bluuebunny/crossref_metadata_2025 huggingface dataset:
Cell death of motoneurons in the chick embryo spinal cord. IV. Evidence that a functional neuromuscular interaction is involved in the regulation of naturally occurring cell death and the stabilization of synapses
Authors: Pittman Randall , Oppenheim Ronald W.
Published: January 2005

Embryos immobilized with neuromuscular blocking agents for differing periods between 4.5 and 9 days of incubation had an increased number of motoneurons in the brachial and lumbar lateral motor columns. Treatment with α‐cobratoxin (α‐CTX) on days 4‐9 for instance, was able to prevent virtually all natural cell death during this period; control embryos had an average of 22,500 lumbar motoneurons on day 5.5, and 13,500 on day 10, whereas treated embryos had approximately 21,000 cells on day 10. Curare, α‐CTX, α‐bungarotoxin (α‐BTX) and botulinum toxin were all about equally effective in preventing cell death. Similar treatment begun after day 12, however, had no effect on cell number. If even a partial immobilization was continued after day 10 (in embryos totally immobilized earlier) most of the excess neurons were maintained, in some cases right up to hatching, at which time the embryos died due to respiratory failure. In contrast, when administration of the immobilizing agents was stopped, allowing the embryos' motility to return to control levels, the excess neurons underwent a delayed cell death and total cell number fell to below control levels by days 16‐18.

Limb muscles from embryos with exces motoneurons exhibited relatively normal differentiation and had acetylcholinesterase (AChE) stained endplates which were innervated. Following curare treatment the two wing muscles, anterior and posterior latissimus dorsi, were found to have an increased number of AChE‐stained endplates, whereas the only leg muscle examined quantitatively – the ischioflexorius (IFL) –did not; the IFL, did, however, have a markedly reduced variance in endplate distance, as well as other apparent differences suggesting an altered pattern of innervation.

Our findings imply that the number of motoneurons undergoing natural cell death is closely related to muscle activity. Thus, functional interactions at the developing neuromuscular junction seem to be critical in controlling cell death. If a retrograde trophic factor is involved its action is somehow related to muscle activity.
Quantitative electron microscopic evidence for reinnervation in the adult rat interpeduncular nucleus after lesions of the fasciculus retroflexus
Authors: Murray M. , Zimmer J. , Raisman G.
Published: January 2005

The method of electron dense degeneration has been used to make a quantitative study of the projection from the habenula through the fasciculus retroflexus (FR) to the interpeduncular nucleus (IPN) in the rat. The IPN is a midline structure onto which the right and left fasciculi converge. In the rostral part of the IPN the fascicular axons from each side form synapses throughout the mediolateral extent of the ventral two‐thirds of the nucleus. In the caudal part of the IPN the fascicular axons from each side terminate to an equal extent in two discrete, parasagittal zones, situated one on each side in the mid‐mediolateral extent of the IPN. These zones contain clusters of neurons located along the course of a characteristic row of arterioles and venules penetrating the IPN from its ventral surface.

In both rostral and caudal parts of the IPN the fascicular axons form single synaptic contacts with the dendrites of the interpeduncular neurons, but caudally, in the two parasagittal zones they also form crest synapses. Crest synapses are only found in this part of the IPN. In crest synapses two presynaptic terminals form markedly asymmetrical contacts with the parallel opposing sides of an attenuated dendritic appendage (the crest). After unilateral fascicular lesions only one member of a pair of axon terminals contacting a crest degenerates. After bilateral fascicular lesions, however, there are many instances in which both members of a crest pair degenerate. This indicates that the axon terminals from the right and left fasciculi are segregated at the level of the crests, in such a way that one terminal comes from the right fasciculus and one from the left.

At longer survivals after unilateral or bilateral fascicular lesions the degeneration is completely removed, but crest synapses are still present, indicating that the presence of fascicular axons is not necessary for the maintenance of crests in the IPN.

To investigate the effects of chronic deafferentation, the left fasciculus was destroyed and, after a survival of at least six weeks (sufficient for all degeneration to be removed) the right fasciculus was destroyed one day before killing. Under these conditions there are many crests in which both axon terminals show degeneration. The proportion of such doubly degenerating crest synapses is similar to that found after acute (1 day) bilateral lesions, indicating that axons from the right fasciculus have reinnervated sites formerly occupied by the left fasciculus. We conclude that during normal development there is some constraint which prevents both sides of a crest being innervated by axons from the fasciculus of the same side of the brain, but that this constraint is not effective after unilateral fascicular lesions in the adult.
Further observations on hippocampal neurons in dispersed cell culture
Authors: Banker Gary A. , Cowan W. Maxwell
Published: January 2005

