Virtual Reality Environmental Enrichment Effects on Craving for Cigarette in Smokers.

Background: Preclinical studies suggested the exposure to environmental enrichment (EE) as an intervention able to prevent or reduce nicotine-taking and nicotine-seeking behaviors. Virtual reality (VR) may help to test the effects of EE in smokers in a reproducible and feasible manner. Materials and Methods: In the present study, 31 smokers (14 women) were divided into two groups: (1) exposure to a virtual EE (VR-EE) and (2) exposure to a virtual neutral environment (VR-NoEE). Cigarette craving was assessed as basal and evoked, at different timepoints during the session. Behavior activity during VR exposure, mood, and subjective measures were also collected. Results: EE exposure in VR significantly reduced craving scores from basal timepoint. This was not observed in the VR-NoEE group, which significantly increased craving compared with values at neutral scenario. When both groups were exposed to smoking-related VR scenario, the VR-EE group showed an increased craving compared with previous timepoint up to score values not different from those in the VR-NoEE group. A significant positive correlation between basal craving scores and interactive behavior with virtual smoking cues was observed in the VR-NoEE but not in the VR-EE group. Conclusion: These findings suggest that virtual EE might have an inhibitory effect in smokers on basal, but not on evoked cigarette craving. Noteworthily, the interactive activity correlation to craving scores in the VR-NoEE participants was not observed in the VR-EE group, adding further evidence that the enrichment simulation was nonetheless able to modify behavior in the smoking-related scenario.

Nature-based experience in Venetian lagoon: Effects on craving and wellbeing in addict residential inpatients.

Introduction: It is known that exposure to the natural environment may positively modulate mental processes and behaviors; in particular, it can reduce stress, anxiety, and depressive symptoms. This suggests a potential integration of "nature experience" into the treatment for substance use disorder (SUD) since various types of addiction are associated with anxiety and depression. Considering that only one study has been reported to date in patients with alcohol use disorder, the effect of nature experience in SUD patients' needs to be further investigated. This study aimed to test the effects of exposure to a natural lagoon environment on craving and measures of wellbeing in SUD patients in comparison to exposure to an urban environment. Methods: Twenty-four SUD patients were divided into three groups of eight participants and exposed to two walking sessions (interspersed with a 1-week wash-out period) in a natural environment typical of the Venetian lagoon, an Urban walk, or staying at the residential center based on a Latin-square design. Before and after each session, drug craving, mood, wellbeing, agency, openness to the future, and restorativeness were assessed. Results: The Nature walk significantly decreased craving in participants compared to their pre-walk values, and compared to craving after the Urban walk, with the latter significantly increased vs. pre-walk values. The Nature walk significantly decreased negative mood and increased wellbeing and agency. Openness to the future and restorativeness measures showed significant improvement after the Nature walk compared to the Urban walk. On the other hand, craving scores after the Urban Walk positively correlated with negative mood and a Sense of Negative Agency values and negatively correlated with wellbeing scores. Discussion: Our results confirm that "nature experience" may improve mood, wellbeing, attention, stress relief, openness, and sense of being active in SUD patients. Moreover, we also showed a specific effect on drug craving-a key symptom of SUD.

Ecocebo: How the interaction between environment and drug effects may improve pharmacotherapy outcomes.

This narrative review describes the research on the effects of the association between environmental context and medications, suggesting the benefit of specific design interventions in adjunction to pharmacotherapy. The literature on Evidence-Based Design (EBD) studies and Neuro-Architecture show how contact with light, nature, and specific physical features of urban and interior architecture may enhance the effects of analgesic, anxiolytics, and antidepressant drugs. This interaction mirrors those already known between psychedelics, drugs of abuse, and setting. Considering that the physical feature of space is a component of the complex placebo configuration, the aim is to highlight those elements of built or natural space that may help to improve drug response in terms of efficacy, tolerability, safety, and compliance. Ecocebo, the integration of design approaches such as EBD and Neuro-Architecture may thus contribute to a more efficient, cost-sensitive, and sustainable pharmacotherapy.

Brief exposure to enriched environment rapidly shapes the glutamate synapses in the rat brain: A metaplastic fingerprint.

