-
Frontiers in Neuroscience 2024Olfaction is understudied in neuroimaging research compared to other senses, but there is growing evidence of its therapeutic benefits on mood and well-being. Olfactory... (Review)
Review
Olfaction is understudied in neuroimaging research compared to other senses, but there is growing evidence of its therapeutic benefits on mood and well-being. Olfactory imagery can provide similar health benefits as olfactory interventions. Harnessing crossmodal visual-olfactory interactions can facilitate olfactory imagery. Understanding and employing these cross-modal interactions between visual and olfactory stimuli could aid in the research and applications of olfaction and olfactory imagery interventions for health and wellbeing. This review examines current knowledge, debates, and research on olfaction, olfactive imagery, and crossmodal visual-olfactory integration. A total of 56 papers, identified using the PRISMA method, were evaluated to identify key brain regions, research themes and methods used to determine the suitability of fNIRS as a tool for studying these topics. The review identified fNIRS-compatible protocols and brain regions within the fNIRS recording depth of approximately 1.5 cm associated with olfactory imagery and crossmodal visual-olfactory integration. Commonly cited regions include the orbitofrontal cortex, inferior frontal gyrus and dorsolateral prefrontal cortex. The findings of this review indicate that fNIRS would be a suitable tool for research into these processes. Additionally, fNIRS suitability for use in naturalistic settings may lead to the development of new research approaches with greater ecological validity compared to existing neuroimaging techniques.
PubMed: 38356646
DOI: 10.3389/fnins.2024.1266664 -
Aging Clinical and Experimental Research Feb 2024Non-invasive brain stimulation (NIBS) is a burgeoning approach with the potential to significantly enhance cognition and functional abilities in individuals who have... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Non-invasive brain stimulation (NIBS) is a burgeoning approach with the potential to significantly enhance cognition and functional abilities in individuals who have undergone a stroke. However, the current evidence lacks robust comparisons and rankings of various NIBS methods concerning the specific stimulation sites and parameters used. To address this knowledge gap, this systematic review and meta-analysis seek to offer conclusive evidence on the efficacy and safety of NIBS in treating post-stroke cognitive impairment.
METHODS
A systematic review of randomized control trials (RCT) was performed using Bayesian network meta-analysis. We searched RCT in the following databases until June 2022: Cochrane Central Register of Controlled Trials (CENTRAL), PUBMED, and EMBASE. We compared any active NIBS to control in terms of improving cognition function and activities of daily living (ADL) capacity following stroke.
RESULTS
After reviewing 1577 retrieved citations, a total of 26 RCTs were included. High-frequency (HF)-repetitive transcranial magnetic stimulation (rTMS) (mean difference 2.25 [95% credible interval 0.77, 3.66]) was identified as a recommended approach for alleviating the global severity of cognition. Dual-rTMS (27.61 [25.66, 29.57]) emerged as a favorable technique for enhancing ADL function. In terms of stimulation targets, the dorsolateral prefrontal cortex exhibited a higher ranking in relation to the global severity of cognition.
CONCLUSIONS
Among various NIBS techniques, HF-rTMS stands out as the most promising intervention for enhancing cognitive function. Meanwhile, Dual-rTMS is highly recommended for improving ADL capacity.
Topics: Humans; Transcranial Direct Current Stimulation; Network Meta-Analysis; Stroke; Brain; Cognitive Dysfunction
PubMed: 38345751
DOI: 10.1007/s40520-023-02662-x -
Heliyon Feb 2024Previous studies have reported alterations in brain structure in major depressive disorder (MDD) patients with suicide attempts. However, age-related changes in suicidal...
BACKGROUND
Previous studies have reported alterations in brain structure in major depressive disorder (MDD) patients with suicide attempts. However, age-related changes in suicidal MDD patients remain unclear.