The growth of the processes of dissociated hippocampal neurons from 18‐ to 20‐day‐old rat fetuses has been studied in vitro using a method that permits cells to be maintained at relatively low plating densities for periods up to three weeks (Banker and Cowan, '77). Most of the cells are spherical or ovoid when they first attach to the substratum (either polylysine or collagen) but within 24 to 48 hours they begin to put out processes, and by the end of the first week in culture a significant proportion (∼45%) come to resemble normal pyramidal cells with a more‐or‐less triangular shaped soma, a single dominant dendrite‐like process emerging from the apex of the soma, and several “basal dendrites” arising from the opposite pole of the cell. Comparisons of the lengths of these dendrite‐like processes with those of hippocampal cells in the brains of animals sacrificed on the fourth post‐natal day and impregnated by a variant of the Golgi‐Cox method, indicate that in some cases the rate of process formation in vitro approximates that in vivo and that the general form of the neurons is remarkably like that of immature pyramidal cells. After a week in culture a second type of process can be recognized. These tend to be finer than those we have identified as dendrites; they are relatively uniform in diameter, frequently give off branches at right angles, and in the electron microscope can be seen to form synapses upon the larger processes and cell somata. These axon‐like processes differ from the axons of normal pyramidal cells in two important respects: (i) most commonly they arise from one of the dendritic processes, including, on occasion, the putative “apical” dendrites, and only rarely from the base of the perikaryon; (ii) there may be two or more such processes from a single cell. The thicker, tapering processes can be shown (after incubation in 3H‐uridine) to contain large amounts of RNA; newly‐synthesized RNA does not extend into the finer, axon‐like processes.
Cerebellar corticonuclear – nucleocortical topography: A study of the tree shrew (Tupaia) paraflocculus
Authors: Haines D. E. , Pearson J. C.
Published: January 2005

Following injections of horseradish peroxidase (HRP) into parafloccular cortex, the location of nucleocortical cells in the cerebellar nuclei was determined and compared to the distribution of corticonuclear fibers arising from the same cortical region. Parafloccular corticonuclear fibers, visualized utilizing the Fink and Heimer (1967) method, project to caudal and lateral NIP and caudal and ventral NL. No degeneration is seen in either the NIA or NM. HRP‐positive nucleocortical cells (DAB‐technique) are found in caudal and lateral NIP and caudal NL with the former containing greater numbers of reactive somata. Rostral regions of the NL, medial NIP as well as the NIA and NM are divoid of cells containing HRP reaction product.

At least two identifiable populations of HRP‐positive nucleocortical cells are seen. Numerous reactive cells are found in the NIP and NL ipsilateral to the injection site and sparse numbers of HRP‐containing somata are present in homologous areas of the contralateral NL and NIP. Contralateral nucleocortical cells are not only sparse in number but do not receive direct input from the opposite cortex to which they project. Consequently, these particular cells represent non‐reciprocal neurons in corticonuclear –; nucleocortical feedback loops. Ipsilateral nucleocortical cells are numerous and found almost exclusively within the distribution of parafloccular corticonuclear fibers. Also seen on the ipsilateral side interspersed among the HRP‐positive somata are numerous fibers which contain non‐granular homogeneous reaction product. These fibers represent diffusely filled axons of Purkinje cells which were damaged during the injection process. The location of ipsilateral nucleocortical cells within the borders of corticonuclear terminal fields coupled with their intimate opposition to some orthogradely filled terminal branchlets of Purkinje axons, indicates the probability of a precise interaction between these two fiber systems. Although a few HRP‐positive ipsilateral cells are found outside the boundaries of corticonuclear terminal fields they represent only a small fraction of the total number of reactive cells and, indeed, may function as part of the reciprocal cell population.
Accessory abducens nucleus and its relationship to the accessory facial and posterior trigeminal nuclei in cat
Authors: Hutson K. A. , Glendenning K. K. , Masterton R. B.
Published: January 2005

Retrograde transport of HRP by the abducens nerve results in the labelling of its principal nucleus and, in addition, a second nucleus about 2.5 mm ventrolateral to the principal nucleus. The presence of this second or accessory nucleus of the abducens in a mammal confirms the observations of several Nineteenth Century anatomists and rebuts the conclusions of more recent investigators who argued that the nucleus was allied instead to the facial or trigeminal nerves.

The same HRP technique applied to the facial or trigeminal nerves shows that the accessory nucleus of the abducens is in the same parasagittal plane as the accessory nucleus of the facial nerve and the most caudal cells of the motor trigeminal nucleus. The accessory abducens and accessory facial nuclei fall in a ventrocaudal to dorsorostral line between the principal nucleus of the facial and the motor nucleus of the trigeminal with the accessory abducens just caudal and ventral to the accessory facial.
The effect of the sequence of contralateral cortical and collicular lesions on the rate of relearning a visual discrimination by cats
Authors: Stern Judith F. , Winterkorn Jacqueline M. S. , Meikle Thomas H.
Published: January 2005

