bluuebunny/crossref_metadata_2025 huggingface dataset:
Embryonic development of choline acetyltransferase in thoracic spinal motor neurons: Somatic and autonomic neurons may be derived from a common cellular group
Authors: Phelps Patricia E. , Barber Robert P. , Vaughn James E.
Published: January 2005

This investigation focused on the relationship between neurotransmitter phenotype expression and rat motor neuron development, as studied with choline acetyltransferase (ChAT) immunocytochemical techniques. The development of two subclasses of motor neurons, somatic and autonomic efferents, was examined in the upper thoracic spinal cord. ChAT was first detected in a few neurons on embryonic day 121/2 (E121/2), and in numerous cells located in a single, ventrolaterally located column in the intermediate zone on E13. By E14, this group‐ of ChAT‐positive neurons was more intensely immunoreactive, and their axons could be traced to appropriate targets in developing somatic muscle and paravertebral sympathetic ganglia. During the E15–16 period, somatic and autonomic motor neurons separated into two distinct subgroups, with the latter cells being observed to translocate dorsally. By E17, these autonomic motor neurons reached their final positions in the midportion of the intermediate zone. The autonomic motor neurons were observed to extend transverse dendritic bundles across the spinal cord between E15–16, but evidence of the longitudinal bundles of sympathetic preganglionic dendrites was not observed until after birth.

A recent study of cholinergic thoracic motor neurons found that both somatic and autonomic cells were generated synchronously during the Ell‐12 period (Barber et al., Soc Neurosci Abstr 15:588, 1989). In combination with the present results, these data indicate that no more than V‐A days are necessary after motor neuron genesis before a few cells begin to express detectable levels of ChAT, and that no more than 2 days are required before large numbers express this marker of the cholinergic phenotype. Further comparisons of the present findings with those of previous investigations of the development of both somatic and autonomic motor neurons (Dennis et al., Dev Biol 81:266, 1981; Rubin, J Neurosci 5:685, 697, 1985) indicate that these cells contain ChAT at the time their axons are growing toward their respective peripheral targets 1 day before the time when physiological evidence of function is manifest. Furthermore, the present results suggest that both subclasses of motor neurons initially migrate together from the ventricular zone into a single motor column within the ventral intermediate zone, and that the autonomic neurons subsequently translocate dorsally. Thus, autonomic motor neurons appear to be an exception to the generalization that postmitotic neurons migrate directly from the germinal zone to their final positions within the central nervous system.
Birthdates of trigeminal ganglion cells contributing axons to the infraorbital nerve and specific vibrissal follicles in the rat
Authors: Rhoades Robert W. , Enfiejian Howard L. , Chiaia Nicolas L. , Macdonald Gordon J. , Miller Michael W. , McCann Patricia , Goddard Charles M.
Published: January 2005

Prenatal labelling with [3H]‐thymidine was combined with retrograde tracing techniques in adult rats to determine the birthdates of the trigeminal (V) ganglion cells that contributed axons to the infraorbital nerve (ION) and the generation of the subsets of ION cells that innervated specific vibrissae follicles (C‐1 and C‐5). The V ganglion cells contributing axons to the ION are born between embryonic (E‐, E‐0 = the day of conception) days 9.5 and 14.5. The percentages (normalized so that they total 100%) of the total V ganglion population born on E‐9.5 through E‐14.5 were 5.8, 25.7, 19.8, 23.4, 21.0, and 4.4%, respectively. The distribution of birthdates for the V ganglion cells that were retrogradely labelled from the ION closely matched that for the ganglion as a whole. All of these neurons were also born on E‐9.5 through E‐14.5, and the percentages born on each day were 6.3, 23.6, 18.1, 24.0, 23.6, and 4.4%. Finally, a similar distribution of birthdates was obtained for the V ganglion cells that were retrogradely labelled after injection of retrograde tracers into either the C‐1 or C‐5 vibrissae follicles. We were unable to detect any distinctive spatial distributions for either all V ganglion or ION cells born on a specific embryonic day. Furthermore, neurons with a given birthdate and that innervated a given follicle were distributed throughout the entire region containing all of the ganglion cells supplying the follicle in question. Therefore, it appears that the V ganglion cells contributing axons to the ION are born over the entire period of ganglion neurogenesis and further that the organization of the ION's innervation of the periphery is not a function of cell birthdate.
Cell migration in the rat embryonic neocortex
Authors: Bayer Shirley A. , Altman Joseph , Russo Raymond J. , Dai Xiaofeng , Simmons James A.
Published: January 2005

