Distribution patterns and individual variations of callosal connections in the albino rat

Záborszky, László; Wolff, Joachim R.

doi:10.1007/bf00305478

Cited by 55 publications

(15 citation statements)

References 47 publications

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“…Previous studies of the callosal pathway in the rat have led to the interpretation that fibers originating from all regions of striate cortex converge onto lateral portions of contralateral striate cortex (Nauta and Bucher, 1954;Zaborszky and Wolff, 1982;Miller and Vogt, 1984). These studies did not report differences in the organization of facilitated by recognizing that the callosal pattern in this region resembles that described by Shatz (1977a,b) in the 17/18 callosal region of Siamese cats.…”

Section: A L B 1mentioning

confidence: 79%

Two rules for callosal connectivity in striate cortex of the rat

Lewis

Olavarría

1995

J of Comparative Neurology

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In the rat, callosal cells occupy lateral as well as medial portions of striate cortex. In the region of the border between areas 17 and 18, which contains a representation of the vertical meridian of the visual field, cells projecting through the corpus callosum are concentrated throughout the depth of the cortex. In contrast, in medial portion of striate cortex, where peripheral portions of the visual field are represented, callosal cells are preferentially found in infragranular layers. These differences in topography and laminar distribution suggest that these callosal regions, referred to as medial and lateral callosal regions in the present study, subserve different functions. We explored this possibility by analyzing the patterns of callosal linkages in these two callosal regions. We charted the location of retrogradely labeled cells within striate cortex of one hemisphere after placing restricted injections of one or more fluorescent tracers into selected sites in the contralateral striate cortex. We found the medial and lateral callosal regions have distinctly different topographic organizations. Injections into medial striate cortex of one hemisphere produced labeled cells predominantly in mirror-symmetric loci in medial portions of contralateral striate cortex. The arrangement of these connections suggests that they mediate direct interactions between cortical regions representing visual fields located symmetrically on opposite sides of the vertical meridian of the visual field. In contrast, the mapping in the lateral callosal region is reversed: injections into the 17/18a border produced labeled fields located medial to the contralateral 17/18a border, while injections slightly medial to the 17/18a border produced labeled fields located at the contralateral 17/18a border.(ABSTRACT TRUNCATED AT 250 WORDS)

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Section: A L B 1mentioning

confidence: 79%

Two rules for callosal connectivity in striate cortex of the rat

Lewis

Olavarría

1995

J of Comparative Neurology

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“…A significant decline in glucose utilization at 2.0 MAC isoflurane has been detected in rat corpus callosum (25). In rats, callosal connectivity is higher between bilateral M1 regions than between bilateral S1 regions (34,35). Thus, metabolic depression of interhemispheric corticocortical connectivity at high isoflurane levels may also have accounted for the observed larger loss of functional connectivity between bilateral motor regions.…”

Section: Discussionmentioning

confidence: 93%

Temporal scaling properties and spatial synchronization of spontaneous blood oxygenation level‐dependent (BOLD) signal fluctuations in rat sensorimotor network at different levels of isoflurane anesthesia

et al. 2011

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Spontaneous fluctuations in the blood oxygenation level-dependent (BOLD) MRI signal during the resting state are increasingly being studied in healthy and diseased brain in humans and animal models. Yet, the relationship between functional brain status and the characteristics of spontaneous BOLD fluctuations remains poorly understood. In order to obtain more insights into this relationship and, in particular, the effects of anesthesia thereupon, we investigated the spatial and temporal correlations of spontaneous BOLD fluctuations in somatosensory and motor regions of rat brain at different inhalation levels of the frequently applied anesthetic isoflurane. We found that the temporal scaling, characterized by the Hurst exponent (H), showed persistent behavior (H > 0.5) at 0.5-1.0% isoflurane. Furthermore, low-pass-filtered spontaneous BOLD oscillations were correlated significantly in bilateral somatosensory and bilateral motor cortices, reflective of interhemispheric functional connectivity. Under 2.9% isoflurane anesthesia, the temporal scaling characteristics approached those of Gaussian white noise (H = 0.5), the relative amplitude of BOLD low-frequency fluctuations declined, and cross-correlations of these oscillations between functionally connected regions decreased significantly. Loss of interhemispheric functional connectivity at 2.9% isoflurane anesthesia was stronger between bilateral motor regions than between bilateral somatosensory regions, which points to distinct effects of anesthesia on differentially organized neuronal networks. Although we cannot completely rule out a possible contribution from hemodynamic signals with a non-neuronal origin, our results emphasize that spatiotemporal characteristics of spontaneous BOLD fluctuations are related to the brain's specific functional status and network organization, and demonstrate that these are largely preserved under light to mild anesthesia with isoflurane.

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“…Exceptions to this rule have been noted, however, especially in heterotopic connections (Miller and Vogt 1984). Zaborsky and Wolff (1982) described the distribution of axonal terminals after complete callosotomy in rats. Their Fig.…”

Section: Commissural Connectionsmentioning

confidence: 99%

“…A detailed comparison of the two sets of data is difficult because of incomplete labelling in Fig. 4 of Zaborsky and Wolff (1982), different planes of cutting, and use of different reference cytoarchitectonic maps.…”

Section: Commissural Connectionsmentioning

confidence: 99%

Afferents to different layers of the dorsolateral isocortex in rats

et al. 1995

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Fluorescent somatopetal tracers were used to infiltrate, by diffusion rather than injections, the dorsolateral cortex of one hemisphere in rats. In different animals the tracers penetrated into the cortex to different depths. We found several interesting features of the commissural system: first, there were no areas without commissural neurons. At least a few labelled cell bodies were present in a single-cell layer also in "acallosal" cortical areas. Secondly, there is a considerable variety of laminar distribution patterns of labelled perikarya in different areas. Thirdly, some cortical fields, which cytoarchitecturally appear uniform, can be subdivided according to different distributions of cell bodies with commissural projections. Fourthly, when only supragranular layers were infiltrated, labelled cell bodies were present mainly in the supragranular layers of the contralateral cortex. Infiltration of the first layer alone did not label any neurons in the contralateral cortex but did label neurons in layer VIb ipsilaterally. In the subcortex, the labelled perikarya were found in the structures already known to project directly to the cortex. In rats with the tracer restricted mainly to the supragranular layers, a conspicuously reduced labelling was found in the basal forebrain and the thalamus. In the thalami of those animals, labelled neurons were found only in paralamellar nuclei. The high sensitivity of the tracer used, together with infiltration of the entire dorsolateral cortex, allows us to conclude that probably all sources of innervation of the isocortex in rats have been seen.

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Distribution patterns and individual variations of callosal connections in the albino rat

Cited by 55 publications

References 47 publications

Two rules for callosal connectivity in striate cortex of the rat

Two rules for callosal connectivity in striate cortex of the rat

Temporal scaling properties and spatial synchronization of spontaneous blood oxygenation level‐dependent (BOLD) signal fluctuations in rat sensorimotor network at different levels of isoflurane anesthesia

Afferents to different layers of the dorsolateral isocortex in rats

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