Visual field deficits which follow ablation of the posterior two‐thirds of one cerebral hemisphere in the cat have been shown to be ameliorated by ablation of the contralateral superior colliculus. The present study was designed to determine whether the sequence in which contralateral cortical and collicular lesions are made is a significant factor affecting the rate of monocular relearning through the eye ipsilateral to the cortical lesion. Nine adult cats had the optic chiasm sectioned, were trained to criterion monocularly on a dark‐light discrimination, and were divided into two groups. Four cats (Group S) had one superior colliculus ablated, followed one month later by ablation of the contralateral two‐thirds of the neocortex. Five cats (Group C) had the same lesions in the reverse order. One month after the second brain lesion, each cat was retrained monocularly through each eye on the dark‐light discrimination for food reward in a Y‐maze. Through the eye ipsilateral to the cortical lesion, all cats in Group S relearned to criterion more rapidly than cats previously reported with only unilateral neocortical lesions. Four of the five cats in Group C were severely retarded in relearning and two of these cats failed to relearn. The results show that when chiasm‐sectioned cats are trained monocularly in a Y‐maze on a dark‐light discrimination, ablation of the superior colliculus prior to ablation of the contralateral neocortex facilitates relearning through the eye ipsilateral to the cortical ablation. When ablation of the superior colliculus follows the neocortical lesion, learning occurs but is not facilitated by the additional lesion.
Cell growth in the monocular segment of the lateral geniculate nucleus following the opening or closing of one eye
Authors: Anker Robyn , Cragg Brian
Published: January 2005

Both eyes were closed in 12 kittens soon after birth, and one eye was reopened at 23 days. From 14 to 26 days later, the cells in the monocular segment of the LGN connected to the open eye became significantly larger than the corresponding cells on the other side of the brain that were connected to the eye that was still closed. Up to 26 days after eye opening, the response of the monocular segment was similar to that of the binocular segment, so the latter may not be dependent on mutual inhibition or competition between sets of cells connected to each eye. From 30 to 60 days after eye opening, however, there were no differences between the monocular segments, but marked differences between the binocular A laminae where mutual inhibition and competition can occur.

In seven more kittens both eyes were untouched until 23 days, when one eye was closed. Between 3 and 31 days later the deprived cells in the monocular segment of the LGN were not more than 8% smaller than those on the other side of the brain, and the measurements were not significantly different in any one cat. Within the binocular part of lamina A, cell growth is retarded by eye closure in two phases. Neither the early phase from 4‐6 days nor the later phase from 21 days onwards occurred in the monocular segment, so both may be dependent on mutual inhibition or competition between the sets of cells connected to each eye.

Two possible explanations of this difference between the effects of eye opening and eye closing are discussed.
The morphology and distribution of striate cortex terminals in the inferior and lateral subdivision of the Macaca monkey pulvinar
Authors: Ogren Marilee P. , Hendrickson Anita E.
Published: January 2005

The origin of the various types of axon terminals in Macaca pulvinar remains uncertain because of the contradictory results obtained in EM degeneration studies. We have used EM‐autoradiography to determine the morphology of terminals in the inferior and lateral pulvinar which originate from neurons in visual cortex. After injections of H3 proline into area 17, both the small diameter (RS) and the large diameter (RL) terminals containing round vesicles and making asymmetric contacts are labeled in the two pulvinar subdivisions. Labeled and unlabeled terminals are intermixed within the pulvinar focus which suggests that the dendrites of the same pulvinar neuron receive overlapping inputs from several cortical areas. Because only 5% of the pulvinar terminals are RLs (Ogren and Hendrickson, '79), and this small number of RLs originates from at least two visual cortical areas plus the superior colliculus (Partlow et al., '77), superior colliculus input to inferior pulvinar is small compared to the combined RS and RL cortical input.

Together the findings from this study and the preceding paper (Ogren and Hendrickson, '79), show that while pulvinar is typical of other thalamic nuclei in the structure of its neurons and synapses, it differs in that the input from subcortical structures is minimal. It is suggested that inferior and lateral pulvinar function principally as integrators of visual cortical information.
Synaptic contacts on glial cells in the abdominal ganglion of Aplysia californica
Authors: Colonnier M. , Tremblay J. P. , McLennan H.
Published: January 2005

Two types of glial cells have been identified in the neuropil and in the subcapsular space of the abdominal ganglion of Aplysia californica. In the neuropil, a first type of glial cell has a light staining cytoplasm and gives rise to processes which may contain bundles of filaments, a flocculent material or bundles of microtubules and membranous sacs. Synaptic contacts have been seen very rarely on their somata and more frequently on their “filamentous” and “flocculent” processes. A second type of glial cell has a darkly staining cytoplasm and gives rise to dense processes. Synaptic contacts are frequently seen on these processes. In the subcapsular zone, there are also two types of glial cells, one with a clear and the other with a dense cytoplasm. The processes of the clear glial cells contain glycogen‐like particles and sometimes bundles of filaments. These processes surround the bundles of neuronal profiles which form the perisomatic plexus. Such enveloping processes receive synaptic contacts from the neuronal profiles in the bundles. The dense glial cells of the subcapsular zone also receive synaptic contacts, but this is a rare occurrence.
The rabbit and the cat: A comparison of some features of response properties of single cells in the primary visual cortex
Authors: Murphy E. Hazel , Berman Nancy
Published: January 2005

Receptive field characteristics of single cells in primary visual cortex of rabbit were studied. Seventy‐two percent of cells were found to be orientation selective, and the remainder had concentric, uniform, movement selective or pure direction selective receptive fields. Single cells were also recorded from primary visual cortex of cat to permit a comparison of visual cortical organization in cats and rabbits. Laminar organization of receptive field types was observed in rabbits which was similar in most respects to that described in the cat. Although the major categories of orientation selective cells (simple, complex, hypercomplex) were similar for both cat and rabbit, many differences emerged: (I) tuning of orientation selectivity was narrower in cats than in rabbits; (II) units which preferred oblique orientations were less frequently represented in rabbits than in cats; (III) orientation preferences appeared to be arranged in cluster in rabbit cortex; in rabbits we found no evidence of the columnar organization of orientation selectivity which characterizes cat visual cortex.

