Isolated trochlear palsy due to midbrain stroke

Trochlear palsy from intra-axial lesions usually accompanies other neurological deficits, and isolated trochlear palsy due to midbrain stroke is extremely rare. We report two patients with isolated trochlear nerve palsy due to circumscribed dorsal midbrain strokes, one from infarction and the other from hemorrhage, which are located in the region of the trochlear nucleus or adjacent fascicle. Focal brain stem stroke should be considered as a rare cause of trochlear palsy even though there are no associated neurological deficits.     

Oxytocin and/or steroid hormone binding globulin infused into the ventral tegmental area modulates progestogen-mediated lordosis

Estradiol (E₂) and progesterone (P₄) have classical, steroid receptor-mediated actions in the ventral medial hypothalamus to initiate lordosis of female rodents. P₄ and the P₄ metabolite and neurosteroid, 5α-pregnan-3α-ol-20-one (3α,5α-THP), have non-classical actions in the midbrain ventral tegmental area (VTA) to modulate lordosis. We investigated the role of steroid hormone binding globulin (SHBG) and oxytocin in the VTA as mechanisms for these effects. Rats were ovariectomized and surgically implanted with bilateral guide cannulae aimed at the VTA. Rats were E₂-primed (10 μg/0.2 ml) at hour 0, and administered 100 (Experiments 1 and 2), 500 (Experiment 3), or 0 (Experiment 1 and 4) μg/0.2 ml P₄ at hour 44. At hour 47.5, rats received bilateral infusions to the VTA, and were tested for lordosis 30 min post-infusion. Experiment 1: rats were infused with sterile saline vehicle or SHBG (4.5 pg/μl) to the VTA. SHBG, compared to vehicle, to the midbrain VTA significantly increased lordosis in E₂- and P₄-primed, but not E₂-primed, rats. Experiment 2: rats were infused with bilateral infusions of sterile saline or oxytocin (1.0 pg/μl). Compared to vehicle, oxytocin to the VTA increased lordosis. Experiment 3: rats were administered bilateral intra-VTA infusions of saline or an oxytocin receptor antagonist, d(CH₂)₅,[TYr(ME)²,Thr⁴,Tyr-NH^9,2] (1.2 pg/μl). Compared to vehicle, the oxytocin receptor antagonist to the VTA attenuated lordosis of E₂- and P₄-primed rats. Experiment 4: rats were E₂-primed and infused with vehicle, oxytocin, or oxytocin antagonist. There were no effects of these manipulations in E₂-primed rats. Thus, SHBG and/or oxytocin may have actions in the VTA for progestogen-facilitated lordosis.     

A combined histological and MRI brain atlas of the common marmoset monkey, Callithrix jacchus

The common marmoset, Callithrix jacchus, is of growing importance for research in neuroscience and related fields. In the present work, we describe a combined histological and magnetic resonance imaging (MRI) atlas constructed from the brains of two adult female marmosets. Histological sections were processed from Nissl staining and digitized to produce an atlas in a large format that facilitates visualization of structures with significant detail. Naming of identifiable brain structures was performed utilizing current terminology. The histological sections and a simplified schematic atlas are available online at http://udn.nichd.nih.gov/brainatlas_home.html.     

Alarm calls and referentiality in Australian magpies: between midbrain and forebrain, can a case be made for complex cognition?

The ability to communicate intentionally and referentially about predators by issuing specific and unique alarm calls per predator type, usually considered indicative of forebrain activity, is generally regarded as evidence of complex cognition. However, the neurobiology of such expressions is not well-understood and the relationship of song to alarm calls is not clear. In the very few studies of brain activity in calls of non-songbirds and songbirds so far, it was found that it is only the midbrain that is involved in the production of calls. The paper argues that such midbrain activity, even in so-called referential signalling, may have been misconstrued as higher cognition when, in fact, it may be merely indicative of a well-preserved (even ‘clever’) midbrain survival mechanism of prey species, and may be based on instantaneous ‘non-thinking’ activities of the midbrain. This does not rule out that, in specific species of songbird and in specific types of calls, the production of alarm calls may indeed involve activity and interaction of nuclei in midbrain and forebrain. Such a possible interaction in the production of vocalisations (unlearned and learned) has also been shown in some songbirds, including the zebra finch. A study of alarm calls in Australian magpies (Gymnorhina tibicen), a prolific songbird, is used here to give an example of possible considered responses in alarm calling based on behavioural evidence.     

