Ascending projections of the posterior nucleus of the hypothalamus: PHA-L analysis in the rat

With the exception of a report by R. B. Veazey, D. G. Amaral, and W. M. Cowan (1982, J. Comp. Neurol. 207:135–156) that examined the projections of the posterior hypothalamic area in the monkey by using the autoradiographic technique, the ascending projections of the posterior nucleus (PH) of the hypothalamus have not been systematically examined in any species. The present report describes the ascending projections of PH in the rat by using the anterograde anatomical tracer, Phaseolus vulgaris -leucoagglutinin (PHA-L). The major ascending route for PH fibers is the medial forebrain bundle. PH fibers project densely to several subcortical and cortical sites. The subcortical sites are the subthalamus/hypothalamus (zona incerta, the supramammillary nucleus, lateral, perifornical, dorsal, and anterior nuclei/areas), the thalamus (lateroposterior, laterodorsal, parafascicular, reuniens, paraventricular, central medial, paracentral, central lateral and intermediodorsal nuclei), the amygdala (central, lateral, and medial nuclei), the septal area (bed nucleus of atria terminalis, medial and lateral septum), and the basal forebrain (horizontal/vertical limbs of diagonal band nuclei and lateral preoptic area). The cortical sites are the perirhinal, insular, frontal (lateral agranular), prelimbic, and infralimbic cortices. The diversity of PH projections to subcortical and cortical “limbic-related” sites and to several structures with direct input to the hippocampus (supramammillary nucleus, reuniens, paraventricular and laterodorsal nuclei of the thalamus, medial and lateral septum, and perirhinal cortex) suggest that the PH may serve a critical role in various components of emotional behavior, including mnemonic processes associated with significant emotional events. © 1995 Wiley-Liss, Inc.     

Insular carcinoma of the thyroid. An uncommon but aggressive neoplasm

Insular carcinoma of the thyroid is an infrequent entity, named in 1984 by Carcangiu when he described its characteristic histology. Clinically and morphologically it is considered to be in an intermediate position between well-differentiated carcinoma of the thyroid (papillary or follicular) and undifferentiated or anaplastic carcinoma of the thyroid. However, most authors believe it to be an independent entity. The prognosis of this tumor is worse than that of classic carcinoma of the thyroid, and most authors advise aggressive therapy, which in some cases can achieved prolonged survival. We describe 2 patients who experienced recurrence after treatment for the primary tumor. The recurrences were treated but the clinical courses differed.     

"Central command" and insular activation during attempted foot lifting in paraplegic humans

The relationship between cardiovascular regulation and brain activation was investigated during attempted foot lifting in paraplegic subjects and during rhythmic handgrip exercise at one-third of maximum voluntary contraction force. Brain areas of interest were the primary sensory-motor area and the insula, a hypothesized center for a central nervous feed-forward mechanism involved in cardiovascular control ("central command"). This mechanism is complementary to the usual known feedback pathways such as skeletal muscle afferent signals. Regional cerebral blood flow (rCBF) was measured in eight normal and three paraplegic subjects using positron emission tomography (PET) and oxygen-15-labeled water. Statistical parametric maps were calculated from the images comparing rest and handgrip. Paraplegics were also scanned during attempted foot lifting, a condition without sensory feedback. During activation tasks, heart rate and mean arterial pressure increased. PET activation responses (P < 0.05, corrected for multiple comparisons) were found in the contralateral primary sensory-motor area, the supplementary motor area, ipsilateral cerebellum, and bilaterally in the insula. A conjunction analysis showing responses common to handgrip and attempted foot lifting revealed activation in the right central insula (P < 0.05, corrected) in concordance with the concept of a central command feed-forward hypothesis.     

Where to set the threshold between well differentiated and poorly differentiated follicular carcinomas of the thyroid

A critical review of the literature reveals that different types of thyroid carcinomas have been interpreted as poorly differentiated, including the tall and columnar cell variants as well as carcinomas with insular, trabecular, and solid growth patterns. In some publications the growth patterns have been emphasized, while in others histologic patterns and cytologic features are considered important for identification. However, insular, trabecular, nodular, and solid growth patterns lack specificity because they can be observed in hyperplastic lesions and benign thyroid tumors. The cytologic features of the vast majority of poorly differentiated thyroid carcinomas are similar to or overlap with those of papillary or follicular carcinomas. Cytologic atypia, mitotic activity, and necrosis—believed by some investigators to be useful clues in the diagnosis of poorly differentiated carcinomas—do not reflect cell differentiation, especially in endocrine organs. It is therefore not surprising that the immunohistochemical profile and the molecular abnormalities described in this heterogeneous group of carcinomas lack specificity and are not useful diagnostic tools. Because poorly differentiated thyroid carcinomas have not been well defined, currently it is not possible to set the threshold between well-differentiated and poorly differentiated thyroid carcinomas with follicular phenotype. The authors believe that the vast majority of poorly differentiated thyroid carcinomas are in fact examples of papillary or follicular carcinomas with unusual growth patterns.     

