Fos-like immunoreactivity in the caudal diencephalon and brainstem following lateral hypothalamic self-stimulation (original) (raw)
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Increased ipsilateral expression of Fos following lateral hypothalamic self-stimulation
Brain Research, 1996
Immunohistochemical labeling of Fos protein was used to visualize neurons activated by rewarding stimulation of the lateral hypothalamic level of the medial forebrain bundle (MFB). Following training and stabilization of performance, seven rats were allowed to self-stimulate for 1 h prior to anesthesia and perfusion. Brains were then processed for immunohistochemistry. Two control subjects were trained and tested in an identical manner except that the stimulator was disconnected during the final 1 h test. Among the structures showing a greater density of labeled neurons on the stimulated side of the brains of the experimental subjects were the septum, lateral preoptic area (LPO), medial preoptic area. bed nucleus of the stria terminalis, substantia innominata (SI), and the lateral hypothalamus (LH). Several of these structures, the LPO. Sl, and LH, have been implicated in MFB self-stimulation by the results of psychophysical, electrophysiological. and lesion studies.
Neuroscience, 2016
The dorsal diencephalic conduction system (DDC) is an important pathway of the brain reward circuitry, linking together forebrain and midbrain structures. The present work was aimed at describing the effect of a DDC lesion on the distribution of Fos-like immunoreactivity (FLIR) following intracranial self-stimulation (ICSS) of the lateral hypothalamus (LH). Rats were implanted with monopolar electrodes and divided into three groups; the first two groups were trained to self-stimulate at the LH, whereas the third group received no stimulation and served as a control. Among the two groups that were trained for ICSS, one of them received a lesion at the DDC and was tested for ICSS on the subsequent 5days. On the last day of testing, control rats were placed in operant chambers without receiving any stimulation, and the remaining rats were allowed to receive the stimulation for 1h. All rats were then processed for FLIR. As previously shown, a lesion at the DDC resulted in significant at...
Attenuation of medial forebrain bundle reward by anterior lateral hypothalamic lesions
Behavioural Brain Research, 1996
Psychophysical data consistent with rostro-caudal conduction along reward-relevant neurons linking the lateral hypothalamus (LH) and ventral tegmental area (VTA) have lead to the hypothesis that some of the directly activated neurons responsible for medial forebrain bundle (MFB) self-stimulation arise anterior to the level of the LH. This hypothesis has been challenged on the grounds that lesions to the anterior LH (ALH) often fail to degrade the rewarding value of stimulating more posterior MFB sites. The present study was aimed at investigating the effect of lesion location and stimulation current on the efficacy of ALH lesions in an effort to account for the inconsistencies in the earlier data. Self-stimulation thresholds were obtained for LH and VTA sites by estimating the number of pulses per stimulation train required for half-maximal responding at each of 3 currents. Electrolytic lesions (anodal, 1.0 mA for 10 s) were then made to the ALH at varying medial-lateral coordinates. In 7 of the 14 rats with MFB stimulation sites, lesions to the ALH produced increases in threshold which often declined over the next several days to weeks; in 5 cases thresholds remained elevated by 0.1 to 0.25 loglo units above baseline up to the end of testing. In all but one case, the effective lesions were centered in the lateral ALH. Increases in threshold were more likely to be detected when stimulating at low currents; at low currents fewer neurons are recruited and the lesion can have a greater proportional effect on threshold. These data support the hypothesis that cell bodies, terminals, or fibers of passage in the ALH contribute to the rewarding effect of stimulating more posterior MFB sites.
Brain Research, 1995
c-fos immunoreactivity was used to map brain areas in which neurons reacted either to electrical stimulation or to microinjection of the excitatory amino acid kainate and of the GABA A antagonist, SR-95531, applied to the medial hypothalamus of freely moving rats. All these stimulations induced flight behavior of moderate intensity. Immunoreactive cells were found within a radius of 0.5 mm around the stimulated area. Distally, clusters of labeled cells were found ipsilaterally in the piriform and entorhinal cortices, in several amygdaloid nuclei, in the bed nucleus of the stria terminalis, in the septo-hypothalamic nucleus, in the paraventricular, anterior and dorsomedial hypothalamic nuclei, in the paraventricular thalamic nucleus, in the dorsal periaqueductal gray extending to the cuneiform nucleus, and bilaterally in the supramamillary decussation and the locus coeruleus. The specificity of the brain areas thus labeled was indicated by the unilateral pattern of activation as well as by the different pattern obtained after control microinjection of saline. Therefore, these results are likely to provide sound information about the brain structures involved in defensive/aversive behavior evoked from the medial hypothalamus.
Brain Research, 1989
Electrical self-stimulation in the lateral hypothalamus was recorded in both hemispheres of 20 rats before and after making a lesion either by unilateral radiofrequency stimulation or by injection of N-methyl-D.L-aspartate into the region of the peduncular-pontine nucleus. For the animals which received the radiofrequency lesion, a rate-intensity function was established for 3 stimulation intensities 3 days before and 5 days after the lesion. For the animals in which N-methyl-D.L-aspartate was injected, a reinforcement threshold was measured 3 days before and after the lesion using a psychophysical method-of-limits procedure. With the rate-intensity procedure a decrease in the rate of self-stimulation was observed at the highest stimulation intensity through the electrode situated contralateral to the side of the lesion. Similarly, with the reinforcement threshold method, a significant increase in threshold was found from the electrode placed in the hemisphere contralateral but not ipsilateral to the site of the lesion. These data suggest an involvement of primarily crossed pathways coursing to or from the peduncular-pontine nucleus as being involved in the control of lateral hypothalamic self-stimulation.