Three‐dimensional reconstructions of the normal rat embryonic (E) neocortex on days E15, E17, E19, and E21, using Skandha (software designed by J. Prothero, University of Washington, Seattle), show that the neocortical ventricular zone shrinks rapidly in the medial direction during cortical morphogenesis. [3H]thymidine autoradiography indicates that the shrinkage of the ventricular zone occurs before neurons in lateral and ventrolateral parts of layers IV‐II are generated. Consequently, most of these neurons originate 400–1000 μm medial to their settling sites in the cortical plate. Embryos killed at daily intervals up to E21 after a single injection of [3H]thymidine on either E17 or E18 revealed the presence of a prominent migratory path, the lateral cortical stream, used by neurons migrating to the lateral and ventrolateral cortical plate; neurons migrating to the dorsal cortical plate follow a direct radial path. Arrival times of neurons in the cortical plate depend on the migratory path and are proportional to the overall distance travelled. Neurons that migrate only radially arrive in the dorsal cortical plate in two days (shortest route). Neurons that migrate laterally arrive in the lateral cortical plate in 3 days (longer route) and in the ventrolateral cortical plate in 4 days (longest route). [3H]thymidine autoradiography also shows that cells generated in the neocortical ventricular zone migrate in the lateral cortical stream for 5 or more days and accumulate in a reservoir. Cells leave the reservoir to enter the piriform cortex and destinations (as yet undetermined) in the basal telencephalon. The lateral cortical stream is found wherever the neocortical primordium surrounds the basal ganglia and is absent behind the basal ganglia, A computer analysis of nuclear orientation in anterior and posterior parts of the intermediate zone in the dorsal neocortex between days E17 and E22 shows that horizontally oriented nuclei are more common anteriorly where many cells are migrating laterally than posteriorly where most cells are migrating radially.
Histamine‐immunoreactive neurons in the midbrain and suboesophageal ganglion of the sphinx moth Manduca sexta
Authors: Homberg U. , Hildebrand J. G.
Published: January 2005

This paper describes the distribution of histamine‐like immunoreactivity in the midbrain and suboesophageal ganglion of the sphinx moth Manduca sexta. Intense immunocytochemical staining was detected in ten bilateral pairs of neurons in the median protocerebrum and in one pair of neurons in the suboesophageal ganglion. Whereas most areas of the brain and suboesophageal ganglion are innervated by one or more of these neurons, typically no immunoreactive fibers were found in the mushroom bodies, the protocerebral bridge, and the lateral horn of the protocerebrum. The 11 histamine‐immunoreactive neurons were reconstructed from serial sections. Ten neurons have bilateral arborizations, often with axonal projections in symmetric areas of both hemispheres. One neuron, whose soma resides in the lateral protocerebrum, has only unilateral projections. Of the 11 neurons, 6 occur in pairs with similar morphological features. In addition to these neurons, weak histamine‐like immunoreactivity was detected in 7–13 interneurons that were not reconstructed individually. The central projections of the ocellar nerves from the intracranial ocelli also exhibit histamine‐like immunoreactivity. The single‐cell reconstructions reveal similarities between the organization of histamine‐ and serotonin‐immunoreactive neurons in the brain and suboesophageal ganglion of this insect.
Efferent projections of the infralimbic cortex of the rat
Authors: Hurley Karen M. , Herbert Horst , Moga Margaret M. , Saper Clifford B.
Published: January 2005

On the basis of stimulation studies, it has been proposed that the infralimbic cortex (ILC), Brodmann area 25, may serve as an autonomic motor cortex. To explore this hypothesis, we have combined anterograde tracing with Phaseolus vulgaris leucoagglutinin (PHA‐L) and retrograde tracing with wheat germ aggutinin conjugated to horseradish peroxidase (WGA‐HRP) to determine the efferent projections from the ILC.

Axons exit the ILC in one of three efferent pathways. The dorsal pathway ascends through layers III and V to innervate the prelimbic and anterior cingulate cortices. The lateral pathway courses through the nucleus accumbens to innervate the insular cortex, the perirhinal cortex, and parts of the piriform cortex. In addition, some fibers from the lateral pathway enter the corticospinal tract. The ventral pathway is by far the largest and innervates the thalamus (including the paraventricular nucleus of the thalamus, the border zone between the paraventricular and medial dorsal nuclei, and the paratenial, reuniens, ventromedial, parafasicular, and subparafasicular nuclei), the hypothalamus (including the lateral hypothalamic and medial preoptic areas, and the suprachiasmatic, dorsomedial, and supramammillary nuclei), the amygdala (including the central, medial, and basomedial nuclei, and the periamygdaloid cortex) and the bed nucleus of the stria terminalis. The ventral efferent pathway also provides descending projections to autonomic cell groups of the brainstem and spinal cord including the periaqueductal gray matter, the parabrachial nucleus, the nucleus of the solitary tract, the dorsal motor vagal nucleus, the nucleus ambiguus, and the ventrolateral medulla, as well as lamina I and the intermediolateral column of the spinal cord.

The ILC has extensive projections to central autonomic nuclei that may subserve a role in modulating visceral responses to emotional stimuli, such as stress.
Rod and cone specific domains in the interphotoreceptor matrix
Authors: Mieziewska Kristina E. , van Veen Theo , Murray John M. , Aguirre Gustavo D.
Published: January 2005

