scholarly journals On a peculiarity of the cerebral commissures in certain Marsupialia, not hitherto recognised as a distinctive feature or the Diprotodontia

1902 ◽  
Vol 70 (459-466) ◽  
pp. 226-231 ◽  
Keyword(s):  
Distinctive Feature ◽  
Anterior Commissure ◽  
Considerable Time ◽  
Dorsal Area ◽  
Cerebral Commissures ◽  
Coronal Section ◽  
The Brain

It has been known for a considerable time that some of the fibres of the ventral commissure of the cerebrum in certain Marsupials dissociate themselves from the rest of the commissure as soon as they have crossed the mesial plane; and that, instead of passing bodily into the external capsule, which is the usual course of the fibres of the ventral or anterior commissure, they form an aberrant bundle which associates itself with the internal capsule so as to reach the dorsal area of the neopallium by a shorter and slightly less circuitous course (fig. 2). This peculiarity was represented in the drawings of sections through the brains of Macropus and Phascolomys , in 1865, by the late W. H. Flower. It was more distinctly shown in a diagram illustrating a coronal section through the brain of a Derbian Wallaby which was published 27 years later by Johnson Symington.

Neuronal pathways for activation of inhibitory interneurons in pyriform cortex of the rabbit

1983 ◽  
Vol 50 (1) ◽  
pp. 74-88 ◽  
Author(s):  
M. Satou ◽  
K. Mori ◽  
Y. Tazawa ◽  
S. F. Takagi
Keyword(s):  
Anterior Commissure ◽  
Peak Amplitude ◽  
Excitatory Postsynaptic Potential ◽  
Inhibitory Interneurons ◽  
Onset Latency ◽  
Lateral Olfactory Tract ◽  
Peak Period ◽  
Pyriform Cortex ◽  
Spatial Facilitation ◽  
The Brain

The neuronal pathways responsible for the fast inhibitory postsynaptic potentials (IPSPs) elicited in principal cells in the pyriform cortex (PC) by volleys from the olfactory bulb (OB), the lateral olfactory tract (LOT), the anterior commissure (AC), and the deep-lying structures of the PC (DPC) were studied in the rabbit. The central latencies of the fast IPSPs (measured from the onset of the monosynaptic excitatory postsynaptic potential (EPSP) elicited by volleys through the LOT) ranged between 3.0 and 9.3 ms (5.5 +/- 1.3 (SD) ms; n = 54) in the case of OB shocks and between 4.5 and 6.5 ms (5.1 +/- 0.7 (SD) ms; n = 7) in the case of LOT shocks. The onset latencies of the fast IPSPs were between 2.5 and 11.8 ms (5.1 +/- 1.8 (SD) ms; n = 66) in the case of DPC shocks and between 3.5 and 10.1 ms (5.8 +/- 1.5 (SD) ms; n = 61) in the case of AC shocks. The conditioning OB or LOT shocks almost completely eliminated the LOT-evoked fast IPSP when the testing shock was applied at the peak period of the conditioning slow IPSP. The conditioning OB shocks also eliminated the initial part of the OB-evoked fast IPSP, leaving the later part of the fast IPSP almost unchanged. Thus, the onset latency of the OB-evoked fast IPSP was lengthened by 7.1 +/- 2.9 (SD) ms (n = 35) by the conditioning OB shock. The conditioning OB or DPC shocks left the peak amplitude of the DPC-evoked fast IPSP almost unaffected. Similarly, the conditioning OB or AC shocks left the peak amplitude of the AC-evoked fast IPSP almost unaffected. The conditioning OB, DPC, or AC shocks had only a slight influence on the onset latency of the DPC- or AC-evoked fast IPSPs. Rhythmical steps at intervals of 3-5 ms were observed in the rising phase of the OB-evoked fast IPSP. This was interpreted as a result of a repetitive impingement of interneuronal discharges on the impaled cells. Spatial facilitation was observed among the fast IPSPs evoked by volleys from the OB, DPC, and AC when shocks were applied at suitable intervals. A slight facilitation was also seen between the LOT-evoked fast IPSP and the DPC- or AC-evoked fast IPSP. These results were interpreted as a result of the convergence of excitatory synaptic inputs onto the presumed inhibitory interneurons from the four structures of the brain. A temporal facilitation of the fast IPSPs was observed when the OB, DPC, or AC shocks were applied repetitively at short intervals. This suggests a temporal facilitation of the spike discharges of the presumed inhibitory interneurons under similar conditions. From these results, criteria were determined for identifying the inhibitory interneurons.