Environmental enrichment (EE) has been shown to produce beneficial effects in addiction disorders; however, due to its configurational complexity, the underlying mechanisms are not yet fully elucidated. Recent evidence suggests that EE, acting as a metaplastic agent, may affect glutamatergic mechanisms underlying appetitive memory and, in turn, modulate reward-seeking behaviours: here, we have investigated such a possibility following a brief EE exposure. Adult male Sprague-Dawley rats were exposed to EE for 22 h and the expression of critical elements of the glutamate synapse was measured 2 h after the end of EE in the medial prefrontal cortex (mPFC), nucleus accumbens (NAc) and hippocampus (Hipp) brain areas, which are critical for reward and memory. We focused our investigation on the expression of NMDA and AMPA receptor subunits, their scaffolding proteins SAP102 and SAP97, vesicular and membrane glutamate transporters vGluT1 and GLT-1, and critical structural components such as proteins involved in morphology and function of glutamatergic synapses, PSD95 and Arc/Arg3.1. Our findings demonstrate that a brief EE exposure induces metaplastic changes in glutamatergic mPFC, NAc and Hipp. Such changes are area-specific and involve postsynaptic NMDA/AMPA receptor subunit composition, as well as changes in the expression of their main scaffolding proteins, thus influencing the retention of such receptors at synaptic sites. Our data indicate that brief EE exposure is sufficient to dynamically modulate the glutamatergic synapses in mPFC-NAc-Hipp circuits, which may modulate rewarding and memory processes.

The effects of virtual reality environmental enrichments on craving to food in healthy volunteers.

RATIONALE: Environmental enrichment (EE) is a non-pharmacological approach that has been shown to be effective in reducing food-taking in rats. Studies in human volunteers are still in their infancy, given the difficulty to translate the complexity of EE in clinical practice. Virtual reality (VR) is a promising methodological approach, but no study has yet applied it to model and test EE in humans. OBJECTIVES: The present study is the first to assess the effects of virtual EE on craving for palatable food. METHODS: Eighty-one healthy volunteers (43 women) were divided into three groups: (i) exposure to a virtual EE (VR-EE), (ii) exposure to a virtual neutral environment (VR-NoEE), and (iii) without exposure to VR (No VR). Craving for palatable food at basal level and evoked by neutral and palatable food images was assessed before and after the VR simulation. Behavior during VR exposure and subjective measures related to the experience were also collected. RESULTS: VR-EE group showed a significantly greater decrease in pre-post craving difference compared to No VR for all assessments and at basal level compared to VR-NoEE. Interestingly, an inverse correlation between craving and deambulation in the VR simulation emerged in VR-EE group only. CONCLUSIONS: The study highlighted the feasibility of exposing human subjects to an EE as a virtual simulation. Virtual EE induced effects on basal craving for food that suggest the potential for further improvements of the protocol to extend its efficacy to palatable food cues.

Study protocol-Evoked craving in high-dose benzodiazepine users.

Benzodiazepine (BDZ) abuse, especially concerning high doses of BDZs, is an impairing substance use disorder (SUD) that is often difficult to treat. Craving and cue reactivity (CR) are two important phenomena that have a prominent role in maintaining addiction and triggering relapses in BDZ abuse; nevertheless, they have rarely been addressed in scientific literature. The present study aims to fill these gaps by implementing a highly innovative virtual reality (VR) design to assess the impact of substance-related environmental cues on BDZ craving, as well as their influence on patients' affective states. Therefore, on one hand, this research will contribute to the assessment of VR feasibility in the study of these phenomena, and, on the other, it will help disentangle the role that CR and craving have on mood and attention, which are equally important factors to consider when treating SUDs. We will recruit a healthy control group and a patient group comprising people seeking treatment for BDZ detoxification. The experimental design will consist of the presentation of three VR scenarios, one neutral, one BDZ-related but without BDZ cues, and another with BDZ cues. The craving will be measured through a virtual analog scale (VAS); the Profile of Mood States (POMS) and Alcohol Attention Scale (AAS) questionnaires in a modified version will also be administered. We will additionally control for VR-induced feelings of sickness by administering the Simulator Sickness Questionnaire (SSQ), and the Presence Questionnaire (PQ) will be used to investigate participants' sense of presence in virtual environments. We expect patients to exhibit higher levels of craving, and that the craving will be higher after exposure to a cue-related virtual environment as compared to a neutral scenario.

Environmental Enrichment Induces Meningeal Niche Remodeling through TrkB-Mediated Signaling.

