Why Does the Face Predict the Brain? Neural Crest Induction, Craniofacial Morphogenesis, and Neural Circuit Development

Bones, brains, and bias-neural crest cell contribution to craniofacial structure

Implicit bias is a natural part of the human psyche and facial appearance is one of the first aspects that people notice when encountering new individuals. The cranial neural crest is key to formation of the facial structure as it is a developmentally transient and plastic cell population that contributes to the neural, muscular, cartilage and bone structures of the face and head. This remarkable cell population, within the context of genetic potential, can play a substantial role in determining how individuals' faces and heads form as well as contributing to anterior brain development. How humans interpret face and head features can lead to biased perceptions, including perceived cognitive ability associated with differences across craniofacial phenotypes. In this Opinion Article, we offer strategies to introduce students to an overview of cranial neural crest development linked to primary research in model organisms and in humans. We then bridge this knowledge with a follow-up activity to foster awareness of cognitive processes and implicit bias in human perception. We provide explicit Learning Goals and guided learning strategies to achieve clear Learning Outcomes. We have developed critical thinking assignments and self-reflection opportunities to engage students and shed light on misconceptions regarding craniofacial features. By introducing the generalized processes whereby neural crest cells contribute to head and face formation, we provide an opportunity to focus on bones, brains, and bias in development in order to encourage students to consider how implicit bias shapes human interaction and scientific work.

Low to Moderate Prenatal Alcohol Exposure and Facial Shape of Children at Age 6 to 8 Years

Importance

In addition to confirmed prenatal alcohol exposure and severe neurodevelopmental deficits, three cardinal facial features are included in the diagnostic criteria for fetal alcohol spectrum disorder. It is not understood whether subtle facial characteristics occur in children without a diagnosis but who were exposed to a range of common pregnancy drinking patterns and, if so, whether these persist throughout childhood.

Objective

To determine whether subtle changes in facial shape with prenatal alcohol exposure found in 12-month-old children were evident at age 6 to 8 years using extended phenotyping methods and, if so, whether facial characteristics were similar to those seen in fetal alcohol spectrum disorder.

Design, Setting, and Participants

In a prospective cohort study in Melbourne, Victoria, Australia, commencing in July 2011 with follow-up through April 2021, pregnant women were recruited in the first trimester from low-risk, metropolitan, public maternity clinics over a period of 12 months. Three-dimensional craniofacial images from 549 children of European descent taken at age 12 months (n = 421 images) and 6 to 8 years (n = 363) were included. Data analysis was performed from May 2021 to October 2024.

Exposures

Predominantly low to moderate prenatal alcohol exposure in the first trimester or throughout pregnancy compared with controls without prenatal alcohol exposure.

Main Outcomes and Measures

Following hierarchical facial segmentation, phenotype descriptors were computed. Hypothesis testing was performed for 63 facial modules to analyze different facial parts independently using principal component analysis and response-based imputed predictor (RIP) scores. Comparison was made with a clinical discovery sample of facial images of children with a confirmed diagnosis of partial or full fetal alcohol syndrome.

Results

A total of 549 children took part in the 3-dimensional craniofacial image analysis, of whom 235 (42.8%) contributed an image at both time points. Time 1 included 421 children, comprising 336 children (159 [47.3%] female) with any prenatal alcohol exposure and 85 control children (45 [52.9%] female); time 2 included 363 children, comprising 260 children with any prenatal alcohol exposure (125 [48.1%] female; mean [SD] age, 6.9 [0.7] years) and 103 control children (53 [51.5%] female; mean [SD] age, 6.8 [0.7] years). At both time points, there was consistent evidence for an association between prenatal alcohol exposure and the shape of the eyes (eg, module 15: RIP partial Spearman ρ, 0.19 [95% CI, 0.10-0.29; P < .001] at 6-8 years) and nose (eg, module 5: RIP partial Spearman ρ, 0.19 [95% CI, 0.09-0.27; P < .001] at 6-8 years), whether exposure occurred only in trimester 1 or throughout pregnancy. Facial variations observed differed from those in the clinical discovery sample.