scholarly journals Callosal Atrophy Correlates with Temporal Lobe Volume and Mental Status in Alzheimer's Disease

2000 ◽  
Vol 27 (3) ◽  
pp. 204-209 ◽  
Author(s):  
Sandra E. Black ◽  
Scott D. Moffat ◽  
David C. Yu ◽  
Jayson Parker ◽  
Peter Stanchev ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Temporal Lobe ◽  
Rating Scale ◽  
Anterior Commissure ◽  
Cognitive Status ◽  
Cognitive Test ◽  
Temporal Lobes ◽  
Cerebral Commissures ◽  
State Examination

Background:Recent studies have reported significant atrophy of the corpus callosum (CC) in Alzheimer's Disease (AD). However, it is currently unknown whether CC atrophy is associated with specific cortical volume changes in AD. Moreover, possible atrophy in extra-callosal commissures has not been examined to date. The purpose of the present study was to quantify atrophy in two cerebral commissures [the CC and the anterior commissure (AC)], to correlate this measure with cognitive status, and to relate commissural size to independent measures of temporal lobe volume in AD patients.Methods:A sample of AD patients and of age- and education-matched normal control subjects (NCs) underwent MRI and a cognitive test battery including the Dementia Rating Scale and Mini Mental State examination. Mid-sagittal regional areas within CC and AC were measured along with superior, middle and inferior temporal lobes volumes.Results:Alzheimer's Disease patients had significantly smaller callosa than did NCs. The callosal regions most affected in AD included the midbody, isthmus and genu. The isthmus and midbody areas of the CC were positively correlated with cognitive performance and with superior temporal lobe volume in AD patients. The mid-sagittal area of the AC and the superior temporal volumes did not differ between AD patients and NCs.Conclusion:The study demonstrated that the regional morphology of the CC correlates with current cognitive status and temporal lobe atrophy in AD. As well, the lack of difference for the AC suggests that commissural atrophy in AD is regionally specific.

Peptide neurohormones: their role in thermoregulation and fever

1983 ◽  
Vol 61 (7) ◽  
pp. 579-593 ◽  
Author(s):  
W. D. Ruwe ◽  
W. L. Veale ◽  
K. E. Cooper
Keyword(s):  
Body Temperature ◽  
Anterior Commissure ◽  
Extracellular Fluid ◽  
Current Evidence ◽  
Central Administration ◽  
Febrile Response ◽  
Axonal Projections ◽  
The Central Nervous System ◽  
Convulsive Disorders ◽  
The Brain

The neural elements of the rostral diencephalon in the mammal have been implicated in the regulation of body temperature. Moreover, it may be the neural elements within this region of the brain which activate the febrile mechanisms in response to pyrogen. Is it possible that the neuropeptides located within this area of the brain serve as neurochemical intermediaries involved in temperature regulation, fever, and (or) antipyresis? Central administration of several neuropeptides can elicit marked changes in the core temperature of an animal. Although most of these purative neuroregulators exert only a very minor influence on thermoregulation, a small number of the neuropeptides have been shown to have a profound effect on the system controlling this basic vegetative function. One of these peptides, arginine vasopressin (AVP) may play a role as an endogenous antipyretic. The neuroanatomical localization of this peptide, as well as its axonal projections, are consistent with such a role for this neurohypophyseal peptide in the mediation of antipyresis. In addition, current evidence suggests that AVP does function as a neurotransmitter. Examination of the febrile response to pyrogen in both the periparturient animal and the neonate indicates that an elevation in plasma levels of AVP is closely correlated with the diminution in the febrile response. Also, when AVP is perfused into punctate regions of the brain, a pyrogen-induced fever may be markedly suppressed. AVP appears to act primarily within the septal area, 2- to 3-mm rostral to the anterior commissure. During the development of fever, the release of AVP is altered within these same loci. As body temperature decreases during the febrile state, there is a concomitant increase in the amount of AVP released into the extracellular fluid of these septal sites. Very recent findings suggest that AVP may have additional central neurochemical functions. For example, this peptide may be involved in the etiology of some forms of convulsive disorders. The precise manner in which body temperature is regulated by the central nervous system normally and during fever is not well understood. In particular, the central mechanism of action of AVP in these processes remains to be determined. Currently, it is clear that the critical central mechanisms which are active in thermoregulation and fever are quite complex and will require many more years of investigation before the exact role of each can be enunciated.

