Mesencephalon

BACKGROUND: Trema micrantha is a tree widely distributed throughout the Americas. The tree produces highly palatable leaves that have been associated with natural poisoning in goats, sheep and horses, in which hepatic necrosis and hepatic encephalopathy have been observed. OBJECTIVES: This study describes malacia and haemorrhage in the central nervous system due to T. micrantha consumption, with minimal to absent hepatic lesions. STUDY DESIGN: Retrospective case series...

The temporal dynamic expression of Sonic Hedgehog (SHH) and signaling during early midbrain dopaminergic (mDA) neuron development is one of the key players in establishing mDA progenitor diversity. However, whether SHH signaling is also required during later developmental stages and in mature mDA neurons is less understood. We study the expression of SHH receptors Ptch1 and Gas1 (growth arrest-specific 1) and of the transcription factors Gli1, Gli2 and Gli3 in mouse midbrain during embryonic development [embryonic day (E) 12...

The loss of nigral dopaminergic neurons and the resulting dopamine (DA) depletion in the striatum (STR) lead to altered neuronal activity and enhanced beta activity in various regions of the basal ganglia (BG) motor loop in patients with Parkinson's disease and in rodents in the 6-hydroxydopamine (6-OHDA)-lesioned rat model. Intrastriatal DA graft implantation has been shown to re-innervate the host brain and restore DA input. Here, DA cell grafts were implanted into the STR of 6-OHDA-lesioned rats and the effect on neuronal activity under urethane anesthesia (1...

OBJECTIVES: Impaired response inhibition is related to neurodevelopmental disorders, such as Tourette's disorder (TD) and obsessive-compulsive disorder (OCD). Unlike OCD, in which neural correlates of response inhibition have been extensively studied, TD literature is limited. By using a Stop-Signal task, we investigated the neural mechanisms underlying response inhibition deficits in TD compared to OCD and healthy controls (HCs). METHODS: Twenty-three TD patients, 20 OCD patients and 22 HCs were scanned (3T MRI)...

The ventral mesencephalic neural precursor cells (vmNPCs) that give rise to dopaminergic (DA) neurons have been identified by the expression of distinct genes (e.g., Lmx1a, Foxa2, Msx1/2). However, the commitment of these NPCs to the mesencephalic DA neuronal fate has not been functionally determined. Evaluation of the plasticity of vmNPCs suggests that their commitment occurs after E10.5. Here we show that E9.5 vmNPCs implanted in an ectopic area of E10.5 mesencephalic explants, retained their specification marker Lmx1a and efficiently differentiated into neurons but did not express the gene encoding tyrosine hydroxylase (Th), the limiting enzyme for dopamine synthesis...

Genetic variants of Neuregulin 1 (NRG1) and its neuronal tyrosine kinase receptor ErbB4 are associated with risk for schizophrenia, a neurodevelopmental disorder characterized by excitatory/inhibitory imbalance and dopamine (DA) dysfunction. To date, most ErbB4 studies have focused on GABAergic interneurons in the hippocampus and neocortex, particularly fast-spiking parvalbumin-positive (PV+) basket cells. However, NRG has also been shown to modulate DA levels, suggesting a role for ErbB4 signaling in dopaminergic neuron function...

OBJECTIVE: The aim of this study was to investigate whether the use of combination quantitative metrics (mamillopontine distance [MPD], pontomesencephalic angle, and mesencephalon anterior-posterior/medial-lateral diameter ratios) with qualitative signs (dural enhancement, subdural collections/hematoma, venous engorgement, pituitary gland enlargements, and tonsillar herniations) provides a more accurate diagnosis of intracranial hypotension (IH). METHODS: The quantitative metrics and qualitative signs of 34 patients and 34 control subjects were assessed by 2 independent observers...

BACKGROUND: The cells of the mesencephalic trigeminal nucleus (MTN) are the proprioceptive sensory neurons that innervate the jaw closing muscles. These cells differentiate close to the two key signalling centres that influence the dorsal midbrain, the isthmus, which mediates its effects via FGF and WNT signalling and the roof plate, which is a major source of BMP signalling as well as WNT signalling. METHODS: In this study, we have set out to analyse the importance of FGF, WNT and BMP signalling for the development of the MTN...

Ephrin-A5 has been implicated in the regulation of brain morphogenesis and axon pathfinding. In this study, we used bacterial homologous recombination to express a LacZ reporter in various ephrin-A5 BAC clones to identify elements that regulate ephrin-A5 gene expression during mesencephalon development. We found that there is mesencephalon-specific enhancer activity localized to a specific +25.0 kb to +30.5 kb genomic region in the first intron of ephrin-A5. Further comparative genomic analysis indicated that two evolutionary conserved regions, ECR1 and ECR2, were present within this 5...

Diencephalic-mesencephalic junction dysplasia is a rare malformation characterized by a poorly defined junction between the diencephalon and the mesencephalon, associated with a characteristic butterfly-like contour of the midbrain (butterfly sign). This condition may be variably associated with other brain malformations, including callosal abnormalities and supratentorial ventricular dilation, and is a potential cause of developmental hydrocephalus. Here, we have reported 13 fetuses with second-trimester obstructive ventriculomegaly and MR features of diencephalic-mesencephalic junction dysplasia, correlating the fetal imaging with available pathology and/or postnatal data...