The insoluble matrix domain of the interphotoreceptor matrix (IPM) from normal dog, cat, and mouse retinae were characterized using lectin cytochemistry. The lectins WGA (wheat germ agglutinin) and PNA (peanut agglutinin) were used to label interphotoreceptor matrix microdomains in cryosections of retinal tissue and in extracted insoluble matrix. Retinal cryosections and extracted matrix were examined by epifluorescence microscopy and scanning confocal laser microscopy, the latter allowed for the removal of all background fluorescence and gave increased resolution. The insoluble matrix was extracted as a continuous sheet that was comprised of two photoreceptor‐specific matrix domains distinguished both by the size of the domains, and by differential binding of WGA and PNA lectins. Each domain encloses a photoreceptor inner and outer segment. Individual rod‐associated domains were connected into a hexagonal lattice and this pattern was regularly interrupted by the larger cone‐associated domains which have 8–10 surrounding rod domains. The PNA lectin primarily labeled the cone‐associated matrix with faint binding to the rod matrix; the WGA lectin labeled both the rod‐ and cone‐associated matrix.
Anatomic evidence of nociceptive inputs to primary somatosensory cortex: Relationship between spinothalamic terminals and thalamocortical cells in squirrel monkeys
Authors: Gingold Scott I. , Greenspan Joel D. , Apkarian A. Vania
Published: January 2005

This study examined anatomic pathways that are likely to transmit noxious and thermal cutaneous information to the primary somatosensory cortex. Anterograde and retrograde labeling techniques were combined to investigate the relationship between spinothalamic (STT) projections and thalamocortical neurons in the squirrel monkey (Saimiri sciureus). Large injections of diamidino yellow (DY) were placed in the physiologically defined hand region of primary somatosensory cortex (hSI), and wheat germ agglutinin‐horseradish peroxidase (WGA‐HRP) was injected in the contralateral cervical enlargement (C5T1). Both DY‐labeled neuronal cell bodies and HRP‐labeled STT terminal‐like structures were visualized within single thalamic sections in each animal. Quantitative analysis of the positions and numbers of retrogradely labeled neurons and anterogradely labeled terminal fields reveal that: (1) ventral posterior lateral (VPL), ventral posterior inferior (VPI), and central lateral (CL), combined, receive 87% of spinothalamic inputs originating from the cervical enlargement; (2) these three nuclei contain over 91% of all thalamocortical neurons projecting to hSI that are likely to receive STT input; and (3) these putatively contacted neurons account for less than 24% of all thalamic projections to hSI. These results suggest that three distinct spinothalamocortical pathways are capable of relaying nociceptive information to the hand somatosensory cortex. Moreover, only a small portion of thalamocortical neurons are capable of relaying STT‐derived nociceptive and thermal information to the primary somatosensory cortex.
Cerebellar Purkinje cell markers are expressed in retinal bipolar neurons
Authors: Berrebi Albert S. , Oberdick John , Sangameswaran Lakshmi , Christakos Sylvia , Morgan James I. , Mugnaini Enrico
Published: January 2005

Previous studies have been directed at the elucidation of neuron‐specific gene expression in the mammalian central nervous system. In particular, we have identified a series of marker molecules that are expressed in cerebellar Purkinje cells with varying degrees of specificity. Here, we show by light microscopic immunocytochemistry and Northern transfer and hybridization that two of these markers, namely, L7 and PEP19, are expressed in the retina of mouse and rabbit, while a third marker, cerebellin, is absent. Light and electron microscopic immunocytochemistry proves that L7‐like immunoreactivity is restricted to rod bipolar cells, while PEP19‐like immunoreactivity is distributed in both rod and cone bipolars. PEP19 is also expressed by subsets of amacrine and ganglion cells. The density of PEP19‐positive bipolar cells is greater than that of L7‐positive bipolar cells, although the density of each is approximately equal in central and peripheral portions of the retina. An antiserum to a fourth Purkinje cell marker, vitamin D‐dependent calcium‐binding protein‐28 kD (CaBP), reveals primarily axon‐less horizontal cells, but also subsets of rod bipolar, amacrine, and, in the mouse but not in the rabbit, ganglion cells. The processes of immunoreactive cell bodies form discrete bands in the internal plexiform layer, and mixtures of the antisera help distinguish their identity. Thus, these Purkinje cell markers can be used at the electron microscopic level to unravel the extremely complex neuropil of this retinal layer. Furthermore, knowledge of the retinal distribution of this panel of molecules is of general value for future studies of retinal neuronal typology and can serve to map the densities of subsets of bipolar cells throughout the retina. The expression of L7 and PEP19 in bipolar cells and in Purkinje cells suggests a biochemical relationship between these two spatially distant neuronal populations.
The relationship between reproductive state and “sexually” dimorphic brain areas in sexually reproducing and parthenogenetic whiptail lizards
Authors: Wade Juli , Crews David
Published: January 2005

The anterior hypothalamus‐preoptic area and ventromedial hypothalamus are sexually dimorphic in the reproductively active whiptail lizard Cnemidophorus inornatus. The anterior hypothalamus‐preoptic area, which is involved in the control of male‐typical copulatory behaviors, is larger in males, whereas the ventromedial hypothalamus, which is involved in the control of female‐typical receptivity, is larger in females. In the parthenogenetic whiptail lizard C. uniparens, which is a direct descendant of C. inornatus and exhibits both male‐like and female‐like pseudosexual behaviors, both brain areas are comparable in size to those of female C. inornatus. This study was conducted to determine whether these brain areas change in size in either species or sex during a time of year when these animals are reproductively inactive, or after removal of the gonads. In male C. inornatus both brain areas changed during reproductive inactivity (either seasonally or surgically induced) and became equivalent to the size characteristic of reproductively active female C. inornatus. When corrected for brain size, the anterior hypothalamus‐preoptic area was significantly smaller in intact hibernating and castrated males than in intact males from the summer breeding season. Conversely, the ventromedial hypothalamus was significantly larger in intact hibernating and castrated males than in intact males from the summer breeding season. The two brain areas were not significantly different among the groups of female C. inornatus or parthenogenetic C. uniparens. These results suggest that (1) the brain of whiptail lizards may differentiate seasonally and (2) the female state may be a neutral one to which the male brain reverts during reproductive inactivity.
Rod‐signal interneurons in the rabbit retina: 2. AII amacrine cells
Authors: Vaney David I. , Gynther Ian C. , Young Heather M.
Published: January 2005