Towards the Development of a Comprehensive HIC: Predicted Injury – Brain Material Dependency

1999 ◽  
Author(s):  
L. Taleb ◽  
M. J. Brown ◽  
M. M. Sadeghi
Keyword(s):  
Head Injuries ◽  
Diffuse Axonal Injury ◽  
Frontal Plane ◽  
Head Injury Criterion ◽  
Brain Material ◽  
Coronal Section ◽  
Inertial Loading ◽  
Strain Model ◽  
The Brain

Abstract This study proposes a systematic computer simulation technique, using strain as a criterion to assess the severity of brain damage under rotational loading, in particular diffuse axonal injury (DAI). A plane strain model representing realistically a section of the brain in the frontal plane (coronal section) is used in this investigation. The Brain-Skull interface has been modelled using a new representation, allowing the brain to move in a true bio-fidelic way, as well as taking into account the damping role of the Cerebrospinal Fluid (CSF), which acts as a buoy forming a protective cushion around the brain. Based on accident reconstruction data from the literature, the model is validated against the injury observed on the victims. Furthermore, this study proposes a parametric study of brain material properties to assess their effect on the brains’ dynamic response and suggests a new injury criterion for the DAI. It appears that the need to develop a comprehensive head injury criterion (CHIC) which takes into account head injuries caused by non-direct impact or by inertial loading becomes crucial.

The development of a simple scaffold of axon tracts in the brain of the embryonic zebrafish, Brachydanio rerio

Development ◽  
1990 ◽  
Vol 108 (1) ◽  
pp. 121-145 ◽  
Author(s):  
S.W. Wilson ◽  
L.S. Ross ◽  
T. Parrett ◽  
S.S. Easter
Keyword(s):  
Anterior Commissure ◽  
Olfactory Nerve ◽  
Histochemical Staining ◽  
Brachydanio Rerio ◽  
Posterior Commissure ◽  
Zebrafish Brain ◽  
Transmission Electron ◽  
Tubulin Antibodies ◽  
Dorsal Telencephalon ◽  
The Brain

We have examined neuronal differentiation and the formation of axon tracts in the embryonic forebrain and midbrain of the zebrafish, between 1 and 2 days postfertilisation. Axons were visualised with three techniques; immunocytochemistry (using HNK-1 and antiacetylated tubulin antibodies) and horseradish peroxidase (HRP) labelling in whole-mounted brains, and transmission electron microscopy. Differentiation was monitored by histochemical staining for acetylcholinesterase (AChE). These independent methods demonstrated that a simple grid of tracts and commissures forms the initial axon scaffold of the brain. At 1 day, the olfactory nerve, four commissures, their associated tracts and three other non-commissural tracts are present. By 2 days, these tracts and commissures have all greatly enlarged and, in addition, the optic nerve and tract, and three new commissures and their associated tracts have been added. Small applications of HRP at various sites revealed the origins and projections of some of these earliest axons. Retrogradely labelled cell bodies originated from regions that were also positive for AChE activity. At 1 day, HRP-labelled axons were traced: (1) from the olfactory placode through the olfactory nerve to the dorsal telencephalon; (2) from the telencephalon into the tract of the anterior commissure and also to the postoptic region of the diencephalon; (3) from the hindbrain through the ventral midbrain and diencephalon to the postoptic commissure; (4) from the dorsal diencephalon (in or near the epiphysis) to the tract of the postoptic commissure; (5) from ventral and rostral midbrain through the posterior commissure. Three new projections were demonstrated at 2 days: (1) from the retina through the tract of the postoptic commissure to the tectum; (2) from the telencephalon to the contralateral diencephalon; and (3) from the telencephalon to the ventral flexure. These results show that at 1 day, the zebrafish brain is impressively simple, with a few small, well-separated tracts but by 2 days the brain is already considerably more complex. Most of the additional axons added onto pre-existent tracts rather than pioneered new ones supporting the notion that other axons play a crucial role in the guidance of early central nervous system (CNS) axons.