The effects of a midbrain glioma on memory and other functions: a longitudinal single case study

Our understanding of the effects of midbrain damage on cognition is largely based on animal studies, though there have been occasional investigations of the effects of human midbrain lesions on cognition. This investigation of a rare case of a glioma initially confined to the dorsal midbrain explores the effects of disease progression on IQ, memory, and choice reaction time. Extensive dorsal midbrain damage did not appear to affect IQ and various memory functions (including span, working memory, story recall, and remote memory). Choice reaction time latencies increased, while verbal and spatial learning and long-term memory deteriorated with tumour growth, but it was not clear how far the deterioration reflected midbrain damage or damage outside the midbrain.     

The physiological and pharmacological role of basic fibroblast growth factor in the dopaminergic nigrostriatal system

Basic fibroblast growth factor (FGF-2) is a physiological relevant neurotrophic factor in the nigrostriatal system and hence a promising candidate for the establishment of alternative therapeutic strategies in Parkinson's disease. FGF-2 and its high-affinity receptors (FGFR) display an expression in the developing, postnatal, and adult substantia nigra (SN) and in the striatum. Exogenous application promoted survival, neurite outgrowth and protection from neurotoxin-induced death of dopaminergic (DA) neurons both in vitro and in vivo. In animal models of Parkinson's disease, co-transplantation of fetal DA cells with FGF-2 expressing cells increased survival and functional integration of the grafted DA neurons resulting in improved behavioral performance. Analyzing the physiological function of the endogenous FGF-2 system during development and after neurotoxin-induced lesion revealed for the DA neurons of the SNpc a dependence on FGFR3 signaling during development. In addition, in the absence of FGF-2 an increased number of DA neurons was found, whereas enhanced levels of FGF-2 resulted in a reduced DA cell density. Following neurotoxin-induced lesion of DA neurons, FGF-2-deleted mice displayed a higher extent of DA neuron death whereas in FGF-2 overexpressing mice more DA neurons were protected. According to the data, FGF-2 seems to promote DA neuron survival via FGFR3 during development, whereas absence of this ligand could be compensated by other members of the FGF family. In contrast, in the adult organism, FGF-2 cannot be compensated by other factors under lesion conditions suggesting a central role for this molecule in the nigrostriatal system.     

CT中脑背侧脑池出血对原发性脑干损伤的早期诊断价值

目的 分析颅脑外伤急诊CT中脑背侧脑池出血的表现,探讨其对临床原发性脑干损伤的早期诊断价值.方法 回顾性分析52例颅脑外伤患者临床表现及影像学资料,并依据GCS评分分为轻、中、重及特重型.所有患者均在伤后48 h内接受CT检查,CT采用常规程序扫描.MRI检查则根据病情变化在伤后1周内完成,采用自旋回波T1WI、T2WI序列.结果 所有病例的CT表现均与MRI的T1WI、T2WI序列行比较研究,其中39例颅脑损伤患者的急诊CT有中脑背侧环池或四叠体池出血表现,合并弥漫性脑肿胀19例,脑实质出血灶单发或多发点状出血灶11例,直径小于2 cm;37例MRI检查存在不同程度的脑干组织损伤表现.结论 重型和特重型颅脑外伤(GCS<9分)伤后早期CT的中脑背侧脑池出血表现高度提示原发性脑干损伤可能,对提高原发性脑干损伤早期诊断水平具有重要的参考价值.