摘要:

AbstractThe topographical interrelations of Claustroneocortical cells and their degree of divergent collateralization were investigated in cat by means of retrograde fluorescent double labeling. The tracers Fast Blue (FB) and Nuclear Yellow (NY) were injected in several combinations in two different cortical fields. FB‐labeled and NY‐labeled cells were found in all cases in the insular portion of the ipsilateral claustrum (C1I). The distributions of labeled cells confirmed the organization reported in previous studies. In some cases the two labeled cell populations were segregated in different parts of the C1I; in other cases there was more or less overlap in the two distributions. The degree of overlap was not simply related to the topographic proximity of the injected cortical territories.In all cases the vast majority of cells were single labeled. In one case both FB and NY were injected in the same cortical area in order to control that claustral axons can retrogradely transport two tracers back to the same parent cell bodies. In this control case C1I cells were double labeled. All together these data indicate that widely divergent Claustroneocortical projections take origin mainly from separate ce

ISSN:0092-7317    

DOI:10.1002/cne.902150202

出版商:Alan R. Liss, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractThalamic and cortical afferents to the insular and perirhinal cortex of the rat were investigated, Unilateral injections of horseradish peroxidase (HRP) were made iontophoretically along the rhinal sulcus. HRP injections covered or invaded areas along the rhinal fissure from about the level of the middle cerebral artery to the posterior end of the fissure. The most anterior injection labeled a few cells in the mediodorsal nucleus. More posterior injections labeled neurons in the basal portion of the nucleus ventralis medialis, thus suggesting that this cortical region constitutes the rat's gustatory (insular) cortex. We consider the cortex situated posterior to the gustatory cortex in and above the rhinal sulcus as the core region of the rat's (associative) insular cortex, as this cortex receives afferents from the regions of and between the nuclei suprageniculatus and geniculatus medialis, pars magnocellularis. It includes parts of the cortex termed perirhinal in other studies. The cortex dorsal and posterior to the insular cortex we consider auditory cortex, as it receives afferents from the principal part of the medial geniculate nucleus, and the cortex ventral to the insular cortex (below the fundus of the rhinal sulcus) we consider to constitute the pre‐piriform cortex, which is athalamic. The posterior part of the perirhinal cortex (area 35) receives afferents from nonspecific thalamic nuclei (midline nuclei).Cortical afferents to the injection loci arise from a number of regions, above all from regions of the medial and sulcal prefrontal cortex. Those injections confined to the projection cortex of the suprageniculate‐magno‐cellular medial geniculate nuclear complex also led to labeling in contra‐lateral prefrontal regions, particularly in area 25 (infralimbic region).A comparison of our results with those on the insular cortex of cats and monkeys suggests that on the basis of thalamocortical connections, topographical relations, and involvements of neurons in information processing and overt behavior, the insular cortex has to be regarded as a heterogeneous region which may be separated intoprefrontal insular, gustatory(somato‐sensory) insular, andassociative insula

ISSN:0092-7317    

DOI:10.1002/cne.902150203

出版商:Alan R. Liss, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractWe devised a computer program to analyze the dendritic geometry of dentate granule cells as seen in rapid Golgi impregnations from the mouse. Three dimensional coordinates were recorded by using a computer‐assisted microscope. Geometric parameters are of two general types: (1) LINEAR parameters include the number of dendritic segments per branch order and their individual and aggregate lengths. (2) ANGULAR parameters define the spatial relationships of branch points and segment terminals with each other and with the axis of symmetry derived for all the dendrites. We find that values for linear parameters are highly variable and more susceptible to artifacts. Values for most angular parameters are more highly constrained and are presumably the best descriptors of the class‐characteristic conical shape of granule cell dendrites. Additional features which are necessary to describe granule cell dendrites fully are: (1) Branching frequency is highest proximal to the cell soma, (2) deviant segments are kept “on course” to ensure axial symmetry, and (3) terminal segments end at the plane of the cortical surface. A critical analysis of the various parameters suggests the hypothesis that the characteristic and uniform geometry of granule cell dendrites is controlled largely by factors residing in the molecular layer where growth and differentiation are sustained. An additional finding of potential interest is that there are two subpopulations of granule cells with a twofold difference in spine