Psychiatric Syndromes Following Blast

1942 ◽  
Vol 88 (371) ◽  
pp. 328-340 ◽  
Author(s):  
E. W. Anderson
Keyword(s):  
Structural Changes ◽  
High Explosive ◽  
Psychiatric Symptoms ◽  
Moderate Degree ◽  
Considerable Time ◽  
Common Features ◽  
Cerebral Trauma ◽  
History Of ◽  
Trained Observers ◽  
The Brain

This paper is concerned with a group of cases presenting certain psychiatric symptoms following exposure to the detonation of a nearby high-explosive bomb. These cases show features and present problems which appear from the current literature in this country to have received insufficient attention, or none at all. The cases to be presented are not all of equal significance, but in each there are certain common features which, from the psychiatric angle, have a definite and unmistakable organic stamp, and indicate a relationship, direct or indirect, of the syndromes to structural changes in the brain. These symptoms are characteristic in fact of a slight or moderate degree of cerebral trauma. This relationship is prone to be too easily overlooked. The reasons for this are :(1) The absence in many cases of a definite history of head injury.(2) The absence as a rule of at least a long period of unconsciousness.In consequence, when the patient is seen perhaps some considerable time later this possibility is not considered, and the reaction is dismissed as psychogenic. That this can be done even by trained observers was demonstrated in three of the cases about to be described. All the patients except one were Naval personnel who were exposed to blast in air-raids either ashore or at sea.

scholarly journals 𝓲-SATA: A MATLAB based toolbox to estimate Current Density generated by Transcranial Direct Current Stimulation in an Individual Brain

2020 ◽  
Author(s):  
Rajan Kashyap ◽  
Sagarika Bhattacharjee ◽  
Ramaswamy Arumugam ◽  
Kenichi Oishi ◽  
John E. Desmond ◽  
...  
Keyword(s):  
Direct Current ◽  
Current Density ◽  
Transcranial Direct Current Stimulation ◽  
Anterior Commissure ◽  
Weak Current ◽  
Posterior Commissure ◽  
Direct Current Stimulation ◽  
Total Current Density ◽  
Magnetic Resonance Imaging Mri ◽  
The Brain

AbstractBackgroundTranscranial Direct Current Stimulation (tDCS) is a technique where a weak current is passed through the electrodes placed on the scalp. The distribution of the electric current induced in the brain due to tDCS is provided by simulation toolbox like Realistic-volumetric-Approach-based-Simulator-for-Transcranial-electric-stimulation (ROAST). However, the procedure to estimate the total current density induced at the target and the intermediary region of the cortex is complex. The Systematic-Approach-for-tDCS-Analysis (SATA) was developed to overcome this problem. However, SATA is limited to standardized headspace only. Here we develop individual-SATA (𝓲-SATA) to extend it to individual head.MethodT1-weighted images of 15 subjects were taken from two Magnetic Resonance Imaging (MRI) scanners of different strengths. Across the subjects, the montages were simulated in ROAST. 𝓲-SATA converts the ROAST output to Talairach space. The x, y and z coordinates of the anterior commissure (AC), posterior commissure (PC), and Mid-Sagittal (MS) points are necessary for the conversion. AC and PC are detected using the acpcdetect toolbox. We developed a method to determine the MS in the image and cross-verified its location manually using BrainSight®.ResultDetermination of points with 𝓲-SATA is fast and accurate. The 𝓲-SATA provided estimates of the current-density induced across an individual’s cortical lobes and gyri as tested on images from two different scanners.ConclusionResearchers can use 𝓲-SATA for customizing tDCS-montages. With 𝓲-SATA it is also easier to compute the inter-individual variation in current-density across the target and intermediary regions of the brain. The software is publicly available.

scholarly journals Effect of olfactory bulb ablation on spread of a neurotropic coronavirus into the mouse brain.

1990 ◽  
Vol 172 (4) ◽  
pp. 1127-1132 ◽  
Author(s):  
S Perlman ◽  
G Evans ◽  
A Afifi
Keyword(s):  
Olfactory Bulb ◽  
Hepatitis Virus ◽  
Anterior Commissure ◽  
Olfactory Pathway ◽  
Surgical Ablation ◽  
Viral Transport ◽  
The Central Nervous System ◽  
Trigeminal Nerves ◽  
The Brain

Previous results suggested that, after intranasal inoculation, mouse hepatitis virus (MHV), a neurotropic coronavirus, entered the central nervous system (CNS) via the olfactory and trigeminal nerves. To prove this hypothesis, the effect of interruption of the olfactory pathway on spread of the virus was studied using in situ hybridization. Unilateral surgical ablation of this pathway prevented spread of the virus via the olfactory tract on the side of the lesion. MHV RNA could be detected, however, at distal sites on the operated side, indicating that the virus spread via well-described circuits involving the anterior commissure from the control (intact) side of the brain. Viral transport via the trigeminal nerve was not affected by removal of the olfactory bulb, showing that the surgical procedure was specific for the olfactory pathway. These results prove conclusively that MHV gains entry to the CNS via a transneuronal route, and spreads to additional sites in the brain via known neuroanatomic pathways.