METHODS
We performed a systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Embase, PubMed, and Web of Science were searched to identify relevant studies from inception to January 2023. All voxel-based and surface-based morphometry studies comparing suicidal MDD patients to MDD or healthy controls were included. Studies were then grouped by age range (old, middle-age, adolescent) and the commonalities and age-related structural brain alterations were summarized. The included studies were evaluated using the Newcastle-Ottawa Scale (NOS).
RESULTS
A total of 17 studies met the inclusion criteria, including 3 of late-life depression (LLD) patients, 11 of middle-aged depression (MAD) patients, and 3 of adolescent depression (AOD) patients. The majority of studies had moderate to high NOS scores, indicating good quality. Patients in all three age groups exhibited extensive alterations in the lateral, medial, and orbital regions of the frontal lobes. Furthermore, suicidal MAD patients showed a specific decrease in the gray matter volume of the dorsolateral prefrontal cortex compared to suicidal LLD patients. Cortical thickness and left angular gyrus volume were decreased in suicidal MAD and suicidal LLD patients, but increased in suicidal AOD patients.
CONCLUSION
This systematic review summarizes structural brain changes in suicidal MDD patients at three age groups: elderly, middle-aged, and adolescent. These findings help elucidate the common circuitry of MDD related to suicide over the lifespan and highlight unique circuitry associated with different ages. These findings may help predict the risk of suicide in MDD patients at different ages.
PubMed: 38317985
DOI: 10.1016/j.heliyon.2024.e24894 -
Translational Psychiatry Jan 2024Major depressive disorder (MDD) is marked by altered processing of emotional stimuli, including facial expressions. Recent neuroimaging research has attempted to...
Major depressive disorder (MDD) is marked by altered processing of emotional stimuli, including facial expressions. Recent neuroimaging research has attempted to investigate how these stimuli alter the directional interactions between brain regions in those with MDD; however, methodological heterogeneity has made identifying consistent effects difficult. To address this, we systematically examined studies investigating MDD-associated differences present in effective connectivity during the processing of emotional facial expressions. We searched five databases: PsycINFO, EMBASE, PubMed, Scopus, and Web of Science, using a preregistered protocol (registration number: CRD42021271586). Of the 510 unique studies screened, 17 met our inclusion criteria. These studies identified that compared with healthy controls, participants with MDD demonstrated (1) reduced connectivity from the dorsolateral prefrontal cortex to the amygdala during the processing of negatively valenced expressions, and (2) increased inhibitory connectivity from the ventromedial prefrontal cortex to amygdala during the processing of happy facial expressions. Most studies investigating the amygdala and anterior cingulate cortex noted differences in their connectivity; however, the precise nature of these differences was inconsistent between studies. As such, commonalities observed across neuroimaging modalities warrant careful investigation to determine the specificity of these effects to particular subregions and emotional expressions. Future research examining longitudinal connectivity changes associated with treatment response may provide important insights into mechanisms underpinning therapeutic interventions, thus enabling more targeted treatment strategies.