ISSN:0092-7317    

DOI:10.1002/cne.902150204

出版商:Alan R. Liss, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractLight (LM) and electron microscopic (EM) qualitative and quantitative analyses were employed to determine the tempo and spatial gradients of Synaptogenesis and cellular differentiation in the superficial superior collic‐ulus (SC) of the rhesus monkey between embryonic (E) days E47 and E84. 3y E47, a majority of the neurons of the prospective superficial gray layer (SGS) have arrived at their final positions and contribute to a uniform band of small, darkly Nissl‐stained neurons at the outer surface of the SC. By E54, cells in the middle of the rostral pole of the superficial SC become considerably larger, paler staining, and less densely packed than the more medially or laterally located cells. These regional differences, which extend posteriorly through about the middle of the SC at this age, are evident on both the LM and EM levels and were confirmed by a quantitative EM analysis of the cytodifferentiation and Synaptogenesis in the SGS. Several overlapping EM probes made across the medial, middle, and lateral regions of the SGS at each of three coronal levels reveal consistently more developed neuropil and smaller amounts of extracellular space in the middle region than in the medial and lateral portions of the more anterior SC. Further the densities of synapses, both in terms of synapses/μm2of totalcross‐secti area and synapses/μm2of neuropil alone, are also higher in the middle than the peripheral regions. Most of the middle‐peripheral differences found in the mid‐E.50s are still evident by the early E60s, but have disappeared by midgestation (E80s). The present results are interpreted to indicate that the middle region of the SGS at a given transverse level begins to mature significantly earlier than the medial or lateral areas. Since our previous 3H‐thymi‐dine analysis (Cooper and Rakic, 1981 a) failed to reveal significant regional variation in the time of neuron origin in the superficial SC, the observed spa‐tiotemporal gradients of neuronal maturation in the primate SGS probably do not arise from underlying gradients of cellu

ISSN:0092-7317    

DOI:10.1002/cne.902150205

出版商:Alan R. Liss, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractPostdeafferentation reorganization in the central terminal fields of spared dorsal root axons was evaluated by examining the intraspinal distribution of horseradish peroxidase‐labeled sciatic nerve afferent fibers at various intervals following the removal of several lumbar dorsal root ganglia. The sciatic projection to the spinal cord, as determined by the pattern and density of intraspinal reaction product, was remarkably stable following the ganglionectomies. For as long as 3 months later, there was no evidence that sciatic afferent fibers had formed anomalous connections either with new spinal segments or in denervated areas within normal segments of entry. These findings cast doubt upon the existence of anatomic reorganization within the spinal cord following its partial deafferentation and suggest that physiological processes other than new axonal growth underlie observations such as postdenervation alterations in the response properties of dorsal horn neurons and the recovery of behavioral functio

ISSN:0092-7317    

DOI:10.1002/cne.902150206

出版商:Alan R. Liss, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractTo learn whether salt taste responses change during mammalian development, we recorded from multifiber preparations of the chorda tympani while stimulating the anterior tongue in sheep fetuses, lambs, and adults. Stimuli were 0.5 M NH4C1, KC1, NaCl, and LiCl, and 0.05–0.75 M concentration series of the first three salts. Ultrastructural studies were made of taste buds at different ages to determine whether morphological elements such as microvilli and tight junctions are present in young fetuses.Substantial changes occur in relative salt taste responses, throughout development. In fetuses that are beginning the last third of gestation, NaCl and LiCl elicit much smaller response magnitudes than NH4C1 and KC1. Throughout the rest of gestation and postnatally, the NaCl and LiCl responses gradually increase in magnitude relative to NH4C1 and KCL In adults, NaCl, LiCl, and NH4Cl all elicit similar response magnitudes and KC1 is less effective as a taste stimulus. At ages when response ratios for the 0.5 M salts are changing, there are no changes in shapes of the response/concentration functions for individual salts. Furthermore, microvilli are present on taste bud cell apices and tight junctions are found between cells in the youngest fetuses studied. Therefore, initial stimulus‐receptor membrane contacts are probably similar to those in adults.Our data suggest that different membrane components interact with the various monochloride salts and that taste receptors contain different proportions of these various membrane components at different developmental stages. Therefore young taste bud cells do not have the same salt response characteristics as mature cells, and a changing neural substrate underlies development of salt taste function, both pre‐ and postna

