A remote-control leucotome for neurophysiological experimentation

Cazard, P

doi:10.1016/0013-4694(74)90234-x

Cited by 9 publications

(1 citation statement)

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“…The animals were anesthetized again and divided into two groups. In the first group, dorsal fornix sections were made by introducing a remote control leucotome (Cazard, 1974) stereotaxically through the previously drilled hole 5 mm ventral to dural surface and by moving the blade according to a predetermined angle (40 *). In the second group, sham operations were performed in exactly the same way except that the blade was not extracted from the knife.…”

Section: Methodsmentioning

confidence: 99%

Parallel modifications of spatial memory performances, exploration patterns, and hippocampal theta rhythms in fornix-damaged rats: Reversal of oxotremorine.

Maho¹,

Dutrieux²,

Ammassari–Teule³

1988

Behavioral Neuroscience

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Learning scores and degrees of divergence of the exploratory patterns (EP) displayed during the acquisition stage of a radial eight-arm maze task were examined in fornix-damaged and sham-operated rats injected either with oxotremorine (0.1 mg/kg) or saline. Modifications of hippocampal rhythmic slow activity (theta) recorded in each condition were analyzed in CA1 and dentate gyrus. Dorsal fornix sections reduced choice accuracy but also induced the adoption of weakly divergent EP. Oxotremorine in animals with lesions reinstates both learning scores and degree of divergence of EP at the levels respectively observed in saline sham-operated animals. Finally, oxotremorine in sham-operated animals did not significantly improve choice accuracy but strongly modified the EP. Preoperatively, theta rhythms indicated a decrease of frequency after oxotremorine administration. Postoperatively, they showed an increase of frequency in animals with lesions that were reinstated at the preoperative level by oxotremorine.

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Section: Methodsmentioning

confidence: 99%

Parallel modifications of spatial memory performances, exploration patterns, and hippocampal theta rhythms in fornix-damaged rats: Reversal of oxotremorine.

Maho¹,

Dutrieux²,

Ammassari–Teule³

1988

Behavioral Neuroscience

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Functional reorganization of the noradrenergic system after partial fornix section: a behavioral and autoradiographic study

et al. 1993

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Previous experiments revealed that the cholinergic deficit in rats with a partial fornix section was accompanied by an increase in turnover of noradrenaline (NE) in the hippocampus. This noradrenergic hyperactivity contributed to the cognitive deficit in lesioned rats, probably by interaction with the cholinergic system. The present experiment examines the reorganization of the noradrenergic system after the damage induced by partial fornix section and attempts to determine if the increase in NE turnover is of locus coeruleus (LC) origin, or if it is a result of local regulation at the noradrenergic terminals. Rats were submitted to knife-cut section of the fornix, resulting in a decrease in choline acetyltransferase activity in the hippocampus, correlated with a significant behavioral deficit in a spatial memory task. Lesioned rats learned a nonspatial memory task normally. Sections of brains of these rats were submitted to quantitative autoradiography. [125I]Iodopindolol binding was assessed in the dorsal and ventral hippocampus to determine availability of beta receptors. This was found to be significantly lower in lesioned rats. [125I]Iodoclonidine was used to determine alpha 2 receptors binding in dorsal and ventral hippocampus and in LC. There was no difference in alpha 2 receptors in LC, a significant decrease in dorsal regions of the hippocampus, and a significant increase in ventral regions. Muscarinic M1 receptors in the hippocampus showed no changes after the lesion.

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Noradrenergic hyperactivity after partial fornix section: role in cholinergic dependent memory performance

et al. 1992

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Rats with unilateral or bilateral partial section of the fornix were impaired on an eight arm radial maze task. Neurochemical analysis of hippocampal tissue four weeks after the lesions revealed a 50% reduction of choline acetyltransferase (ChAT) activity. The cholinergic marker was correlated negatively with the number of errors in the maze; the lower the ChAT activity, the higher the error score. The fornix lesion also induced a 50% reduction in norepinephrine (NE), but no change in the noradrenergic metabolite methylhydroxyphenylglycol (MHPG), suggesting a net increase in turnover of NE in these animals. Additional lesion of the noradrenergic system with the neurotoxin DSP4 reduced both MHPG and NE levels by more than 90%, compared to nonlesioned controls, and reversed the behavioral deficit. This treatment had no further effect on cholinergic markers. There was a significant negative correlation between ChAT activity and the index of NE turnover, suggesting that hyperactivity in the noradrenergic system after fornix section inhibits the spared cholinergic function and thus exacerbates the cognitive deficit. The pattern of neurochemical results bear a striking resemblance to those seen in some Alzheimer's patients and suggest that an equilibrium among neurotransmitters is important to cognitive function.

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A remote-control leucotome for neurophysiological experimentation

Cited by 9 publications

References 0 publications

Parallel modifications of spatial memory performances, exploration patterns, and hippocampal theta rhythms in fornix-damaged rats: Reversal of oxotremorine.

Parallel modifications of spatial memory performances, exploration patterns, and hippocampal theta rhythms in fornix-damaged rats: Reversal of oxotremorine.

Functional reorganization of the noradrenergic system after partial fornix section: a behavioral and autoradiographic study

Noradrenergic hyperactivity after partial fornix section: role in cholinergic dependent memory performance

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