scholarly journals Rhythm generation, coordination, and initiation in the vocal pathways of male African clawed frogs

2017 ◽  
Vol 117 (1) ◽  
pp. 178-194 ◽  
Author(s):  
Ayako Yamaguchi ◽  
Jessica Cavin Barnes ◽  
Todd Appleby
Keyword(s):  
Brain Stem ◽  
Anterior Commissure ◽  
Temporal Structure ◽  
Central Pattern Generators ◽  
Nucleus Ambiguus ◽  
Motor Nucleus ◽  
Vertebrate Species ◽  
Extended Amygdala ◽  
Pattern Generators ◽  
The Brain

Central pattern generators (CPGs) in the brain stem are considered to underlie vocalizations in many vertebrate species, but the detailed mechanisms underlying how motor rhythms are generated, coordinated, and initiated remain unclear. We addressed these issues using isolated brain preparations of Xenopus laevis from which fictive vocalizations can be elicited. Advertisement calls of male X. laevis that consist of fast and slow trills are generated by vocal CPGs contained in the brain stem. Brain stem central vocal pathways consist of a premotor nucleus [dorsal tegmental area of medulla (DTAM)] and a laryngeal motor nucleus [a homologue of nucleus ambiguus (n.IX-X)] with extensive reciprocal connections between the nuclei. In addition, DTAM receives descending inputs from the extended amygdala. We found that unilateral transection of the projections between DTAM and n.IX-X eliminated premotor fictive fast trill patterns but did not affect fictive slow trills, suggesting that the fast and slow trill CPGs are distinct; the slow trill CPG is contained in n.IX-X, and the fast trill CPG spans DTAM and n.IX-X. Midline transections that eliminated the anterior, posterior, or both commissures caused no change in the temporal structure of fictive calls, but bilateral synchrony was lost, indicating that the vocal CPGs are contained in the lateral halves of the brain stem and that the commissures synchronize the two oscillators. Furthermore, the elimination of the inputs from extended amygdala to DTAM, in addition to the anterior commissure, resulted in autonomous initiation of fictive fast but not slow trills by each hemibrain stem, indicating that the extended amygdala provides a bilateral signal to initiate fast trills. NEW & NOTEWORTHY Central pattern generators (CPGs) are considered to underlie vocalizations in many vertebrate species, but the detailed mechanisms underlying their functions remain unclear. We addressed this question using an isolated brain preparation of African clawed frogs. We discovered that two vocal phases are mediated by anatomically distinct CPGs, that there are a pair of CPGs contained in the left and right half of the brain stem, and that mechanisms underlying initiation of the two vocal phases are distinct.

scholarly journals Germinoma Mimicking Brain Inflammation: A Case Report

2019 ◽  
Vol 6 ◽  
pp. 2329048X1984818 ◽  
Author(s):  
Katarzyna Pierzchlewicz ◽  
Małgorzata Bilska ◽  
Elżbieta Jurkiewicz ◽  
Dariusz Chmielewski ◽  
Elżbieta Moszczyńska ◽  
...  
Keyword(s):  
Sleep Disturbances ◽  
Antinuclear Antibodies ◽  
Anterior Commissure ◽  
Brain Biopsy ◽  
Brain Inflammation ◽  
Abnormal Behavior ◽  
Immunomodulatory Treatment ◽  
Caudate Nuclei ◽  
T2 Hyperintensity ◽  
The Brain

The authors report a case of a germinoma of the brain in the child with symptoms restricted to central nervous system. Ten-year-old girl presented initially with sight deterioration, learning difficulties, abnormal behavior, polydipsia, and polyuria. Brain magnetic resonance examination revealed T2 hyperintensity of the corpus callosum, anterior commissure, and caudate nuclei. Brain biopsy revealed extensive macrophage infiltration. Given these results and positive antinuclear antibodies in the blood, immunosuppressive and immunomodulatory treatment was implemented but it was not effective. The patient developed progressive quadriparesis, sleep disturbances, and dementia. Second brain biopsy was performed and it revealed germinoma cells. Chemotherapy was administered, but the girl died due to disseminated intravascular coagulation syndrome. The reported case shows an unusual coexistence of germinoma with prominent inflammation in the brain and highlights the importance of brain biopsy in such complex cases.

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