bluuebunny/crossref_metadata_2025_split huggingface dataset:
Topography of projections from the auditory cortex to the inferior colliculus in the rat
Authors: Herbert Horst , Aschoff Andreas , Ostwald Joachim 
Published: January 2005

AbstractWe examined the organization of descending projections from auditory and adjacent cortical areas to the inferior colliculus (IC) in the rat by using the retrograde and anterograde transport of wheat germ agglutinin‐horseradish peroxidase.Small tracer injections were placed into cytologically defined subnuclei of the IC. On the basis of the resulting pattern of retrogradely labeled neurons in the cortex, different cortical areas and fields were defined. Two secondary areas located ventrocaudally (Te2) and ventrally (Te3) to the primary auditory area (Te1) were delineated. The primary auditory area was subdivided into a posterior (Te1.p), a medial (Te1.m), and an anterior (Te1.a) auditory field. In addition, we outlined an area located rostrally to the auditory areas comprising a part of the secondary somatosensory cortex, as well as a dorsal belt surrounding dorsally the auditory areas.The following basic patterns of corticocollicular projections are revealed: (1) layers 2 and 3 of the dorsal cortex of the IC (DC2, DC3) are differentially innervated by the primary auditory fields (Te1.p and Te1.a project bilaterally to DC2, while Te1.m projects bilaterally and in topographical order to DC3); cells in Te1.m, arranged in caudal to rostral sequence, project to corresponding loci in DC3 arranged from dorsolateral to ventromedial; (2) the fibrocellular capsule of the IC, comprising layer 1 of the dorsal and external cortex of the IC, receives input from the secondary auditory area Te2; (3) layers 2 and 3 of the external cortex of the IC are only weakly innervated by the primary and secondary auditory cortex; (4) the intercollicular zone receives its major input from the secondary auditory area Te3, the secondary somatosensory cortex, and the dorsal belt; and (5) finally, the central nucleus of the IC receives no input from the temporal cortex at all.Our results demonstrate that the corticocollicular projections are highly organized. These pathways may modulate auditory processing in different functional circuits of the inferior colliculus.
All peroneal motoneurons of the rat survive crush injury but some fail to reinnervate their original targets
Authors: Swett John E. , Hong Chang‐Zern , Miller Peter G. 
Published: January 2005

AbstractThis is a quantitative study of the motoneuronal population of the rat's common peroneal nerve following severe crush injury of the sciatic nerve or its component branches. The crush was performed unilaterally under anesthesia for 60 seconds with hemostat jaws covered with tubing to form a smooth, 2 mm long, injured zone. Recovery from injury was allowed for 14 to 188 days. It was measured behaviorally using the sciatic functional index (SFI) and electrophysiologically by comparing the conduction velocity and amplitudes of evoked muscle action potentials prior to injury, and again after injury just before the nerve was labeled with horseradish peroxidase (HRP), and/or its wheat germ agglutinin conjugate (WGA‐HRP), 48–72 hours before sacrifice. The motoneurons were retrogradely labeled on both sides so that the uninjured side might serve as a control. On the injured side the nerves were labeled either distal or proximal to the crush site, The tibialis anterior muscles on both sides were removed and weighed. Spinal segments L2 to L6 were cut in serial, frozen cross‐sections. HRP reaction products were formed using TMB as the chromogen. The normal peroneal nerve was found to contain 634 ± 26 motoneurons (22 cases). The number of motoneurons labeled 5–15 mm distal to the injury site (22 cases) was 535 ± 69 or 84.4% of normal. In 12 cases in which the nerve was labeled 5 mm proximal to the injury normal population numbers (648 ± 30) were found. These counts demonstrated that the unlabeled 15.6% in the distal labeled cases had not vanished as a result of cell death. Instead, the unlabeled group was composed mainly of small motoneurons whose axons probably had not regenerated distal to the crushed zone. Mean soma size of injured neurons increased to maximum 3–6 weeks after injury and then gradually decreased in size over the following weeks to nearly normal values. This transient increase in size was due to two factors: (1) soma swelling in response to axonal injury, and (2) absence of many small motoneurons, presumably γ‐motoneurons, which were either incapable of, or prevented from, regenerating beyond the injury zone long after larger motoneurons had reinnervated their targets. SFI scores, muscle weights, and amplitude ratios of evoked potentials recovered to control values by 70–80 days post‐injury. Conduction velocities remained 20–25% below normal at the end of 80 days. These data suggest that because all motoneurons survived injury, it is possible for all of them to reinnervate their original targets under certain conditions providing that proper pathguides are available.
Projection of the mammalian superior colliculus upon the dorsal lateral geniculate nucleus: Organization of tectogeniculate pathways in nineteen species
Authors: Harting John K. , Huerta Michael F. , Hashikawa T. , van Lieshout David P. 
Published: January 2005

