Identification of multisegmental nociceptive afferents that modulate locomotor circuits in the neonatal mouse spinal cord

Compared to proprioceptive afferent collateral projections, less is known about the anatomical, neurochemical, and functional basis of nociceptive collateral projections modulating lumbar central pattern generators (CPG). Quick response times are critical to ensure rapid escape from aversive stimuli. Furthermore, sensitization of nociceptive afferent pathways can contribute to a pathological activation of motor circuits. We investigated the extent and role of collaterals of capsaicin‐sensitive nociceptive sacrocaudal afferent (nSCA) nerves that directly ascend several spinal segments in Lissauer's tract and the dorsal column and regulate motor activity. Anterograde tracing demonstrated direct multisegmental projections of the sacral dorsal root 4 (S4) afferent collaterals in Lissauer's tract and in the dorsal column. Subsets of the traced S4 afferent collaterals expressed transient receptor potential vanilloid 1 (TRPV1), which transduces a nociceptive response to capsaicin. Electrophysiological data revealed that S4 dorsal root stimulation could evoke regular rhythmic bursting activity, and our data suggested that capsaicin‐sensitive collaterals contribute to CPG activation across multiple segments. Capsaicin's effect on S4‐evoked locomotor activity was potent until the lumbar 5 (L5) segments, and diminished in rostral segments. Using calcium imaging we found elevated calcium transients within Lissauer's tract and dorsal column at L5 segments when compared to the calcium transients only within the dorsal column at the lumbar 2 (L2) segments, which were desensitized by capsaicin. We conclude that lumbar locomotor networks in the neonatal mouse spinal cord are targets for modulation by direct multisegmental nSCA, subsets of which express TRPV1 in Lissauer's tract and the dorsal column. J. Comp. Neurol. 521:2870–2887, 2013. © 2013 Wiley Periodicals, Inc.     

CAC Classics

Background : Thalamotomy has been reported to be successful in ameliorating the motor symptoms of tremor and/or rigidity in people with Parkinson's disease (PD), emphasising the bona fide contribution of this subcortical nucleus to the neural circuitry subserving motor function. Despite evidence of parallel yet segregated associative and motor corticosubcortical-cortical circuits, comparatively few studies have investigated the effects of this procedure on cognitive functions. In particular, research pertaining to the impact of thalamotomy on linguistic processes is fundamentally lacking. Aims : The purpose of this research was to investigate the effects of thalamotomy in the language dominant and non-dominant hemispheres on linguistic functioning, relative to operative theoretical models of subcortical participation in language. This paper compares the linguistic profiles of two males with PD, aged 75 years (10 years of formal education) and 62 years (22 years of formal education), subsequent to unilateral thalamotomy procedures within the language dominant and non-dominant hemispheres, respectively. Methods & Procedures : Comprehensive linguistic profiles comprising general and high-level linguistic abilities in addition to on-line semantic processing skills were compiled up to 1 month prior to surgery and 3 months post-operatively, within perceived "on periods (i.e., when optimally medicated). Pre- and post-operative language performances were compared within-subjects to a group of 16 non-surgical Parkinson's controls (NSPD) and a group of 16 non-neurologically impaired adults (NC). Outcomes & Results : The findings of this research suggest a laterality effect with regard to the contribution of the thalamus to high-level linguistic abilities and, potentially, the temporal processing of semantic information. This outcome supports the application of highlevel linguistic assessments and measures of semantic processing proficiency to the clinical management of individuals with dominant thalamic lesions. Conclusions : The results reported lend support to contemporary theories of dominant thalamic participation in language, serving to further elucidate our current understanding of the role of subcortical structures in mediating linguistic processes, relevant to cortical hemispheric dominance.     

FreeSurfer-based segmentation of hippocampal subfields: A review of methods and applications,with a novel quality control procedure for ENIGMA studies and other collaborative efforts

Structural hippocampal abnormalities are common in many neurological and psychiatric disorders, and variation in hippocampal measures is related to cognitive performance and other complex phenotypes such as stress sensitivity. Hippocampal subregions are increasingly studied, as automated algorithms have become available for mapping and volume quantification. In the context of the Enhancing Neuro Imaging Genetics through Meta Analysis Consortium, several Disease Working Groups are using the FreeSurfer software to analyze hippocampal subregion (subfield) volumes in patients with neurological and psychiatric conditions along with data from matched controls. In this overview, we explain the algorithm's principles, summarize measurement reliability studies, and demonstrate two additional aspects (subfield autocorrelation and volume/reliability correlation) with illustrative data. We then explain the rationale for a standardized hippocampal subfield segmentation quality control (QC) procedure for improved pipeline harmonization. To guide researchers to make optimal use of the algorithm, we discuss how global size and age effects can be modeled, how QC steps can be incorporated and how subfields may be aggregated into composite volumes. This discussion is based on a synopsis of 162 published neuroimaging studies (01/2013–12/2019) that applied the FreeSurfer hippocampal subfield segmentation in a broad range of domains including cognition and healthy aging, brain development and neurodegeneration, affective disorders, psychosis, stress regulation, neurotoxicity, epilepsy, inflammatory disease, childhood adversity and posttraumatic stress disorder, and candidate and whole genome (epi-)genetics. Finally, we highlight points where FreeSurfer-based hippocampal subfield studies may be optimized.     

Effect of catheter diameter on resting pressures in anal fissure patients

PURPOSE: Controversy exists as to whether fissure patients have elevated resting pressures when compared with control patients. The diameter of manometry catheters used in past studies varies widely (1.5–25 mm) and may have contributed to differences observed in resting pressures. A prospective study was undertaken to determine the influence of manometry catheter diameter on maximum resting pressure in patients with idiopathic chronic anal fissures. METHODS: A total of 28 fissure patients and 28 control patients had manometry performed with both a 1.8-mm and a 4.8-mm (external diameter) water-perfused catheter. RESULTS: Mean maximum resting pressure (RP) for fissure patients as measured with the 1.8-mm catheter was 86 (range, 65–115) mmHg and 83 (range, 47–117) mmHg with the 4.8-mm catheter (P=0.65). Mean maximum RP for control patients with the 1.8-mm catheter was 70 (range, 30–108) mmHg and 72 (range, 35–109) mmHg with the 4.8-mm catheter (P=0.07). When fissure and control patients were compared, a significantly higher mean RP was observed in the fissure group for both the 1.8-mm catheter (86 vs.70 mmHg, respectively;P=0.01) and the 4.8-mm catheter (83 vs.72 mmHg, respectively;P=0.03). There was no significant difference in length of the high-pressure zone within each group or when the fissure group and controls were compared, regardless of catheter used. For both groups of patients, there was a significantly higher incidence of ultraslow waves (USWs) observed with the 4.8-mm catheter when compared with the 1.8-mm catheter. The USW frequency was not significantly different when fissure and control groups were compared with either catheter type. CONCLUSIONS: Catheter size did not influence measured maximum RP in fissure patients. The maximum RP was significantly greater for fissure patients overall when compared with the control group, regardless of catheter used. There was an increased frequency of USWs noted with the larger catheter size in all patients; however, these USWs only became apparent when catheter was left at each station until a true baseline RP was obtained.Supported in part by a Columbia-Presbyterian Department of Surgery Research Grant.Poster presentation at the meeting of The American Society of Colon and Rectal Surgeons, Orlando, Florida, May 8 to 13, 1994.