Jonathan Morrow

University of Michigan | U-M · Department of Psychiatry

When a neutral stimulus is repeatedly paired with an appetitive reward, two different types of conditioned approach responses may develop: a sign-tracking response directed toward the neutral cue, or a goal-tracking response directed toward the location of impending reward delivery. Sign-tracking responses have been postulated to result from attrib...

Rationale Acetylcholinergic antagonists have shown some promise in reducing addiction-related behaviors in both preclinical and clinical studies. However, the psychological mechanisms by which these drugs are able to affect addictive behavior remain unclear. A particular key process for the development of addiction is the attribution of incentive s...

Sprague Dawley (SD) rats are among the most widely used outbred laboratory rat populations. Despite this, the genetic characteristics of SD rats have not been clearly described, and SD rats are rarely used for experiments aimed at exploring genotype-phenotype relationships. In order to use SD rats to perform a genome-wide association study (GWAS),...

Ketamine has emerged as a novel treatment for common psychiatric conditions such as Major Depressive Disorder (MDD) and anxiety disorders, many of which can be initiated and exacerbated by psychological stress. Sex differences in the frequency of both anxiety and depressive disorders are well known and could be due to sex differences in neuroendocr...

RationalePrior research suggests that the neural pathway from the lateral hypothalamic area (LHA) to the paraventricular nucleus of the thalamus (PVT) mediates the attribution of incentive salience to Pavlovian reward cues. However, a causal role for the LHA and the neurotransmitters involved have not been demonstrated in this regard.Objectives To...

RationalePavlovian conditioned approach paradigms are used to characterize the nature of motivational behaviors in response to stimuli as either directed toward the cue (i.e., sign-tracking) or the site of reward delivery (i.e., goal-tracking). Recent evidence has shown that activity of the endocannabinoid system increases dopaminergic activity in...

Research on the attribution of incentive salience to drug cues has furthered our understanding of drug self-administration in animals and addiction in humans. The influence of social cues on drug-seeking behavior has garnered attention recently, but few studies have investigated how social cues gain incentive-motivational value. In the present stud...

Psychoactive substance use is a nearly universal human behavior, but a significant minority of people who use addictive substances will go on to develop an addictive disorder. Similarly, though ~90% of people experience traumatic events in their lifetime, only ~10% ever develop post-traumatic stress disorder (PTSD). Substance use disorders (SUD) an...

The attribution of incentive-motivational value to drug-related cues underlies relapse and craving in drug addiction. One method of addiction treatment, cue-exposure therapy, utilizes repeated presentations of drug-related cues in the absence of drug (i.e., extinction learning); however, its efficacy has been limited due to an incomplete understand...

Research on the attribution of incentive salience to drug cues has furthered our understanding of drug self-administration in animals as well as drug relapse and craving in humans. The influence of peers and other social cues on drug-seeking has garnered more attention recently, but few studies have investigated the ability of social cues to gain i...

The attribution of incentive-motivational value to drug-related cues underlies relapse and craving in drug addiction. One method of addiction treatment, cue-exposure therapy, utilizes repeated presentations of drug-related cues in the absence of drug (i.e., extinction learning); however, its efficacy has been limited due to an incomplete understand...

Sprague Dawley ( SD ) rats are one of the most commonly used outbred rat strains. Despite this, the genetic characteristics of SD are poorly understood. We collected behavioral data from 4,625 SD rats acquired predominantly from two commercial vendors, Charles River Laboratories and Harlan Sprague Dawley Inc. Using double-digest genotyping-by-seque...

Exposure to prolonged, uncontrollable stress reduces reward-seeking behavior, resulting in anhedonia in neuropsychiatric disorders, such as posttraumatic stress disorder. However, it is unclear to what degree stressed subjects lose interest in rewards themselves or in reward-related cues that instigate reward-seeking behavior. In the present study,...

Mast cells are resident immune cells in the thalamus that can degranulate and release hundreds of signaling molecules (i.e., monoamines, growth factors, and cytokines) both basally and in response to environmental stimuli. Interestingly, mast cell numbers in the brain show immense individual variation in both rodents and humans. We used a Pavlovian...