A comparison of our data with those previously reported for mouse, rat, hamster and opossum visual cortex suggest that mammals in which a significant proportion of visual cortical cells are not orientation selective have in common certain patterns of cortical organization involving a less precise and less specialized representation of stimulus orientation.
Projections of lamprey spinal neurons determined by the retrograde axonal transport of horseradish peroxidase
Authors: Tang D. , Selzer M. E.
Published: January 2005

The spinal cords of larval sea lampreys (Petromyzon marinus) and adult river lampreys (Ichthyomyzon unicuspis) were injected with horseradish peroxidase through a transection 1 cm caudal to the last gill. Some animals also had a spinal hemisection 1 cm caudal to the injection. After recovery periods of 1 to 52 days, the spinal cords were treated with diaminobenzidine and hydrogen peroxide, and the projections of various cell types determined in wholemount slides. From these observations the following conclusions were drawn.

Most dorsal cells (primary sensory cells) are bipolar with a long rostral projection and a short caudal projection of no more than 5‐10 mm. Both processes travel in the ipsilateral dorsal column. Their peripheral processes enter the dorsal roots as branches of their central axons. Some dorsal cells send processes out three or more dorsal roots both rostral and caudal to the cell body.

Myotomal motoneurons have characteristic locations in the medial gray column and send prominent transversely oriented dendrites into the lateral columns. A few motoneurons are unusually large.

In addition to giant interneurons the majority of smaller rostrally projecting interneurons also have decussating axons. A recently described cell type, the oblique bipolar cell, appears to have an exclusively crossed rostral projection.

Although most edge cells project rostrally, as many as 20% may have a caudal projection or both rostral and caudal projections. Edge cells project equally to the ipsilateral and contralateral spinal hemicord, but their processes do not extend more than about 18 mm in sea lamprey larvae and 37 mm in adult river lampreys.

Lateral cells project exclusively to the ipsilateral caudal hemicord. A few cells which resemble lateral cells in location and in possessing large lateral dendrites, project rostrally. However, these have atypical morphologic features which probably distinguish them from true lateral cells.

Thus far, regardless of cell type, all decussating axons seem to pass ventral to the central canal, while decussating medial dendrites pass dorsally.
Relations between cell body size, axon diameter and axon conduction velocity of triceps surae alpha motoneurons during the postnatal development in the cat
Authors: Cullheim S. , Ulfhake B.
Published: January 2005

Triceps surae α‐motoneurons in cats of different postnatal ages were stained intracellularly with horseradish peroxidase (HRP) and studied light microscopically. In individual neurons, the mean diameter of the cell body and the intramedullary axon diameter were measured and related to the axon conduction velocity.

The mean diameter of the cell body grew from 39.6 μm at birth to 57.6 μm in the adult cat, while the corresponding figures for the intramedullary axon diameters were 2.4 μm and 6.7 μm. During the same period of time, the axon conduction velocity increased from 11.3 m/s to 93.5 m/s, and the ratio between the conduction velocity and the intramedullary diameter of the axon (CV/d ratio) increased from 4.6 to 14.1.

The results indicate that the growth of the cell body is smaller and completed earlier than the growth in diameter of the intramedullary and, in particular, the peripheral parts of the axon. The considerable change of the CV/d ratio during the postnatal development may be explained by previously described immature morphological properties of the axon in very young kittens, and by a changing relation between the dimensions of the intramedullary and peripheral parts of the axon.
In vivo metabolic activity of a putative circadian oscillator, the rat suprachiasmatic nucleus
Authors: Schwartz W. J. , Davidsen L. C. , Smith C. B.
Published: January 2005

The suprachiasmatic nucleus (SCN) has been proposed as a site for an endogenous circadian oscillator in mammals, since lesions of the nucleus abolish a wide spectrum of overt circadian rhythms. To demonstrate that a directly measurable property of the SCN itself in intact (unlesioned) animals is affected by environmental light and exhibits circadian rhythmicity, we used the autoradiographic 2‐deoxy‐D‐[14C]glucose method to determine glucose utilization of rat SCN under a variety of lighting conditions. Our experiments indicate an important role for the SCN in circadian rhythm organization, and we believe the deoxyglucose method will prove useful as a tool for better understanding the functions and mechanisms of circadian clocks.
Quantitative analysis of sex differences in hormone accumulation in the zebra finch brain: Methodological and theoretical issues
Authors: Arnold Arthur P.
Published: January 2005

