THE FIMBRIA-FORNIX/CINGULAR BUNDLE PATHWAYS: A REVIEW OF NEUROCHEMICAL AND BEHAVIOURAL APPROACHES USING LESIONS AND TRANSPLANTATION TECHNIQUES

Extensive lesions of the fimbria-fornix pathways and the cingular bundle deprive the hippocampus of a substantial part of its cholinergic, noradrenergic and serotonergic afferents and, among several other behavioural alterations, induce lasting impairment of spatial learning and memory capabilities. After a brief presentation of the neuroanatomical organization of the hippocampus and the connections relevant to the topic of this article, studies which have contributed to characterize the neurochemical and behavioural aspects of the fimbria-fornix lesion “syndrome” with lesion techniques differing by the extent, the location or the specificity of the damage produced, are reviewed. Furthermore, several compensatory changes that may occur as a reaction to hippocampal denervation (sprouting, changes in receptor sensitivity and modifications of neurotransmitter turnover in spared fibres) are described and discussed in relation with their capacity (or incapacity) to foster recovery from the lesion-induced deficits. According to this background, experiments using intrahippocampal or “parahippocampal” grafts to substitute for missing cholinergic, noradrenergic or serotonergic afferents are considered according to whether the reported findings concern neurochemical and/or behavioural effects. Taken together, these experiments suggest that appropriately chosen fetal neurons (or other cells such as, for instance, genetically-modified fibroblasts) implanted into or close to the denervated hippocampus may substitute, at least partially, for missing hippocampal afferents with a neurochemical specificity that closely depends on the neurochemical identity of the grafted neurons. Thereby, such grafts are able not only to restore some functions as they can be detected locally, namely within the hippocampus, but also to attenuate some of the behavioural (and other types of) disturbances resulting from the lesions. In some respects, also these graft-induced behavioural effects might be considered as occurring with a neurochemically-defined specificity. Nevertheless, if a graft-induced recovery of neurochemical markers in the hippocampus seems to be a prerequisite for also behavioural recovery to be observed, this neurochemical recovery is neither the one and only condition for behavioural effects to be expressed, nor is it the one and only mechanism to account for the latter effects. © 1997 Elsevier Science Ltd. All Rights Reserved.     

Digital tapping of the superficial temporal artery: significance in carotid duplex sonography.

To determine whether tapping on the superficial temporal artery correctly identifies the ECA during carotid sonography, prospective evaluation of the reflection of the temporal tap on the spectral waveform was recorded and graded as 3+, 2+, 1+, or 0 in each ECA, ICA, and CCA, with 3+ being the most brisk response in each carotid system (ipsilateral CCA, ICA, and ECA). The pattern of response was evaluated in patients with and without hemodynamically significant (> than 50% diameter) stenoses in CCA, ICA, and ECA. The most frequent pattern of response to tapping on the superficial temporal artery was 3+ in the ECA, 2+ in the CCA, and 1+ or 0 in the ICA. This pattern was found in 41% (82/200) of systems overall. Whether or not stenoses were present in any branch of the extracranial carotid system, the strongest response (3+) was found in the ECA (58/200 [87%] with stenosis; 119/200 [89%] without stenosis, and lesser responses in the other arteries: 2+ in the CCA 31/200 [46%] with stenosis; 63/200 [47%] without stenosis, and 1+ or 0 in the ICA 58/200 [87%] with stenosis and 103/200 [77%] without stenosis). This pattern was unaltered by the degree of stenosis in the ECA or in the ICA. In 92.5% of the systems interrogated, the response was greater in the ECA than in the ICA. Tapping on the superficial temporal artery may be used as a reliable method of identifying the ipsilateral ECA even in instances of significant atherosclerotic disease in the ECA, CCA, or ICA.     

Serum Neopterin and β2-Microglobulin Concentrations in Monoclonal Gammopathies

ABSTRACT Serum neopterin and β₂-microglobulin concentrations were investigated in 46 patients with multiple myeloma and in 28 patients with asymptomatic monoclonal gammopathy followed for long periods (median 9.6 years) and showing an absence of evolution. Seventy-two per cent of the patients with multiple myeloma showed β₂-microglobulin concentrations higher than 3 mg/1 with a mean of 6.84 mg/1, whereas all the patients with asymptomatic monoclonal gammopathies had concentrations lower than 3 mg/1 with a mean of 1.64 mg/1. Concerning serum neopterin concentrations, 91% of the patients with multiple myeloma had values with in pathological limits (>8 nmol/1) with a mean of 34 nmol/1, whereas all but one of the patients with asymptomatic monoclonal gammopathy had normal values with a mean of 5.19 nmol/1. The differences thus observed in these two groups of patients are highly significant (p<0.001). Serum neopterin concentration, unrelated to renal insufficiency, seems to be useful in the differentiation of malignant or benign asymptomatic monoclonal gammopathies.     

Ossification of the fetal spine

The neural arch ossification centers in the distal fetal spine were evaluated with ultrasound (US) during the second trimester of pregnancy in 239 fetuses. Ossification of the neural arch centers occurred in a predictable pattern and in a caudal direction. An additional vertebral level became ossified every 2-3 weeks from L-5 through S-5 after 16 weeks gestational age; by 22 weeks, S-2 was ossified in all fetuses studied. Radiographic and histologic correlation was performed in one fetus, and the method of establishing vertebral level with US proved accurate. In addition, the origin of the echoes at US corresponded to the histologic ossification centers. In 95% of the fetuses, S-1 was at the top of the iliac wing. Therefore, the level of ossification in the distal fetal spine could be rapidly assessed. Ossification to S-2 by 22 weeks, with a normal transverse configuration, normal overlying integument, and normal cranial structures, should lead to reassurance in excluding neural tube defects, except for distal sacral lesions.