An analysis of potentially converging inputs to the rostral ventral thalamic nuclei of the cat |
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Authors: | M E Anderson J L DeVito |
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Institution: | (1) Departments of Rehabilitation Medicine, Physiology and Biophysics, and Biological Structure and Regional Primate Research Center, University of Washington, 98195 Seattle, WA, USA |
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Abstract: | Summary Potentially convergent inputs to cerebellar-receiving and basal ganglia-receiving areas of the thalamus were identified using horseradish peroxidase (HRP) retrograde tracing techniques. HRP was deposited iontophoretically into the ventroanterior (VA), ventromedial (VM), and ventrolateral (VL) thalamic nuclei in the cat. The relative numbers of labeled neurons in the basal ganglia and the cerebellar nuclei were used to assess the extent to which the injection was in cerebellar-receiving or basal ganglia-receiving portions of thalamus. The rostral pole of VA showed reciprocal connections with prefrontal portions of the cerebral cortex. Only the basal ganglia and the hypothalamus provided non-thalamic input to modulate these cortico-thalamo-cortical loops. In VM, there were reciprocal connections with prefrontal, premotor, and insular areas of the cerebral cortex. The basal ganglia (especially the substantia nigra), and to a lesser extent, the posterior and ventral portions of the deep cerebellar nuclei, provided input to VM and may modulate these corticothalamo-cortical loops. The premotor cortical areas connected to VM include those associated with eye movements, and afferents from the superior colliculus, a region of documented importance in oculomotor control, also were labeled by injections into VM. The dorsolateral portion of the VA-VL complex primarily showed reciprocal connections with the medial premotor (area 6) cortex. Basal ganglia and cerebellar afferents both may modulate this cortico-thalamo-cortical loop, although they do not necessarily converge on the same thalamic neurons. The cerebellar input to dorsolateral VA-VL was from posterior and ventral portions of the cerebellar nuclei, and the major potential brainstem afferents to this region of thalamus were from the pretectum. Mid- and caudo-lateral portions of VL had reciprocal connections with primary motor cortex (area 4). The dorsal and anterior portions of the cerebellar nuclei had a dominant input to this corticothalamo-cortical loop. Potentially converging brainstem afferents to this portion of VL were from the pretectum, especially pretectal areas to which somatosensory afferents project.List of Abbreviations AC
central amygdaloid nucleus
- AL
lateral amygdaloid nucleus
- AM
anteromedial thalamic nucleus
- AV
anteroventral thalamic nucleus
- BC
brachium conjunctivum
- BIC
brachium of the inferior colliculus
- Cd
caudate nucleus
- CL
centrolateral thalamic nucleus
- CM
centre median nucleus
- CP
cerebral peduncle
- CUN
cuneate nucleus
- DBC
decussation of the brachium conjunctivum
- DR
dorsal raphe nuclei
- EC
external cuneate nucleus
- ENTO
entopeduncular nucleus
- FN
fastigial nucleus
- FX
fornix
- GP
globus pallidus
- GR
gracile nucleus
- IC
internal capsule
- ICP
inferior cerebellar peduncle
- IP
interpeduncular nucleus
- IVN
inferior vestibular nucleus
- LD
lateral dorsal thalamic nucleus
- LGN
lateral geniculate nucleus
- LH
lateral hypothalamus
- LP
lateral posterior thalamic complex
- LRN
lateral reticular nucleus
- LVN
lateral vestibular nucleus
- MB
mammillary body
- MD
mediodorsal thalamic nucleus
- MG
medial geniculate nucleus
- ML
medial lemniscus
- MLF
medial lengitudinal fasciculus
- MT
mammillothalamic tract
- MVN
medial vestibular nucleus
- NDBB
nucleus of the diagonal band of Broca
- NIA
anterior nucleus interpositus
- NIP
posterior nucleus interpositus
- OD
optic decussation
- OT
optic tract
- PAC
paracentral thalamic nucleus
- PPN
pedunculopontine region
- PRO
gyrus proreus
- PRT
pretectal region
- PT
pyramidal tract
- PTA
anterior pretectal region
- PTM
medial pretectal region
- PTO
olivary pretectal nucleus
- PTP
poterior pretectal region
- Pul
pulvinar nucleus
- Put
putamen
- RF
reticular formation
- RN
red nucleus
- Rt
reticular complex of the thalamus
- S
solitary tract
- SCi
superior colliculus, intermediate gray
- SN
substantia nigra
- ST
subthalamic nucleus
- VA
ventroanterior thalamic nucleus
- VB
ventrobasal complex
- VL
ventrolateral thalamic nucleus
- VM
ventromedial thalamic nucleus
- III
oculomotor nucleus
- IIIn
oculomotor nerve
- 5S
spinal trigeminal nucleus
- 5T
spinal trigeminal tract
- VII
facial nucleus |
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Keywords: | Thalamic afferents Basal ganglia Cerebellar nuclei Thalamo-cortico-thalamic loops |
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