The autoradiographic method was used to compare the numbers of hormone accumulating cells in several brain regions in male and female zebra finches (Poephila guttata) after injection of tritiated testosterone. The brain regions examined were the caudal nucleus of the hyperstriatum ventrale (HVc), magnocellular nucleus of the anterior neostriatum (MAN), robust nucleus of the archistriatum (RA), nucleus intercollicularis of the midbrain (ICo), the tracheosyringeal hypoglossal motor nucleus (nXIIts), and periventricular magnocellular nucleus of the anterior hypothalamus (PVM). All but the last of these regions are thought to be involved in the control of vocalizations in passerine song birds. Males have significantly more labelled cells in HVc and MAN. In RA, there is no difference in total percentage of labelled cells, but there is a sex difference in size distribution of labelled cells. No sex difference was detected in other brain regions. These differences are found when using a criterion for cell labelling which is based on the Poisson distribution, and the relative merits are evaluated of various quantitative criteria used in the analysis of steroid autoradiograms. The magnitude of the observed sex difference may be influenced by several biasing factors, yet the sex difference persists when corrections are applied to eliminate the biases, indicating that the sex difference is not an artifact of autoradiographic procedure. The magnitude of the sex difference in hormone accumulation has certain implications for the process of sexual differentiation of the brain.
Secondary trigeminocerebellar projections in sheep studied with the horseradish peroxidase tracing method
Authors: Saigal R. P. , Karamanlidis A. N. , Voogd J. , Mangana O. , Michaloudi H.
Published: January 2005

Secondary trigeminocerebellar connections have been studied with HRP histochemistry in 25 sheep. The results indicate that almost all of the cerebellar cortex except flocculus, ventral paraflocculus and lobules I‐IV receives bilateral (mostly ipsilateral) fibers from the trigeminal nuclei.

A topographical organization of trigeminocerebellar fibers is present. The mesencephalic tract nucleus projects to the anterior lobe, the simple lobule (HVI), lobules VI, VIII, and the dorsal paraflocculus. The ventral group of the princeps and spinal tract (mainly IDV) nuclei projects to all lobules studied in vermis and hemispheres. More dorsal parts of these nuclei have a more restricted projection field including the vermal lobules VI, VII, and IX and the hemisphere. Cells within and ventral to the motor nucleus of the trigeminal nerve were found labeled after injections into the anterior lobe, the simple lobule, and lobule IX. Labeled cells in the region of the nucleus ovalis and close to the solitary tract project to the simple and paramedian lobule and lobule IX.
Acetylcholinesterase mutants in drosophila and their effects on the structure and function of the cental nervous system
Authors: Greenspan Ralph J. , Finn James A. , Hall Jeffrey C.
Published: January 2005

Mutations that eliminate acetylcholinesterase (AChE) activity were used to study the effects of disrupted acetylcholine metabolism on the form and function of the central nervous system in Drosophila melanogaster. Mutants in the Ace gene, which have no AChE activity, usually die in early development, but the postembryonic effects of this lesion can be studied in genetic mosaics, or with conditional mutants.

Adult mosaics, which expressed Ace mutations in part of their CNS, exhibited morphological defects in any ganglionic neuropile whose cells were mutant. The defects included reduction in ganglionic volume, a condensed appearance, and for a very large clone, degeneration. Examination of many such mosaics indicated that small clones restricted to one side of the CNS were not usually lethal. However, mosaics with large clones, with clones on either side of the posterior slope of the protocerebrum, or with clones encompassing symmetrical structures on both sides of the CNS rarely survived to adulthood. Mosaics with AChE‐null tissue on either side of the optic lobes or the posterior‐inferior protocerebrum had marked deficits in optomotor behavior, although they were outwardly normal in their movements and posture. Mosaics with Ace mutant tissue in the first‐order optic lobe, the lamina, lacked a synaptic component of the electroretinogram, the “off” transient. Tests of courtship behavior revealed that AChE mosaics with mutant clones in the superior protocerebrum were often capable of demonstrating male courtship. However, their behavior was quantitatively and perhaps qualitatively deficient.

In order to study critical periods for the effects of mutant AChE, temperature‐sensitive mutations of the Ace gene were isolated. Flies bearing certain of these new mutations produced AchE activity that was thermolabile in vivo and in vitro. The critical period during which the mutants were most susceptible to conditional lethality was late in embryogenesis.
Prefrontal system in the rat visualized by means of labeled deoxyglucose—further evidence for functional heterogeneity of the neostriatum
Authors: Divac Ivan , Diemer Nils H.
Published: January 2005

An epileptic focus was formed in the anteromedial part of the prefrontal cortex in rats by means of intracortical injection of penicillin, and radioactively labeled deoxyglucose was immediately injected intravenously. Autoradiograms revealed that, in addition to the injected cortical area, a number of formations increased their consumption of deoxyglucose.

The labeled formations were the posterior medial and perirhinal cortical areas, the anteromedial part of the neostriatum, the anterior and intermediodorsal part of globus pallidus, the entopeduncular nucleus, the reticular portion of the substantia nigra, the claustrum, and the basolateral nucleus of amygdala. In addition, several thalamic nuclei were activated, including the entire parataenial, paraventricular, anteromedial, and axial nuclei, as well as distinct parts of the mediodorsal and lateral nuclei and, in the instances of spread of cortical activity to the dorsal surface, of the ventral nucleus. In some animals, activation of the ventral tegmental area of Tsai was also found.

All these formations have previously been shown by neuroanatomcial techniques to be directly connected with the anteromedial cortex of the neostriatum. Some of them were included in the “prefrontal system.” The present findings, in agreement with earlier neurobehavioral studies, indicate that, in the rat, the anteromedial part of the neostriatum, but not other neostriatal regions, is functionally related to the anteromedial part of the prefrontal cortex.