Conclusions and Relevance

Low to moderate prenatal alcohol exposure was associated with characteristic changes in the face, which persisted until at least 6 to 8 years of age. A linear association between alcohol exposure levels and facial shape was not supported.

AI and early diagnostics: mapping fetal facial expressions through development, evolution, and 4D ultrasound

The development of facial musculature and expressions in the human fetus represents a critical intersection of developmental biology, neurology, and evolutionary anthropology, offering insights into early neurological and social development. Fetal facial expressions, shaped by Cranial Nerve VII, reflect evolutionary adaptations for nonverbal communication and exhibit minimal asymmetry in universal expressions. Advancements in 4D ultrasound imaging and artificial intelligence (AI) have introduced innovative methods for analyzing these movements, revealing their potential as diagnostic tools for neurodevelopmental disorders like Bell's Palsy and Ramsay Hunt Syndrome before birth. These technologies promise early interventions that could significantly improve neonatal outcomes. By integrating imaging, AI, and longitudinal studies, researchers propose a multidisciplinary approach to establish diagnostic criteria for fetal facial movements. However, translating these advancements into clinical practice requires addressing ethical and practical challenges, refining imaging and AI methodologies, and fostering interdisciplinary collaboration. The review highlights the universality of fetal expressions while emphasizing the importance of distinguishing typical variability from pathological markers. In conclusion, these findings suggest transformative potential for maternal-fetal medicine, paving the way for proactive strategies to manage neurodevelopmental risks. Focused research is essential to fully harness these innovations and establish a new frontier in perinatal science.

Craniofacial anomalies in schizophrenia-relevant GFAP.HMOX10-12m mice

Subtle craniofacial dysmorphology has been reported in schizophrenia patients. This dysmorphology includes midline facial elongation, frontonasal anomalies and a sexually dimorphic deviation from normal directional asymmetry of the face, with male patients showing reduced and female patients showing enhanced facial asymmetry relative to healthy control subjects. GFAP.HMOX10-12m transgenic mice (Mus musculus) that overexpress heme oxygenase-1 in astrocytes recapitulate many schizophrenia-relevant neurochemical, neuropathological and behavioral features. As morphogenesis of the brain, skull and face are highly interrelated, we hypothesized that GFAP.HMOX10-12m mice may exhibit craniofacial anomalies similar to those reported in persons with schizophrenia. We examined craniofacial anatomy in male GFAP.HMOX10-12m mice and wild-type control mice at the early adulthood age of 6-8 months. We used computer vision techniques for the extraction and analysis of mouse head shape parameters from systematically acquired 2D digital images, and confirmed our results with landmark-based geometric morphometrics. We performed skull bone morphometry using digital calipers to take linear distance measurements between known landmarks. Relative to controls, adult male GFAP.HMOX10-12m mice manifested craniofacial dysmorphology including elongation of the nasal bones, alteration of head shape anisotropy and reduction of directional asymmetry in facial shape features. These findings demonstrate that GFAP.HMOX10-12m mice exhibit craniofacial anomalies resembling those described in schizophrenia patients, implicating heme oxygenase-1 in their development. As a preclinical mouse model, GFAP.HMOX10-12m mice provide a novel opportunity for the study of the etiopathogenesis of craniofacial and other anomalies in schizophrenia and related disorders.

