Medial Forebrain Bundle Of Rats Research Articles

Potentials evoked by stimulation of the medial forebrain bundle in rats

Stimulation of any point of the MFB of rats, evoked a “wavelet” in any other point of the same bundle. This was presumably an envelope of fiber action potentials, and was conducted bidirectionally at 0.6–1.0 m/sec. Stimulation of the anterior portion of the MFB evoked a monosynaptic monophasic potential which had its virtual generator in a restricted portion of the preoptic and anterior lateral hypothalamic area. This potential was a standing wave and was electrotonically propagated to various parts of the brain. The monophasic potential suffered a pronounced post-tetanic potentiation. This was competitively antagonized by increasing stimulus strength, up to a stimulus strength maximum, beyond which a constant degree of post-tetanic potentiation was still found. Neither the monophasic potential nor its post-tetanic potentiation were affected by eserine, atropine, pyrogallol, amphetamine, LSD, bromo-LSD, nethalide, tolazoline, strychnine nor picrotoxin; both this potential and its post-tetanic potentiation were reduced reversibly by harmine. Stimulation of the anterior portion of the MFB caused when it was strong, or after a tetanus, a long latency wave which was found throughout the hypothalamus. Stimulation of the tuberculum olfactorium evoked a complex potential in the homolateral amygdala; stimulation of the lateral hypothalamic area evoked a potential in the septum, which suffered posttetanic potentiation. Probably neither of these connections is through the MFB.