The evidence that frequency modulated (FM) 50kHz ultrasonic vocalizations (USVs) reflect a
positive emotional state in rats is reviewed. Positive emotional states in humans are …

Background Numerous experimental studies, conducted primarily over the past 10 years,
show that there are sex differences in opioid analgesia. This review summarizes the …

Rationale: The availability of the highly selective and specific kappa opioid agonist
enadoline provides an opportunity to explore the function of kappa receptors in humans and …

The opioid system regulates affective processing, including pain, pleasure, and reward.
Restricting the role of this system to hedonic modulation may be an underestimation …

The literature on the effects of opioids on psychomotor and cognitive functioning in humans
is evaluated. Some studies have examined the acute and chronic effects of various opioids …

Objectives To investigate whether preoperative risk for delirium moderates the effect of
postoperative pain and opioids on the development of postoperative delirium. Design …

Opioids are thought to worsen the performance of psychomotor tasks due to their sedating
and mental-clouding effects. As a result, some safety regulations currently restrict the use of …

Successful opioid therapy often depends on achieving a balance between analgesic
effectiveness and side effects. The risk of opioid-induced cognitive impairment often hinders …

Although the rate of onset of a drug effect is commonly believed to contribute to a drug's
abuse liability, only a few systematic experimental studies have been conducted examining …

Positive emotional states have been shown to confer resilience to depression and anxiety in
humans, but the molecular mechanisms underlying these effects have not yet been …