However, an extensive literature demonstrates that the effects of psychoactive drugs are dependent on whether administration is contingent on behavior.
We examined whether contingent administration of amphetamine into the medial olfactory tubercle without visual signals increased lever pressing.
Contingent administration of nicotine without visual signals faintly reinforces lever pressing, while the co-presentation of visual signals with nicotine makes lever pressing much more vigorous.
Only a handful of studies have examined the functional output of NAc MSNs in the cocaine contingent administration model (Mu et al., 2010).
More importantly, the NAc MSNs from IV yoked mice, which serves as a better non-contingent administration control for IV masters than mice receiving non-contingent IP injections, did not show any changes in RMP, Rin, depolarizing current necessary to evoke APs, and Thr of APs, which is different from the controls with non-contingent IP injections.
Cocaine self-administration (but not yoked non-contingent administration) modifies this effect, such that DA subsequently increases inhibitory currents through a D1-dependent mechanism that persists during withdrawal [ 266].
Passive membrane properties and spontaneous synaptic transmission of MSNs from master mice were different in the NAc shell versus core before cocaine re-exposure, consistent with previous observations using non-contingent administration (Martin et al., 2006), in which opposite changes in excitability of MSNs were reported between shell and core.
Additionally, the effects of both drugs can be disparate, and even opposite, depending on contingent versus noncontingent administration, temporal pattern of administration, abstinence, route of administration and intake.
It admitted the plantations and buildings had "deteriorated", but said they were tended by volunteers and employees from the BIOT administration, while the British Marine contingent cleared graveyards and cemeteries of vegetation.
To address this question, we utilized an inducible version of the MMTV-Wnt1 model in which Wnt1 production is contingent upon administration of the small molecule, doxycycline.