Neural precursors (NPs) present in the hippocampus can be modulated by several neurogenic stimuli, including environmental enrichment (EE) acting through BDNF-TrkB signaling. We have recently identified NPs in meninges; however, the meningeal niche response to pro-neurogenic stimuli has never been investigated. To this aim, we analyzed the effects of EE exposure on NP distribution in mouse brain meninges. Following neurogenic stimuli, although we did not detect modification of the meningeal cell number and proliferation, we observed an increased number of neural precursors in the meninges. A lineage tracing experiment suggested that EE-induced ß3-Tubulin+ immature neuronal cells present in the meninges originated, at least in part, from GLAST+ radial glia cells. To investigate the molecular mechanism responsible for meningeal reaction to EE exposure, we studied the BDNF-TrkB interaction. Treatment with ANA-12, a TrkB non-competitive inhibitor, abolished the EE-induced meningeal niche changes. Overall, these data showed, for the first time, that EE exposure induced meningeal niche remodeling through TrkB-mediated signaling. Fluoxetine treatment further confirmed the meningeal niche response, suggesting it may also respond to other pharmacological neurogenic stimuli. A better understanding of the neurogenic stimuli modulation for meninges may be useful to improve the effectiveness of neurodegenerative and neuropsychiatric treatments.

Where Dopaminergic and Cholinergic Systems Interact: A Gateway for Tuning Neurodegenerative Disorders.

Historically, many investigations into neurodegenerative diseases have focused on alterations in specific neuronal populations such as, for example, the loss of midbrain dopaminergic neurons in Parkinson's disease (PD) and loss of cholinergic transmission in Alzheimer's disease (AD). However, it has become increasingly clear that mammalian brain activities, from executive and motor functioning to memory and emotional responses, are strictly regulated by the integrity of multiple interdependent neuronal circuits. Among subcortical structures, the dopaminergic nigrostriatal and mesolimbic pathways as well as cholinergic innervation from basal forebrain and brainstem, play pivotal roles in orchestrating cognitive and non-cognitive symptoms in PD and AD. Understanding the functional interactions of these circuits and the consequent neurological changes that occur during degeneration provides new opportunities to understand the fundamental inter-workings of the human brain as well as develop new potential treatments for patients with dysfunctional neuronal circuits. Here, excerpted from a session of the European Behavioral Pharmacology Society meeting (Braga, Portugal, August 2019), we provide an update on our recent work in behavioral and cellular neuroscience that primarily focuses on interactions between cholinergic and dopaminergic systems in PD models, as well as stress in AD. These brief discussions include descriptions of (1) striatal cholinergic interneurons (CINs) and PD, (2) dopaminergic and cholinergic modulation of impulse control, and (3) the use of an implantable cell-based system for drug delivery directly the into brain and (4) the mechanisms through which day life stress, a risk factor for AD, damage protein and RNA homeostasis leading to AD neuronal malfunction.

Remote clinical trials: A timely opportunity for a virtual reality approach and its potential application in neurology.

The COVID-19 pandemic boosted the expansion and development of new remote models of care and clinical research modalities. Health systems are going to implement telemedical innovations in the near future. Virtual clinical trials (VCT), also known as remote or decentralized ones, may profoundly change the way how clinical studies are conducted, for the benefit of patients with chronic and neurological diseases who are often fragile and may have limited access to traditional healthcare facilities. Despite significant progress, several limitations still need to be addressed to implement telemedicine technologies for VCT. The information and communication technology (ICT) devices (e.g., mobile apps and wearables) may be applied to VCTs but show some practical issues that may hamper the compliance with rigorous research criteria and protocols. We herewith discuss the advantages and disadvantages of virtual reality (VR) in combination with other ICT devices and solutions to improve the conduction of VCT in patients with neurological disorders. The so-called "digital divide," that is, the gap between people who can and those who cannot access high-speed and broadband internet connections, and issues related to VR, such as VR sickness, should be addressed to improve larger VCT participation to neurological patients.

A virtual reality study on postretrieval extinction of smoking memory reconsolidation in smokers.

Exposure to smoking-related stimuli may induce the reconsolidation of smoking-related memories in smokers. Research has proposed that extinction applied after the retrieval of a smoking memory may inhibit reconsolidation and prevent craving. The aim of this study was to test the effect of postretrieval extinction (PRE) on the reconsolidation of smoking memory by using a virtual reality (VR) simulation in smokers. On the day 1 session, the study exposed 46 smokers to a neutral and then to a smoking VR scenario under a fixed-block protocol. On day 2, the study randomized participants into three groups (G) and exposed them to a 15-s VR immersion in smoking (G1, G3) or neutral (G2) scenario for memory retrieval. After 15 min, the study exposed G1 and G2 to a VR PRE during the temporal window of memory vulnerability, whereas the study exposed G3 to extinction immediately after retrieval. On day 3, the study exposed all groups to neutral and smoking scenarios similar to day 1. All groups significantly increased craving for cigarettes after exposure to the smoking scenario on day 1 (p < 0.01). On day 3, VR PRE after a 15-second VR smoking memory retrieval was able to inhibit reconsolidation in G1, but not in G3 exposed to PRE before the window of vulnerability, or in G2 not exposed to the smoking memory retrieval. These findings show the superiority of VR PRE after smoking memory retrieval compared to a standard extinction procedure.