Topics: Humans; Brain; Brain Mapping; Depressive Disorder, Major; Emotions; Facial Recognition; Magnetic Resonance Imaging; Prefrontal Cortex
PubMed: 38272868
DOI: 10.1038/s41398-024-02734-0 -
NeuroImage. Clinical 2024Changes in eating behaviour including reductions in appetite and food intake, and healthier food cue reactivity, reward, hedonics and potentially also preference,... (Review)
Review
Changes in eating behaviour including reductions in appetite and food intake, and healthier food cue reactivity, reward, hedonics and potentially also preference, contribute to weight loss and its health benefits after obesity surgery. Functional magnetic resonance imaging (fMRI) has been increasingly used to interrogate the neural correlates of eating behaviour in obesity, including brain reward-cognitive systems, changes after obesity surgery, and links with alterations in the gut-hormone-brain axis. Neural responses to food cues can be measured by changes in blood oxygen level dependent (BOLD) signal in brain regions involved in reward processing, including caudate, putamen, nucleus accumbens, insula, amygdala, orbitofrontal cortex, and top-down inhibitory control, including dorsolateral prefrontal cortex (dlPFC). This systematic review aimed to examine: (i) results of human fMRI studies involving obesity surgery, (ii) important methodological differences in study design across studies, and (iii) correlations and associations of fMRI findings with clinical outcomes, other eating behaviour measures and mechanistic measures. Of 741 articles identified, 23 were eligible for inclusion: 16 (69.6%) longitudinal, two (8.7%) predictive, and five (21.7%) cross-sectional studies. Seventeen studies (77.3%) included patients having Roux-en-Y gastric bypass (RYGB) surgery, six (26.1%) vertical sleeve gastrectomy (VSG), and five (21.7%) laparoscopic adjustable gastric banding (LAGB). The majority of studies (86.0%) were identified as having a very low risk of bias, though only six (27.3%) were controlled interventional studies, with none including randomisation to surgical and control interventions. The remaining studies (14.0%) had a low risk of bias driven by their control groups not having an active treatment. After RYGB surgery, food cue reactivity often decreased or was unchanged in brain reward systems, and there were inconsistent findings as to whether reductions in food cue reactivity was greater for high-energy than low-energy foods. There was minimal evidence from studies of VSG and LAGB surgeries for changes in food cue reactivity in brain reward systems, though effects of VSG surgery on food cue reactivity in the dlPFC were more consistently found. There was consistent evidence for post-operative increases in satiety gut hormones glucagon-like-peptide 1 (GLP-1) and peptide YY (PYY) mediating reduced food cue reactivity after RYGB surgery, including two interventional studies. Methodological heterogeneity across studies, including nutritional state, nature of food cues, post-operative timing, lack of control groups for order effects and weight loss or dietary/psychological advice, and often small sample sizes, limited the conclusions that could be drawn, especially for correlational analyses with clinical outcomes, other eating behaviour measures and potential mediators. This systematic review provides a detailed data resource for those performing or analysing fMRI studies of obesity surgery and makes suggestions to help improve reporting and design of such studies, as well as future directions.
Topics: Humans; Cross-Sectional Studies; Obesity; Feeding Behavior; Magnetic Resonance Imaging; Weight Loss
PubMed: 38237270
DOI: 10.1016/j.nicl.2024.103563 -
Journal of Integrative Neuroscience Nov 2023Gambling Disorder (GD) is a behavioral addiction listed within the diagnostic category of substance-related and addictive disorders. Recently, transcranial magnetic...
BACKGROUND
Gambling Disorder (GD) is a behavioral addiction listed within the diagnostic category of substance-related and addictive disorders. Recently, transcranial magnetic stimulation (TMS), which non-invasively stimulates the brain and has neuromodulatory properties, has emerged as an innovative treatment tool for GD, thus offering a new option for the management of this complex disorder. The present review explored the efficacy of TMS as a possible non-pharmacological treatment for GD.
METHODS
An exhaustive search was performed across the MEDLINE, Web of Science, and EMBASE databases using a specific search string related to GD and TMS. A total of 20 papers were selected for full-text examination, out of which eight fulfilled the inclusion criteria and were therefore systematically analyzed in the present review.
RESULTS
This review included eight studies: three randomized-controlled trials (RCTs), three non-controlled studies, one case series, and one case report. Two cross-over RCTs described a decrease in craving after high-frequency (excitatory), repetitive transcranial magnetic stimulation (rTMS) over the left dorsolateral prefrontal cortex (DLPFC) and the medial prefrontal cortex (PFC), respectively; another study applying low-frequency (inhibitory) rTMS on the right DLPFC did not find any positive effect on craving. Among uncontrolled studies, one demonstrated the beneficial effect of high-frequency rTMS over the left DLPFC, while another showed the efficacy of a continuous theta burst stimulation protocol directed over the pre-supplementary motor area, bilaterally.
