A wide variety of topics are being taught in U.S. medical schools under the umbrella of CAM. For the most part, the instruction appears to be founded on the assumption that unconventional therapies are effective, but little scientific evidence is offered. This approach is questionable, especially since mainstream medicine owes much of its success to a foundation of established scientific principles.

Cerebellar climbing fibers have a unique relationship with the dendritic tree of cerebellar Purkinje cells and have been proposed as a key input in establishing long-term plastic changes in the cerebellar cortex. Although both glutamate and aspartate and a number of neuropeptides have been implicated as climbing fiber-released neurotransmitters/neuromodulators, the in vivo release of these substances during climbing fiber stimulation remains to be demonstrated. In the present study, climbing fibers were activated with harmaline and rats or mice were implanted with a microdialysis probe or a microperfusion probe, respectively, to measure amino acid or peptide release. Additional rats were euthanized at various timepoints post-harmaline injection and Fos immunocytochemistry was used to visualize the activation pattern of the inferior olive, cerebellar cortex and deep nuclei over time. Fos expression was first detected in the inferior olive at 15 min post-harmaline injection followed by expression in the deep cerebellar nuclei (30 min) and then in the cerebellar cortex (1 h). Between 2 and 6 h Purkinje cells expressing Fos were found in variable numbers in both the vermal and paravermal regions and there was a distinct parasagittal-banding pattern in the vermal region. Of several amino acids measured following harmaline administration only glutamate and aspartate levels increased significantly in the first dialysate sample compared to preharmaline levels and their release was blocked by prior lesion of the inferior olive. Citrulline also increased following climbing fiber stimulation, but this occurred in the second and third dialysate samples and may reflect nitric oxide production. Four peptides were examined in cerebellar microperfusates following climbing fiber stimulation. Only corticotropin releasing factor (CRF), calcitonin gene related peptide (CGRP) and bradykinin were significantly increased compared to pre-harmaline levels. These results suggest that glutamate, aspartate, CRF and CGRP are released from climbing fibers during activation of the olivocerebellar system.

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The paratrigeminal nucleus (PTN) receives primary visceral afferent projections through cranial nerves IX and X and somatic afferent projections through cranial nerve V and dorsal roots as far caudally as C7. Pressure injections of the anterograde tracer tetramethylrhodamine dextran into the PTN in the rat resulted in bilateral labeling in the nucleus of the tractus solitarius, dorsal motor nucleus of the vagus nerve, and parabrachial nucleus. Anterograde labeling in the parabrachial nucleus was strongest in the external medial, external lateral, and ventral lateral subnuclei. Anterograde labeling was also found in the contralateral paratrigeminal nucleus, lamina I of the spinal trigeminal nucleus subnucleus caudalis, and ventroposteromedial nucleus of the thalamus. The collateral organization of PTN neurons was demonstrated by injecting different fluorescent retrograde tracers into the terminal fields of PTN projections as determined by the anterograde tracing experiments. Double-labeled neurons were found in the paratrigeminal nucleus following all combinations of injection sites. The most prominent PTN efferent projections and the most highly collateralized were to the nucleus of the tractus solitarius and parabrachial nucleus. The efferent and collateral connections of the paratrigeminal nucleus may provide a neuroanatomical substrate for integrating convergent visceral and somatic afferent information used to modulate autonomic function and behavior related to thermoregulation, nociception, and gustation.

The fine structure of the pharyngomotor semicompact and laryngomotor loose formations of the rat nucleus ambiguus was studied in single and serial sections by means of light and electron microscopy. Motoneurons and their dendrites were identified after retrograde labelling by injections of neuroanatomical tracers into pharyngeal and laryngeal muscles or nerves. Pharyngeal motoneurons measured 39 x 29 microns and had 2-25 axosomatic synapses per somatic profile, representing an estimated average of 182 synapses per soma. Laryngeal motoneurons measured 42 x 30 microns with 6-33 synapses per profile, or an average of 339 synapses per soma. In both subdivisions, axon terminals that contained round vesicles and formed symmetric junctions and terminals that contained pleomorphic vesicles and formed symmetric junctions were distributed in approximately equal proportions on somata and dendrites, forming over 90% of the synapse population. A small percentage (2-8%) of synapses had a subsurface cistern situated below the axon terminal (C type). Small, atypical motoneurons measuring 15 x 5 microns with an invaginated nucleus were also present in both subdivisions. The ultrastructure and synaptology of pharyngeal and laryngeal motoneurons are characterized by similarities to those of spinal motoneurons and by their relatively large numbers of axosomatic synapses in comparison to esophageal motoneurons of the compact formation of the nucleus ambiguus.