L5 spondylolysis: Anatomical study comparing healed and unhealed lesions.

The anatomy and pathogenesis of spondylolysis has been widely studied; however, the microanatomy of spondylolysis of the lumbar vertebra has not been well described. Therefore, we aim to better elucidate this anatomy. Twenty dry bone specimens of healed and unhealed spondylolysis of the L5 vertebra were collected from human skeletal remains. Twelve L5 vertebrae were examples of unhealed spondylolysis and eight specimens exhibited a healed (i.e., bony fusion of the lesion) spondylolysis lesion. The specimens underwent macro and microanatomical analysis followed by CT and microCT imaging. Finally, selected healed and unhealed lesions were submitted for histological analysis using Mason Trichrome staining. The pars interarticularis of two L5 vertebrae without signs of healed/unhealed spondylolysis were evaluated histologically as controls. Of the 12 unhealed L5 pars defects, three were unilateral on left side. Of the eight healed pars defects, all were unilateral and seven of these were on left sides. One unilateral pars defect also had spina bifida occulta. Both on imaging and histological analysis, healed pars defects were only so superficially and not at deeper levels. Histologically, unhealed edges were made up of dense cortical bone while healed edges were made up primarily of trabecular bone. Based on our anatomical findings, the so-called healed spondylolysis lesions, although externally fused, are not thoroughly fused internally. Moreover, the anterior and posterior edges of the unhealed spondylosysis lesions are irregular and show signs of long-term disarticulation. Taken together, these data suggest that such 'healed' lesions might not be as stable as the normal L5 pars interarticularis.

Top 100 most cited journal articles in anatomy.

The number of citations a journal article receives can be used to represent its impact on its field. The aim of the current study was to identify and characterize the top 100 cited articles in journals related to anatomy. The Journal Citation Report database was searched to identify journals categorized as anatomy and morphology. The top 15 most highly cited journals were selected for review. The articles from these journals were then sorted by "Times Cited". The timeline used was 1976-2001. The top 100 most cited articles were extracted for analysis. Articles were excluded if they focused on basic scientific research or animal studies. Fifteen journals were identified based on our criteria using the Journal Citation Report database and the articles were sorted by most cited; 916 anatomy articles were screened to select the top 100 cited since 1976. Among the selected articles, 46 were published in Journal of Anatomy, 13 in Clinical Anatomy, 12 in Microscopy Research and Technique, 11 in Surgical and Radiologic Anatomy, seven in Brain Structure & Function, five in Annals of Anatomy - AnatomischerAnzeiger, three in Anatomical Record - Advances in Integrative Anatomy and Evolutionary Biology, two in Cells Tissues Organs, and one in Developmental Dynamics. Our study identified the top 100 journal articles in anatomy with a clinical and surgical focus. This compilation of articles could help anatomists and clinicians familiarize themselves with impactful research included in terms of study type and field of anatomy, journal of publication, and recurring authors.

The Sphenoparietal Sinus Revisited: Anatomical and Histological Study With Application to Interventional Procedures and Skull Base Surgery.

Background The sphenoparietal sinus (SPS) is implicated in various clinical pathologies, specifically arteriovenous fistulas and venous sinus thrombosis. This study is aimed to better understand this venous structure of the skull base via histological examination. Methods Ten embalmed and latex-injected adult body donors' heads (20 sides) underwent microdissection of the SPS using a surgical microscope. The entire dura on the underside of the lesser wing of the sphenoid bone encompassing the region known as the groove for the SPS was harvested from each body donor and submitted for histological analysis (H&E, Periodic acid-Schiff [PAS], Masson's Trichrome). Five left and five right transverse sinuses were harvested and analyzed histologically as controls. Results A definitive SPS was identified in 14/20 (70%) of the latex-injected body donors. When present, the sinuses were classified as small, medium, or large. Tributaries included the middle meningeal veins, superficial Sylvian vein, and anterior temporal veins. All sinuses drained medially into the cavernous sinus. For the body donors analyzed histologically, 17 (85%) were consistent with a dural venous sinus and not a vein and were observed to have a rich nerve and arterial supply within their walls. The histological findings of the SPS were similar to those seen for the transverse sinus. The combined prevalence for the SPS in gross and histological body donors was 78%. Conclusions Our findings support the presence of SPS in the majority of body donors. To our knowledge, this is the first histological study of the SPS.

Trabeculae in the basilar venous plexus: anatomical and histological study with application to intravascular procedures.

Few studies have examined the basilar venous plexus (BVP) and to our knowledge, no previous study has described its histology. The present anatomical study was performed to better elucidate these structures. In ten cadavers, the BVP was dissected. The anatomical and histological evaluation of the intraluminal trabeculae within this sinus were evaluated. Once all gross measurements were made, the clivus and overlying BVP were harvested and submitted for histological analysis. A BVP was identified in all specimens and in each of these, intraluminal trabeculae were identified. The mean number of trabeculae per plexus was five. These were most concentrated in the upper half of the clivus and were more often centrally located. These septations traveled in a posterior to anterior direction and usually, from inferiorly to superiorly however some were noted to travel horizontally. In a few specimens the trabeculae had wider bases, especially on the posterior attachment to the meningeal layer of dura mater. More commonly, the trabeculae ended in a denticulate form at their two terminal ends. The trabeculae were on average were 0.85 mm in length. The mean width of the trabeculae was 0.35 mm. These septations were consistent with the cords of Willis as are found in the lumen of some of the other intradural venous sinuses. An understanding of the internal anatomy of the BVP can aid in our understanding of venous pathology. Furthermore, this knowledge will benefit patients undergoing interventional treatments that involve the BVP.

