Fiber dissection and 3-tesla diffusion tensor tractography of the superior cerebellar peduncle in the human brain: emphasize on the cerebello-hypthalamic fibers.

Experimental studies in various species using tract-tracing techniques showed clear evidence of the presence of cerebello-hypothalamic projections. However, these connections were not clearly described in humans. In the present study we aimed to describe the direct cerebello-hypothalamic connections within the superior cerebellar peduncle (SCP) using fiber dissection techniques on cadaveric brains and diffusion tensor tractography (DTI) in healthy adults. Fiber dissection was performed in a stepwise manner from lateral to medial on 6 cerebral hemispheres. The gray matter was decorticate and fiber tracts were revealed. The SCP was exposed and the fibers were traced distally using wooden spatulas. The MRI examinations were performed in seven cases using 3-tesla 3T unit. The direct cerebello-hyothalamic pathways were exposed using high-spatial-resolution DTI. The present study using both fiber dissection and DTI in adult human showed direct cerebello-hypothalamic fibers within the SCP. The SCP fibers course anterolateral to the cerebral aqueduct reaching the level of the red nucleus of the midbrain. The majority of the fibers crosses over and reached the contralateral diencephalic structures and some of these fibers terminated at the contralateral anterior hypothalamic area. Some of the uncrossed SCP fibers reached the ipsilateral diencephalic structures and terminated at the ipsilateral posterior hypothalamic area. We further reported the close relationship of the SCP with the MCP, lateral lemniscus, red nucleus and substantia nigra. In the DTI evaluations of the SCP we exposed unilateral left cerebello-hypothalamic fibers in five cases and bilateral cerebello-hypothalamic fibers in two cases. The present study demonstrates the direct cerebello-hypothalamic connections within the SCP for the first time using fiber dissection and DTI technique in the human brain. The detailed knowledge of the cerebello-hypothalamic fibers can outline the unexplained deficit that may occur during regional surgery.

Do the Dento-Thalamic Connections of Genetic Absence Epilepsy Rats from Strasbourg Differ from Those of Control Wistar Rats?

The thalamo-cortical circuit is important in the genesis of absence epilepsy. This circuit can be influenced by connecting pathways from various parts of central nervous system. The aim of the present study is to define the dento-thalamic connections in Wistar animals and compare the results with genetic absence epilepsy rats from Strasbourg (GAERS) using the biotinylated dextran amine (BDA) tracer. We injected BDA into the dentate nucleus of 13 (n = 6 Wistar and n = 7 GAERS) animals. The dento-thalamic connections in the Wistar animals were denser and were connected to a wider range of thalamic nuclei compared with GAERS. The dentate nucleus was bilaterally connected to the central (central medial [CM], paracentral [PC]), ventral (ventral medial [VM], ventral lateral [VL], and ventral posterior lateral [VPL]), and posterior (Po) thalamic nuclei in Wistar animals. The majority of these connections were dense contralaterally and scarce ipsilaterally. Contralateral connections were present with the parafascicular (PF), ventral posterior medial, ventral anterior (VA), and central lateral (CL) thalamic nuclei in Wistar animals. Whereas in GAERS, bilateral connections were observed with the VL and CM. Contralateral connections were present with the PC, VM, VA, and PF thalamic nuclei in GAERS. The CL, VPL, and Po thalamic nucleus connections were not observed in GAERS. The present study showed weak/deficit dento-thalamic connections in GAERS compared with control Wistar animals. The scarce information flow from the dentate nucleus to thalamus in GAERS may have a deficient modulatory role on the thalamus and thus may affect modulation of the thalamo-cortical circuit.

The Cerebello-Hypothalamic and Hypothalamo-Cerebellar Pathways via Superior and Middle Cerebellar Peduncle in the Rat.

The connections between the cerebellum and the hypothalamus have been well documented. However, the specific cerebellar peduncle through which the hypothalamo-cerebellar and cerebello-hypothalamic connections pass has not been demonstrated. The present study aims to define the specific cerebellar peduncle through which connects the cerebellum to specific hypothalamic nuclei. Seventeen male albino rats received 20-50-nl pressure injections of either Fluoro-Gold (FG) or biotinylated dextran amine (BDA) tracer into the superior (SCP), middle (MCP), and inferior (ICP) cerebellar peduncle. Following 7-10 days of survival period, the animals were processed according to the appropriate protocol for the two tracers used. Labeled cells and axons were documented using light or fluorescence microscopy. The present study showed connections between the hypothalamus and the cerebellum via both the SCP and the MCP but not the ICP. The hypothalamo-cerebellar connections via the SCP were from the lateral, dorsomedial, paraventricular, and posterior hypothalamic nuclei, and cerebello-hypothalamic connections were to the preoptic and lateral hypothalamic nuclei. The hypothalamo-cerebellar connections via the MCP were from the lateral, dorsomedial, ventromedial, and mammillary hypothalamic nuclei; and cerebello-hypothalamic connections were to the posterior, arcuate, and ventromedial hypothalamic nuclei. The hypothlamo-cerebellar connections were denser compared to the cerebello-hypothlamic connections via both the SCP and the MCP. The connection between the cerebellum and the hypothalamus was more prominent via the SCP than MCP. Both the hypothlamo-cerebellar and cerebello-hypothalamic connections were bilateral, with ipsilateral preponderance. Reciprocal connections were with the lateral hypothalamic nucleus via the SCP and the ventromedial nucleus via the MCP were observed. Cerebellum takes part in the higher order brain functions via its extensive connections. The knowledge of hypothalamo-cerebellar and cerebello-hypothalamic connections conveyed within the SCP and MCP can be important for the lesions involving the MCP and SCP. These connections can also change the conceptual architecture of the cerebellar circuitry and deepen current understanding.

