Linked Life Data

8275273

Source:http://linkedlifedata.com/resource/pubmed/id/8275273

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1994-2-10
pubmed:abstractText
The postural adjustments that accompany the limb flexion following stimulation of the motor cortex in the cat are in part at least mediated by the lateral vestibular nucleus (LVN). In fact, inactivation of vestibulospinal (VS) neurons by unilateral injection of GABA agonists into the LVN decreased the early component of the responses in all of the postural limbs without modifying the threshold, latency, or amplitude of the cortically induced flexion movement. Just the opposite result was obtained after injection into the same structure of GABA antagonists. Experiments were performed to find out whether these VS influences were somatotopically organized. Microinjection of 0.25 microL of the GABA-A agonist muscimol or the GABA-B agonist baclofen (at 1.5 to 4 micrograms/microL saline) into the rostroventral part of the LVN (rvLVN) of one side produced hypotonia in the ipsilateral and hypertonia in the contralateral forelimb. The same injection also reduced the early component of the postural responses to cortical stimulation in both forelimbs, but not in the hindlimbs. On the other hand, unilateral injection of the same agents into the dorsocaudal part of the LVN (dcLVN) produced similar effects, but they were limited to the hindlimbs. The results obtained, which lasted for about 2 to 3 h, were not only site-specific but were also dose-dependent. Injection into the rvLVN or dcLVN of 0.25 microL of the GABA-A antagonist bicuculline or the GABA-B antagonist phaclofen (at 8 or 5 micrograms/microL saline) produced localized changes in posture as well as in the post-urokinetic responses to cortical stimulation. These were opposite in sign to those elicited by the corresponding agonists. In conclusion, it appears that: 1) the motor cortex utilizes descending volleys passing through the LVN in order to elicit the early postural adjustments during a cortically induced limb movement; 2) the resulting VS influences are somatotopically organized; 3) the amplitude of these postural responses can be affected by inhibitory influences probably exerted by Purkinje cells of the cerebellar vermis on the related VS neurons through both GABA-A and GABA-B receptors.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0957-4271
pubmed:author
pubmed:issnType
Print
pubmed:volume
3
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
391-407
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1993
pubmed:articleTitle
Somatotopical effects of local microinjection of GABAergic agents in Deiters nucleus on the posturokinetic responses to cortical stimulation.
pubmed:affiliation
Dipartimento di Fisiologia e Biochimica, Università di Pisa, Italy.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't