AbstractAnterograde and retrograde transport methods have been used to analyze the projection of the superior colliculus upon the dorsal lateral geniculate nucleus in 19 mammalian species. Our retrograde findings reveal that tectogeniculate neurons are relatively small, and lie dorsally within the superficial gray. These small tectogeniculate neurons are spatially related to a dense tier of W‐cell retinal input.Our anterograde tracing results show that tectogeniculate axons are visuotopically distributed to small‐celled regions of the lateral geniculate in all nineteen species. In the majority of these species, the small‐celled, tectally innervated regions of the lateral geniculate lie adjacent to the optic tract and contain W‐cell‐like neurons. Our findings suggest that neuroanatomical demonstration of the tectogeniculate projection is a relatively simple and straightforward way of revealing regions of the lateral geniculate which contain W‐cells. This is true even in species in which the lateral geniculate lacks obvious cellular laminae, and in regions of the lateral geniculate where W‐cells are few in number.The present data are especially interesting in light of the cortical projections of tectally innervated, small‐celled regions of the lateral geniculate to the patches or puffs within layer III of area 17. Since these regions of small‐celled geniculocortical axons are co‐extensive with zones (“blobs”) rich in cytochrome oxidase, it might be that information carried over the tectogeniculate circuitry plays an important role in the functions of the blob system.
Distribution of vasoactives intestinal peptide‐ and substance P‐containing nerves originating from neurons of airway ganglia in cat bronchi
Authors: Dey Richard D. , Altemus Jeffrey B. , Michalkiewicz Mieczyslaw 
Published: January 2005

AbstractThis study examined the possibility that vasoactive intestinal peptide (VIP)‐ and substance P (SP)‐containing nerve fibers in bronchial smooth muscle, glands, epithelium, and blood vessels originate from neurons of airway ganglia. Explants of airway walls were maintained in culture with the expectation that nerve fibers from neurons of airway ganglia would remain viable, whereas fibers originating from neurons not present in the airway walls would degenerate. Airways were dissected and placed into culture dishes containing CMRL 1066 medium for 3, 5, and 7 days. In controls (noncultured), VIP‐ and SP‐like immunoreactivity was observed in nerve fibers associated with bronchial smooth muscle, glands, and blood vessel walls and in nerve cell bodies of airway ganglia. Nerve fibers containing SP were also observed within the bronchial epithelium. After 3,5, and 7 days in culture, VIP‐ and SP‐containing fibers were identified in all of the same locations except in the airway epithelium where SP‐containing fibers could not be demonstrated. VIP and SP were frequently colocalized in the same nerve fibers of bronchial smooth muscle and glands in controls and cultured airways. There were no statistically significant differences in nerve fiber density for either VIP‐ or SP‐containing fibers in bronchial smooth muscle between controlled and cultured airways. VIP concentrations in cultured airways were significantly less than in controls. The results suggest that a large proportion of VIP‐ and SP‐containing nerve fibers supplying bronchial smooth muscle, glands, and blood vessels in the airways originate from neurons of airway ganglia.
Projections of physiologically characterized globular bushy cell axons from the cochlear nucleus of the cat
Authors: Smith Philip H. , Joris Philip X. , Carney Laurel H. , Yin Tom C. T. 
Published: January 2005