AII amacrine cells, which are the third‐order neurons in the rod pathway, can be differentially labelled in rabbit retina by injecting Nuclear Yellow into the posterior chamber. Under ultraviolet excitation, the labelled retina appears strongly metachromatic, with the AII nuclei fluorescing silvery‐yellow and the nuclei of other amacrine cells fluorescing blue. Labelled AH cells were injected with Lucifer Yellow under direct microscopic control in a superfused retinal preparation, and the dye was later photoconverted to an opaque reaction produc.

Rabbit AII amacrines, which number about 525,000 cells, reach a maximum density of 2,500–3,000 cells/mm2 on the peak visual streak, dropping to 400–500 cells/mm2 at the superior margin. These narrow‐field amacrines have a bistratified dendritic morphology, with distinctive “lobular appendages” in sublamina a of the inner plexiform layer and wider ranging “arboreal dendrites” in sublamina b. Although the lobular field area increases 10‐fold from the visual streak to the far periphery, the lobular field coverage is almost uniform across the retina, averaging 1.0 in inferior retina and 0.8 in superior retina. The dendritic field area of the arboreal dendrites also increases with eccentricity from the visual streak, but there are pronounced differences between inferior and superior retina. The arboreal fields are 2 to 3 times larger than the lobular fields throughout the inferior retina but up to 15 times larger in the superior retina. The arboreal field overlap is only 1.8 at the peak visual streak, increasing slightly to about 2.4 over most of the inferior retina; the overlap increases sharply in the superior retina, however, reaching values of 10 or more in the far periphery. Both the lobular and arboreal fields of AII cells are spaced more regularly than the somata, thus covering apparent gaps in the somatic arra.

An analysis of the potential convergence and divergence between rod bipolar cells and AII amacrine cells in the rabbit retina indicates that the neuronal architecture of the rod circuit is not organized in a uniform module that is simply scaled‐up from central to peripheral retina. Moreover, peripheral fields in the superior and inferior retina that have equivalent densities of interneurons show markedly different rod bipolar → AII amacrine convergence ratios, with the result that many more rod photoreceptors converge on an AII amacrine cell in the superior retina than in the inferior retina. In the rabbit retina, much of the convergence in the rod circuit must occur in the outer retina, whereas, in the central cat retina, it is more evenly distributed between the inner and outer retin.
Ecdysteroid receptors in the central nervous system of Manduca sexta: Their changes in distribution and quantity during larval‐pupal development
Authors: Bidmon Hans‐Jürgen , Granger Noelle A. , Cherbas Peter , Maròy Peter , Stumpf Walter E.
Published: January 2005

Ecdysteroids act initially by binding to nuclear and possibly also extranuclear receptors. The presence and expression of these receptors in the insect brain was investigated in the present study as a means of defining these neurons involved in ecdysteroid‐regulated processes at different developmental stages. Early in the fifth larval stadium of Manduca sexta, when endogenous ecdysteroid levels are low, receptors for ecdysteroids in cerebral neurons are either absent or present at low levels. Receptors can be reliably detected only on day 0 and are not found again until day 3.5, at the beginning of the commitment peak in the ecdysteroid titer, when they occur in a small stage‐specific population of cells. At this time, ecdysteroid receptors are found mainly in nuclei but are also observed at low levels in cytoplasm. By day 4.8, ecdysteroid receptors are exclusively nuclear, and the number of target cells has increased dramatically in several brain regions, including those with known neurosecretory cell groups. This population and organization of ecdysteroid target cells is constant up to day 6, after which time the number of target neurons declines. By day 7.8, only 10% of the number of labelled neurons seen on days 4.8–6.8 remain in peripheral areas. In the pupal brains, ecdysteroid receptors reappear in a new population of neurons. The results indicate changes in the genomic regulation of a varying neuron population by ecdysteroids during fifth stadium developmen.
Organization of visceral and limbic connections in the insular cortex of the rat
Authors: Allen Gary V. , Saper Clifford B. , Hurley Karen M. , Cechetto David F.
Published: January 2005

The anterograde and retrograde transport of horseradish peroxidase was used to study the anatomical organization of visceral and limbic terminal fields in the insular cortex. Following injections into the ventroposterolateral parvicellular (VPLpc) and ventroposteromedial parvicellular (VPMpc) visceral relay nuclei of the thalamus, dense anterograde and retrograde labeling was present in the posterior granular and dysgranular insular cortices, respectively. The parabrachial nucleus had extensive connections with the posterior dysgranular cortex and to a lesser degree with the anterior dysgranular and granular cortices. In contrast, injections into the medial prefrontal cortex and mediodorsal nucleus of the thalamus resulted in dense anterograde and retrograde labeling primarily in the anterior agranular cortex, whereas injections in the amygdala resulted in axonal labeling in the agranular and dysgranular insular cortices. Injections into the lateral hypothalamic area resulted in dense anterograde and retrograde labeling mainly in the agranular and dysgranular cortices and moderate to light labeling in the granular cortex.