Chronic paternal alcohol exposures induce dose-dependent changes in offspring craniofacial shape and symmetry

Although dose-response analyses are a fundamental tool in developmental toxicology, few studies have examined the impacts of toxicant dose on the non-genetic paternal inheritance of offspring disease and dysgenesis. In this study, we used geometric morphometric analyses to examine the impacts of different levels of preconception paternal alcohol exposure on offspring craniofacial shape and symmetry in a mouse model. Procrustes ANOVA followed by canonical variant analysis of geometric facial relationships revealed that Low-, Medium-, and High-dose treatments each induced distinct changes in craniofacial shape and symmetry. Our analyses identified a dose threshold between 1.543 and 2.321 g/kg/day. Below this threshold, preconception paternal alcohol exposure induced changes in facial shape, including a right shift in facial features. In contrast, above this threshold, paternal exposures caused shifts in both shape and center, disrupting facial symmetry. Consistent with previous clinical studies, changes in craniofacial shape predominantly mapped to regions in the lower portion of the face, including the mandible (lower jaw) and maxilla (upper jaw). Notably, high-dose exposures also impacted the positioning of the right eye. Our studies reveal that paternal alcohol use may be an unrecognized factor contributing to the incidence and severity of alcohol-related craniofacial defects, complicating diagnostics of fetal alcohol spectrum disorders.

Diphthamide deficiency promotes association of eEF2 with p53 to induce p21 expression and neural crest defects

Diphthamide is a modified histidine residue unique for eukaryotic translation elongation factor 2 (eEF2), a key ribosomal protein. Loss of this evolutionarily conserved modification causes developmental defects through unknown mechanisms. In a patient with compound heterozygous mutations in Diphthamide Biosynthesis 1 (DPH1) and impaired eEF2 diphthamide modification, we observe multiple defects in neural crest (NC)-derived tissues. Knockin mice harboring the patient's mutations and Xenopus embryos with Dph1 depleted also display NC defects, which can be attributed to reduced proliferation in the neuroepithelium. DPH1 depletion facilitates dissociation of eEF2 from ribosomes and association with p53 to promote transcription of the cell cycle inhibitor p21, resulting in inhibited proliferation. Knockout of one p21 allele rescues the NC phenotypes in the knockin mice carrying the patient's mutations. These findings uncover an unexpected role for eEF2 as a transcriptional coactivator for p53 to induce p21 expression and NC defects, which is regulated by diphthamide modification.

Shaping faces: genetic and epigenetic control of craniofacial morphogenesis

Major differences in facial morphology distinguish vertebrate species. Variation of facial traits underlies the uniqueness of human individuals, and abnormal craniofacial morphogenesis during development leads to birth defects that significantly affect quality of life. Studies during the past 40 years have advanced our understanding of the molecular mechanisms that establish facial form during development, highlighting the crucial roles in this process of a multipotent cell type known as the cranial neural crest cell. In this Review, we discuss recent advances in multi-omics and single-cell technologies that enable genes, transcriptional regulatory networks and epigenetic landscapes to be closely linked to the establishment of facial patterning and its variation, with an emphasis on normal and abnormal craniofacial morphogenesis. Advancing our knowledge of these processes will support important developments in tissue engineering, as well as the repair and reconstruction of the abnormal craniofacial complex.

A Novel Perspective on Neuronal Control of Anatomical Patterning, Remodeling, and Maintenance

While the nervous system may be best known as the sensory communication center of an organism, recent research has revealed a myriad of multifaceted roles for both the CNS and PNS from early development to adult regeneration and remodeling. These systems work to orchestrate tissue pattern formation during embryonic development and continue shaping pattering through transitional periods such as metamorphosis and growth. During periods of injury or wounding, the nervous system has also been shown to influence remodeling and wound healing. The neuronal mechanisms responsible for these events are largely conserved across species, suggesting this evidence may be important in understanding and resolving many human defects and diseases. By unraveling these diverse roles, this paper highlights the necessity of broadening our perspective on the nervous system beyond its conventional functions. A comprehensive understanding of the complex interactions and contributions of the nervous system throughout development and adulthood has the potential to revolutionize therapeutic strategies and open new avenues for regenerative medicine and tissue engineering. This review highlights an important role for the nervous system during the patterning and maintenance of complex tissues and provides a potential avenue for advancing biomedical applications.

