scholarly journals Mandibular musculature constrains brain–endocast disparity between sarcopterygians

2020 ◽  
Vol 7 (9) ◽  
pp. 200933
Author(s):  
T. J. Challands ◽  
Jason D. Pardo ◽  
Alice M. Clement
Keyword(s):  
Muscle Mass ◽  
Trigeminal Nerve ◽  
Adductor Muscle ◽  
Ambystoma Mexicanum ◽  
Brain Morphology ◽  
Micro Ct ◽  
Latimeria Chalumnae ◽  
Dermal Bones ◽  
The Brain ◽  
Ct And Mri

The transition from water to land by the earliest tetrapods in the Devonian Period is seen as one of the greatest steps in evolution. However, little is understood concerning changes in brain morphology over this transition. Here, we determine the brain–braincase relationship in fishes and basal lissamphibians as a proxy to elucidate the changes that occurred over the fish–tetrapod transition. We investigate six basal extant sarcopterygians spanning coelacanths to salamanders ( Latimeria chalumnae, Neoceratodus, Protopterus aethiopicus, P. dolloi, Cynops, Ambystoma mexicanum ) using micro-CT and MRI and quantify the brain–braincase relationship in these extant taxa. Our results show that regions of lowest brain–endocast disparity are associated with regions of bony reinforcement directly adjacent to masticatory musculature for the mandible except in Neoceratodus and Latimeria . In Latimeria this deviation from the trend can be accounted for by the possession of an intracranial joint and basicranial muscles, whereas in Neoceratodus difference is attributed to dermal bones contributing to the overall neurocranial reinforcement. Besides Neoceratodus and Latimeria, regions of low brain–endocast disparity occur where there is less reinforcement away from high mandibular muscle mass, where the trigeminal nerve complex exits the braincase and where endolymphatic sacs occupy space between the brain and braincase wall. Despite basal tetrapods possessing reduced adductor muscle mass and a different biting mechanism to piscine sarcopterygians, regions of the neurocranium lacking osteological reinforcement in the basal tetrapods Lethiscus and Brachydectes broadly correspond to regions of high brain–endocast disparity seen in extant taxa.

scholarly journals Endocranial morphology of Palaeocene Plesiadapis tricuspidens and evolution of the early primate brain

2014 ◽  
Vol 281 (1781) ◽  
pp. 20132792 ◽  
Author(s):  
Maeva J. Orliac ◽  
Sandrine Ladevèze ◽  
Philip D. Gingerich ◽  
Renaud Lebrun ◽  
Thierry Smith
Keyword(s):  
Brain Size ◽  
Brain Evolution ◽  
Primate Evolution ◽  
Brain Morphology ◽  
Micro Ct ◽  
Crown Group ◽  
Partial Reconstruction ◽  
Primate Brain ◽  
Size And Morphology ◽  
The Brain

Expansion of the brain is a key feature of primate evolution. The fossil record, although incomplete, allows a partial reconstruction of changes in primate brain size and morphology through time. Palaeogene plesiadapoids, closest relatives of Euprimates (or crown-group primates), are crucial for understanding early evolution of the primate brain. However, brain morphology of this group remains poorly documented, and major questions remain regarding the initial phase of euprimate brain evolution. Micro-CT investigation of the endocranial morphology of Plesiadapis tricuspidens from the Late Palaeocene of Europe—the most complete plesiadapoid cranium known—shows that plesiadapoids retained a very small and simple brain. Plesiadapis has midbrain exposure, and minimal encephalization and neocorticalization, making it comparable with that of stem rodents and lagomorphs. However, Plesiadapis shares a domed neocortex and downwardly shifted olfactory-bulb axis with Euprimates. If accepted phylogenetic relationships are correct, then this implies that the euprimate brain underwent drastic reorganization during the Palaeocene, and some changes in brain structure preceded brain size increase and neocortex expansion during evolution of the primate brain.

The musculature and nervous system of the plerocercoid larva of Dibothriorhynchus grossum (Rud.)