AbstractWe made intraaxonal recordings from 30 individual globular bushy cell axons in the trapezoid body of the cat using HRP‐filled glass microelectrodes. With subsequent HRP injection, we determined their axonal projection patterns.For cells with characteristic frequencies (CFs) above 3 kHz, short‐tone peristimulus time histograms (PSTHs) at CF were typically primarylike at low tone intensities and primarylike with notch (PLN) or onset with low sustained activity (OL) at higher stimulus levels. Cells with CFs between 1 and 3 kHz showed the same response features with the spikes in the sustained region of the response phase‐locked to the stimulus tone. Cells with CFs below 1 kHz showed phase‐locked PSTHs with exceptionally high levels of synchrony compared to eighth nerve fibers with comparable CFs. This exceptional phase‐locking was also noted when cells with CFs of 1–3 kHz were presented with tones below 1 kHz.Although the globular bushy cell axons were not completely filled from the soma of origin to terminal fields in the contralateral brainstem, a number of consistent anatomical features were distinguished in the population. All but one of the myelinated axons crossed the midline in the middle, large fiber component of the trapezoid body. Ipsilaterally, the axon always gave off from one to four collateral branches whose major targets were the posterior periolivary nucleus (PPO) and the lateral nucleus of the trapezoid body (LNTB). Minor termination sites for ipsilateral collateral branches were the dorsolateral periolivary nucleus (DLPO) and the lateral superior olive (LSO). Contralaterally the axon gave rise to one or two calyces of Held in the medial nucleus of the trapezoid body (MNTB). Three other major collateral branches arose from the contralateral axon and innervated a consistent set of areas. One headed caudally to innervate an area just ventromedial to the facial nucleus. Another followed the sixth nerve dorsally to innervate the dorsomedial periolivary nucleus (DMPO). A third collateral headed rostrally toward the ventral nucleus of the lateral lemniscus (VNLL), giving off occasional small sidebranches. Although each injected axon gave rise to a collateral that innervated the MNTB, it did not necessarily give rise to all three of the other collateral branches.
Enrichment of cholinergic synaptic terminals on GABAergic neurons and coexistence of immunoreactive GABA and choline acetyltransferase in the same synaptic terminals in the striate cortex of the cat
Authors: Beaulieu Clermont , Somogyi Peter 
Published: January 2005

AbstractThe synaptic circuits underlying cholinergic activation of the cortex were studied by establishing the quantitative distribution of cholinergic terminals on GABAergic inhibitory interneurons and on non‐GABAergic neurons in the striate cortex of the cat. Antibodies to choline acetyltransferase and GABA were used in combined electron microscopic immunocytochemical experiments.Most of the cholinergic boutons formed synapses with dendritic shafts (87.3%), much fewer with dendritic spines (11.5%), and only occasional synapses were made on neuronal somata (1.2%). Overall, 27.5% of the postsynaptic elements, all of them dendritic shafts, were immunoreactive for GABA, thus demonstrating that they originate from inhibitory neurons. This is the highest value for the proportion of GABAergic postsynaptic targets obtained so far for any intra‐ or subcortical afferents in cortex. There were marked variations in the laminar distribution of targets. Spines received synapses most frequently in layer IV (23%) and least frequently in layers V–VI (3%); most of these spines also received an additional synapse from a choline acetyltransferase‐negative bouton, The proportion of GABA‐positive postsynaptic elements was highest in layer IV (49%, two‐thirds of all postsynaptic dendritic shafts), and lowest in layers V–VI (14%). The supragranular layers showed a distribution similar to that of the average of all layers. The quantitative distribution of targets postsynaptic to choline acetyltransferase‐positive terminals is very different from the postsynaptic targets of GABAergic boutons, or from the targets of all boutons in layer IV reported previously. In both cases the proportion of GABA‐positive dendrites was only 8–9% of the postsynaptic elements. At least 8% of the total population of choline acetyltransferase‐positive boutons, presumably originating from the basal forebrain, were also immunoreactive for GABA. This raises the possibility of cotransmission at a significant proportion of cholinergic synapses in the cortex.The present results demonstrate that cortical GABAergic neurons receive a richer cholinergic synaptic input than non‐GABAergic cells. The activation of GABAergic neurons by cholinergic afferents may increase the response specificity of cortical cells during cortical arousal thought to be mediated by the basal forebrain. The laminar differences indicate that in layer IV, at the first stage of the processing of thalamic input, the cholinergic afferents exert substantial inhibitory influence in order to raise the threshold and specificity of cortical neuronal responses. Once the correct level of activity has been set at the level of layer IV, the influence can be mainly facilitatory in the other layers.
Topography of the projection from the central complex of the thalamus to the sensorimotor striatal territory in monkeys
Authors: François C. , Percheron G. , Parent A. , Sadikot A. F. , Fenelon G. , Yelnik J. 
Published: January 2005

