effects under suppression instructions, and that EXP 1 was more demanding than EXP 2.

Evidence suggesting superiority of visual (verbal) vs. auditory test presentation modality in the P300-based, Complex Trial Protocol for concealed autobiographical memory detection.

One group of participants received a series of city name stimuli presented on trials of the Complex Trial Protocol (CTP) version of a P300-based, concealed information test (CIT). Stimuli were presented on alternating trials in either auditory or visual presentation modality. In 1/7 of the trials the participant's home town (probe) repeatedly appeared in a series of 6 other (irrelevant) repeated city names. In both modalities, probe stimuli produced larger P300s than irrelevant stimuli. Visual stimuli produced shorter behavioral reaction times and P300 latencies, as well as larger P300 probe amplitudes, probe-irrelevant amplitude differences, and individual diagnostic accuracies than the same stimuli presented in the auditory modality. Possible reasons for these effects are discussed, and subject to discussed limitations, the applied conclusion reached is that in all CITs, visual presentation of stimuli, if feasible, should be preferentially used.

Importance of the brow in facial expressiveness during human communication.

OBJECTIVE: The objective of this study was to evaluate laterality and upper/lower face dominance of expressiveness during prescribed speech using a unique validated image subtraction system capable of sensitive and reliable measurement of facial surface deformation. RATIONALE: Observations and experiments of central control of facial expressions during speech and social utterances in humans and animals suggest that the right mouth moves more than the left during nonemotional speech. However, proficient lip readers seem to attend to the whole face to interpret meaning from expressed facial cues, also implicating a horizontal (upper face-lower face) axis. STUDY DESIGN: Prospective experimental design. Experimental maneuver: recited speech. OUTCOME MEASURE: image-subtraction strength-duration curve amplitude. METHODS: Thirty normal human adults were evaluated during memorized nonemotional recitation of 2 short sentences. Facial movements were assessed using a video-image subtractions system capable of simultaneously measuring upper and lower specific areas of each hemiface. RESULTS: The results demonstrate both axes influence facial expressiveness in human communication; however, the horizontal axis (upper versus lower face) would appear dominant, especially during what would appear to be spontaneous breakthrough unplanned expressiveness. CONCLUSION: These data are congruent with the concept that the left cerebral hemisphere has control over nonemotionally stimulated speech; however, the multisynaptic brainstem extrapyramidal pathways may override hemiface laterality and preferentially take control of the upper face. Additionally, these data demonstrate the importance of the often-ignored brow in facial expressiveness. LEVEL OF EVIDENCE: Experimental study. EBM levels not applicable.

Multiple rapid swallow responses during esophageal high-resolution manometry reflect esophageal body peristaltic reserve.

OBJECTIVES: Dysphagia may develop following antireflux surgery as a consequence of poor esophageal peristaltic reserve. We hypothesized that suboptimal contraction response following multiple rapid swallows (MRS) could be associated with chronic transit symptoms following antireflux surgery. METHODS: Wet swallow and MRS responses on esophageal high-resolution manometry (HRM) were characterized collectively in the esophageal body (distal contractile integral (DCI)), and individually in each smooth muscle contraction segment (S2 and S3 amplitudes) in 63 patients undergoing antireflux surgery and in 18 healthy controls. Dysphagia was assessed using symptom questionnaires. The MRS/wet swallow ratios were calculated for S2 and S3 peak amplitudes and DCI. MRS responses were compared in patients with and without late postoperative dysphagia following antireflux surgery. RESULTS: Augmentation of smooth muscle contraction (MRS/wet swallow ratios >1.0) as measured collectively by DCI was seen in only 11.1% with late postoperative dysphagia, compared with 63.6% in those with no dysphagia and 78.1% in controls (P≤0.02 for each comparison). Similar results were seen with S3 but not S2 peak amplitude ratios. Receiver operating characteristics identified a DCI MRS/wet swallow ratio threshold of 0.85 in segregating patients with late postoperative dysphagia from those with no postoperative dysphagia with a sensitivity of 0.67 and specificity of 0.64. CONCLUSIONS: Lack of augmentation of smooth muscle contraction following MRS is associated with late postoperative dysphagia following antireflux surgery, suggesting that MRS responses could assess esophageal smooth muscle peristaltic reserve. Further research is warranted to determine if antireflux surgery needs to be tailored to the MRS response.

The value of multiple rapid swallows during preoperative esophageal manometry before laparoscopic antireflux surgery.

BACKGROUND: When multiple swallows are rapidly administered, esophageal peristalsis is inhibited, and pronounced lower esophageal sphincter relaxation ensues. After the last swallow of the series, a robust contraction sequence results. The authors hypothesize that multiple rapid swallows (MRS) may have value in predicting esophageal transit symptoms in patients undergoing laparoscopic antireflux surgery (LARS). METHODS: Records of patients undergoing esophageal high-resolution manometry (HRM) before LARS were evaluated. The evaluation of MRS included adequate inhibitory response during swallows and the contraction pattern after MRS. Dysphagia was scored based on a product of symptom frequency and severity using 5-point Likert scales. A composite dysphagia score comprised the sum of scores for solid and liquid dysphagia, and a score of 4 or higher was considered clinically significant. The normal and abnormal MRS responses of patients with preoperative, early, and late postoperative dysphagia were compared with those of patients with no dysphagia. RESULTS: In this study, 63 patients (mean age, 60.3 ± 1.7 years, 48 women) undergoing HRM before LARS successfully performed MRS (median, 5 swallows; longest interval between swallows, 3.2 ± 0.1 s). After MRS, 14 patients (22.2%) had an intact peristaltic sequence. Complete failure of peristalsis was seen in 21 (33.3%), and incomplete esophageal inhibition in 25 (39.7%) of the remaining patients. When stratified by presence or absence of dysphagia, 58.3% of the subjects without dysphagia had a normal MRS response, whereas 83.3% had formation of peristaltic segments after MRS. In contrast, only 14% of the subjects with dysphagia had a normal MRS response (p ≤ 0.003 vs. the subjects with no dysphagia). Abnormal MRS responses were more prevalent in the patients with any preoperative and late postoperative dysphagia (p = 0.04 across groups) and in those with clinically significant dysphagia (p = 0.08 across groups). CONCLUSIONS: High-resolution manometry with MRS helps to predict dysphagia in subjects undergoing preoperative esophageal function testing before LARS.