岛叶的功能及对心率变异性的影响

心率变异性作为判断心脏自主神经状态的无创性指标常被用来定量分析自主神经的功能状态，其时域及频域降低与恶性心律失常、心功能不全，乃至心源性猝死等有关。人类的岛叶是控制交感神经和副交感神经介导的心血管调节最重要的皮层区域，多数学者在临床实践中发现，岛叶病变会导致心血管功能紊乱及自主神经功能状态的变化，因此岛叶与心脏功能之间的联系倍受重视。     

狗脑岛皮质向听系神经核簇的传出投射

本文共用成年狗14只,分二组,分别用电凝及Kainic acid微量注射法破坏左侧脑岛皮质。二组均用山鸟法追踪脑岛的传出性溃变纤维。在双侧蜗神经核、上橄榄核、外侧丘系核中均发现了溃变纤维及终末。多数核团毁损侧的溃变量多于对侧。其中左蜗神经腹核,上橄榄内、外侧核,外侧丘系腹核的溃变量较大。溃变纤维还大量出现在下丘核及内侧膝状体核,毁损侧的溃变仍比对侧多。本文在电凝及Kainic acid注射两组实验结果的对比中,未发现明显的差异。本文对脑岛向听系核簇传出纤维投射的意义做了讨论。认为这种投射可能在听觉的反馈调控中起某些作用。脑岛可能是听觉二级皮质中枢的一部分。     

Cytopathology of insular carcinoma of the thyroid.

Four pure insular carcinomas (IC) and one IC with focal anaplastic carcinoma (AC) of the thyroid with cytologic evaluation by fine-needle aspiration (FNA) were reviewed. The needle aspirates from the four pure ICs revealed abundant monomorphic follicular cells present singly, in small, loose aggregates, and in cohesive trabecular and acinar clusters. Tumor cells showed fragile, ill-defined, granular cytoplasm and oval nuclei with conspicuous or inconspicuous nucleoli. The case of IC with focal AC yielded, in addition to the follicular cells as seen in the FNA of the 4 cases of pure IC, large pleomorphic malignant cells with prominent nucleoli that were characteristic for an AC, giant-cell type. No intact insulae of tumor cells were identified in any of the 5 cases. Thus, a thyroid IC may be suspected if abundant cohesive and dyshesive monomorphic follicular cells are present in the tumor FNA. However, a firm diagnosis of thyroid IC can only be made by histologic examination of the excised tumor.     

Posterior insular activity contributes to the late laser-evoked potential component in EEG recordings

ObjectiveNociceptive activity in some brain areas has concordantly been reported in EEG source models, such as the anterior/mid-cingulate cortex and the parasylvian area. Whereas the posterior insula has been constantly reported to be active in intracortical and fMRI studies, non-invasive EEG and MEG recordings mostly failed to detect activity in this region. This study aimed to determine an appropriate inverse modeling approach in EEG recordings to model posterior insular activity, assuming the late LEP (laser evoked potential) time window to yield a better separation from other ongoing cortical activity.MethodsIn 12 healthy volunteers, nociceptive stimuli of three intensities were applied. LEP were recorded using 32-channel EEG recordings. Source analysis was performed in specific time windows defined in the grand-average dataset. Two distinct dipole-pairs located close to the operculo-insular area were compared.ResultsOur results show that posterior insular activity yields a substantial contribution to the latest part (positive component) of the LEP.ConclusionsEven though the initial insular activity onset is in the early LEP time window, modeling the insular activity in the late LEP time window might result in better separation from other ongoing cortical activity.SignificanceModeling the late LEP activity might enable to distinguish posterior insular activity.     

Within‐limb somatotopic representation of acute muscle pain in the human contralateral dorsal posterior insula

It is well established that the insular cortex processes noxious information. We have previously shown that noxious inputs from the arm and leg are coarsely organized somatotopically within the dorsal posterior insula. The same has been shown for inputs from C tactile afferents, which mediate affective touch, and it has been suggested that the insula may be responsible for the localization of some somatosensory stimuli. Knowing the degree of spatial detail may have significant implications for the potential role of the dorsal posterior insula in the processing of noxious stimuli. Using high‐resolution functional magnetic resonance imaging (fMRI), we compared insula activation patterns in 13 subjects during muscle pain induced by injection of hypertonic saline (5%) into three muscles within the same limb: shoulder (deltoid), forearm (flexor carpi radialis), and hand (first dorsal interosseous). Mapping the maximally activated voxels within the contralateral dorsal posterior insula in each individual subject during each pain stimulus revealed a clear somatotopy of activation within the contralateral dorsal posterior insula. Shoulder pain was represented anterior to forearm pain and medial to hand pain. This fine somatotopic organization may be crucial for pain localization or other aspects of the pain experience that differ depending on stimulation site. Hum Brain Mapp, 2010. © 2010 Wiley‐Liss, Inc.     

Cortical processing of tactile direction discrimination based on spatiotemporal cues in man

Tactile direction discrimination (TDD), the ability to determine the direction of an object's movement across the skin, is used clinically to detect and quantify tactile dysfunction. We have previously identified a cortical network for TDD based on skin stretch information that includes the second somatosensory, anterior insular and dorsolateral prefrontal cortices. In the present study we investigated cortical processing of TDD based on spatiotemporal cues. Sixteen healthy subjects (8 females; mean age, 25.5 years; range, 23-32 years) were stimulated with a low-friction, spatiotemporal rolling wheel on the right thigh during functional magnetic resonance imaging (fMRI). The subjects were instructed to indicate the distal or proximal rolling direction of the stimulus. The fMRI contrast between rolling wheel stimulation and rest showed activations in several areas which included the left (contralateral) primary somatosensory, bilateral second somatosensory, bilateral anterior insular, and bilateral dorsolateral prefrontal cortices. We conclude that, spatiotemporal TDD is processed in a largely similar distributed cortical network as skin stretch TDD. Further, spatiotemporal TDD activated primary somatosensory cortex whereas a role for this area in processing of skin stretch TDD has not been demonstrated.