Parasitology ◽  
1941 ◽  
Vol 33 (4) ◽  
pp. 373-389 ◽  
Author(s):  
Gwendolen Rees
Keyword(s):  
Nervous System ◽  
Muscle Mass ◽  
Nerve Cells ◽  
The Body ◽  
Lateral Nerve ◽  
Posterior Median ◽  
The Brain ◽  
Ventral Muscle ◽  
Nerve Cords ◽  
Extrinsic Muscles

1. The structure of the proboscides of the larva of Dibothriorhynchus grossum (Rud.) is described. Each proboscis is provided with four sets of extrinsic muscles, and there is an anterior dorso-ventral muscle mass connected to all four proboscides.2. The musculature of the body and scolex is described.3. The nervous system consists of a brain, two lateral nerve cords, two outer and inner anterior nerves on each side, twenty-five pairs of bothridial nerves to each bothridium, four longitudinal bothridial nerves connecting these latter before their entry into the bothridia, four proboscis nerves arising from the brain, and a series of lateral nerves supplying the lateral regions of the body.4. The so-called ganglia contain no nerve cells, these are present only in the posterior median commissure which is therefore the nerve centre.

scholarly journals Magnetic Resonace–Based Attenuation Correction for Micro–Single-Photon Emission Computed Tomography

2012 ◽  
Vol 11 (2) ◽  
pp. 7290.2011.00036 ◽  
Author(s):  
Vincent Keereman ◽  
Yves Fierens ◽  
Christian Vanhove ◽  
Tony Lahoutte ◽  
Stefaan Vandenberghe
Keyword(s):  
Attenuation Correction ◽  
Single Photon ◽  
Photon Emission ◽  
The Body ◽  
Emission Computed Tomography ◽  
Micro Ct ◽  
Mr Images ◽  
Brain Scans ◽  
The Brain ◽  
Photon Emission Computed Tomography

Attenuation correction is necessary for quantification in micro–single-photon emission computed tomography (micro-SPECT). In general, this is done based on micro–computed tomographic (micro-CT) images. Derivation of the attenuation map from magnetic resonance (MR) images is difficult because bone and lung are invisible in conventional MR images and hence indistinguishable from air. An ultrashort echo time (UTE) sequence yields signal in bone and lungs. Micro-SPECT, micro-CT, and MR images of 18 rats were acquired. Different tracers were used: hexamethylpropyleneamine oxime (brain), dimercaptosuccinic acid (kidney), colloids (liver and spleen), and macroaggregated albumin (lung). The micro-SPECT images were reconstructed without attenuation correction, with micro-CT-based attenuation maps, and with three MR-based attenuation maps: uniform, non-UTE-MR based (air, soft tissue), and UTE-MR based (air, lung, soft tissue, bone). The average difference with the micro-CT-based reconstruction was calculated. The UTE-MR-based attenuation correction performed best, with average errors ≤ 8% in the brain scans and ≤ 3% in the body scans. It yields nonsignificant differences for the body scans. The uniform map yields errors of ≤ 6% in the body scans. No attenuation correction yields errors ≥ 15% in the brain scans and ≥ 25% in the body scans. Attenuation correction should always be performed for quantification. The feasibility of MR-based attenuation correction was shown. When accurate quantification is necessary, a UTE-MR-based attenuation correction should be used.

CT and MRI of the Brain in Inherited Neurometabolic Disorders

1992 ◽  
Vol 7 (1_suppl) ◽  
pp. S112-S131 ◽  
Author(s):  
Jan Brismar
Keyword(s):  
World Literature ◽  
Autosomal Recessive ◽  
Wide Spectrum ◽  
Neurometabolic Disorder ◽  
Neurometabolic Disorders ◽  
Number Of Patients ◽  
Pediatric Neurologist ◽  
The Brain ◽  
Very High ◽  
Ct And Mri

The incidence of many autosomal recessive neurometabolic disorders is very high in Saudi Arabia, probably as a result of the frequency of consanguineous marriages. Because our hospital is the main referral center for the entire Kingdom, we examine a large number of patients who have a wide spectrum of neurometabolic disorders. We add our experience and review the world literature. Though a specific diagnosis is radiologically possible in a few disorders, the diagnosis must always be verified biochemically. When the patient is referred from a pediatric neurologist with the diagnosis of neurometabolic disorder, the aim of the neuroradiologist is to determine the amount of brain damage present and to follow the response to given therapy. When the patient is referred with a nonspecific diagnosis, such as delayed development, the aim is to suggest the possibility of a neurometabolic disorder and to initiate further evaluation including possible therapy and genetic counseling. (J Child Neurol 1992;7(Suppl):S112-S131.)