Our results indicate that ascending visceral afferents, VPLpc, VPMpc, and parabrachial nuclei, are topographically organized in the granular and dysgranular fields of the insular cortex, whereas the agranular cortex appears to receive highly integrated limbic afferents from the infralimbic cortex and the mediodorsal nucleus of the thalamus. Although these visceral and limbic inputs to the insular cortex are segregated for the most part into different longitudinally oriented strips of cortex, limbic input from the lateral hypothalamic area and the amygdala, which have extensive autonomic as well as limbic connections, are more diffusely distributed over the different regions of the insular cortex. This organization may subserve a role for the insular cortex in integration of autonomic response with ongoing behaviour and emotion.
Distribution of FMRFamide‐related peptides in the blood‐feeding bug Rhodnius prolixus
Authors: Tsang Paul W. , Orchard Ian
Published: January 2005

Immunohistochemistry was used to study the distribution of FMRFamide‐like material in the central and peripheral nervous systems and visceral tissues of 5th instar Rhodnius prolixus. Over 200 immunoreactive cell bodies and their processes as well as extensive neuropile regions were distributed throughout the nervous system. Immunoreactive processes were seen over the cephalic aorta, corpus cardiacum/corpus allatum complex, and in neurohaemal sites on the abdominal nerves. In visceral tissues, immunoreactive processes were seen innervating the salivary glands, the foregut, and the hindgut. Immunoreactive cells were also found in the anterior midgut (i.e., the crop and the anterior intestine). A radioimmunoassay specific for “RFamide” carboxy‐terminal peptides was used to quantify the amount and the distribution of FMRFamide‐like material. Reversed‐phase high performance liquid chromatography of nervous tissue extracts revealed several peaks of immunoreactive material. The results suggest the existence of a number of FMRFamide‐related peptides in Rhodnius which may have roles in both central and peripheral transmission, may be released as neurohormones and may have endocrine functions in the gut.
Superior paraolivary nucleus in the pigmented guinea pig: Separate classes of neurons project to the inferior colliculus and the cochlear nucleus
Authors: Schofield Brett R.
Published: January 2005

The superior paraolivary nucleus is a large component of the superior olivary complex in rodents and a major source of input to the inferior colliculi and the cochlear nuclei. In the present study, retrograde transport of the fluorescent tracers Fluoro‐Gold, Fluoro‐Ruby (tetramethyl rhodamine conjugated to dextran), fluorescein‐coated microspheres, and Fast Blue were used to reveal the morphology and collateral projection patterns of cells in the superior paraolivary nucleus.

The ascending projections to the inferior colliculus from the superior paraolivary nucleus arise mainly from round, multipolar cells, including large cells that project exclusively to the inferior colliculi and not to the cochlear nuclei. Projections to the ipsilateral and contralateral inferior colliculi arise from cells with similar morphology and, in fact, many of the cells that project contralaterally project ipsilaterally as well. Projections to the ipsilateral and contralateral cochlear nuclei arise primarily from cells that do not have collicular projections. On average, the somas of these cells are significantly smaller and more elongated than those that project to the inferior colliculi. Overlap between these ascending and descending systems is restricted to a small percentage of cells that send collateral projections to both the ipsilateral cochlear nucleus and the ipsilateral inferior colliculus. These cells are small and moderately elongated. Thus the ascending and descending projections examined here arise largely from different cells that belong to different morphological classes.
Early development of the retinal line of decussation in normal and albino ferrets
Authors: Cucchiaro Josephine B.
Published: January 2005

This work describes the retinal origin of the crossed and uncrossed projections in newborn, 9‐day‐old and adult normally pigmented and albino ferrets. Horseradish peroxidase (HRP) was injected unilaterally into the thalamic and midbrain visual centers of ferrets to label retinal ganglion cells retrogradely.

In normally pigmented adults, the retinal line of decussation was sharp and passed through the area centralis. Ganglion cells with uncrossed axons occupied the entire temporal retina. In albino adults, ganglion cells with uncrossed axons were distributed in the periphery of the temporal retina away from the area centralis. In the normally pigmented adults, about 11% of the retinal ganglion cells had uncrossed axons compared to about 4% in the albinos. At birth, normally pigmented ferrets had a sharp line of decussation with most (about 98%) uncrossed ganglion cells found in the temporal retina. In the newborn albinos, most uncrossed ganglion cells were in the temporal retina (about 89%), but there were many fewer than in the normal neonates and, as in the albino adults, the uncrossed ganglion cells were distributed along the temporalmost margin of the retina. In the normal neonates, about 11% of the ganglion cells had uncrossed axons, compared to about 3% in the albino neonates. The area centralis and visual streak were not evident until 9 days after birth.