Anatomical network modules of the human central nervous-craniofacial skeleton system

Anatomical network analysis (AnNA) is a systems biological framework based on network theory that enables anatomical structural analysis by incorporating modularity to model structural complexity. The human brain and facial structures exhibit close structural and functional relationships, suggestive of a co-evolved anatomical network. The present study aimed to analyze the human head as a modular entity that comprises the central nervous system, including the brain, spinal cord, and craniofacial skeleton. An AnNA model was built using 39 anatomical nodes from the brain, spinal cord, and craniofacial skeleton. The linkages were identified using peripheral nerve supply and direct contact between structures. The Spinglass algorithm in the igraph software was applied to construct a network and identify the modules of the central nervous system-craniofacial skeleton anatomical network. Two modules were identified. These comprised an anterior module, which included the forebrain, anterior cranial base, and upper-middle face, and a posterior module, which included the midbrain, hindbrain, mandible, and posterior cranium. These findings may reflect the genetic and signaling networks that drive the mosaic central nervous system and craniofacial development and offer important systems biology perspectives for developmental disorders of craniofacial structures.

Characterization of SHH, SOX3, WNT3A and WNT9B Proteins in Human Non-Syndromic Cleft Lip and Palate Tissue

Orofacial clefts have been associated with specific cleft candidate genes which encode regulatory proteins required for orofacial region development. Cleft candidate genes encode proteins involved with the cleft morphopathogenesis process, but their exact interactions and roles are relatively unclear in human cleft tissue. This study evaluates the presence and correlations of Sonic Hedgehog (SHH), SRY-Box Transcription Factor 3 (SOX3), Wingless-type Family Member 3A (WNT3A) and 9B (WNT9B) protein containing cells in different cleft tissue. Non-syndromic cleft-affected tissue was subdivided into three groups-unilateral cleft lip (UCL) (n = 36), bilateral cleft lip (BCL) (n = 13), cleft palate (CP) (n = 26). Control tissue was obtained from five individuals. Immunohistochemistry was implemented. The semi-quantitative method was used. Non-parametric statistical methods were applied. A significant decrease in SHH was found in BCL and CP tissue. SOX3, WNT3A and WNT9B had a significant decrease in all clefts. Statistically significant correlations were found. The significant decrease in SHH could be associated with BCL and CP pathogenesis. SOX3, WNT3A and WNT9B could have morphopathogenetic involvement in UCL, BCL, and CP. Similar correlations imply the presence of similar pathogenetic mechanisms in different cleft variations.

Transcriptomic Heterogeneity of Skin Across Different Anatomic Sites

Multiomic studies, including RNA sequencing, single-cell RNA sequencing, and epigenomics, can provide insight into the connection between anatomically heterogeneous gene expression profile of the skin and dermatoses-predisposed sites, in which RNA sequencing is essential. Therefore, in this study, 159 skin samples collected mainly from discarded normal skin tissue during surgical treatment for benign skin tumors were used for RNA sequencing. On the basis of cluster analysis, the skin was divided into four regions, with each region showing specific physiological characteristics through differentially expressed gene analysis. The results showed that the head and neck region, perineum, and palmoplantar area were closely associated with lipid metabolism, hormone metabolism, blood circulation, and related neural regulation, respectively. Transcription factor enrichment indicated that different regions were associated with the development of adjacent tissues. Specifically, the head and neck region, trunk and extremities, perineum, and palmoplantar area were associated with the central nervous, axial, urogenital, and vascular systems, respectively. The results were imported into an open website (https://dermvis.github.io/) for retrieval. Our transcriptomic data elucidated that human skin exhibits transcriptomic heterogeneity reflecting physiological and developmental variation at different anatomic sites and provided guidance for further studies on skin development and dermatoses predisposed sites.