ISSN:0092-7317    

DOI:10.1002/cne.902150207

出版商:Alan R. Liss, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractWe previously reported that male rat lumbar motoneurons accumulate radioactivity after injection of tritiated testosterone (T) or dihydrotestoster‐one (DHT), but not estradiol (E). We now report autoradiographic evidence that lumbar motoneurons in male rats accumulate T or its metabolites more frequently than do female motoneurons. However, this sex difference in hormone accumulation by motoneurons is not observed following the injection of DHT or E, both of which are normal metabolites of T. Very few motoneurons from any population accumulated E or its metabolites. In fact, some motoneurons had fewer silver grains over their nuclei than would be expected by chance, thus suggesting that these cells not only failed to accumulate E or its metabolites, but actively or passively excluded them from their nuclei. Virtually every motoneuron of either sex accumulated hormone after DHT injection. Following T injection, more motoneurons were labeled in males (72–77%) than in females (28ndash39%), indicating a sex difference in hormone accumulation. Taken together, these results suggest that either (1) there are separate receptors for T and DHT, and motoneurons have more T receptors (but equal numbers of DHT receptors) in males than in females, or (2) the motoneurons of male rats have greater access to systemically administered T or its metabolites than do those of fema

ISSN:0092-7317    

DOI:10.1002/cne.902150208

出版商:Alan R. Liss, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractA description is given of the growth of segmental nerves 13 to 16 (SN13 to SN16) from the brachial myotomes into the ventral and dorsal premuscle cell masses of the chick forelimb. At stage 25 (Hamburger and Hamilton, 1951), segmental nerves have converged to form two nerve trunks which enter the ventral and dorsal premuscle cell masses. These nerves grow into the limb, parallel to its proximodistal axis. The nerve trunk in the ventral compartment, the brachialis longus inferior (bli n), grows on the brachial artery as far as the metacarpals. The nerve trunk in the dorsal compartment, the brachialis longus superior (bls n), grows on the precartilage adjacent to a dorsal premuscle density as far as the metacarpals.The brachialis longus inferior and superior nerve trunks give rise to a number of nerves during their growth to the metacarpals. Each of these nerves appears at the time of formation of a new premuscle cell density. At late stage 25, a posterior and ventral premuscle density forms in the middle of the stylopodium; posterior fascicles of the bli n diverge at this level and grow toward this new density to form the ulnar nerve. By stage 26 a posterior and ventral premuscle density is prominent over the bli n, at the junction of the stylopodium and the zeugopodium; ventral fascicles of the bli n grow into this density to form the flexor digitorum profundus nerve. At this stage a posterior and dorsal premuscle density forms just beyond the junction of the stylopodium and zeugopodium. Posterior fascicles of the bls n diverge at this level and grow toward this density to form a nerve from which the extensor metacarpi ulnaris, extensor digitorum communis, and radialis la‐terialis nerves are destined to form. At stage 29 the premuscle cell masses of the autopodium have formed. The remaining nerve fascicles comprising the bls n (the radialis profundus nerve) grow into the autopodium and branch to innervate each of the dorsal premuscles. The remaining nerve fascicles comprising the bli n (the middle nerve) grow into the autopodium and branch to innervate each of the ventral premuscle

ISSN:0092-7317    

DOI:10.1002/cne.902150209

出版商:Alan R. Liss, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractWe examined the somatosensory properties of 391 neurons in the inferior olive in 20 cats that were anesthetized with barbiturate or decere‐brated. A response consisted of a single spike with a variable number of wavelets followed by a long refractory period. Neurons responsive to natural somatosensory stimuli were recorded in all olivary subdivisions. The dorsal accessory olive (DAO) contained the highest proportion of responsive units (96%), compared with 66% for the medial accessory olive (MAO) and 43% for the principal olivary (PO) nucleus. Within the rostral DAO we found a refined cutaneous map of the entire contralateral body surface. In the caudal DAO responsiveness to manipulation of deep tissues became prominent, and both individual limbs and bilateral pairs were represented. In the medial region of the PO responsiveness to taps predominated and bilaterally symmetrical fields were frequent. The lateral PO was unresponsive under the conditions of these experiments. The MAO was distinguished by a greater complexity of receptive field and by a preponderance of deep over cutaneous modality. The lateral part of caudal MAO contained cells with interesting spatial patterns of excitation and inhibition, whereas most cells in the rostral MAO had purely excitatory fields. A teleceptive area receiving visual and auditory input was recognized in the medial MAO and nearby structures such as the dorsal cap. Contact and proprioceptive signals arriving via climbing fibers may provide the cerebellum with information necessary to relate the body to external object

ISSN:0092-7317    

DOI:10.1002/cne.902150210

出版商:Alan R. Liss, Inc.    

年代:1983

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.902150201

出版商:Alan R. Liss, Inc.    

年代:1983

数据来源: WILEY