Smokers "Context Reactivity" in Virtual Domestic Environments.

INTRODUCTION: Although the effects of proximal smoking cues have been widely studied in smokers, little is known on the features associated with background spatial context effect, that is, "context reactivity." The aim of this study was to investigate context reactivity exhibited by smokers in virtual cue-free domestic scenarios. METHODS: Sixty-nine participants divided in 2 cohorts (33 smokers and 36 non-smokers) were exposed to a virtual reality session with 4 domestic room scenarios presented in a balanced order: bedroom, bathroom, kitchen, and living room. RESULTS: We showed that (i) it is possible to elicit smoking craving in smokers in virtual reality, and (ii) these effects are room dependent and (iii) associated with a lower sense of presence; furthermore, (iv) smokers reported higher craving scores for alcohol and food in a room-dependent fashion compared to non-smokers. CONCLUSION: Our study provides an experimental paradigm for assessing context reactivity in smokers and suggests a potential use for the identification of non-pharmacological interventions as a co-adjuvant of smoking cessation treatment.

Continuous Infusion of Flumazenil in the Management of Benzodiazepines Detoxification.

An effective approach in the treatment of benzodiazepine (BZD) overdosing and detoxification is flumazenil (FLU). Studies in chronic users who discontinued BZD in a clinical setting suggested that multiple slow bolus infusions of FLU reduce BZD withdrawal symptoms. The aim of this study was to confirm FLU efficacy for reducing BZD withdrawal syndrome by means of continuous elastomeric infusion, correlated to drugs plasma level and patients' compliance. Methods: Seven-day FLU 1 mg/day subcutaneously injected through an elastomeric pump and BZDs lormetazepam, clonazepam, and lorazepam were assessed by HPLC-MS/MS in serum of patients before and after 4 and 7 days of FLU continuous infusion treatment. Changes in withdrawal severity were assessed by using the BZD Withdrawal Scale (BWS). Results: Fourteen patients (mean age ± SD 42.5 ± 8.0 years, 5 male and 9 female), admitted to the hospital for high-dose BZD detoxification, were enrolled in the study. Serum FLU concentrations significantly decreased from 0.54 ± 0.33 ng/ml (mean ± SD) after 4 days of treatment to 0.1 ± 0.2 ng/ml at the end of infusion. Lormetazepam concentrations were 502.5 ± 610.0 ng/ml at hospital admission, 26.2 ± 26.8 ng/ml after 4 days, and 0 at the end of treatment. BWS values decreased during FLU treatment temporal period. FLU was well-tolerated by patients. Conclusions: Elastomeric FLU infusion for BZD detoxification is a feasible administration device to maintain adequate, constant, and tolerated FLU concentrations for reducing BZD withdrawal symptoms.

Metaplastic Effects of Ketamine and MK-801 on Glutamate Receptors Expression in Rat Medial Prefrontal Cortex and Hippocampus.

Ketamine and MK-801 by blocking NMDA receptors may induce reinforcing effects as well as schizophrenia-like symptoms. Recent results showed that ketamine can also effectively reverse depressive signs in patients' refractory to standard therapies. This evidence clearly points to the need of characterization of effects of these NMDARs antagonists on relevant brain areas for mood disorders. The aim of the present study was to investigate the molecular changes occurring at glutamatergic synapses 24 h after ketamine or MK-801 treatment in the rat medial prefrontal cortex (mPFC) and hippocampus (Hipp). In particular, we analyzed the levels of the glutamate transporter-1 (GLT-1), NMDA receptors, AMPA receptors subunits, and related scaffolding proteins. In the homogenate, we found a general decrease of protein levels, whereas their changes in the post-synaptic density were more complex. In fact, ketamine in the mPFC decreased the level of GLT-1 and increased the level of GluN2B, GluA1, GluA2, and scaffolding proteins, likely indicating a pattern of enhanced excitability. On the other hand, MK-801 only induced sparse changes with apparently no correlation to functional modification. Differently from mPFC, in Hipp, both substances reduced or caused no changes of glutamate receptors and scaffolding proteins expression. Ketamine decreased NMDA receptors while increased AMPA receptors subunit ratios, an effect indicative of permissive metaplastic modulation; conversely, MK-801 only decreased the latter, possibly representing a blockade of further synaptic plasticity. Taken together, these findings indicate a fine tuning of glutamatergic synapses by ketamine compared to MK-801 both in the mPFC and Hipp.