The present and earlier similar studies suggest that the mammalian forebrain contains a number of “systems”, each of which consists of a neocortical area and a set of associated subcortical sites.
Relationship between enkephalinergic neurons and the vasopressin‐oxytocin neuroendocrine system of the cat: An immunohistochemical study
Authors: Micevych Paul , Elde Robert
Published: January 2005

Localization of enkephalins and opiate binding sites in the central nervous system of rats has been reported by several authors. These studies did not reveal an extensive enkephalinergic system in the hypothalamo‐hypophyseal axis of rats. The present paper reports on an extensive enkephalinergic system in the cat hypothalamo‐hypophyseal system. Sections of paraformaldehyde fixed cat hypothalami were incubated with anti‐methionine enkephalin serum, anti‐vasopressin serum, and anti‐oxytocin serum. Immunohistochemical localization of methionine enkephalin fibers and terminals in the median eminence, hypophyseal stalk, and pars nervosa was similar, but not identical to the distribution of vasopressin and oxytocin in these structures. Neuronal perikarya localized with the three antisera in the nucleus supraopticus and nucleus paraventricularis were of a similar size and morphology. In cats treated with colchicine prior to sacrifice, the anti‐methionine enkephalin serum revealed a group of periventricular cell bodies. Cell bodies were not localized in this area with anti‐vasopressin or anti‐oxytocin sera. The functional significance of such an extensive enkephalinergic system in the cat hypothalamo‐hypophyseal axis is discussed.
A light and electron microscopic study of the effects of 3‐acetylpyridine intoxication on the inferior olivary complex and cerebellar cortex
Authors: Anderson W. A. , Flumerfelt B. A.
Published: January 2005

The effects of 3‐acetylpyridine (3‐AP) intoxication on the inferior olivary complex and cerebellar cortex of the rat were examined at both the light and electron microscopic level. Following intraperitoneal injection of 65 mg of 3‐AP per kg body weight, the inferior olivary neurons were observed to undergo a rapid form of electron dense degeneration. A complete bilateral involvement of the nuclear complex was well advanced as early as 12 hours following injection. Marked astrocytic proliferation also occurred by 12 hours and appeared essential for neuronal fragmentation and disintegration. Microglial activity was prominent in the later stages, from 60 hours onwards, and participated in the phagocytic removal of degenerating neuronal fragments. By the end of the second week, all cytoplasmic and nuclear debri was removed. Concurrently, degenerative changes in the cerebellar cortex were evident from 12 hours onwards. All climbing fiber varicosities were observed to be degenerative as early as 24 hours following treatment. Electron microscopic observations revealed that these electron dense fragments were largely phagocytized and cleared by Bergmann glial cells around 7 days. The sensitivity of the olivocerebellar system to 3‐AP thus provides a convenient and selective means of eliminating all of the inferior olivary neurons and their axons, the climbing fibers of the cerebellar cortex. In contrast to the more conventionally used electrolytic methods, 3‐AP causes a complete bilateral ablation of all olivary neurons while avoiding the problems inherent to electrolytic procedures, such as incomplete destruction of the nucleus and involvement of fibers of passage.
Prenatal and postnatal development of GABA‐accumulating cells in the occipital neocortex of rat
Authors: Chronwall Bibie , Wolff Joachim R.
Published: January 2005

The development of the 3H‐GABA‐accumulating cells in the neocortex has been followed by light microscopical autoradiography, and after resectioning of the original autoradiograms, by electron microscopy. The validity of the methods used are discussed. The study has been limited to the primary visual cortex and its precursors of rat, from embryonic day (E) 15 to adult.

GABA‐accumulating cells were found from E 16 onwards in the occipital cortex, which is one to two days after cells arrive in the pallial anlage and one day before the first synapses have been found. Until E 18, the prevalent positions of labeled cells were in lamina I and below the cortical plate. Later, labeled cells also occurred as strands within the cortical plate. During the perinatal period, more and more GABA‐accumulating neurons and glial cells began to differentiate and show a characteristic distribution at the periphery of unlabeled cell clusters. From postnatal day 11, no apparent change in density or position of labeled neurons took place.

At prenatal stages, two main types of labeled cells were found: 1) Comparatively large cells with rounded nuclei and rough endoplasmic reticulum consisting of narrow, electron‐lucent cisterns. These cells were tentatively identified as preneurons. 2) Smaller, polymorphous cells with irregular nuclei and rough endoplasmic reticulum with wide cisterns filled with a dense matrix. These cells are probably precursors of glial cells. Both labeled neurons and glial cells were identified at postnatal stages. In young and adult rats, only neurons to be characterized as nonpyramidal neurons were labeled. Synapses were not found on the perikarya of labeled cells until E 21. Also, in postnatal preparations, labeled neurons showed few axo‐somatic synapses.