Role of ipsilateral forebrain in lateral hypothalamic stimulation reward in rats
Physiology & Behavior, 1982
The forebraln was ablated unilaterally to a level dorsal to the thalamus and anterior commissure. Ipsilateral lateral hypothalamic electrodes were then implanted and the animal was tested for self-stimulation behavior. Tests included an initial test for behavioral reactivity to changes in reward level and then two estimates of the quantitative relationships between stimulation parameters: the number-current and charge-duration relationships. Comparison between these findings and those known for intact rats suggest that the substrate for unilateral hypothalamic stimulation reward is not impaired by removal of the ipsilateral tissue.
Neuroscience, 1997
Neuronal expression of Fos, the protein product of the immediate early gene c-fos has been used as a high resolution metabolic marker for mapping polysynaptic pathways in the brain. We used Fos immunohistochemistry to reveal neuronal activation following self-stimulation of the ventral pallidum. Four groups of rats were allowed to self-stimulate for 30 min with 0.4 s trains of cathodal rectangular pulses of constant intensity (0.4 mA) and duration (0.1 ms). Each group was assigned a different pulse frequency, (3, 17, 24 and 50 pulses/stimulation train), which was preselected from within each animal's rate-frequency function. The subjects that were assigned three pulses failed to self-stimulate and were considered as controls. The subjects that were assigned 17 pulses self-stimulated at half-maximal rate, whereas those that were assigned 24 and 50 pulses self-stimulated at maximal rates. The animals were sacrificed 90 min after the self-stimulation session and their brains were processed for Fos-like immunoreactivity. Fos-like immunoreactivity was found to increase as a function of pulse frequency in several brain regions known to be involved in drug and/or brain stimulation reward (medial prefrontal cortex, lateral septum, nucleus accumbens, lateral hypothalamus and ventral tegmental area), whereas it was not affected in structures devoid of such involvement (substantia nigra reticulata and dorsolateral striatum). The level of Fos expression induced by trains of 50 pulses was considerably higher than that produced by 24 pulses although both frequencies supported the same (maximal) self-stimulation rate.
Behavioural Brain Research, 1990
It has been proposed that the directly stimulated axons underlying the rewarding effect of medial forebrain bundle (MFB) stimulation originate in the forebrain and descend at least as far as the ventral tegmentum. However, little is known about the location of the somata that give rise to these axons. Among the nuclei that contribute fibers to the descending component of the MFB and project past the lateral hypothalamus (LH) and ventral tegmental area (VTA) are cell groups within the amygdaloid complex. In this study, the rewarding effectiveness of stimulating the LH and VTA was measured before and after the amygdaloid complex was damaged by electrolytic lesions. Changes in rewarding effectiveness were inferred from shifts in the frequency required to sustain a half-maximal rate of lever-pressing at each of 3 currents. Following the lesions, there was no clear evidence of substantial, sustained decreases in rewarding effectiveness at the 14 stimulation sites, although one subject ceased to self-stimulate reliably. Given that the lesions damaged the principal amygdaloid sources of descending MFB fibers, these results suggest that the amygdaloid complex is not a major source of the directly activated fibers responsible for the rewarding effect of MFB stimulation.
Effects of NMDA Lesions of the Medial Basal Forebrain on LH and VTA Self-Stimulation
Physiology & Behavior, 1998
ARVANITOGIANNIS, A., L. RISCALDINO AND P. SHIZGAL. Effects of NMDA lesions of the medial basal forebrain on LH and VTA self-stimulation. PHYSIOL BEHAV 65 (4/5) 805-810, 1999.-Rewarding stimulation of the medial forebrain bundle (MFB) increases Fos-like immunoreactivity in many brain areas, including an ipsilateral, basal forebrain region extending from the medial preoptic area (MPO) to the lateral preoptic area, and substantia innominata. Excitotoxic lesions of the lateral portion of this region have been found to produce large sustained or transient increases in the number of pulses required to maintain half-maximal lever-pressing (required number of pulses) for MFB stimulation. In the present study, changes in self-stimulation of the lateral hypothalamus and ventral tegmental area were assessed following excitotoxic lesions of more medial structures, including the MPO and bed nucleus of the stria terminalis. Increases in the required number of pulses (up to 0.16 log 10 units) were seen in only 2 of 10 subjects. In two other rats, the reward effectiveness of the stimulation was moderately increased after the lesion as manifested in decreases of up to 0.14 log 10 units in the required number. No appreciable change from baseline was seen in the remaining six subjects. The simplest interpretation of these results is that neurons with cell bodies in the medial portion of the basal forebrain may make a smaller contribution to the rewarding effect of MFB stimulation than neurons in the lateral portion. © 1999 Elsevier Science Inc.