Smoking-related cue reactivity in a virtual reality setting: association between craving and EEG measures.

BACKGROUND: Cue-reactivity is the array of responses that smokers exhibit when exposed to conditioned and contextual stimuli previously associated to substance use. The difficulty to experimentally recreate the complexity of smokers' spatial experience and context requires more ecological models. Virtual reality (VR) creates a state of immersion close to reality allowing controlled assessments of behavioral responses. To date, no studies investigated brain activation associated to smoking cue-reactivity in VR using electroencephalography (EEG). AIMS: To investigate whether a VR cue-reactivity paradigm (a) may increase smoking craving, (b) is feasible with EEG recording, and (c) induces craving levels associated to EEG desynchronization. METHODS: Smokers (N = 20) and non-smokers (N = 20) were exposed to neutral and smoking-related VR scenarios, without and with smoking conditioned stimuli, respectively. EEG was recorded from occipital and parietal leads throughout the sessions to assess alpha band desynchronization. Smoking and food craving and presence visual analogue scales (VAS) were assessed during the session. RESULTS: To be smoker, but not non-smoker, significantly influenced smoking craving VAS induced by smoking cue VR but not by neutral VR. No significant food craving changes was observed during the VR sessions. The new finding was that EEG alpha band power in posterior leads was significantly increased by the smoking context scenario only in smokers, and that the degree of smoking (i.e., heavy vs. light) was significantly associated to this neurophysiological measure. CONCLUSIONS: This study demonstrated, for the first time, the feasibility of EEG recording in a VR setting, suggesting that EEG desynchronization may be a neurophysiological marker of smoking cue-reactivity.

A descriptive study of exercise dependence: a short report among Italian and Japanese runners.

Background: Exercise dependence is a phenomenon characterized by behavioral, physiological and psychological symptoms similarly to substance use disorders. Although exercise addiction is not classified as a mental health disorder. A descriptive study of exercise dependence in two different countries, Italy and for the first time Japan was performed.Methods: We interviewed 229 Italian and 198 Japanese runners by using the exercise dependence scale-21 (EDS-R), a questionnaire to assess exercise dependence.Results: In Italy, 86.9% of subjects were nondependent symptomatic, 4.4% wxercise-dependent, and 8.7% were nondependent asymptomatic. In Japan, participants were classified as nondependent symptomatic (49%) and nondependent asymptomatic (51%), but none considered as at-risk. Significant differences were found in all the seven EDS-R categories between the two cohorts.Conclusions: Exercise dependence is a complex with many contributing factors such as neuroadaptation to protracted exposure to exercise, runner's features and contextual factors. The role of social and cultural factors of exercise dependence would need further investigations.

Glutamate receptors and metaplasticity in addiction.

Chronic drug use is a neuroadaptive disorder characterized by strong and persistent plasticity in the mesocorticolimbic reward system. Long-lasting effects of drugs of abuse rely on their ability to hijack glutamate receptor activity and long-term synaptic plasticity processes like long-term potentiation and depression. Importantly, metaplasticity-based modulation of synaptic plasticity contributes to durable neurotransmission changes in mesocorticolimbic pathways including the ventral tegmental area and the nucleus accumbens, causing 'maladaptive' drug memory and higher risk for drug-seeking relapse. On the other hand, drug-induced metaplasticity can make appetitive memories more malleable to modification, offering a potential target mechanism for intervention. Here we review the literature on the role of glutamate receptors in addiction-related metaplasticity phenomena.

Cytokine-, Neurotrophin-, and Motor Rehabilitation-Induced Plasticity in Parkinson's Disease.

Neuroinflammation and cytokine-dependent neurotoxicity appear to be major contributors to the neuropathology in Parkinson's disease (PD). While pharmacological advancements have been a mainstay in the treatment of PD for decades, it is becoming increasingly clear that nonpharmacological approaches including traditional and nontraditional forms of exercise and physical rehabilitation can be critical adjunctive or even primary treatment avenues. Here, we provide an overview of preclinical and clinical research detailing the biological role of proinflammatory molecules in PD and how motor rehabilitation can be used to therapeutically modulate neuroinflammation, restore neural plasticity, and improve motor function in PD.