From these results we conclude that the retinal line of decussation is essentially mature by birth in the ferret, and the degree of t he albino's abnormality is as extreme in neonates as in adults. The retinal decussation is virtually mature at a stage of development when the crossed and uncrossed retinal afferent axons are completely intermingled in their target nuclei and prior to the onset of significant retinal ganglion cell loss.
Neuromuscular organization of the buccal system in Aplysia californica
Authors: Scott Marsha L. , Govind C. K. , Kirk Mark D.
Published: January 2005

The intrinsic muscles and peripheral nerves in the buccal system of the sea hare Aplysia californica were studied to build a foundation on which to base future investigations of feeding in intact animals. A detailed description of the bilaterally paired intrinsic muscles is given identifying previously unreported muscles. Each of the six buccal nerves (n1‐n6) and the cerebrobuccal connective (CBC) have been characterized in several respects. Cell bodies in the buccal ganglion with projections into each of the buccal nerves have been identified via the cobalt backfilling technique. All nerves contain axons of cell bodies in the ipsilateral as well as the contralateral ganglia. For each nerve, there is a consistent pattern in the distribution of cell bodies in the paired ganglia with the number of cell bodies in the contralateral ganglion being less than or equal to the number in the ipsilateral ganglion. Although the total number of backfilled cell bodies varies among the nerves, their size ranges are similar with the majority being small. Nerves 1, 2, 4, 5, and 6 provide motor innervation to the intrinsic buccal muscles in varying degrees with nerve 4 supplying all the intrinsic muscles; nerve 2 supplies only one. The axon composition of each nerve was scrutinized and revealed large numbers of axon profiles, the majority of which were less than 2 μm in diameter. The present study provides a framework for analysis of feeding behavior in Aplysia californica.
Comparison of serotonin 5‐HT1 receptors and innervation in the visual cortex of normal and dark‐reared cats
Authors: Mower George D.
Published: January 2005

The visual cortical serotoninergic system was compared in normal and dark‐reared cats to determine whether visual experience is necessary for its normal development. In vitro receptor binding of [3H]5‐HT indicated an increase in 5‐HT1 receptor number in dark‐reared cats with no change in affinity. This elevation was specific to the visual cortex and no changes were found in the frontal cortex as a result of dark rearing. Autoradiographic histology revealed that in the normal cat visual cortex, 5‐HT1 receptors were present in all cortical layers and were slightly more dense in supragranular and infragranular layers. In dark‐reared cats, there was a marked elevation in receptor density in supragranular and infragranular layers and little change within layer IV.

Immunohistochemical techniques (anti‐5‐HT) were used to compare serotoninergic innervation in the visual cortex of normal and dark‐reared cats. In normal cat visual cortex, serotonin fibers were most dense in the superficial layers (I‐III), least dense in layers IV and VI, and intermediate in layer V. No differences were found between normal and dark‐reared cats in the laminar distribution or density of serotoninergic innervation.

These results indicate that visual experience is necessary for the normal development of the visual cortical serotonin system. The findings that the effects of dark rearing were specific to the visual cortex and that within the visual cortex these effects were specific to supra‐ and infragranular layers are consistent with a possible role for serotonin in the prolonged physiological plasticity that occurs in the visual cortex of dark‐reared cats.
Auditory, electrosensory, and mechanosensory lateral line pathways through the forebrain in channel catfishes
Authors: Striedter Georg F.
Published: January 2005

The forebrain auditory, electrosensory, and mechanosensory lateral line pathways in the channel catfish, Ictalurus punctatus, were examined by applying the fluorescent tracer DiI to (1) the auditory part of the torus semicircularis, (2) the electrosensory part of the torus semicircularis, (3) the lateral preglomerular nucleus, and (4) the anterior tuberal nucleus. Three distinct pathways ascend from the torus semicircularis to the telencephalon; they course through either (1) the lateral preglomerular nucleus of the posterior tuberculum, (2) the anterior tuberal nucleus of the hypothalamus, or (3) the central posterior nucleus of the dorsal thalamus. The anatomical data suggest that each of these ascending pathways carries information from more than one sensory modality. The lateral preglomerular nucleus receives an electrosensory input from nucleus electrosensorius in the diencephalon, but it also receives auditory and mechanosensory inputs directly from the torus semicircularis. The anterior tuberal and central posterior nuclei receive primarily auditory and mechanosensory, but also minor electrosensory, inputs. The efferent projections of the central posterior nucleus are presently unknown, but the lateral preglomerular and anterior tuberal nuclei project to nonoverlapping portions of the telencephalon.