Identity, lineage and fates of a temporally distinct progenitor population in the embryonic olfactory epithelium

We defined a temporally and transcriptionally divergent precursor cohort in the medial olfactory epithelium (OE) shortly after it differentiates as a distinct tissue at mid-gestation in the mouse. This temporally distinct population of Ascl1+ cells in the dorsomedial OE is segregated from Meis1+/Pax7+ progenitors in the lateral OE, and does not appear to be generated by Pax7+ lateral OE precursors. The medial Ascl1+ precursors do not yield a substantial number of early-generated ORNs. Instead, they first generate additional proliferative precursors as well as a distinct population of frontonasal mesenchymal cells associated with the migratory mass that surrounds the nascent olfactory nerve. Parallel to these in vivo distinctions, isolated medial versus lateral OE precursors in vitro retain distinct proliferative capacities and modes of division that reflect their in vivo identities. At later fetal stages, these early dorsomedial Ascl1+ precursors cells generate spatially restricted subsets of ORNs as well as other non-neuronal cell classes. Accordingly, the initial compliment of ORNs and other OE cell types is derived from at least two distinct early precursor populations: lateral Meis1/Pax7+ precursors that generate primarily early ORNs, and a temporally, spatially, and transcriptionally distinct subset of medial Ascl1+ precursors that initially generate additional OE progenitors and apparent migratory mass cells before yielding a subset of ORNs and likely supporting cell classes.

Empirical Study of Autism Spectrum Disorder Diagnosis Using Facial Images by Improved Transfer Learning Approach

Autism spectrum disorder (ASD) is a neurological illness characterized by deficits in cognition, physical activities, and social skills. There is no specific medication to treat this illness; only early intervention can improve brain functionality. Since there is no medical test to identify ASD, a diagnosis might be challenging. In order to determine a diagnosis, doctors consider the child's behavior and developmental history. The human face can be used as a biomarker as it is one of the potential reflections of the brain and thus can be used as a simple and handy tool for early diagnosis. This study uses several deep convolutional neural network (CNN)-based transfer learning approaches to detect autistic children using the facial image. An empirical study is conducted to select the best optimizer and set of hyperparameters to achieve better prediction accuracy using the CNN model. After training and validating with the optimized setting, the modified Xception model demonstrates the best performance by achieving an accuracy of 95% on the test set, whereas the VGG19, ResNet50V2, MobileNetV2, and EfficientNetB0 achieved 86.5%, 94%, 92%, and 85.8%, accuracy, respectively. Our preliminary computational results demonstrate that our transfer learning approaches outperformed existing methods. Our modified model can be employed to assist doctors and practitioners in validating their initial screening to detect children with ASD disease.

Evolution and dysfunction of human cognitive and social traits: A transcriptional regulation perspective

Evolutionary changes in brain and craniofacial development have endowed humans with unique cognitive and social skills, but also predisposed us to debilitating disorders in which these traits are disrupted. What are the developmental genetic underpinnings that connect the adaptive evolution of our cognition and sociality with the persistence of mental disorders with severe negative fitness effects? We argue that loss of function of genes involved in transcriptional regulation represents a crucial link between the evolution and dysfunction of human cognitive and social traits. The argument is based on the haploinsufficiency of many transcriptional regulator genes, which makes them particularly sensitive to loss-of-function mutations. We discuss how human brain and craniofacial traits evolved through partial loss of function (i.e. reduced expression) of these genes, a perspective compatible with the idea of human self-domestication. Moreover, we explain why selection against loss-of-function variants supports the view that mutation-selection-drift, rather than balancing selection, underlies the persistence of psychiatric disorders. Finally, we discuss testable predictions.