AbstractThe distribution of axons arising from the central complex (or centre médian‐parafascicular complex) and terminating in the striatum was studied in seven macaques and one squirrel monkey. Deposits of anterograde tracers were made in the two lateral‐most subdivisions of the central complex, i.e., the middle part (or pars media) and the lateral part (or pars paralateralis). All injections avoided the pars parafascicularis. The intrastriatal distribution of labeled axonal endings was mapped in relation to the standard ventricular (CA‐CP) system of coordinates. Labeled endings were observed in the major posterior and dorsal parts of the putamen (excluding its anteromedial and ventral parts) and also in a restricted ventrolateral part of the caudate nucleus. The topography of the central territory of the striatum, denned as the striatal space receiving axons from the central complex, was found to correspond exactly to that of the cortical sensorimotor territory delineated after cortical injections. The termination pattern of the central axons within the striatum was patchy. Viewed as a whole, the irregular and hazy patches formed oblique streaks, parallel one with the other. The three‐dimensional reconstructions of data from transverse sections revealed that the streaks were bi‐dimensional pictures of three‐dimensional parasagittal layers covering the whole anteroposterior extent of the cortical sensorimotor territory of the striatum. Our work shows that the pars media of the central complex, which receives selectively pallidal afferent axons (Francois et al., '88: Brain Res. 473:181–186), is the main source of the centroputaminal projection. The probable implication of this in a closed sensorimotor loop of the basal ganglia is discussed.
Synaptic connections of the auditory nerve in cats: Relationship between endbulbs of held and spherical bushy cells
Authors: Ryugo David K. , Sento Seishiro 
Published: January 2005

AbstractThis report focuses on a class of large synaptic endings, the endbulbs of Held. These endings are located in the anteroventral cochlear nucleus and arise from the axons of type I spiral ganglion neurons. Axons were stained with horseradish peroxidase (HRP) using intracellular injections of single fibers or extracellular injections into the auditory nerve. Individual endbulbs or pairs of endbulbs that converged onto the same spherical bushy cell were examined with the aid of a light microscope and subjected to morphometric analyses. Endbulbs of fibers having low spontaneous discharge rates (SR, ≤ 18 spikes/sec) have a more complex shape than those of high SR fibers (> 18 s/s), a feature represented by systematic differences in endbulb silhouette perimeter without differences in endbulb silhouette area. Consequently, the ratio, silhouette area divided by silhouette perimeter, yields a “form factor” separating endbulbs of high SR from those of low SR. High SR fibers had ratios > 0.52 (mean = 0.63 ± 0.09), whereas low SR fibers had ratios <.52 (mean = 0.45 ± 0.06). Pairs of endbulbs with unknown physiological properties had similar form factor values, despite the wide range of values observed in the endbulb population. These data imply that endbulbs converging upon the cell body of a spherical bushy cell arise from fibers of the same SR group.Electron microscopic examination was conducted on the endbulb of one physiologically characterized and intracellularly stained auditory nerve fiber (CF = 1.4 kHz; SR = 55 s/s) and its unstained endbulb mate with the aid of serial ultrathin sections. In addition to the well‐known axosomatic synapses, these endbulbs formed axodendritic synapses: 11.7% for the HRP‐labeled endbulb and 13.3% for the unlabeled endbulb. The axodendritic synapses appear to occur on dendrites of nearby spherical bushy cells and may represent a mechanism whereby single endbulbs can disperse activity to multiple neurons in the cochlear nucleus. We propose that axosomatic synapses preserve fiber SR groupings, whereas axodendritic synapses may not.
Species‐specific distribution of aromatic L‐amino acid decarboxylase in the rodent adrenal gland, cerebellum, and olfactory bulb
Authors: Baker Harriet , Abate Cory , Szabo Aniko , Joh Tong H. 
Published: January 2005

