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  • 1
    Electronic Resource
    Electronic Resource
    Peripheral nerve autografts to the rat spinal cord: Study on the origin and course of regenerating fibres (1986)
    Springer
    Acta neurochirurgica 82 (1986), S. 57-63 
    Details
    ISSN: 0942-0940
    Keywords: Peripheral nerve autografts ; Rat spinal cord ; Horseradish peroxidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Autologous sciatic nerve grafts were implanted to the lower thoracic spinal cord (SC) of adult rats. The grafts were longitudinally placed on both sides of the SC midline over the dura mater and their cut ends were inserted into the dorsal white matter of the SC. Eight to 60 weeks later the grafts were exposed. In a first experimental group (A) either horseradish peroxidase (HRP) or lectin conjugated horseradish peroxidase (WGA-HRP) was injected into the grafts in order to investigate the origin and the course of regenerated fibres entering the grafts. In a second experimental group (B) the SC was acutely transected between the upper and lower graft insertions and either HRP or WGA-HRP was injected into the caudal stump of the SC in order to investigate the ability of regenerating axons once entered the grafts to re-enter the SC. In group A retrogradely labelled cells were found in the SC scattered in proximity of both the caudal and rostral graft insertions and in the ventral horns as far as 30 mm rostrally to the grafts. Labelled cells were also located in the spinal ganglia, at the level of the grafts and up to 6 segments caudal to them. In group B retrogradely labelled cells were present in the SC rostrally to the transection, both in proximity of the upper graft insertions and in the ventral horns as far as 30 mm rostrally to the grafts. These findings demonstrate that PN grafts implanted to the SC of adults rats can be innervated by regenerated axons arising from both intraspinal neurons and dorsal root ganglion cells (group A); furthermore axons from intraspinal neurons entered and elongated in the grafts can reenter the SC (group B).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01456320
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  • 2
    Electronic Resource
    Electronic Resource
    Interhemispheric influences on area 19 of the cat (1985)
    Springer
    Experimental brain research 59 (1985), S. 171-184 
    Details
    ISSN: 1432-1106
    Keywords: Area 19 ; Split-chiasm cats ; Ipsilateral visual field representation ; Interhemispheric relations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Anatomical studies have shown an extensive network of homotopic and heterotopic interhemispheric connections in area 19 of the cat visual cortex (Segraves and Rosenquist 1982a; 1982b). We have investigated their functional organization by recording visual responses in area 19 of cats following a midsagittal section of the optic chiasm. This operation interrupts all crossed optic fibers coming both from the nasal and the temporal retinae; as a result, each hemisphere receives optic fibers only from the lateral hemiretina of the ipsilateral eye which conveys information from the contralateral visual field. Visual information transmitted to the same hemisphere from the contralateral retina and the ipsilateral visual field must be attributed to an indirect, interhemispheric pathway. We found that a rather high proportion of neurons (31.8%) in area 19 of seven split-chiasm cats responded to visual stimuli presented to the contralateral eye. 1 — All neurons receiving this interhemispheric activation were also driven by the ipsilateral eye via an intrahemispheric pathway. 2 — The property of binocularity was significantly related to the visuotopic map in that both receptive fields of each binocular neuron adjoined or were in the immediate vicinity of the vertical meridian. 3 — Due to the small size of receptive fields in area 19, the contribution of the interhemispheric pathway to the representation of the visual field is rather limited and it is certainly less extensive than that predicted by anatomical studies. The representation of the ipsilateral visual field in area 19 of intact cats, as assessed electrophy-siologically, was comparable to that found in split-chiasm cats. Recordings in areas 17–18 of split-chiasm cats showed that the visual field represented through the corpus callosum in these visual areas is certainly not less and probably more, extensive than that found in area 19. The results support the conclusion that the relation to the vertical meridian and the receptive field size can explain the organization of the interhemispheric connections in the visual areas studied so far.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237677
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  • 3
    Electronic Resource
    Electronic Resource
    Efferent fibers from the motor cortex terminate bilaterally in the thalamus of rats and cats (1985)
    Springer