These data were correlated with other events of the structural and functional development of the neocortex. The delay between the appearance of GABA accumulating cells and synaptogenesis indicates that apart from being an inhibitory neurotransmitter, GABA might play a specific morphogenetic role in synaptogenesis. This could even be its primary function during early developmental stages.
Corticopontine visual projections in macaque monkeys
Authors: Glickstein Mitchell , Cohen Janet Lee , Dixon Bryan , Gibson Alan , Hollins Mark , Labossiere Eilene , Robinson Farrel
Published: January 2005

These experiments were designed to study the projections to the pons from visual and visual association cortex of monkeys by degeneration staining and horseradisch peroxidase (HRP) methods. When lesions were made in these cortical visual areas, degenerated fibers were found in the rostral dorsolateral area of the pontine nuclei. When HRP was injected among visually responsive cells in this region of the pons, layer V cortical pyramidal cells were labeled. These labeled cells were concentrated most heavily on both banks of the superior temporal and intraparietal fissures, and on the rostral bank of the parieto‐occipital fissure. The efferent targets and receptive field properties of these cortical regions are consistent with their possible role in visual guidance of movement.
Efferent projections of the deep mesencephalic nucleus (pars medialis) in the rat
Authors: Veazey R. B. , Severin C. M.
Published: January 2005

The projections of the medial part of the deep mesencephalic nucleus (DMN) were traced by autoradiography and retrograde horseradish peroxidase (HRP) techniques. No ascending projections were observed from the medial part of the DMN; however, two groups of descending fibers were observed. One group crossed the midline and coursed to the caudal part of the red nucleus. At this point, these fibers divided into two distinct bundles. One bundle of fibers passed caudally to terminate in the contralateral pontine reticular nucleus, superior olive‐trapezoid body complex, gigantocellular nucleus, and upper cervical spinal cord. The other bundle entered the medial longitudinal fasciculus (MLF) and coursed through the pons and medulla without termination, to enter the cervical spinal cord where terminations were noted in the dorsal horn. The other group of fibers from the medial DMN descended through the ipsilateral pons and medulla, projecting to the pontine reticular nucleus, superior olive‐trapezoid body complex, gigantocellular nucleus, and upper cervical spinal cord. These findings indicate that the medial part of the DMN is likely to be involved in complex sensorimotor events via reticulobulbar and reticulospinal connections.
The nucleus of the solitary tract in the monkey: Projections to the thalamus and brain stem nuclei
Authors: Beckstead Robert M. , Morse Joel R. , Norgren Ralph
Published: January 2005

The projections of the nucleus of the solitary tract (NST) were studied by autoradiographic anterograde fiber‐tracing and horseradish peroxidase (HRP) retrograde cell‐labeling. Tritiated proline and leucine were deposited in electrophysiologically identified regions of NST. Injections of NST at levels caudal to where the vagus enters the nucleus, from which responses were evoked by stimulation of cranial nerves IX and X, revealed topographically organized bilateral projections to, most prominently, the ventrolateral medullary reticular formation which contains neurons of the ambiguus complex, and to the lateral and medial parabrachial nuclei, including a small portion of the medially adjacent central gray substance. Labeled fibers in the ventrolateral reticular formation were present from the nucleus retroambigualis rostralward to the retrofacial nucleus, with the densest concentration located over the nucleus ambiguus proper. The parabrachial projection was confirmed using HRP and shown to originiate from cells in the medial subdivision of NST. Due to the problem of fibers en passant, it was not possible to interpret conclusively the cell‐labeling seen around the solitary tract after HRP injections made in the region of the nucleus ambiguus. Labeled fibers were also traced from caudal NST to the dorsal motor nucleus of the vagus, but their origin could not be determined with certainty. Other labeled axons, traced to circumscribed parts of the inferior olivary complex and via the contralateral medial lemniscus to VPL of the thalamus, were shown in HRP experiments to originate from the dorsal column nuclei rather than NST. No labeled fibers were traced into the spinal cord, nor were any cells labeled in NST after large HRP deposits in upper cervical segments.

Isotope deposits at levels of NST rostral to the entrance of the vagus, from which responses were evoked by rapid stimulation of the tongue, revealed an ipsilateral projection which ascends as a component of the central tegmental tract to the parvicellular part of the ventral posteromedial thalamic nucleus (VPMpc). After small HRP deposits in VPMpc, labeled cells in NST were restricted to the rostral part of the lateral subdivision. No labeled axons were traced from rostral NST to the ambiguus complex or parabrachial area. Injections of 3H‐amino acids at intermediate levels of NST resulted in fiber‐labeling in VPMpc, the parabrachial area, and the ambiguus complex.
Number and distribution of neurons in leech segmental ganglia
Authors: Macagno E. R.
Published: January 2005

The number of neurons and their distribution were determined for specific segmental ganglia from the nerve cord of four different species of leech. Quantitative data were obtained by using computer‐aided techniques for the analysis of nerve structure from serially sectioned or whole‐mounted tissue. The species studied were Hirudo medicinalis, Macrobdella decora, Haemopis marmorata (family Hirudinidae), and Haementeria ghilianii (family Glossophoniidae).

Two sets of ganglia were studied in each species: middle ganglia (9, 10, and 11) and sex ganglia (5 and 6). The middle ganglia, as well as the rest of the 21 segmental ganglia, except 5 and 6, are thought to be quite similar. The sex ganglia are associated with the sexual organs and appear to have more neurons.

