It is well established that serotonergic fibers distribute throughout the brain. Abnormal densities or patterns of serotonergic fibers have been implicated in neuropsychiatric disorders. Although many classical studies have examined the distribution pattern of serotonergic fibers, most of them were either limited to specific brain areas or had limitations in demonstrating the fine axonal morphology. In this study, we utilize male mice expressing green fluorescence protein under the serotonin transporter (SERT) promoter to map the topography of serotonergic fibers across the rostro-caudal extent of each brain area. We demonstrate previously unreported regional density and fine-grained anatomy of serotonergic fibers. Our findings include: (a) SERT fibers distribute abundantly in the thalamic nuclei close to the midline and dorsolateral areas, in most of the hypothalamic nuclei with few exceptions such as the median eminence and arcuate nuclei, and within the basal amygdaloid complex and lateral septal nuclei, (b) the source fibers of innervation of the hippocampus traverse through the septal nuclei before reaching its destination, (c) unique, filamentous type of straight terminal fibers within the nucleus accumbens, (d) laminar pattern of innervation in the hippocampus, olfactory bulb and cortex with heterogenicity in innervation density among the layers, (e) cortical labeling density gradually decreases rostro-caudally, (f) fibers traverse and distribute mostly within the gray matter, leaving the white fiber bundles uninnervated, and (g) most of the highly labeled nuclei and cortical areas have predominant anatomical connection to limbic structures. In conclusion, we provide novel, regionally specific insights on the distribution map of serotonergic fibers using transgenic mouse.

Maternally inherited duplication of chromosome 15q11-q13 (Dup15q) is a pathogenic copy number variation (CNV) associated with autism spectrum disorder (ASD). Recently, paternally derived duplication has also been shown to contribute to the development of ASD. The molecular mechanism underlying paternal Dup15q remains unclear. Here, we conduct genetic and overexpression-based screening and identify Necdin (Ndn) as a driver gene for paternal Dup15q resulting in the development of ASD-like phenotypes in mice. An excess amount of Ndn results in enhanced spine formation and density as well as hyperexcitability of cortical pyramidal neurons. We generate 15q dupΔNdn mice with a normalized copy number of Ndn by excising its one copy from Dup15q mice using a CRISPR-Cas9 system. 15q dupΔNdn mice do not show ASD-like phenotypes and show dendritic spine dynamics and cortical excitatory-inhibitory balance similar to wild type animals. Our study provides an insight into the role of Ndn in paternal 15q duplication and a mouse model of paternal Dup15q syndrome.

Introduction: The temporo-mandibular joint (TMJ) is a synovial joint between the articular fossa of the temporal bone and the mandibular condyle. It is condylar variety of joint. The most important functions of the TMJ are mastication and speech and are of great interest to anatomists, dentists, orthodontists and oro-maxillo-facial surgeons. The study was conducted with objective to establish the surface projection of Temporo-mandibular joint (TMJ) using tragus of ear as land mark. Materials and methods: Twenty five cadavers dissected in pre auricular area on both right and left side were studied. Out of 25 cadavers, 18 were male and seven were females. The temporo-mandibular joints were exposed on both sides, keeping the tragus of the ear intact. Altogether fifty temporo-mandibular joints were studied. On living persons, condylar head of TMJ were palpated while the subjects were carrying out side to side movement of lower jaw. The distance between the summit of the tragus and the marking on condylar head was measured with the help of divider and scale. Result: The mean distance in millimeter (mm) from midpoint of condylar head to the summit of tragus in all living subjects and cadavers (n=150) was 12.5 ± 3.5 mm and the mean length of distal phalanx of fore finger in all living subjects and cadavers (n=150) was 22 ± 4 mm. Conclusion: The mandibular condyle can be palpated at 12.5 ± 3.5 mm distance from summit of tragus of ear (i.e. Half-length of distal phalanx of fore finger which is 22 ± 4 mm) just below the inferior border of zygomatic arch.