Mutations affecting neurogenesis and brain morphology in the zebrafish, Danio rerio

Development ◽  
1996 ◽  
Vol 123 (1) ◽  
pp. 205-216 ◽  
Author(s):  
Y.J. Jiang ◽  
M. Brand ◽  
C.P. Heisenberg ◽  
D. Beuchle ◽  
M. Furutani-Seiki ◽  
...  
Keyword(s):  
Cell Types ◽  
Brain Morphology ◽  
Abnormal Development ◽  
Radial Glial Cells ◽  
Complementation Groups ◽  
Early Neurogenesis ◽  
Radial Glial ◽  
General Organization ◽  
Neurogenic Mutants ◽  
The Brain

In a screen for embryonic mutants in the zebrafish a large number of mutants were isolated with abnormal brain morphology. We describe here 26 mutants in 13 complementation groups that show abnormal development of large regions of the brain. Early neurogenesis is affected in white tail (wit). During segmentation stages, homozygous wit embryos display an irregularly formed neural keel, particularly in the hindbrain. Using a variety of molecular markers, a severe increase in the number of various early differentiating neurons can be demonstrated. In contrast, late differentiating neurons, radial glial cells and some nonneural cell types, such as the neural crest-derived melanoblasts, are much reduced. Somitogenesis appears delayed. In addition, very reduced numbers of melanophores are present posterior to the mid-trunk. The wit phenotype is reminiscent of neurogenic mutants in Drosophila, such as Notch or Delta. In mutant parachute (pac) embryos the general organization of the hindbrain is disturbed and many rounded cells accumulate loosely in the hindbrain and midbrain ventricles. Mutants in a group of 6 genes, snakehead(snk), natter (nat), otter (ott), fullbrain (ful), viper (vip) and white snake (wis) develop collapsed brain ventricles, before showing signs of general degeneration. atlantis (atl), big head (bid), wicked brain (win), scabland (sbd) and eisspalte (ele) mutants have different malformation of the brain folds. Some of them have transient phenotypes, and mutant individuals may grow up to adults.

scholarly journals Agreement Between Computed Tomography And Magnetic Resonance Imaging In Measuring Optic Nerve Sheath Diameter

2018 ◽  
Vol 10 (3) ◽  
pp. 22
Author(s):  
Haider N. Al-Tameemi ◽  
Neda M. Helel
Keyword(s):  
Magnetic Resonance Imaging ◽  
Optic Nerve ◽  
Magnetic Resonance ◽  
Ct Scan ◽  
Optic Nerve Sheath Diameter ◽  
Resonance Imaging ◽  
Perfect Agreement ◽  
Nerve Sheath ◽  
The Brain ◽  
Ct And Mri

BACKGROUND: Neuroimaging is increasingly used as a non-invasive method to assess raised intracranial pressure (ICP). Optic nerve sheath diameter (ONSD) measurement using brain magnetic resonance imaging (MRI) has been shown to correlate well with invasively measured ICP, however little research has been conducted on the ONSD measurement using computerized tomography (CT) in correlation with ICP. This study was done to investigate whether CT scan can reliably replace MRI in measuring ONSD.METHOD: A cross-sectional comparative study was conducted on 50 adult patients (29 females and 21 males), who underwent both CT and MRI of the brain along 10-month period. Using the brain axial section, the transverse ONSD was measured at 3 mm behind the globe in both modalities. Agreement between CT and MRI readings was assessed using intraclass correlation (ICC) and Kappa method.RESULTS: There was a strongly positive and statistically significant correlation between ONSD measurement using CT scan and MRI (p value <0.001). There was almost perfect agreement between CT scan and MRI in measuring ONSD (ICC=0.987 and Kappa =0.837). Similar agreement was obtained when cases stratified into normal (≤ 5mm) and thickened (> 5mm) ONSD (ICC=0.947 and 0.972 respectively).CONCLUSION: CT scan is a reliable substitute for MRI in measuring ONSD with almost perfect agreement between the two modalities. It might be good practice to include ONSD measurement in the initial evaluation of brain CT scan in any patient with suspected raised ICP.

scholarly journals Skeletal muscle mass and sarcopenia can be determined with 1.5-T and 3-T neck MRI scans, in the event that no neck CT scan is performed

