Fundamental differences in excitatory pyramidal cells across cortical areas and species highlight the implausibility of extrapolation from mouse to primate neurons and cortical networks. Far less is known about comparative regional and species‐specific features of neurochemically distinct cortical inhibitory interneurons. Here, we quantified the density, laminar distribution, and somatodendritic morphology of inhibitory interneurons expressing one or more of the calcium‐binding proteins (CaBPs) (calretinin [CR], calbindin [CB], and/or parvalbumin [PV]) in mouse (Mus musculus) versus rhesus monkey (Macaca mulatta) in two functionally and cytoarchitectonically distinct regions—the primary visual and frontal cortical areas—using immunofluorescent multilabeling, stereological counting, and 3D reconstructions. There were significantly higher densities of CB+ and PV+ neurons in visual compared to frontal areas in both species. The main species difference was the significantly greater density and proportion of CR+ interneurons and lower extent of CaBP coexpression in monkey compared to mouse cortices. Cluster analyses revealed that the somatodendritic morphology of layer 2–3 inhibitory interneurons is more dependent on CaBP expression than on species and area. Only modest effects of species were observed for CB+ and PV+ interneuron morphologies, while CR+ neurons showed no difference. By contrast to pyramidal cells that show highly distinctive area‐ and species‐specific features, here we found more subtle differences in the distribution and features of interneurons across areas and species. These data yield insight into how nuanced differences in the population organization and properties of neurons may underlie specializations in cortical regions to confer species‐ and area‐specific functional capacities.

Much is known about differences in pyramidal cells across cortical areas and species, but studies of interneurons have focused on comparisons within single cortical areas and/or species. Here we quantified the distribution and somato-dendritic morphology of interneurons expressing one or more of the calcium binding proteins (CaBPs) calretinin (CR), calbindin (CB) and/or parvalbumin (PV) in mouse (Mus musculus) versus rhesus monkey (Macaca mulatta) in two functionally and cytoarchitectonically distinct regions- the primary visual and frontal cortical areas. The density, laminar distribution and morphology of interneurons were assessed in serial brain sections using immunofluorescent multi-labeling, stereological counting and 3D reconstructions. There were significantly higher densities of CB+ and PV+ neurons in visual compared to frontal areas in both species. The main species difference was the significantly greater density and proportion of CR+ interneurons and lower extent of CaBP co-expression in monkey compared to mouse cortices. Cluster analyses revealed that the somato-dendritic morphology of layer 2-3 inhibitory interneurons is more dependent on CaBP expression than on species and area. Only modest effects of species were observed for CB+ and PV+ interneuron morphologies, while CR+ neurons showed no difference. By contrast to pyramidal cells which show highly distinctive area- and species-specific features, here we found more subtle differences in the distribution and features of interneurons across areas and species. These data yield insight into how nuanced differences in the population organization and properties of neurons may underlie specializations in cortical regions to confer species and area-specific functional capacities.

Breathing, swallowing, coughing, and voice production are controlled by tightly coordinated actions of intrinsic muscles of the larynx. Students report having difficulty with understanding the movements of cartilages, muscles, and vocal folds in 3D space. Cadaveric dissections have limitations to demonstrating these movements due to limited accessibility, small structures, and difficulty with simulating muscle contraction. In this project we developed a 3D printed model and used an interactive website of the larynx to teach laryngeal muscle actions as a supplement to cadaveric dissection. We hypothesized that students trained on the 3D model would perform better at solving clinical questions involving intrinsic muscles of the larynx compared to students trained using the interactive website. The model was printed from a 3D model of the larynx created by the University of Dundee and BodyParts3D and the Database Center for Life Science https://sketchfab.com/3d‐models/anatomy‐of‐the‐larynx‐a00bc73a303c46248db6a13a88b23404. The model was assembled using the 3D printed cartilages and rubber bands which represented muscles. When a student tugs on the rubber band, the arytenoid cartilages and vocal folds move in the same action as when the muscle contracts in normal conditions. The interactive website is from Dr. Ahmet Sinav https://www1.columbia.edu/sec/itc/hs/medical/anatomy_resources/anatomy/larynx/ and shows animations of the muscle actions as well as video footage from a transnasal endoscopic procedure. One group of students was trained on the movements of the larynx using the website and the other the model. Both groups were then asked to answer clinical questions based on both the model and website. Overall mean scores on the quiz were 90.9% for the students trained on the model (n=22) and 81.6% for the students trained on the website (n=17) a difference that was not statistically significant based on a Mann‐Whitney U test (p=0.19). Students also rated the model and the website using a 1–5 Likert scale. The students trained on the model reported mean ratings of 4.09 and 3.91 for the model and website respectively. A Wilcoxon Sign test was conducted, and the difference was not statistically significant (p= 0.32). The students trained on the model reported mean ratings of 4.33 and 3.94 for the model and website respective. A Wilcoxon Sign test was conducted and the difference was not statistically significant (p= 0.11). The majority of students (27 out of 39) reported that the lesson clarified the anatomy and/or the actions of the muscles of the larynx, regardless of learning modality. Some students reported that the lesson was a great supplement to cadaveric dissection of the larynx because not everyone could participate in the dissections simultaneously, so they could attend the lesson when they could not dissect. While the differences between the two groups were not statistically significant, both groups of students performed well on the clinical questions and they reported that the lesson was an effective suppl...