A cladistic analysis of these indirect torotelencephalic pathways reveals that (1) the pathway through the dorsal thalamus is probably a primitive character for gnathostomes, (2) a well‐developed pathway through the posterior tuberculum is probably a derived character for actinopterygian fishes, (3) the pathway through nucleus electrosensorius is probably a derived character for catfishes and gymnotoid teleosts, and (4) auditory pathways through the hypothalamus probably evolved independently in catfishes and frogs.
Calbindin‐like immunoreactivity in the central auditory system of the mustached bat, Pteronotus parnellii
Authors: Zettel M. L. , Carr C. E. , O'Neill W. E.
Published: January 2005

With the aid of a polyclonal antibody specific for Calbindin D‐28k, we studied the distribution of this calcium‐binding protein in the central auditory system of the mustached bat, Pteronotus parnellii. Components of the cochlear nucleus (CN) that were calbindin‐positive (cabp(+)) included the root of the auditory nerve, multipolar and globular bushy cells in the anteroventral CN, multipolar and octopus cells in the posteroventral CN, and small and medium‐size cells in the dorsal CN. Not stained were spherical bushy cells of the anteroventral CN and pyramidal/fusiform cells in the dorsal CN.

In the superior olivary complex, labeled cells were found in the lateral and medial nuclei of the trapezoid body, the ventral and ventromedial periolivary nuclei, and the anterolateral periolivary nucleus. No cellular labeling was seen in the lateral superior olive. In the medial superior olive, only marginal cells were cabp(−). Labeled fibers could be seen surrounding the ghosts of unlabeled cells in both the latter nuclei.

Most cells in the intermediate nucleus and the columnar division of the ventral nucleus of the lateral lemniscus were cabp(+). However, the dorsal nucleus was cabp(−). A group of cabp(+) cells was also seen in the paralemniscal zone.

The inferior colliculus had a relatively low density of cabp(+) cells. Labeled cells were more common in the caudal half of the central nucleus, and in the external nucleus and dorsal cortex.

In the auditory thalamus, nearly every cell in the medial geniculate body was cabp(+), but those in the suprageniculate nucleus and in the posterior group did not stain.

Small cells in the intermediate layer and giant cells in the deep layers of the superior colliculus were densely cabp(+). In the pons, cabp(+) cells and neuropil could be seen in the medial and lateral pontine nuclei (pontine gray).

In conclusion, calbindin‐like immunoreactivity was found in most of the brainstem auditory system, as well as in regions associated with acoustic orientation or control of vocalization. However, except for a minority of cells of the medial superior olive, it is conspicuously absent from the nuclei receiving binaural input below the level of the inferior colliculus.
Differential expression of mRNAs for the NGF family of neurotrophic factors in the adult rat central olfactory system
Authors: Guthrie Kathleen M. , Gall Christine M.
Published: January 2005

The cellular localization of mRNAs for nerve growth factor (NGF), brain‐derived neurotrophic factor (BDNF), and neurotrophin‐3 (NT3), in the rat central olfactory system was evaluated with in situ hybridization of 35S‐labeled cRNA probes. In the main olfactory bulb, low levels of NGF and BDNF mRNA expression were detected. NGF mRNA was restricted to the glomerular region while BDNF mRNA was predominantly localized to the granule cell layer. No cellular hybridization to NT3 cRNA was seen. The accessory olfactory bulb did not express detectable levels of mRNA for any of the three related neurotrophic factors. Areas which receive olfactory nucleus and in layers 2 and 3 of rostal piriform cortex. BDNF mRNA expression in these areas appeared more robust than that of NGF mRNA, while NT3 mRNA was not detectable. In contrast, tenia tecta exhibited dense labeling with the cRNAs for all three neurotrophic factors. The localization of NGF mRNA to primary target neurons of the olfactory nerve in the periglomerular region of the main olfactory bulb suggests that bulb cells may influence the ingrowth and continual turnover of olfactory sensory afferents. However, as there is a strong correlation between the distribution of neurotrophic factor mRNAs within rostral olfactory structures and the distribution of centrifugal cholinergic neurons of the basal forebrain.
Functional regions within the map of a single digit in raccoon primary somatosensory cortex
Authors: Rasmusson D. D. , Webster H. H. , Dykes R. W. , Biesold D.
Published: January 2005

Electrophysiological recordings were made at a large number of sites in the primary somatosensory cortex of six anesthetized raccoons. A high density of penetrations (110–229 per animal), within or near the representation of the fourth digit, allowed identification of three cortical regions with different physiological properties: a glabrous zone, containing a highly detailed, somatotopically ordered representation of the glabrous surface of the digit; rostral to this a claw‐dominant zone, in which the neurons at most penetrations respond to stimulation of the claw of the fourth digit, but may also receive input from the hairy skin or surrounding glabrous skin; and a more rostral multidigit zone, in which the neurons respond to stimulation of two to five digits, with the dominant digit usually being the one represented caudally (i.e., the fourth digit at most of the sites sampled here). Claw‐dominant zones with receptive fields restricted to digit three or five are also found rostral to the representations of the glabrous skin of the corresponding digit. The glabrous and claw‐dominant zones constitute a complete map of the fourth digit. The multidigit region presumably is a separate map, since its neurons have different spatial convergence, higher thresholds, and a lower incidence of slowly adapting inputs than those in the claw‐dominant and glabrous zones. A comparison between animals with lesions of the basal forebrain and intact animals found no differences in the organization of these zones or in the responses to peripheral input, suggesting that cholinergic inputs to the cortex are not essential to these properties. The detailed description of these regions and the proposed terminology should resolve some inconsistencies in the use of the term “heterogeneous zone” in this species.
Distribution of reduced nicotinamide adenine dinucleotide phosphate diaphorase (NADPH‐d) cells and fibers in the monkey amygdaloid complex
Authors: Pitkänen Asla , Amaral David G.
Published: January 2005

The NADPH‐d histochemical method stains a selective population of neurons in the central nervous system. Although the functional significance of the enzyme in these cells is unknown, it has nonetheless proved to be a useful marker. In the present study we describe the distribution of NADPH‐d‐positive cells and fibers in the amygdaloid complex of the Macaca fascicularis monkey.