Telemedicine and Virtual Reality for Cognitive Rehabilitation: A Roadmap for the COVID-19 Pandemic.

The current COVID-19 pandemic presents unprecedented new challenges to public health and medical care delivery. To control viral transmission, social distancing measures have been implemented all over the world, interrupting the access to routine medical care for many individuals with neurological diseases. Cognitive disorders are common in many neurological conditions, e.g., stroke, traumatic brain injury, Alzheimer's disease, and other types of dementia, Parkinson's disease and parkinsonian syndromes, and multiple sclerosis, and should be addressed by cognitive rehabilitation interventions. To be effective, cognitive rehabilitation programs must be intensive and prolonged over time; however, the current virus containment measures are hampering their implementation. Moreover, the reduced access to cognitive rehabilitation might worsen the relationship between the patient and the healthcare professional. Urgent measures to address issues connected to COVID-19 pandemic are, therefore, needed. Remote communication technologies are increasingly regarded as potential effective options to support health care interventions, including neurorehabilitation and cognitive rehabilitation. Among them, telemedicine, virtual reality, augmented reality, and serious games could be in the forefront of these efforts. We will briefly review current evidence-based recommendations on the efficacy of cognitive rehabilitation and offer a perspective on the role of tele- and virtual rehabilitation to achieve adequate cognitive stimulation in the era of social distancing related to COVID-19 pandemic. In particular, we will discuss issues related to their diffusion and propose a roadmap to address them. Methodological and technological improvements might lead to a paradigm shift to promote the delivery of cognitive rehabilitation to people with reduced mobility and in remote regions.

The Effects of Nicotine on Cortical Excitability After Exercise: A Double-Blind Randomized, Placebo-controlled, Crossover Study.

PURPOSE: The use of smokeless tobacco/nicotine products is common among athletes, but clear evidence for their positive or negative effect on sports performance is lacking. Nicotine is a psychoactive substance involved in numerous neuronal processes including cortical excitability. The aim of this study was to evaluate its effect on cortical excitability associated with aerobic exercise in nicotine-naive healthy volunteers. METHODS: Ten nicotine-naive healthy volunteers were recruited for this double-blind, randomized, crossover study to compare the effect of snus (8 mg nicotine), an oral, smokeless tobacco product, to placebo on cortical excitability before and after aerobic exercise. Transcranial magnetic stimulation (TMS) was used to measure changes in corticomotor excitability (motor-evoked potentials, MEPs) and electromyography of leg muscles during maximal voluntary contractions (MVC) to assess changes in muscle contractions. Before and after aerobic exercise and with or without nicotine treatment, MEPs and MVCs were measured. RESULTS: Analysis of TMS data showed lower motor cortex activation (lower MEP amplitude) after snus administration compared with placebo, whereas electromyography data showed no difference in muscle contraction between snus and placebo treatment. CONCLUSIONS: These findings suggest a general reduction in cortical excitability, without no relevant effect on physical performance.

Hippocampal gamma oscillations by sucrose instrumental memory retrieval in rats across sleep/wake cycle.

Memory reconsolidation is a process allowing previously consolidated memories to be updated. In order for memory reconsolidation to occur, a memory first needs to be reactivated. It has been shown recently that memory retrieval during awake/sleep phases may affect susceptibility to memory reactivation. Given the importance of hippocampal gamma frequencies in memory processes, the purpose of the present research was to study changes in gamma bands power during retrieval of instrumental appetitive memories. Local field potentials were recorded in the CA1 area of dorsal hippocampus of Sprague Dawley rats during retrieval of instrumental appetitive memory performed either during light or dark phases of the circadian cycle. Appetitive memory retrieval was performed by using a protocol of sucrose self-administration in operant chambers equipped with levers (Piva et al., 2018): rats were first trained to self-administer sucrose pellets and, after a 14-days forced abstinence stage, memory retrieval stage consisted in training context exposure. At the retrival stage performed during the light phase, a decreased low-gamma power was observed in CA1 when rats were not lever pressing compared to when they were lever pressing (actual instrumental memory retrieval). Moreover, results showed an inverse correlation between gamma power and rate of responding when retrieval was performed in the dark phase. Our findings suggest that hippocampal gamma power is differently modulated when retrieval is performed during the light phase compared to the dark phase. Further investigations should explore the role of gamma oscillations as potential markers of instrumental appetitive memory reactivation in both light and dark conditions.