Surgical management of maxillary trauma in pediatric special needs patient using modified cap splint

Pediatric maxillofacial trauma is a rare entity, which is primarily the reason for an individual surgeon's inexperience in managing such injuries. More so, maxillary injuries are infrequent. Pediatric maxillofacial injuries are usually a result of blunt force trauma such as falls, motor vehicle accidents, bicycle injuries, sports-related injuries, assault, and child abuse. The atypical pattern of facial injuries in the pediatric population necessitates each surgeon to approach individual cases with a unique and innovative technique of management, while still following the basic principles of surgical management of maxillofacial injuries. Since facial trauma and surgical interventions both have the potential to lead to disturbance in growth and development, management should be as conservative as possible. The foundation of any surgical intervention must be developed keeping in perspective, the future growth, and development of dentofacial structures. Pediatric facial trauma management is in itself a disconcerting situation for a maxillofacial surgeon, but when a special needs child is involved it becomes an even more perplex decision. We present a case of maxillary trauma in a pediatric patient with global developmental delay, the treatment dilemma, and a review of current literature.

Zero-TE MRI: principles and applications in the head and neck

Zero echo-time (ZTE) MRI is a novel imaging technique that utilizes ultrafast readouts to capture signal from short-T2 tissues. Additional sequence advantages include rapid imaging times, silent scanning, and artifact resistance. A robust application of this technology is imaging of cortical bone without the use of ionizing radiation, thus representing a viable alternative to CT for both rapid screening and "one-stop-shop" MRI. Although ZTE is increasingly used in musculoskeletal and body imaging, neuroimaging applications have historically been limited by complex anatomy and pathology. In this article, we review the imaging physics of ZTE including pulse sequence options, practical limitations, and image reconstruction. We then discuss optimization of settings for ZTE bone neuroimaging including acquisition, processing, segmentation, synthetic CT generation, and artifacts. Finally, we examine clinical utility of ZTE in the head and neck with imaging examples including malformations, trauma, tumors, and interventional procedures.

Haplotype-Based Single-Step GWAS for Yearling Temperament in American Angus Cattle

Behavior is a complex trait and, therefore, understanding its genetic architecture is paramount for the development of effective breeding strategies. The objective of this study was to perform traditional and weighted single-step genome-wide association studies (ssGWAS and WssGWAS, respectively) for yearling temperament (YT) in North American Angus cattle using haplotypes. Approximately 266 K YT records and 70 K animals genotyped using a 50 K single nucleotide polymorphisms (SNP) panel were used. Linkage disequilibrium thresholds (LD) of 0.15, 0.50, and 0.80 were used to create the haploblocks, and the inclusion of non-LD-clustered SNPs (NCSNP) with the haplotypes in the genomic models was also evaluated. WssGWAS did not perform better than ssGWAS. Cattle YT was found to be a highly polygenic trait, with genes and quantitative trait loci (QTL) broadly distributed across the whole genome. Association studies using LD-based haplotypes should include NCSNPs and different LD thresholds to increase the likelihood of finding the relevant genomic regions affecting the trait of interest. The main candidate genes identified, i.e., ATXN10, ADAM10, VAX2, ATP6V1B1, CRISPLD1, CAPRIN1, FA2H, SPEF2, PLXNA1, and CACNA2D3, are involved in important biological processes and metabolic pathways related to behavioral traits, social interactions, and aggressiveness in cattle. Future studies should further investigate the role of these candidate genes.

Riding the crest to get a head: neural crest evolution in vertebrates

In their seminal 1983 paper, Gans and Northcutt proposed that evolution of the vertebrate 'new head' was made possible by the advent of the neural crest and cranial placodes. The neural crest is a stem cell population that arises adjacent to the forming CNS and contributes to important cell types, including components of the peripheral nervous system and craniofacial skeleton and elements of the cardiovascular system. In the past few years, the new head hypothesis has been challenged by the discovery in invertebrate chordates of cells with some, but not all, characteristics of vertebrate neural crest cells. Here, we discuss recent findings regarding how neural crest cells may have evolved during the course of deuterostome evolution. The results suggest that there was progressive addition of cell types to the repertoire of neural crest derivatives throughout vertebrate evolution. Novel genomic tools have enabled higher resolution insight into neural crest evolution, from both a cellular and a gene regulatory perspective. Together, these data provide clues regarding the ancestral neural crest state and how the neural crest continues to evolve to contribute to the success of vertebrates as efficient predators.