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Effects of chronic spinalization on ankle extensor motoneurons. I. Composite monosynaptic Ia EPSPs in four motoneuron pools


, : Effects of chronic spinalization on ankle extensor motoneurons. I. Composite monosynaptic Ia EPSPs in four motoneuron pools. Journal of Neurophysiology 71(4): 1452-1467

1. We examined the effects of 6-wk chronic spinalization at the L1-L2 level on composite monosynaptic Ia excitatory postsynaptic potentials (EPSPs) recorded in medial gastrocnemius (MG), lateral gastrocnemius (LG), soleus (SOL), and plantaris (PL) motoneurons. Amplitudes, rise times, and half-widths of composite monosynaptic Ia EPSPs evoked by low-strength electrical stimulation of peripheral nerves were measured in barbiturate-anesthetized cats and compared between unlesioned and chronic spinal preparations. 2. The mean amplitude of homonymous composite Ia EPSPs evoked by 1.2 times threshold (1.2T) stimulation and recorded in all four ankle extensor motoneuron pools increased 26% in chronic spinal animals compared with unlesioned controls. There was also an increased incidence of large-amplitude, short-rise time EPSPs. When the same data were separated according to individual motoneuron species, homonymous EPSP amplitudes in MG motoneurons were found to be unchanged. EPSPs recorded in LG motoneurons and evoked by stimulation of the combined LG and SOL nerve were increased by 46%. Mean EPSP amplitudes recorded in both SOL and PL motoneurons were larger after spinalization but statistical significance was only achieved when values from SOL and PL were combined to produce a larger sample size. 3. In LG motoneurons from chronic spinal animals, all EPSPs evoked by 1.2T stimulation of the LGS nerve were > or = 0.5 mV in amplitude. In unlesioned preparations, one fourth of the LG cells had EPSPs that were < or = 0.2 mV. 4. The mean amplitude of heteronymous EPSPs evoked by 2T stimulation of LGS and MG nerves and recorded in MG and LG motoneurons, respectively, doubled in size after chronic spinalization. Because homonymous EPSP amplitudes were unchanged in MG motoneurons, synaptic mechanisms and not passive membrane properties are likely responsible for increased heteronymous EPSP amplitudes in MG. 5. The mean 10-90% rise time of homonymous composite Ia EPSPs in pooled data from all motoneurons decreased 21% in 6-wk chronic spinal animals. Unlike EPSP amplitude, significant rise time decreases were found in all four motoneuron pools. Compared with the other motoneuron species, the mean homonymous rise time recorded in MG motoneurons was shortest and decreased the least in chronic spinal animals. Rise times of heteronymous Ia EPSPs in MG and LG motoneurons also decreased. The maximum rate of rise of homonymous EPSPs increased in all four motoneuron species. 6. The mean half-widths of Ia composite EPSPs decreased in 6-wk spinalized preparations in all motoneuron species.(ABSTRACT TRUNCATED AT 400 WORDS)

US$29.90

PMID: 8035227


Other references

Barnes, J.; Garcia, D.B.; Ljungqvist, A.; Asher, A.; Espinosa, O., 1997: A simplified method for the determination of 8-hydroxy-2-deoxyguanosine and 2-deoxyguanosine in nuclear DNA by HPLC-UV/EC. Pharmaceutical Research (New York) 14(11 SUPPL ): S579, Nov

Lau, E., 2017: More than what meets the mouth and nose. Lancet. Gastroenterology & Hepatology 2(6): 397-397

Lindberg, B.S.; Martini Nycopensis, O., 2016: The archbishop as a physician. Lakartidningen 112: -

Ivanov, L.A.; Silina, A.A.; Celjniker, J. L., 1952: Transpiration of shelterbelt species in the conditions of the Derkul steppe.. Results are graphed and tabulated of measurements on the transpiration of over 20 species of trees and shrubs used in shelterbelts, conducted in 1949/50 in (1) the Serebryany Bor forest division near Moscow and (2) the Derkul' steppe near Sta...

Sayenko, D.G.; Masani, K.; Milosevic, M.; Robinson, M.F.; Vette, A.H.; McConville, K.M.V.; Popovic, M.R., 2011: Video game-based neuromuscular electrical stimulation system for calf muscle training: a case study. A video game-based training system was designed to integrate neuromuscular electrical stimulation (NMES) and visual feedback as a means to improve strength and endurance of the lower leg muscles, and to increase the range of motion (ROM) of the an...

Lankes, C., 1989: Tissue culture in apple. Problems associated with the in vitro propagation and multiplication of apples are indicated, with reference to tissue age at the onset of culture, endogenous microorganisms, phenols, vitrification, success rates and commercial applications. Intra...

Chaney, A.H.; Liner, E.A.; Johnson, R.M., 1982: Geographic distribution. Caudata. Chiropterotriton prisca. Herpetological Review 13.2: 51

Viana, C.H.C.; Candini, P.H.; Gama, R.D.; Carbone, A.; Santos, I.C.C.; Vianna, W.L.; Barnabe, R.C., 2002: Influence of the day of estrus cycle on synchronization of ovulation induced by porcine LH in sows. Theriogenology 57(1): 390, January 2

Kurka, A., 1975: The life cycle of Bembidion libiale (Coleoptera. Carabidae). Acta Ent Bohemoslovaca, 726: 374-382

Dubnau, D., 1991: The regulation of genetic competence in Bacillus subtilis. Genetic competence develops as a global response of Bacillus subtilis to the onset of stationary phase, in glucose-minimal salts-based media. The onset of competence is accompanied by the expression of several late gene products that are required...