Stress-induced generalization of negative memories is mediated by an extended hippocampal circuit.

Memories of negative experiences exert important control of behavior in the face of actual or anticipated threat. Sometimes, however, this control extends to non-threatening situations, a phenomenon known as overgeneralization of negative memories. Overgeneralization is a reliable cognitive phenotype of major depressive disorder, generalized anxiety disorder, and post-traumatic stress disorder. We therefore sought to develop an animal model to study stress-induced generalization of negative memories (SIG) and determine its dependence on the episodic-like memory circuit. We found that male and female mice, which were trained to differentiate a threatening from neutral context, exhibited robust SIG in response to subsequent social stress. Using chemogenetic circuit manipulations during memory retrieval, we demonstrated that both excitatory afferents to the dorsal hippocampus (DH) from the ventral tegmental area (VTA), and excitatory efferents from the DH to the retrosplenial cortex (RSC) contribute to SIG. Based on the known roles of these projections, we suggest that (1) by targeting subcortical VTA circuits that provide valence signals to the DH, stress prioritizes the retrieval of negative over neutral memories, and (2) by forwarding such information to the RSC, stress engages cortical mechanisms that support the retrieval of general relative to specific memory features. Altogether, these results suggest that various components of the extended hippocampal circuit can serve as treatment targets for memory overgeneralization.

The Top 100 Most Cited Journal Articles in Pediatric Neurosurgery.

With the many papers published in the field of pediatric neurosurgery, it is often difficult to recognize those that have the most impact on future papers, i.e., citable papers. However, citation analysis allows one to better understand which papers are impacting the field the most. Therefore, the current study aimed to evaluate this literature. The Journal Citation Report database was searched for publications with the words "pediatric neurosurgery" or "pediatric neuro" in the title. Using the Web of Science Core Collection, the top 100 journal articles in pediatric neurosurgery from the selected journals were identified and citation analysis was used to identify the most impactful articles. A search was performed on Web of Science Core Collection by searching for each journal under "Publication Name" and using the Boolean "OR" function to separate fields. The results were ordered by the "Times Cited" category, which provided a list of all the articles from the eight journals appearing in the most cited order. The timeline used was from 1976 to 2021. The top 100 most cited articles were extracted from this list for analysis. The following variables were collected from each scientific article: publication journal, impact factor of journal, title, number of citations, year and month of publication, and type of article. Eight journals were identified on the basis of our search criteria and the articles were sorted by most cited; 1609 pediatric neurosurgery journal articles were screened to select the 100 most cited since 1976. This compilation could serve to help clinicians and researchers to familiarize themselves with the journal articles included in terms of study type, study field, journal of publication, and recurring authors.

Stress-related memories disrupt sociability and associated patterning of hippocampal activity: a role of hilar oxytocin receptor-positive interneurons.

In susceptible individuals, memories of stressful experiences can give rise to debilitating socio-affective symptoms. This occurs even when the ability to retrieve such memories is limited, as seen in patients suffering from traumatic amnesia. We therefore hypothesized that the encoding, rather than retrieval, mechanisms of stress-related memories underlie their impact on social and emotional behavior. To test this hypothesis, we used combinations of stress-enhanced and state-dependent fear conditioning, which engage different encoding mechanisms for the formation of stress-related memories. We found that the encoding of stress-enhanced state-dependent memories robustly and sex specifically impairs sociability in male mice and disrupts the asymmetry of dentate gyrus (DG)/CA3 activity accompanying social interactions. These deficits were restored by chemogenetic inactivation of oxytocin receptor-positive interneurons localized in the hilus (Oxtr-HI), and by inactivation of dorsohippocampal efferents to the caudal lateral septum. Together, our data suggest that disrupted patterning of dorsohippocampal DG/CA3 activity underlies stress-induced sociability deficits, and that Oxtr-HI can be a cellular target for improving these deficits.

Excitatory VTA to DH projections provide a valence signal to memory circuits.

The positive or negative value (valence) of past experiences is normally integrated into neuronal circuits that encode episodic memories and plays an important role in guiding behavior. Here, we show, using mouse behavioral models, that glutamatergic afferents from the ventral tegmental area to the dorsal hippocampus (VTA→DH) signal negative valence to memory circuits, leading to the formation of fear-inducing context memories and to context-specific reinstatement of fear. To a lesser extent, these projections also contributed to opioid-induced place preference, suggesting a role in signaling positive valence as well, and thus a lack of dedicated polarity. Manipulations of VTA terminal activity were more effective in females and paralleled by sex differences in glutamatergic signaling. By prioritizing retrieval of negative and positive over neutral memories, the VTA→DH circuit can facilitate the selection of adaptive behaviors when current and past experiences are valence congruent.