Synaptic organization of the rat thalamus: a quantitative study.

First-order thalamic nuclei receive driving afferents from ascending pathways and transmit processed information to the cortex. Higher-order thalamic nuclei receive driver messages from layer 5 of cortex and transmit information from one cortical area to the other. The different types of axon terminals RL (round vesicles, large terminals), RS (round vesicles, small terminals) and F (flattened vesicles) and their synaptic junctions have been here compared in three first-order (ventrobasal, lateral geniculate and anteroventral) and three higher-order (posterior, lateral posterior and mediodorsal) thalamic nuclei of the rat. In the present study, the higher-order relays differ from first-order relays as in the cat, in having fewer driver terminals (RL) and synapses than do the first-order relays. However, the F terminals showed opposite ratios in the first versus higher-order thalamic nuclei. The majority of the terminals in all thalamic nuclei studied were RS terminals. The area measurements of the three types of terminals and synaptic lengths showed no significant differences between first and higher-order nuclei. The driver inputs represent the minority and the modulatory inputs represent the majority of the terminals and synapses in all thalamic nuclei. In conclusion, there is a relative paucity of driver inputs, whereas modulatory inputs establish more numerous synapses to achieve finer modulation.

Decreasing bleeding due to uterine fibroid with electroacupuncture.

OBJECTIVE: To report the usefulness of electroacupuncture (EA) for the management of menorrhagia due to submucous uterine fibroid. DESIGN: Case report. SETTING: University hospital. PATIENT(S): A 48-year-old woman with a symptomatic submucous uterine fibroid, who presented with severe menorrhagia. INTERVENTION(S): Electroacupuncture. MAIN OUTCOME MEASURE(S): Doppler ultrasonographic assessment of uterine blood flow and number of pads used during menorrhagia. RESULT(S): Doppler ultrasound revealed decreased blood flow of the uterine artery with EA stimulation. With repetitive sessions of EA fewer pads were used during menorrhagia. CONCLUSION(S): We present the first human case in which decreasing uterine artery blood flow with EA improved menorrhagia due to uterine fibroma. Electroacupuncture could be a useful, alternative, and relatively noninvasive tool for the management of fibroids with menorrhagia as a severe complaint.

Connections of the zona incerta to the reticular nucleus of the thalamus in the rat.

This study demonstrated that there is a pathway from the zona incerta to the thalamic reticular nucleus. Injections of horseradish peroxidase or Fluorogold were made, using stereotaxic coordinates, into the rostral, intermediate or caudal regions of the thalamic reticular nucleus of adult Sprague-Dawley rats. The results show that the different regions of the thalamic reticular nucleus have distinct patterns of connections with the sectors of the zona incerta. In terms of the relative strength of the connections, injections made into the rostral regions of the thalamic reticular nucleus showed the highest number of labelled cells within the rostral and ventral sectors of the zona incerta; injections made into the intermediate regions of the thalamic reticular nucleus showed labelled cells in the dorsal and ventral sectors; while injections to the caudal regions of the thalamic reticular nucleus showed only a few labelled cells in the caudal sector of the zona incerta. Previous studies have shown that the zona incerta projects to the higher order thalamic nuclei but not first order thalamic nuclei. The labelling observed in the present study may represent collaterals of zona incerta to higher order thalamic nuclei projections.

Morphological study of the perireticular nucleus in human fetal brains.

Abstract The perireticular nucleus consists of scattered neurons that are located in the internal capsule. The presence of perireticular neurons in the rat, ferret, cat and human has been described previously. Evidence suggests that the perireticular neurons in various species decrease in number with increasing gestation, but in humans this finding has not been supported by quantitative data. This study aimed to investigate (1) the morphology of the human fetal perireticular neurons, (2) the average number of perireticular neurons within the anterior and posterior crus of the internal capsule per unit area, and (3) the magnitude and the stage of neuronal loss in the human perireticular nucleus subsequent to maturation. Nissl-stained sections of the internal capsule of human fetal brains of 24, 26.5, 32, 35, 37 and 39 weeks of gestation showed a number of clearly distinguishable large perireticular and small microglia cells. A regular increase of both perireticular and microglial cells was observed up to 32 weeks of gestation, after which a dramatic reduction in the number of both perireticular and microglia cells was observed. The average number of perireticular and the microglia cells per unit area, located within the posterior crus, was more than in the anterior crus of the internal capsule. In the adult, no perireticular neurons were detected within the internal capsule. The results show that perireticular neurons are not restricted to the region lateral to the thalamus and medial to the globus pallidus (posterior crus) but are also present at the region lateral to the caudate nucleus and medial to the globus pallidus (anterior crus).

Cerebellar connections: hypothalamus.

Morphological studies have described reciprocal cerebello-hypothalamic projections in various species. These connections provide evidence for the key role of the cerebellum and hypothalamus in physiological regulatory processes such as autonomic and endocrine homeostasis. Our recent study using horseradish peroxidase (HRP) retrograde axonal transport technique showed cerebellar connections with the posterior and the dorsomedial hypothalamic nuclei. Further, we have demonstrated regional differences of the connections of the dorsomedial hypothalamic nucleus in rat. The results of HRP labelling showed that afferent pathways originating from the anterior and posterior parts of dorsomedial hypothalamic nucleus indicate a number of differences in the projections. The posterior part of the dorsomedial hypothalamic nucleus and the posterior hypothalamic nucleus receives direct distinct projections from the cerebellum, whereas the anterior part of the dorsomedial hypothalamic nucleus does not. Moreover, the posterior part of the dorsomedial nucleus of the hypothalamus when compared to the posterior hypothalamic nucleus has more intense connections with the cerebellum. These observations bring a new perspective on the question of how the cerebellum is involved in the regulation visceromotor functions.