Biomedical subjects

M Cador

Publications and source records attributed to M Cador.

39 records · Page 3Linked to original sources

PubMed1985

Behavioral analysis of the effect of substance P injected into the ventral mesencephalon on investigatory and spontaneous motor behavior in the rat.

In the present experiments the behavioral response to substance P (SP) microinfusion into the ventral tegmental area (VTA), substantia nigra (SN), and sensorimotor cortex (CX) was investigated in detail. The experiments were carried out using an eight-hole box to measure exploratory behavior and a video monitor for the analysis of spontaneous motor behavior. When infused into the VTA, SP (0.125, 0.5, 3.0 micrograms) augmented the frequency and total duration of hole-pokes, and tended to diminish the mean duration of hole-pokes. The strategy and organization of responses, as measured by the order of hole-visits and hole-switching, were unchanged by SP and there was no indication of stereotypy, measured by the number of hole-pokes per hole-visit. The open-field analysis revealed a marked increase in locomotion and rearing, both in the periphery and center of the arena; grooming was decreased by SP. The behavioral profile following SN infusions of SP (3.0 micrograms) was similar to that elicited by VTA infusions, with the exception that center rearing was not enhanced. SP administration into cortex (3 micrograms) had no significant effect on any behavioral measures. It is hypothesized that SP infused into the ventral mesencephalon results in an enhancement of approach response tendencies, suggesting that endogenous SP in this region may regulate spontaneous behavior. The possibility of an interaction between SP and meso-telencephalic dopamine neurons is discussed.

Animals↗

PubMed1985

Behavioral analysis of the effect of neurotensin injected into the ventral mesencephalon on investigatory and spontaneous motor behavior in the rat.

The present experiments examined in detail the behavioral response to microinfusions of neurotensin (NT) into the ventral tegmental area (VTA), substantia nigra (SN) and hippocampus (HPC). The behavioral apparatus consisted of an eight-hole box in which investigatory and spontaneous motor behavior were recorded. Three doses (0.175, 0.5, 4.0 micrograms) of NT were injected into the VTA. The main effect of NT was a strong augmentation of rearing (frequency and duration) both in the periphery and center of the arena, accompanied by a small increase in locomotion and decreased grooming. NT had no effect on the strategy, organization, or duration of exploration but did augment frequency of hole visits towards the end of the session. NT injected into the SN and HPC had no effect on investigatory and spontaneous behavior with the exception of an increase in peripheral locomotion after HPC-NT injections. The results are discussed in terms of a modulatory role of endogenous NT on mesolimbic dopamine neurons.

Animals↗

PubMedDate not supplied

Limbic-striatal interactions in reward-related processes.

Stimuli with formerly motivationally neutral properties gain incentive properties from their predictive association with primary reinforcement, and are termed conditioned reinforcers. Infusions of the indirect dopamine (DA) agonist d-amphetamine into the ventral striatum selectively enhanced responding for a light that was positively correlated with water. These selective stimulatory effects were blocked by 6-OHDA lesions of the ventral, but not dorsal striatum, and resembled those produced by DA itself when infused into the ventral striatum. However, the choice of the lever producing the conditioned reinforcer was not affected by ventral striatal DA depletion. This choice was, however, attenuated by excitotoxic lesions of the basolateral nucleus of the amygdala, suggesting an interaction between this structure and DA-dependent processes of the ventral striatum in the processes by which reward-related stimuli come to affect action. Parallel findings were obtained using a second order schedule of sexual reinforcement. Other observations indicated that the amygdala lesion did not impair the discriminative property of the reward-related stimuli, or affect primary motivation. Experiments using explicit conditional visuo-spatial discrimination tasks suggest that similar discriminative properties are preserved following DA depletion from the ventral, but not the dorsal, striatum. These results possibly represent a dissociation between stimulus-response (or habit) and stimulus-reward associative mechanisms, modulated respectively by the dorsal and ventral striatum.

Animals↗