Molecular mechanisms of memory and learning

The aim of the present review is to discuss the molecular mechanisms of learning and memory. The first part of the review investigates implicit memory in Aplysia, a marine snail, studied by Eric Kandel, the Nobel Prize winner. This form of learning can be broadly divided into two temporal phases, an early and a late phase. The molecular mechanisms of each phase will be analyzed in separate sections.The second part of the review investigates hippocampal-dependent explicit memory in ammals and the mechanism that underlies it, known as long-term potentiation (LTP). Similar to the molecular mechanisms in Aplysia, LTP is divided into an early and a late phase. However, LTP in mammals is a very complicated phenomenon that depends on the regulation of many molecular pathways. Moreover, the scientific community cannot always reach a consensus on the role of some of these molecular mechanisms in LTP. Nevertheless, it will be demonstrated that both explicit and implicit memory occur at a synaptic level, result from/in synaptic strengthening, and share common molecular mechanisms in a variety of species far apart on the phylogenetic scale

Is (poly-) substance use associated with impaired inhibitory control? A mega-analysis controlling for confounders.

Many studies have reported that heavy substance use is associated with impaired response inhibition. Studies typically focused on associations with a single substance, while polysubstance use is common. Further, most studies compared heavy users with light/non-users, though substance use occurs along a continuum. The current mega-analysis accounted for these issues by aggregating individual data from 43 studies (3610 adult participants) that used the Go/No-Go (GNG) or Stop-signal task (SST) to assess inhibition among mostly "recreational" substance users (i.e., the rate of substance use disorders was low). Main and interaction effects of substance use, demographics, and task-characteristics were entered in a linear mixed model. Contrary to many studies and reviews in the field, we found that only lifetime cannabis use was associated with impaired response inhibition in the SST. An interaction effect was also observed: the relationship between tobacco use and response inhibition (in the SST) differed between cannabis users and non-users, with a negative association between tobacco use and inhibition in the cannabis non-users. In addition, participants' age, education level, and some task characteristics influenced inhibition outcomes. Overall, we found limited support for impaired inhibition among substance users when controlling for demographics and task-characteristics

Neuroticism and Negative Urgency in Problematic Alcohol Use: A Pilot Study

BACKGROUND: Problematic alcohol use is common among university students and personality might account for individual differences in developing this maladaptive behavior. Two personality dispositions implicated in problematic alcohol use are negative urgency and neuroticism. However, the relationship of these traits to problematic alcohol use is unclear. In college students high neuroticism is not directly linked to problematic alcohol use. On the other hand, the experience of emotional distress in people high in neuroticism could impair the capacity for impulse control. Loss of impulse control under conditions of negative affect could trigger impulsive drinking and problematic alcohol use in the long run. OBJECTIVES: We investigated this idea by testing whether negative urgency mediates the relationship of neuroticism to problematic alcohol use. METHODS: Participants were 60 undergraduate university students who completed the Urgency subscale of the Urgency, (lack of) Premeditation, (lack of) Perseverance, Sensation Seeking, and Positive Urgency Impulsive Behaviour scale (UPPS-P), the Alcohol Use Disorders Identification Test (AUDIT), and the Neuroticism subscale of the Eysenck Personality Questionnaire Revised short form (EPQ-RSS). RESULTS: The results confirmed our hypothesis as we found an indirect effect of negative urgency on the relationship between neuroticism and problematic alcohol use. CONCLUSIONS/IMPORTANCE: It appears that it is not distress but the tendency to act rashly when distressed that is important in developing problematic alcohol drinking in university students

The role of impulsivity and perceived availability on cue-elicited craving for alcohol in social drinkers

RATIONALE: Previous research has demonstrated a role for impulsivity and perceived availability of the substance in cue-elicited craving. However, their effects on cue-elicited craving for alcohol are still ambiguous. Most important is that there has been no empirical evidence for the potential interaction of these factors on alcohol craving. OBJECTIVES: The aim of the present study was to examine the effects of response inhibition and perceived availability on cue-elicited craving for alcohol in social drinkers. METHODS: Participants were light to moderate social drinkers (N = 75) who were exposed to neutral- and alcohol-related stimuli during a single laboratory session. Response inhibition was assessed with the Stop Signal Task. Participants were randomly assigned to one of two perceived availability groups (n = 37, expecting alcohol; n = 38, not expecting alcohol). RESULTS: Overall craving for alcohol was higher in participants who expected alcohol than in those who did not. This finding was statistically significant only in the alcohol condition. Most important is that there was a significant interaction between response inhibition, perceived availability and time on cue-elicited craving. Regardless of the cue type, impulsive people who expected alcohol experience a significant increase in cue-elicited craving relative to impulsive people who did not expect alcohol. This effect was not observed in the non-impulsive groups. CONCLUSIONS: The results clearly show that perceived availability alone and in combination with response inhibition can modulate alcohol cue reactivity. Theoretical explanations and clinical implications of these findings are discussed

Cue reactivity during treatment, and not impulsivity, predicts an initial lapse after treatment in alcohol use disorders

Both cue-elicited craving and impulsivity have been involved in alcohol misuse. However, their role in relapse has not been very clear. In the present study, we ask whether cue-elicited craving, impulsivity, and their interaction term predict a lapse in problem drinkers. Participants (n=20) were former patients of the clinic, U-Center, in the Netherlands, who had completed a six-week alcohol treatment program and had an abstinence goal. While in treatment, they underwent a cue exposure paradigm in a real alcohol-related setting and their trait impulsivity was measured with the Barratt Impulsiveness Scale version 11 (BIS-11). During the follow-up assessment, patients were contacted again and asked about their alcohol drinking behavior during the first three months after the end of the treatment program. It was found that higher craving and lower trait impulsivity levels are associated with a higher probability of a lapse

The Contribution of Society of Social Psychiatry P. Sakellaropoulos to the Psychiatric Reform in Rural Greece

The present paper aims to describe the structure, function, and goals of two of the oldest Mobile Mental Health Units in Greece, namely, the Mobile Mental Health Unit in Fokida (MMHU-F) and the Mobile Mental Health Unit in Thrace (Alexandroupolis, MMHU-T). Information about their historical background, catchment areas, and current staffing, as well as the services provided by each MMHU is discussed. The focus of the paper is slightly biased towards the MMHU-F because it is the only available mental health service in the whole Fokida prefecture. The major goals of the MMHUs are the diagnosis, treatment, and prevention of relapse of severe mental illness within the community. Other important goals of the MMHUs are psychoeducation, psychological support for the family/caregivers, as well as vocational training and support for patients with severe mental illness. Statistical data depicting the demographic characteristics and diagnostic profiles of patients in each MMHU is also provided, and the differences between the two MMHUs are briefly discussed