NADPH‐d‐positive neurons were distributed throughout the amygdaloid complex. Based on the intensity of the reaction product, three different types of NADPH‐d positive cell were described: type 1 cells, the most intensely stained, varied in morphology and were most commonly found in the accessory basal, basal, and lateral nuclei and in the nucleus of the lateral olfactory tract; type 2 cells, the most common NADPH‐d‐positive cells, were more lightly stained, were generally stellate in shape, and were found in the lateral, basal, and accessory basal nuclei; type 3 cells were very lightly stained, oval or round in shape, and mostly found in the medial, anterior cortical, and paralaminar nuclei.

NADPH‐d staining was also associated with axonal fiber plexuses in various regions of the amygdala. The highest densities of stained fibers were found in the lateral nucleus, the parvicellular portion of the accessory basal nucleus, and the anterior amygdaloid area. The lowest densities of NADPH‐d‐positive fiber staining were found in the amygdalohippocampal area, in the lateral part of the central nucleus, and in the intercalated nuclei. In addition to the neuronal and fiber staining, a diffuse, blue neuropil staining was also observed, most commonly in the anterior cortical nucleus, the medial nucleus, the intercalated nuclei, and especially in the amygdalohippocampal area. The distribution of NADPH‐d staining often respected nuclear boundaries within the amygdala and was particularly helpful in clarifying the borders of the amygdalohippocampal area.
GABA‐synthesizing neurons in the medulla: Their relationship to serotonin‐containing and spinally projecting neurons in the rat
Authors: Jones Barbara E. , Holmes Colin J. , Rodriguez‐Veiga Elisia , Mainville Lynda
Published: January 2005

GABA‐synthesizing neurons were identified in the medulla of the rat by peroxidase‐antiperoxidase (PAP) immunohistochemistry for glutamic acid decarboxylase (GAD). Using diaminobenzidine (DAB) either alone or intensified with silver, a relatively large number of GAD‐immunoreactive neurons were evident within the reticular formation, raphe nuclei and vestibular nuclei. In all these areas, profuse GAD‐immunoreactive varicosities appeared to contact the soma and dendrites of both non‐GABA and GABA neurons. These observations suggest that GABA neurons may act as interneurons or local projection neurons within the medulla and accordingly exert a potent inhibitory and/or disinhibitory control on bulbar projection neurons.

Within the ventral reticular formation (pars alpha and ventralis of the gigantocellular reticular field) and raphe magnus, large numbers of prominent GAD‐immunoreactive neurons resembled in size and morphology and overlapped in distribution the serotonin‐immunoreactive neurons of the same regions. However, by sequential double immunostaining utilizing DAB as a chromogen for serotonin (5‐HT) and benzidine dihydrochloride (BDHC) for GAD, it was found that GAD‐containing neurons were distinct from 5‐HT‐containing neurons.

Following injections of wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP) into the upper cervical spinal cord and combined processing for WGA‐HRP (using tetramethylbenzidine [TMB] with cobalt) and immunohistochemistry (with DAB), a contingent of spinally projecting neurons were found to contain GAD. The GAD‐immunoreactive reticulo‐and raphe‐spinal neurons were most frequent within the pars alpha and ventralis of the gigantocellular reticular fields and the raphe magnus, where they were approximately equal in number to the coexistent, but distinct 5‐HT spinally projecting neurons. GABA neurons of the medulla may thus contribute directly to the bulbar inhibitory influence upon spinal sensory and motor systems.
A possible mechanism of mechanoreception in Ruffini endings in the periodontal ligament of hamster incisors
Authors: Kannari Koichi , Sato Osamu , Maeda Takeyasu , Iwanaga Toshihiko , Fujita Tsuneo
Published: January 2005

The topographical relationship between Ruffini endings and the surrounding collagen fibers in the periodontal ligament of hamster incisors was investigated by means of both immunohistochemistry for neurofilament protein (NFP) and electron microscopy. Periodontal Ruffini endings, a type of stretch receptor, were present exclusively in the alveolar half of the periodontal ligament. Their axon terminals were densely and regularly associated with transverse collagen fibers, possibly forming a mechanoreceptive complex. Since blood sinuses with frequent anastomoses extended throughout the alveolus‐related part, the densely innervated collagen bundles were separated from each other by the vascular spaces. Electron microscopic observation of specimens stained with tannic acid revealed a linkage between the axon terminals of the Ruffini endings and the surrounding collagen filaments. The axon terminals were enveloped by multiple layers of the basal lamina, which were penetrated by collagen filaments. The irregularly arranged collagen filaments were sandwiched between electron‐dense laminae of the multilayered basal lamina. The possible mechanism of mechanoreception by the periodontal Ruffini endings is discussed on the basis of the immunohistochemical and ultrastructural findings.