    Experimental brain research 57 (1985), S. 305-312 
    Details
    ISSN: 1432-1106
    Keywords: Cortico-thalamic system ; Crossed projections ; WGA-HRP anterograde tracing ; Motor cortex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The anterograde transport of lectin-conjugated horseradish peroxidase (WGA-HRP) was here employed in order to visualize crossed cortico-thalamic efferents of the motor cortex in rats and cats. After WGA-HRP cortical injections in the rat retrogradely labeled cells were observed in the ipsilateral thalamus, and heavy anterograde labeling was observed both in the ipsi-and contralateral thalamus. The contralateral anterograde labeling was less intense than the ipsilateral one and it was distributed in the anterior intralaminar structures, in the parafascicular nucleus, in the ventromedial, ventrolateral and ventrobasal nuclei and in the posterior complex, symmetrically to the labeling observed on the ipsilateral side. Further experiments were made in the rat in order to ascertain that the bilateral anterograde labeling in the thalamus derived unilaterally from the cortex. To this purpose, kainic acid was injected unilaterally either into the frontal cortex or into the thalamus, and WGA-HRP was later injected on the same side in the frontal cortex. Moreover, WGA-HRP was injected into the frontal cortex after splitting of the corpus callosum. The results obtained in these experiments confirmed that cortical neurons projected bilaterally upon the thalamus. Further, these experiments indicated that at least the majority of the contralateral fronto-thalamic fibers crossed the midline in the thalamic massa intermedia. WGA-HRP injections into the pericruciate cortex in the cat confirmed the presence of anterogradely labeled terminals in the contralateral anterior and posterior intralaminar, ventral anterior, ventromedial and ventrolateral nuclei. The labeling was in all cases heavier in the intralaminar nuclei than in the other structures, but it was less intense than that observed in the rat. The labeling in the contralateral principal nuclei was heavier in one case in which the injection area diffused into the proreal cortex than in the other cats. Thus, the present results indicate that frontal efferents terminate more densely in the rat's than in the cat's contralateral thalamus. In the latter species frontal fibers are mainly distributed upon the contralateral intralaminar nuclei, whereas in the rat frontal efferents are also heavily distributed upon the ventral nuclear complex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236536
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  • 4
    Electronic Resource
    Electronic Resource
    The thalamo-caudate versus thalamo-cortical projections as studied in the cat with fluorescent retrograde double labeling (1984)
    Springer
    Experimental brain research 54 (1984), S. 225-239 
    Details
    ISSN: 1432-1106
    Keywords: Intralaminar nuclei ; Axon collaterals ; Fluorescent tracers ; Caudate ; Thalamus ; Cerebral cortex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The distribution of thalamic cells projecting to the head of the caudate and their interrelations with thalamo-cortical cells were studied in the cat with different combinations of fluorescent tracers. Injections in the head of the caudate were combined with the injections in the pericruciate, proreal, suprasylvian, anterior cingulate, occipital and ectosylvian cortices. The following results were obtained: (i) Injections in the head of the caudate resulted in retrograde labeling of thalamic cells medially and laterally to the anteromedial (AM) nucleus, and in the medioventral part of the ventral anterior (VA) nucleus. Further, labeled cells were distributed throughout the anterior intralaminar central medial (CeM), paracentral (Pc) and central lateral (CL) nuclei, and the posterior intralaminar center median-parafascicular complex (CM-Pf). Labeled cells were mainly grouped in the mediodorsal parts of the anterior intralaminar nuclei; they were also found in the more dorsal part of the mediodorsal (MD) nucleus, ventral to the thalamic paraventricular (Pv) nucleus and to the habenular complex, (ii) Thalamo-cortical and thalamo-caudate cells overlapped in the medial part of the VA; in the anterior intralaminar nuclei they were either intermingled or were distributed in separate clusters or longitudinal bands. The two cell populations also overlapped in the posterior intralaminar complex. The greatest overlap occurred with the thalamic cell population projecting to the pericruciate cortex. (iii) Thalamic cells bifurcating to the head of the caudate and to the pericruciate cortex were found lateral to the AM, within the VA, and throughout the anterior intralaminar nuclei, especially in the CeM and in the posterior part of the CL; a few branched cells were also found in the CM. Thalamic cells bifurcating to caudate and anterior suprasylvian cortex were also found in the VA. Very few cells (scattered in the anterior thalamus lateral to the AM, as well as in the CeM, Pc and CL) were found to bifurcate to the head of the caudate and the other cortical fields here examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236222
