The callosal connections of the primary somatosensory cortex and the neural bases of midline fusion

Manzoni, T; Barbaresi, Paolo; Conti, Fiorenzo; Fabri, Mara

doi:10.1007/bf00247886

Cited by 217 publications

(70 citation statements)

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“…For instance, in the primary somatosensory area (SI or area 3b) of some mammals, the representations of distal body parts, such as the hand in primates, tend to be sparsely interconnected or acallosal, whereas the proximal and midline body part representations are densely interconnected (for review, see Innocenti, 1986). This observation, together with comparable findings in the visual cortex, have led some investigators to propose that callosal connections are involved in ''fusing'' the midline of sensory representations (e.g., Manzoni et al, 1989;Guillemot et al, 1992; for review, see Innocenti, 1986). Another possibility is that it is the use of the body part in question that dictates the pattern of connectivity.…”

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confidence: 84%

Interhemispheric connections of somatosensory cortex in the flying fox

et al. 1998

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confidence: 84%

Interhemispheric connections of somatosensory cortex in the flying fox

et al. 1998

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“…Also, there are no reports of either contralaterally evoked whisker responses in trigeminal whisker-related nuclei or ipsilaterally evoked responses in whisker-related thalamic nuclei. In other systems and species, ipsilaterally evoked activity in primary sensory cortices has been widely accounted for by transcallosal pathways (Berlucchi et al, 1967;Swadlow, 1974;Manzoni et al, 1989;Iwamura et al, 1994;Schnitzler et al, 1995;Clarey et al, 1996;Swadlow and Hicks, 1997).…”

Section: Identifying the Source Of Ipsilaterally Evoked Activitymentioning

confidence: 99%

Bilateral Integration of Whisker Information in the Primary Somatosensory Cortex of Rats

2001

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The isomorphic representation of the contralateral whisker pad in the rodent cerebral cortex has served as a canonical example in primary somatosensory areas that the contralateral body surface is spatially represented as a topographic map. By characterizing responses evoked by multiwhisker stimuli, we provide direct evidence that the whisker region of the rat primary somatosensory cortex (SI) integrates information from both contralateral and ipsilateral whisker pads. The proportions of SI neurons responsive to ipsilateral whisker stimuli, as well as their response probabilities, increased with the number of ipsilateral whiskers stimulated. Under bilateral whisker stimulation, the responses of 95% of neurons recorded were affected by stimulation of ipsilateral whiskers. Contralateral tactile responses of SI neurons were profoundly influenced by preceding ipsilateral stimuli and vice versa. This effect depended on both the spatial location and the relative timing of bilateral whisker stimuli, leading to both spatial and temporal asymmetries of interaction. Bilateral whisker stimulation resulted in only modest changes in evoked response latency. Previous ipsilateral stimulation was also shown to affect tactile responses evoked by later ipsilateral stimuli. Inactivation of the opposite SI abolished ipsilaterally evoked responses as well as their influence on subsequently evoked contralateral responses in the intact SI. Based on these results, we conclude that the rat SI integrates information from both whisker pads and propose that such interactions may underlie the ability of rats to discriminate bilateral tactile stimuli. Key words: barrel cortex; bilateral; ipsilateral; integration; interhemispheric transfer; inactivation; topographyThe role of the somatosensory cortex (SI) in integrating separate sources of tactile input has been investigated primarily by inferring from extracellular recordings the spatiotemporal transformations performed on convergent subcortical inputs. The whisker region of the SI in rodents is an ideal model for investigating the issue of cortical integration because of its modular topography, which purportedly reflects the arrangement of contralateral whiskers at the periphery (Woolsey and Van der Loos, 1970;Killackey, 1973). Recordings from SI neurons in temporal interaction studies have provided a basic description of the temporal and spatial attributes of cortical integration elicited by paired contralateral whisker stimuli (Simons, 1985;Simons and Carvell, 1989;Brumberg et al., 1996;Fanselow and Nicolelis, 1999). Such studies suggest that the SI may integrate information across multiple contralateral whiskers to generate behaviorally relevant information regarding the animal's surrounding environment.If the rat is to use tactile information from both sides of its face, left and right whisker information must also be integrated. Comparisons between these separate sources of tactile input would then allow the animal to successfully detect the width of an aperture, or the orientation of ...

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“…In the somatosensory system, the corpus callosum is involved mainly with continuity of sensation across the midline (i.e., midline fusion; Innocenti, 1986;Manzoni et al, 1989) and presumably with bimanual function (Guillemot et al, 1992). In the visual system, the corpus callosum functions in binocular vision, in depth perception, and in the integration of the two visual hemifields (see review by Innocenti, 1986).…”

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Comparison of the distribution of parvalbumin-immunoreactive and other synapses onto the somata of callosal projection neurons in mouse visual and somatosensory cortex

Czeiger

White

1997

J. Comp. Neurol.

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The distribution of synapses made by parvalbumin-immunoreactive (pv-ir) and nonimmunoreactive terminals was determined for the cell bodies of callosal projection neurons in the somatosensory and visual areas of mouse cerebral cortex. Callosal neurons were labeled by the retrograde transport of horseradish peroxidase applied to the contralateral hemisphere. The surface areas of somata belonging to callosal cells in somatosensory cortex ranged from 230 to 243 microm2 in size and received roughly one-third of their synapses from pv-ir terminals. Visual cortex, in contrast, contained two populations of callosal cell bodies: relatively large ones ranging in size from 255 to 279 microm2 that received 3-9% of their synapses from pv-ir terminals and smaller cell bodies that both in size (232-237 microm2) and in the proportion of synapses received from pv-ir terminals resemble the callosal cells examined in somatosensory cortex. That different functional areas of the cortex have populations of callosal cells similar in size, and displaying similar patterns of somatic synapses, supports the notion that a common plan of synaptic connectivity characterizes different functional areas. Results in visual cortex indicate that functional areas contain, in addition, area-specific patterns of synapses.

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The callosal connections of the primary somatosensory cortex and the neural bases of midline fusion

Cited by 217 publications

References 100 publications

Interhemispheric connections of somatosensory cortex in the flying fox

Interhemispheric connections of somatosensory cortex in the flying fox

Bilateral Integration of Whisker Information in the Primary Somatosensory Cortex of Rats

Comparison of the distribution of parvalbumin-immunoreactive and other synapses onto the somata of callosal projection neurons in mouse visual and somatosensory cortex

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