CONCLUSION
The included studies showed the promising effect of excitatory stimulation over the left PFC. However, further investigation is needed, particularly in terms of standardizing stimulation protocols and psychometric assessments.
Topics: Humans; Transcranial Magnetic Stimulation; Gambling; Craving; Prefrontal Cortex; Dorsolateral Prefrontal Cortex; Treatment Outcome
PubMed: 38176943
DOI: 10.31083/j.jin2206164 -
Folia Neuropathologica Jan 2024The role of functional magnetic resonance imaging (fMRI) findings in investigation of working memory (WM) deficit in schizophrenia patients is still debatable. The aim...
INTRODUCTION
The role of functional magnetic resonance imaging (fMRI) findings in investigation of working memory (WM) deficit in schizophrenia patients is still debatable. The aim of the study was to investigate the role of fMRI findings of the frontal and parietal brain activity in investigation of WM deficit in schizophrenia patients.
MATERIAL AND METHODS
We used Medline, Embase, and the Cochrane Database to conduct a comprehensive search up to January 2023. Functional MRI findings of schizophrenia patients were compared with healthy patients in comparative studies for assessing their WM capacity in terms of dorsolateral prefrontal cortex and parietal region activation. The Cochrane Risk of Bias Assessment Tool was used to evaluate the research quality.
RESULTS
Ten trials and 676 schizophrenia patients were included in our analysis. For the comparative assessment of primary outcome - alteration in dorsolateral prefrontal cortex and parietal region activity in schizophrenic patients versus healthy controls - we found the pooled odds ratio (OR) of 1.58 [95% CI: 1.09-2.29], I 2 = 61% and p = 0.01 and risk ratio (RR) was 1.27 [95% CI: 1.06-1.53], I 2 = 55% and p = 0.01. The AUC value of 0.944 indicates a favourable overall diagnostic performance of fMRI for the diagnosis of schizophrenia.
CONCLUSIONS
fMRI findings showing abnormalities in the parietal and frontal regions can be used to study schizophrenia patients' WM deficits.
PubMed: 38174682
DOI: 10.5114/fn.2023.132329 -
Journal of Psychiatric Research Feb 2024Based on existing evidence of the effects of the most commonly used non-invasive brain stimulation (NIBS), which includes transcranial magnetic stimulation (TMS) and... (Meta-Analysis)
Meta-Analysis Review
Based on existing evidence of the effects of the most commonly used non-invasive brain stimulation (NIBS), which includes transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS), we conducted a meta-analysis to investigate the cognitive improvement and safety of NIBS on schizophrenia-related cognitive impairment. PubMed, EMBASE, Cochrane Library, and Web of Science were searched. The Cochrane Risk of Bias tool was used to assess the risk of bias of the included RCTs; Review Manager, version 5.4.1, was used to perform the statistical analysis. Twenty double-blind, randomized, sham-controlled trials involving 997 patients were included. As a result, no significant improvement in cognitive function was observed after NIBS treatment. However, the overall treatment effect of the two main NIBS modes (i.e., rTMS and tDCS) was associated with significantly larger improvements in negative symptoms and good tolerability in patients with schizophrenia compared to sham-controls (SMD = -0.56, 95% CI [-1.03, -0.08], p = 0.02, I = 88%). NIBS model and stimulus parameters influenced the effect of NIBS. More favorable effects were observed in patients who received rTMS stimulation (SMD = 0.25, 95% CI [0.01, 0.49], p = 0.04, I = 0%) in the left dorsolateral prefrontal cortex with a stimulation intensity of 20 Hz (p = 0.004) for a period longer than 1 month (p < 0.05). Yet, due to the limited number of included studies and heterogeneity in both study design and target population, the results of this analysis need to be interpreted with caution.