2020 ◽  
Author(s):  
Aniek T. Zwart ◽  
Jan-Niklas Becker ◽  
Maria J. Lamers ◽  
Rudi A. J. O. Dierckx ◽  
Geertruida H. de Bock ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Head And Neck Cancer ◽  
Head And Neck ◽  
Muscle Mass ◽  
Skeletal Muscle Mass ◽  
Correlation Coefficients ◽  
Adverse Outcomes ◽  
Ct Scans ◽  
Mri Scans ◽  
Ct And Mri

Abstract Objectives Cross-sectional area (CSA) measurements of the neck musculature at the level of third cervical vertebra (C3) on CT scans are used to diagnose radiological sarcopenia, which is related to multiple adverse outcomes in head and neck cancer (HNC) patients. Alternatively, these assessments are performed with neck MRI, which has not been validated so far. For that, the objective was to evaluate whether skeletal muscle mass and sarcopenia can be assessed on neck MRI scans. Methods HNC patients were included between November 2014 and November 2018 from a prospective data-biobank. CSAs of the neck musculature at the C3 level were measured on CT (n = 125) and MRI neck scans (n = 92 on 1.5-T, n = 33 on 3-T). Measurements were converted into skeletal muscle index (SMI), and sarcopenia was defined (SMI < 43.2 cm2/m2). Pearson correlation coefficients, Bland–Altman plots, McNemar test, Cohen’s kappa coefficients, and interclass correlation coefficients (ICCs) were estimated. Results CT and MRI correlated highly on CSA and SMI (r = 0.958–0.998, p < 0.001). The Bland–Altman plots showed a nihil mean ΔSMI (− 0.13–0.44 cm2/m2). There was no significant difference between CT and MRI in diagnosing sarcopenia (McNemar, p = 0.5–1.0). Agreement on sarcopenia diagnosis was good with κ = 0.956–0.978 and κ = 0.870–0.933, for 1.5-T and 3-T respectively. Observer ICCs in MRI were excellent. In general, T2-weighted images had the best correlation and agreement with CT. Conclusions Skeletal muscle mass and sarcopenia can interchangeably be assessed on CT and 1.5-T and 3-T MRI neck scans. This allows future clinical outcome assessment during treatment irrespective of used modality. Key Points • Screening for low amount of skeletal muscle mass is usually measured on neck CT scans and is highly clinical relevant as it is related to multiple adverse outcomes in head and neck cancer patients. • We found that skeletal muscle mass and sarcopenia determined on CT and 1.5-T and 3-T MRI neck scans at the C3 level can be used interchangeably. • When CT imaging of the neck is missing for skeletal muscle mass analysis, patients can be assessed with 1.5-T or 3-T neck MRIs.

scholarly journals A new method for reconstructing brain morphology: applying the brain-neurocranial spatial relationship in an extant lungfish to a fossil endocast

2016 ◽  
Vol 3 (7) ◽  
pp. 160307 ◽  
Author(s):  
Alice M. Clement ◽  
Robin Strand ◽  
Johan Nysjö ◽  
John A. Long ◽  
Per E. Ahlberg
Keyword(s):  
Three Dimensional ◽  
Spatial Relationship ◽  
Software Tool ◽  
Morphological Data ◽  
Brain Morphology ◽  
Cranial Cavity ◽  
Distance Map ◽  
Computed Tomographic ◽  
Phylogenetic Implications ◽  
The Brain

Lungfish first appeared in the geological record over 410 million years ago and are the closest living group of fish to the tetrapods. Palaeoneurological investigations into the group show that unlike numerous other fishes—but more similar to those in tetrapods—lungfish appear to have had a close fit between the brain and the cranial cavity that housed it. As such, researchers can use the endocast of fossil taxa (an internal cast of the cranial cavity) both as a source of morphological data but also to aid in developing functional and phylogenetic implications about the group. Using fossil endocast data from a three-dimensional-preserved Late Devonian lungfish from the Gogo Formation, Rhinodipterus , and the brain-neurocranial relationship in the extant Australian lungfish, Neoceratodus , we herein present the first virtually reconstructed brain of a fossil lungfish. Computed tomographic data and a newly developed ‘brain-warping’ method are used in conjunction with our own distance map software tool to both analyse and present the data. The brain reconstruction is adequate, but we envisage that its accuracy and wider application in other taxonomic groups will grow with increasing availability of tomographic datasets.

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