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  • 5
    Electronic Resource
    Electronic Resource
    GABAergic interneurons and neuropil of the intralaminar thalamus: an immunohistochemical study in the rat and the cat, with notes in the monkey (1991)
    Springer
    Experimental brain research 87 (1991), S. 85-95 
    Details
    ISSN: 1432-1106
    Keywords: Thalamus ; Intralaminar nuclei ; GABA ; Inhibition ; Immunohistochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Immunohistochemistry using antibodies to glutamic acid decarboxylase (GAD) was used to investigate the intralaminar nuclei of the thalamus in rat, cat and monkey. Antibodies to gamma aminobutyric acid (GABA) were also used in the cat. Intralaminar immunoreactive cell bodies were not detected in the rat, but were clearly present in cat and monkey. In the latter species, GABA- or GAD-immunopositive perikarya were distributed throughout the anterior intralaminar nuclei, whereas in the posterior intralaminar complex they prevailed in the lateral part of the centre median nucleus and around the fasciculus retrofiexus. Measurements of the area of immunostained intralaminar cell bodies in cat and monkey indicated that they are represented by small neurons. Experiments in the cat, based on retrograde tracers injections involving large sectors of the frontal and parietal cortices and the head of the caudate nucleus, revealed that the GABA- or GAD-immunoreactive cells and the retrogradely labeled projection neurons represented two separate intralaminar cell populations, although the latter also included small cells. Considerable differences were observed in the immunoreactive GABAergic neuropil of the anterior and posterior intralaminar nuclei. Clusters of densely packed bouton-like immunoreactive elements were detected in the former structures in the rat, cat and monkey, and were especially evident in the central lateral nucleus; immunopositive varicose fibers and puncta were diffusely distributed in the posterior intralaminar structures. Taken together with data from the literature, the present findings indicate that in cat and monkey local circuit inhibitory cells regulate not only the activity of principal thalamic nuclei which project densely upon restricted cortical fields, but also of the intralaminar structures which are widely connected with the cerebral cortex and the striatum. Regional variations in the distribution of GABAergic fibers and terminals suggest major differences in the organization of inhibitory circuits and synaptic arrangements of the anterior and posterior intralaminar thalamus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228509
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  • 6
    Electronic Resource
    Electronic Resource
    Trends in the anatomical organization and functional significance of the mammalian thalamus (1996)
    Springer
    Neurological sciences 17 (1996), S. 105-129 
    Details
    ISSN: 1590-3478
    Keywords: Thalamus ; Thalamo-cortical ; Development ; Cortico-thalamic ; Sleep ; Wakefulness ; Intralaminar nuclei ; Thalamic reticular nucleus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Sommario I dati sperimentali degli ultimi decenni hanno determinato una sostanziale revisione della conoscenza dell'organizzazione anatomica e funzionale del talamo e delle interrelazioni fra il talamo e la corteccia cerebrale. La presente revisione dei dati sperimentali à mirata ad una sintesi delle moderne teorie sulle connessioni talamo-corticali e sulle funzioni talamiche e ad un loro inquadramento nella prospettiva storica degli studi sul talamo. In particolare, alla luce dei contributi sperimentali più recenti, viene discusso a) che il talamo possa svolgere diverse funzioni a seconda dello stato funzionale dei sistemi afferenti e b) che le diverse entità cellulari talamiche possano giocare un ruolo cruciale nei diversi stati funzionali.
    Notes: Abstract The last decade has witnessed major changes in the experimental approach to the study of the thalamus and to the analysis of the anatomical and functional interrelations between thalamic nuclei and cortical areas. The present review focuses on the novel anatomical approaches to thalamo-cortical connections and thalamic functions in the historical framework of the classical studies on the thalamus. In the light of the most recent data it is here discussed that: a) the thalamus can subserve different functions according to functional changes in the cortical and subcortical afferent systems; b) the multifarious thalamic cellular entities play a crucial role in the different functional states.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02000842
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