The effect of unilateral selective lesion of the superior colliculus (SC) on Vibrissa Motor Cortex (VMC) organization was studied in adult Rats 72 hours (72Hs-group, n=5) and 3 weeks (3Ws-group, n=5) after quinolinic acid lesion. VMC output was assessed mapping the representation size and thresholds of movement evoked by intracortical microstimulation (ICMS). Under ketamine anaesthesia (50mg\Kg i.p.), the ICMS (30 ms trains of 0.25 ms cathodal pulses at 350 Hz, stimulation current <60 mA) was delivered at a depth of 1.5mm from the pial surface using glass-insulated tungsten microelectrodes (impedance:0.6-1.2MΩ). Comparison between groups evidenced: a) no difference in the size of vibrissae movement representation (mean size in Control-group vs. 72Hs-gorup vs. 3Ws-group: 4.2 0.37 mm2 vs 4.15 0.54 mm2 vs. 4.3 0.21 , P=0.7, ANOVA); b) no difference in the media-lateral frequency distributions of the vibrissa and the forelimb sites (vibrissa sites distribution: 2 =5.3, P>0.05, forelimb sites distribution: 2= 8.63, P>0.05 chi-square test); c) no difference in the mean threshold value required to evoke movements (vibrissa mean threshold in Control-group vs. 72Hs-gorup vs. 3Ws-group: 20.97±2.53µA vs 18.8±2.09µA vs 18.98±1.47µA; forelimb mean threshold in Control-group vs. 72Hs-gorup vs. 3Ws-group: 21.26±2.14µA vs. 19.37±1.35µA vs. 18.64±1.87µA; P>0.05, ANOVA). We conclude that the selective lesion of the SC does not result in any modification in the ipsilateral VMC output. This datum supports the conclusion that the circuitry involved in the cortical regulation of vibrissae movement does not just have one functional prevailing serial pathway but is implemented upon reticular formation and other brain stem nuclei in parallel to the SC.
SUPERIOR COLLICULUS SELECTIVE LESION NOT AFFECT VIBRISSA MOTOR CORTEX OUTPUT IN ADULT RATS.
VERONESI, Carlo;MAGGIOLINI, Emma;FRANCHI, Gianfranco
2007
Abstract
The effect of unilateral selective lesion of the superior colliculus (SC) on Vibrissa Motor Cortex (VMC) organization was studied in adult Rats 72 hours (72Hs-group, n=5) and 3 weeks (3Ws-group, n=5) after quinolinic acid lesion. VMC output was assessed mapping the representation size and thresholds of movement evoked by intracortical microstimulation (ICMS). Under ketamine anaesthesia (50mg\Kg i.p.), the ICMS (30 ms trains of 0.25 ms cathodal pulses at 350 Hz, stimulation current <60 mA) was delivered at a depth of 1.5mm from the pial surface using glass-insulated tungsten microelectrodes (impedance:0.6-1.2MΩ). Comparison between groups evidenced: a) no difference in the size of vibrissae movement representation (mean size in Control-group vs. 72Hs-gorup vs. 3Ws-group: 4.2 0.37 mm2 vs 4.15 0.54 mm2 vs. 4.3 0.21 , P=0.7, ANOVA); b) no difference in the media-lateral frequency distributions of the vibrissa and the forelimb sites (vibrissa sites distribution: 2 =5.3, P>0.05, forelimb sites distribution: 2= 8.63, P>0.05 chi-square test); c) no difference in the mean threshold value required to evoke movements (vibrissa mean threshold in Control-group vs. 72Hs-gorup vs. 3Ws-group: 20.97±2.53µA vs 18.8±2.09µA vs 18.98±1.47µA; forelimb mean threshold in Control-group vs. 72Hs-gorup vs. 3Ws-group: 21.26±2.14µA vs. 19.37±1.35µA vs. 18.64±1.87µA; P>0.05, ANOVA). We conclude that the selective lesion of the SC does not result in any modification in the ipsilateral VMC output. This datum supports the conclusion that the circuitry involved in the cortical regulation of vibrissae movement does not just have one functional prevailing serial pathway but is implemented upon reticular formation and other brain stem nuclei in parallel to the SC.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