The authors describe the treatment of a 36-year-old woman who presented with excessive consumption of antiseptic alcohol swabs. Her behavior was diagnosed as a severe substance use disorder with isopropyl alcohol as the primary drug of choice. Diagnostic and treatment challenges involved in the case are discussed in detail, with particular focus on...

Addiction is a complex behavioral disorder arising from roughly equal contributions of genetic and environmental factors. Behavioral traits such as novelty-seeking, impulsivity, and cue-reactivity have been associated with vulnerability to addiction. These traits, at least in part, arise from individual variation in functional neural systems, such...

The attribution of incentive-motivational value to reward-related cues contributes to cue-induced craving and relapse in addicted patients. Recently, it was demonstrated that subanesthetic ketamine increases motivation to quit and decreases cue-induced craving in cocaine-dependent individuals. Although the underlying mechanism of this effect is cur...

Individual variation in the attribution of motivational salience to reward-related cues is believed to underlie addiction vulnerability. Pavlovian conditioned approach measures individual variation in motivational salience by identifying rats that are attracted to and motivated by reward cues (sign-trackers) or motivationally fixed on the reward it...

There are many facets of the neurobiology of substance use that are distinct in adolescence as compared with adulthood. The adolescent brain is subject to intense subcortical reward processes, but is left with an immature prefrontal control system that is often unable to resist the pull of potentially exciting activities like substance use, even wh...

Cues that are contingently paired with unconditioned, rewarding stimuli can acquire rewarding properties themselves through a process known as the attribution of incentive salience, or the transformation of neutral stimuli into attractive, "wanted' stimuli capable of motivating behavior. Pavlovian conditioned approach (PCA) develops after the respo...

Pavlovian conditioned approach ( PCA ) is a behavioral procedure that can be used to assess individual differences in the addiction vulnerability of drug‐naïve rats and identify addiction vulnerability factors. Using proton magnetic resonance spectroscopy ( ¹ H‐ MRS ) ex vivo , we simultaneously analyzed concentrations of multiple neurochemicals th...

Even when trained under exactly the same conditions outbred male Sprague-Dawley (SD) rats vary in the form of the Pavlovian conditioned approach response (CR) they acquire. The form of the CR (i.e. sign-tracking vs. goal-tracking) predicts to what degree individuals attribute incentive salience to cues associated with food or drugs. However, we hav...

If reward-associated cues acquire the properties of incentive stimuli they can come to powerfully control behavior, and potentially promote maladaptive behavior. Pavlovian incentive stimuli are defined as stimuli that have three fundamental properties: they are attractive, they are themselves desired, and they can spur instrumental actions. We have...

It has been proposed that animals that attribute high levels of incentive salience to reward-related cues may be especially vulnerable to addiction. Individual variation has also been observed in the motivational value attributed to aversive cues, which may confer vulnerability to anxiety disorders such as post-traumatic stress disorder (PTSD). The...

Extensive data implicate serotonin (5-hydroxytryptamine [5-HT]) in the regulation of sleep. Jouvet has hypothesized that 5-HT promotes wakefulness, yet is necessary for subsequent non-rapid eye movement (NREM) sleep, actions he proposes to be mediated by sleep factors. Studies in rat support this dual role for 5-HT. The objectives of this study wer...

Interleukin (IL)-1 and tumor necrosis factor (TNF) are involved in the regulation of non-rapid eye movements sleep (NREMS). Accumulating evidence suggests IL-6 modulates sleep under some pathophysiologic conditions. We used mice lacking a functional IL-6 gene to investigate further a potential role for IL-6 in the regulation of sleep. IL-6 knockout...

Infectious challenge triggers a broad array of coordinated changes within the host organism, including alterations in sleep-wake behavior and body temperature. Pro-inflammatory cytokines orchestrate many of the behavioral, metabolic, and endocrine responses to immune challenge. Although interleukin (IL)-6 mediates several aspects of sickness behavi...

Although it is well established that the cytokines tumor necrosis factor (TNF) and interleukin (IL)-1 regulate sleep, there is no direct evidence implicating IL-6 in the regulation/modulation of sleep. We tested the hypotheses that central administration of rat recombinant IL-6 increases non-rapid eye movements (NREM) sleep of rats, and that centra...