The data reported here indicate that: a) the number of neurons in a specified ganglion varies by one to two percent from animal to animal of a given species; b) the middle ganglia of a particular leech each have approximately the same number of neurons, with a variation also within two percent; c) the middle ganglia of Hirudo, Macrobdella, and Haementeria have some 20 fewer (about 380); d) the sex ganglia of Hirudo, Macrobdella, and Haemopis have a few hundred more neurons than their middle ganglia, with the exact number varying according to the species, but the sex ganglia in Haementeria have only about 20 more neurons than their middle ganglia; e) the distribution of neuronal somata among glial packets is not symmetric about the midsaggital plane of the animal, and the number of somata in each packet is variable; and f) the geometry of the glial packets is generally invariant, but occasionally packets are found in abnormal positions.
Somatosensory thalamus of a prosimian primate (Galago senegalensis). II. An HRP and Golgi study of the ventral posterolateral nucleus (VPL)
Authors: Pearson J. C. , Haines D. E.
Published: January 2005

The topographic arrangement and cytoarchitecture of cells in the ventral posterolateral nucleus (VPL) of a prosimian primate (Galago senegalensis) were studied using horseradish peroxidase (HRP) and Golgi impregnation techniques. Following cortical implants of HRP, reactive neurons in VPL are organized into medially concave lamellae which extend through the dorsoventral and rostrocaudal dimensions of the nucleus. After implant in forelimb and hindlimb areas of motor‐sensory cortex, labeled cells are confined to the medial (VPLm) and lateral (VPLl) portions of VPL, respectively. HRP‐positive cells in the ventral part of each lamella are organized into clusters which correspond to the clusters of cells and “parcellated‐bursts” of preterminal debris previously described in bushbaby VPL (Pearson and Haines, this volume). HRP‐reactive cells in the ventral intermediate nucleus (Vim) are evenly distributed as contrasted to the tightly clustered groups of somata in the adjacent VPL. This evidence argues in favor of the presence of Vim in dorsal thalamus of this prosimian.

Golgi impregnations reveal two main types of relay cells in Galago VPL. Type I cells have multiangular somata, straight distal dendrites, and primary dendritic branch points which are free of appendages. Type II cells have rounded somata, sinuous distal dendrites, and clusters of appendages located at primary branch points. Intermediate cells (i.e., cells with morphological features in between types I and II) are also present in VPL. Comparison of tufted Golgi impregnated cells with neurons labeled with HRP shows definite similarities in somata size and shape, and in the orientation of proximal dendrites. This evidence corroborates the relay nature of the tufted neurons in VPL. Relay cells in Galago VPL have morphological features which are similar to those of relay cells in lateral and medial geniculate nuclei of cat and primate.

Type III cells have small round somata, radiate dendrites with elaborate appendages, and axons which appear to be intrinsic to VPL. Consequently, these cells are considered to be interneurons in the VPL of Galago. Glial‐like neurons (type IV cells) were also observed. These have beaded dendritic processes similar to those which presumably represent presynaptic boutons in other species. Consequently, these cells are also assumed to function intrinsically within VPL.
Physiological development of a monosynaptic connection involved in an adult insect behavior
Authors: Heathcote R. David
Published: January 2005

Locust flight is an exclusively adult behavior whose neural basis has been extensively studied. The coordinated neural pattern underlying this behavior appears rapidly at the end of postembryonic development. This paper examines the ontogeny of elements of the nervous system involved in the behavior. Alternative extreme hypotheses are: (1) the neurons and synapses involved develop concomitant with the behavior, or (2) they are constructed early in development, and are activated at the appropriate time by, for example, the release of inhibition. These hypotheses were evaluated by selecting a synapse that is important in adult flight, and monitoring its physiological features during postembryonic development.

The synapse between the forewing Stretch Receptor (SR) and the First Basalar (BA) motor neuron, two uniquely identified neurons, mediates a monosynaptic reflex which operates only in flight. The EPSP, initiated by SR in BA, was recorded intracellularly during the last four of six postembryonic instars. As early as third instar, the monosynaptic EPSP is present and appears to be as effective as in the adult. It also decrements and summates similarly in younger animals and adults. Therefore, some flight system synapses are present and effective throughout most of postembryonic development, and thus do not develop concomitant with the behavior.
Two‐dimensional maps of the cerebral cortex
Authors: van Essen D. C. , Maunsell J. H. R.
Published: January 2005

A procedure is described for constructing two‐dimensional, unfolded representations of the cerebral cortex. The technique is based on information contained in outlines of histological sections, and it allows an entire hemisphere to be represented on a single cortical map. Maps for different hemispheres from individuals of the same species are similar in size, shape, and organization, and their configuration is largely independent of the plane of sectioning used for reconstruction. Many types of information pertaining to the location and organization of different functional subdivisions can be displayed on cortical maps; representative applications of the technique to mapping cerebral cortex in the macaque and the cat are shown. Areal measurements on cortical maps correspond closely (generally within 20%) to actual surface areas in the intact hemisphere. Therefore, the maps can also be used to provide accurate determinations of the absolute and relative extent of various anatomical and functional subdivisions of the cortex.