Topics: Humans; Transcranial Direct Current Stimulation; Schizophrenia; Transcranial Magnetic Stimulation; Cognition; Cognitive Dysfunction; Brain; Randomized Controlled Trials as Topic
PubMed: 38150769
DOI: 10.1016/j.jpsychires.2023.12.003 -
Neuropsychopharmacology : Official... Mar 2024While pharmacological, behavioral and psychosocial treatments are available for substance use disorders (SUDs), they are not always effective or well-tolerated.... (Meta-Analysis)
Meta-Analysis
While pharmacological, behavioral and psychosocial treatments are available for substance use disorders (SUDs), they are not always effective or well-tolerated. Neuromodulation (NM) methods, including repetitive transcranial magnetic stimulation (rTMS), transcranial direct current stimulation (tDCS) and deep brain stimulation (DBS) may address SUDs by targeting addiction neurocircuitry. We evaluated the efficacy of NM to improve behavioral outcomes in SUDs. A systematic literature search was performed on MEDLINE, PsychINFO, and PubMed databases and a list of search terms for four key concepts (SUD, rTMS, tDCS, DBS) was applied. Ninety-four studies were identified that examined the effects of rTMS, tDCS, and DBS on substance use outcomes (e.g., craving, consumption, and relapse) amongst individuals with SUDs including alcohol, tobacco, cannabis, stimulants, and opioids. Meta-analyses were performed for alcohol and tobacco studies using rTMS and tDCS. We found that rTMS reduced substance use and craving, as indicated by medium to large effect sizes (Hedge's g > 0.5). Results were most encouraging when multiple stimulation sessions were applied, and the left dorsolateral prefrontal cortex (DLPFC) was targeted. tDCS also produced medium effect sizes for drug use and craving, though they were highly variable and less robust than rTMS; right anodal DLPFC stimulation appeared to be most efficacious. DBS studies were typically small, uncontrolled studies, but showed promise in reducing misuse of multiple substances. NM may be promising for the treatment of SUDs. Future studies should determine underlying neural mechanisms of NM, and further evaluate extended treatment durations, accelerated administration protocols and long-term outcomes with biochemical verification of substance use.
Topics: Humans; Transcranial Direct Current Stimulation; Transcranial Magnetic Stimulation; Substance-Related Disorders; Behavior, Addictive; Craving; Prefrontal Cortex
PubMed: 38086901
DOI: 10.1038/s41386-023-01776-0 -
Psychiatry Research Jan 2024Addiction is a substantial health concern; craving-the core symptom of addiction-is strongly associated with relapse. Transcranial direct current stimulation (tDCS) is a... (Meta-Analysis)
Meta-Analysis
Addiction is a substantial health concern; craving-the core symptom of addiction-is strongly associated with relapse. Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that reduces cravings by altering cortical excitability and connectivity in brain regions. This systematic review and meta-analysis was conducted (following the PRISMA guidelines) to evaluate the efficacy of tDCS in reducing cravings for substances. Our analysis included 43 randomized, sham-controlled trials involving 1,095 and 913 participants receiving tDCS and sham stimulation, respectively. We analyzed the changes in craving scores and found that tDCS led to a moderate reduction in cravings compared with the sham effects. This effect was particularly pronounced when bilateral stimulation was used, the anodal electrode was placed on the right dorsolateral prefrontal cortex, current intensities ranged from 1.5 to 2 mA, stimulation sessions lasted 20 minutes, and the electrodes size was ≥35 cm². Notably, tDCS effectively reduced cravings for opioids, methamphetamine, cocaine, and tobacco but not for alcohol or cannabis. Our findings indicate tDCS as a promising, noninvasive, and low-risk intervention for reducing cravings for opioids, methamphetamine, cocaine, and tobacco. Additional studies are warranted to refine stimulation parameters and evaluate the long-term efficacy of tDCS in managing substance cravings.
Topics: Humans; Transcranial Direct Current Stimulation; Craving; Prefrontal Cortex; Substance-Related Disorders; Methamphetamine; Cocaine; Double-Blind Method
PubMed: 38043411
DOI: 10.1016/j.psychres.2023.115621