The chronic and relapsing nature of addiction suggests that drugs produce persistent adaptations in the brain that make individuals with drug addiction particularly sensitive to drug-related cues and stress and incapable of controlling drug-seeking and drug-taking behavior. In animal models, several long-lasting neuroadaptations have been described. However, few studies have used brain-imaging techniques to provide a complete picture of brain functioning in the course of withdrawal from cocaine. In this study, we allowed rats to self-administer cocaine under short-access (1-h/day) or long-access (6-h/day) conditions and used 2-deoxy-2-((18)F)fluoro-d-glucose ((18)FDG) positron emission tomography (PET) scanning to investigate the longitudinal changes in metabolic activity 1 and 4 weeks after discontinuation of cocaine self-administration...

BACKGROUND: Head injuries that cross midline structures of the brain are bihemispheric. Other terms have been used to describe such injuries, but bihemispheric is the most accurate and should be standard nomenclature. Bihemispheric head injuries are associated with greater mortality and morbidity than other penetrating traumatic brain injuries (TBIs). Currently, there is a tendency to manage severe gunshot wounds (GSWs) to the head nonoperatively, despite reports of improved outcome in military patients treated aggressively...

Parkinson's disease (PD) is a neurodegenerative condition which causes a characteristic movement disorder secondary to loss of dopaminergic neurons in the substanitia nigra. The motor disorder responds well to dopamine-replacement therapies, though these result in significant adverse effects due to non-physiological release of dopamine in the striatum, and off-target effects. Cell-based regenerative treatments offer a potential means for targeted replacement of dopamine, in a physiological manner. Dopaminergic neurons for cell-based therapies can be obtained from several sources...

Despite the long-standing interest in the evolution of the brain, relatively little is known about variation in brain anatomy in frogs. Yet, frogs are ecologically diverse and, as such, variation in brain anatomy linked to differences in lifestyle or locomotor behavior can be expected. Here we present a comparative morphological study focusing on the macro- and micro-anatomy of the six regions of the brain and its choroid plexus: the olfactory bulbs, the telencephalon, the diencephalon, the mesencephalon, the rhombencephalon, and the cerebellum...

BACKGROUND AND PURPOSE: Although diffusion-weighted imaging (DWI) is a very sensitive technique for the detection of small ischemic lesions in the human brain, in particular in the brainstem it may fail to demonstrate acute ischemic infarction. In this study, we sought to evaluate the value of additional thin-section coronal DWI for the detection of brainstem infarction. METHODS: In 155 consecutive patients (median age 69 [interquartile range, IQR 57-78] years, 95 [61...

Radiological findings of Dyke-Davidoff-Masson syndrome (DDMS) in patients with different etiologies are presented in our study. The study included 12 patients (seven females, five males) for whom radiological examinations were requested due to reasons such as epilepsy, mental retardation, and/or hemiplegia. CT was performed in 12, MRI in 6, MRA in 1, and DSA in 1 patient. Following imaging findings were evaluated: cerebral and cerebellar involvement (laterality, encephalomalacia), affected territories, ventricular enlargement, sulcal enlargement, calvarial thickening, and paranasal sinus enlargement hyperaeration...

Developmental vitamin D (DVD) deficiency has been proposed as an important risk factor for schizophrenia. Our previous study using Sprague Dawley rats found that DVD deficiency disrupted the ontogeny of mesencephalic dopamine neurons by decreasing the mRNA level of a crucial differentiation factor of dopamine cells, the nuclear receptor related 1 protein (Nurr1). However, it remains unknown whether this reflects a reduction in dopamine cell number or in Nurr1 expression. It is also unclear if any particular subset of developing dopamine neurons in the mesencephalon is selectively affected...

Compelling evidence suggests that mitochondrial dysfunction leading to reactive oxygen species (ROS) production and protein oxidation could represent a critical event in the pathogenesis of Parkinson's disease (PD). Pioneering studies have shown that the mitochondrial matrix contains the Lon protease, which degrades oxidized, dysfunctional, and misfolded protein. Using the PD animal model of 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) intoxication in mice, we showed that Lon protease expression increased in the ventral mesencephalon of intoxicated animals, concomitantly with the appearance of oxidized proteins and dopaminergic cell loss...

The adult-onset Alexander disease (AOAD) dramatically differs from the early onset AD with respect to clinical and neuroradiological findings. Herein we report the detailed clinical and neuroradiological findings of a Turkish family with AOAD. In all three cases, magnetic resonance imaging revealed marked atrophy of the mesencephalon, bulbus, and cervical spinal cord accompanied with signal abnormalities in the same regions along with supratentorial white matter. Basal ganglia were affected in two cases. Molecular genetic analysis revealed heterozygous mutation in the 8th exon of the glial fibrillary acidic protein gene M451I (c...

γ-Aminobutyric acid (GABA) is a major amino acid neurotransmitter in the vertebrate brain. To provide detailed information on the distribution of the GABA in zebrafish (Danio rerio), neurons were labeled with mCherry driven by the glutamic acid decarboxylase 67 (gad67) promoter. In the transgenic line Tg(gad67:mCherry), mCherry-positive gad67 cell bodies were predominantly localized to the olfactory bulb, pallial zones, subpallium zones, parvocellular preoptic nucleus, periventricular gray zone of optic tectum, torus semicircularis, posterior tuberculum, medial longitudinal fascicle, caudal zone of periventricular hypothalamus, and oculomotor nucleus...