AbstractAromatic L‐amino acid decarboxylase (AADC), the enzyme that converts L‐dopa to dopamine, displayed species‐specific differences in both activity and immunoreactivity in the cerebellum, olfactory bulb, and adrenal glands of three rodent species, the hamster, rat, and mouse. Specifically, in the hamster but not the rat or mouse, AADC immunoreactive cells were observed in the cerebellum and adrenal cortex. The unusual distribution of the enzyme was confirmed biochemically. AADC activity was greater in the adrenal gland and the cerebellum in the hamster than in the mouse or rat. In addition, by Western blot analysis, one band of appropriate molecular weight was observed both in the hamster adrenal gland and cerebellum. The rat adrenal gland displayed a similar immunoreactive protein on the Western blot; however, the protein could not be detected in the rat cerebellum by the technique utilized. Tyrosine hydroxylase (TH) immunoreactivity in these same tissues did not differ among the species. In the main olfactory bulb of the mouse, juxtaglomerular cells exhibited very limited immunoreactivity for AADC, but TH‐immunoreactivity in these cells was robust. In contrast, juxtaglomerular cells in the rat displayed a similar intensity of immunostaining for both AADC and TH. AADC activity in the mouse, consistent with the reduced immunostaining for the enzyme, was 50% of that in the rat and the hamster. These data demonstrate that AADC protein, which is contained in cells of diverse function, also displays qualitative and quantitative species specific variations in both distribution and amount.
Inputs to spinocerebellar tract neurones located in Stilling's nucleus in the sacral segments of the rat spinal cord
Authors: Edgley S. A. , Grant G. M. 
Published: January 2005

AbstractSpinocerebellar neurones located in the sacral segments of the rat spinal cord have been identified electrophysiologically. The neurones studied were located 0.7–1.1 mm. deep to the cord dorsum, lateral and dorsal to the central canal in the medial part of lamina VII. Neurones were identified as spinocerebellar by antidromic activation from the cerebellar surface, the lowest threshold stimulation sites being near the midline on the posterior lobe vermis (lobule VIII). Estimates of conduction velocities of the axons ranged from 15–32 m/s (mean 22.8 m/s) and are directly comparable to velocities of presumed ventral spinocerebellar tract neurones recorded in the same animals. In intact animals, activity was most strongly influenced by passive movement of the tail. Activation by proprioceptors was confirmed with nerve stimulation: all of the neurones studied were discharged by stimulation of nerves which innervate ipsilateral tail muscles. In many cases responses appeared close to the threshold of the nerve, indicating that the largest, fastest conducting afferents (group la muscle spindle primary afferents) were responsible for them. Latencies of EPSPs or spikes were brief and in many cases indicative of a monosynaptic connection. We conclude that this group of neurones is powerfully and monosynaptically excited by group I muscle afferents and thus resemble the cells of Clarke's column and cells of the central cervical nucleus, both of which occupy a similar location in the grey matter of more rostral segments.
Distribution of cholecystokinin‐like immunoreactivity within the stomatogastric nervous systems of four species of decapod crustacea
Authors: Turrigiano G. G. , Selverston A. I. 
Published: January 2005

AbstractThe distribution of cholecystokinin‐like immunoreactivity was studied in the stomatogastric nervous systems, pericardial organs, and haemolymph of four species of decapod Crustacea, by using immunocytochemical and radioimmunoassay techniques. Whereas cholecystokinin‐like immunoreactivity was found within the stomatogastric nervous systems of all four species, its distribution in each is unique. Two species (Panulirus interruptus and Homarus americanus) have cholecystokinin‐like immunoreactivity within fibers and neuropil of the stomatogastric ganglion (STG); two other species (Cancer antenarius and Procambarus clarkii) do not. Further, the cholecystokinin‐like immunoreactivity within the STGs of Panulirus and Homarus arise from distinct structures; from a projection of anterior ganglia in Panulirus, and from somata within the posterior motor nerves in Homarus. The staining in the other ganglia of the stomatogastric nervous system also shows some interspecies variability, although it appears to be more highly conserved than staining within the STG. These differences in staining were confirmed by measuring the amount of CCK‐like peptide present in tissue extracts of ganglia by radioimmunoassay.In contrast to the variable staining within the STG, all four species have cholecystokinin‐like immunoreactivity within the neurosecretory pericardial organs and thoracic segmental nerves. This cholecystokinin‐like immunoreactivity is contained within fibers and within varicosities that coat the surface of these structures. The location of this staining and the presence of detectible levels of CCK‐like peptide in the haemolymph suggests that CCK‐like peptides in decapod Crustacea may be utilized as neurohormones.