Organization of postcranial kinesthetic projections to the ventrobasal thalamus in raccoons

Si, Wiener; Ji, Johnson; Em, Ostapoff

doi:10.1002/cne.902580403

Cited by 21 publications

(7 citation statements)

References 41 publications

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“…This is in accord with the physiological findings that the anterodorsal cap of the ventrobasal thalamus is involved in the kinesthetic relay function since evoked potentials could be recorded following electrical stimulation to the deep tissues or muscle afferent fibers (Andersson et al, 1966;Dykes et al, 1981;Friedman and Jones, 1981;Maendly et al, 1981;Jones and Friedman, 1982;Dykes et al, 1986;Wiener et al, 1987). This is in accord with the physiological findings that the anterodorsal cap of the ventrobasal thalamus is involved in the kinesthetic relay function since evoked potentials could be recorded following electrical stimulation to the deep tissues or muscle afferent fibers (Andersson et al, 1966;Dykes et al, 1981;Friedman and Jones, 1981;Maendly et al, 1981;Jones and Friedman, 1982;Dykes et al, 1986;Wiener et al, 1987).…”

Section: Discussionsupporting

confidence: 87%

Ultrastructural study of external cuneothalamic neurons and their synaptic relationships with primary afferents in the gerbil

Lan¹,

Wen²,

Tan³

et al. 1996

J. Comp. Neurol.

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The present study examined the synaptic organization of external cuneothalamic neurons and their relationships with primary afferents in the gerbil external cuneate nucleus (ECN) following an injection of horseradish peroxidase (HRP) into the anterodorsal cap of the ventrobasal thalamus in conjunction with a simultaneous injection of HRP into the contralateral brachial and cervical nerve plexuses. The thalamus-projecting neurons have been shown to be confined to the intermediate portion of the caudal half of the ECN at the light microscopic level (Lan et al., 1994c). In this study, HRP-labelled external cuneothalamic neurons were ultrastructurally characterized by their relatively small-sized soma bearing a variable number of somal spines. Their nucleus had a slightly indented contour with an eccentric nucleolus. The HRP-labelled somata were postsynaptic to many axon terminals, which were classified into round (Rs type; 53.0%), pleomorphic (Ps type; 32.7%), and flattened (Fs type; 14.3%) vesicle-containing boutons. The HRP-labelled dendritic elements were postsynaptic to a greater number of axon terminals, which were also classified into the round (Rd; 64.7%), pleomorphic (Pd; 25.2%), and flattened (Fd; 10.1%) type boutons. These presynaptic axonal boutons tended to synapse on distal and secondary dendrites of external cuneothalamic neurons. In the present simultaneous HRP labelling study, some of the primary afferent terminals made direct synaptic contacts with the dendrites of the external cuneothalamic neurons. In view of the multiple inputs onto the external cuneothalamic neurons, impinging particularly on their somata and secondary dendrites, it is suggested that the proprioceptive information reaching these neurons is intensively modulated and integrated before transmission ultimately to the cerebral sensorimotor cortex.

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Section: Discussionsupporting

confidence: 87%

Ultrastructural study of external cuneothalamic neurons and their synaptic relationships with primary afferents in the gerbil

Lan¹,

Wen²,

Tan³

et al. 1996

J. Comp. Neurol.

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“…A few RFs that were centered on one of the digit pads extended slightly onto the other pad, probably due to the spread of mechanical forces around the crease separating these pads, but no normal RFs included the entire ventral surface of a digit. These normal RFs are comparable in size to those reported by other investigators using a variety of other anesthetics (Welker and Johnson, 1965;Warren et al 1986;Wiener et al 198713). The RFs at deafferented sites shown in Figures 3 and 4 and additional examples in Figure 5B-D show that the RFs at the deafferented sites were almost always larger than the normal RFs.…”

Section: Reorganization Of Vpl In Adult Raccoonsupporting

confidence: 85%

Changes in the organization of the ventroposterior lateral thalamic nucleus after digit removal in adult raccoon

Rasmusson

1996

J. Comp. Neurol.

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The ventroposterior lateral nucleus of the thalamus was studied in seven raccoons that had undergone amputation of the fourth digit between 2 and 5 months previously. Extracellular recordings were made in a series of closely spaced penetrations through the thalamus in chloralose anesthetized animals. The responses to cutaneous stimulation of the forepaw were used to reconstruct the somatotopic organization of the thalamus and to identify recording sites believed to be located in the digit zone that had lost its peripheral input. Twelve penetrations that passed through both of the adjacent fifth and third digit regions were analyzed in detail to delineate this deafferented region. None of the recording sites in this region were completely silent, indicating that the deafferented thalamus had undergone significant reorganization of its inputs. At most sites, the neurons had receptive fields on the skin surrounding the amputation wound and including one of the adjacent digits. Approximately half of the sites had low thresholds in the range of normal thalamic neurons. These results indicate that the ventroposterior thalamus is capable of substantial reorganization, which may account for much of the reorganization seen in somatosensory cortex.

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“…With further investigation and additional techniques, it should be possible to divide the sea lion VP complex further. In other species, a more cell‐dense portion of the VP complex, the ventroposterior superior nucleus, receives proprioceptive input (primates: Kaas et al, ; raccoons: Wiener et al, ; cats: Dykes et al, ). This division is probably present in the superior portion of the VP complex in sea lions as well.…”

Section: Discussionmentioning

confidence: 99%

Somatosensory brainstem, thalamus, and cortex of the California sea lion (Zalophus californianus)

Sawyer

Turner²,

Kaas³

2016

J of Comparative Neurology

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Pinnipeds (sea lions, seals and walruses) are notable for many reasons, including their ape-sized brains, their adaptation to a coastal niche that combines mastery of the sea with strong ties to land, and the remarkable abilities of their trigeminal whisker system. Yet, little is known about the central nervous system of pinnipeds. Here we report on the somatosensory areas of the nervous system of the California sea lion (Zalophus californianus). Using stains for Nissl, cytochrome oxidase, and vesicular glutamate transporters, we investigated the primary somatosensory areas in the brainstem, thalamus and cortex in one sea lion pup, and the external anatomy of the brain in a second pup. We find that the sea lion’s impressive array of whiskers is matched by a large trigeminal representation in the brainstem with well-defined parcellation that resembles the barrelettes found in rodents, but scaled up in size. The dorsal column nuclei are large and distinct. The ventral posterior nucleus of the thalamus has divisions, with a large area for the presumptive head representation. Primary somatosensory cortex is located in the neocortex just anterior to the main vertical fissure, and precisely locating it as we do here is useful for comparing the highly gyrified pinniped cortex to other carnivores. To our knowledge this work is the first comprehensive report on the central nervous system areas for any sensory system in a pinniped. The results may be useful in both the veterinary setting and for comparative studies related to brain evolution.

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Organization of postcranial kinesthetic projections to the ventrobasal thalamus in raccoons

Cited by 21 publications

References 41 publications

Ultrastructural study of external cuneothalamic neurons and their synaptic relationships with primary afferents in the gerbil

Ultrastructural study of external cuneothalamic neurons and their synaptic relationships with primary afferents in the gerbil

Changes in the organization of the ventroposterior lateral thalamic nucleus after digit removal in adult raccoon

Somatosensory brainstem, thalamus, and cortex of the California sea lion (Zalophus californianus)

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