The subcortical brain regions influence the cortical areas during resting-state: an fMRI study

IntroductionNumerous modes or patterns of neural activity can be seen in the brain of individuals during the resting state. However, those functions do not persist long, and they are continuously altering in the brain. We have hypothesized that the brain activations during the resting state should themselves be responsible for this alteration of the activities.MethodsUsing the resting-state fMRI data of 63 healthy young individuals, we estimated the causality effects of each resting-state activation map on all other networks. The resting-state networks were identified, their causality effects on the other components were extracted, the networks with the top 20% of the causality were chosen, and the networks which were under the influence of those causal networks were also identified.ResultsOur results showed that the influence of each activation component over other components is different. The brain areas which showed the highest causality coefficients were subcortical regions, such as the brain stem, thalamus, and amygdala. On the other hand, nearly all the areas which were mostly under the causal effects were cortical regions.DiscussionIn summary, our results suggest that subcortical brain areas exert a higher influence on cortical regions during the resting state, which could help in a better understanding the dynamic nature of brain functions

The neural basis of Number and Person phi-features processing: An fMRI study in highly proficient bilinguals

No studies have investigated the neural correlates of Number and Person agreement processing in bilinguals. Because a previous fMRI study showed difference in L1 and L2 morphosyntactic processing of L1 Turkish–L2 Persian bilinguals, it was of interest whether this difference can be specifically attributed to Number or Person processing. Therefore, we reanalyzed these data at the whole-brain level, revealing a selective response for Number Violations in the pars opercularis (PO), whereas Number and Person Violations activated the posterior superior temporal gyrus (pSTG). These results support the decomposition of agreement projections and their neuroanatomical substrates in bilinguals and confirm the involvement of systematically different feature-checking and feature-mapping mechanisms in Number and Person agreement but shared mechanisms between L1 and L2. Moreover, at variance with previous reports, Number Violations evoked more effects than Person Violations in pSTG, suggesting qualitatively different processing underlying R-expression and pronominal controllers.Peer Reviewe

The Rey Auditory Verbal Learning Test: Age-, Gender- and Education-Related Normative Data for The Iranian Healthy Population

Purpose: Memory and learning have particular importance due to their ubiquitous nature in everyday life and the high prevalence of related complaints. The present study aimed to provide normative data for one of the most widely used tests of verbal memory and learning in Iran and to assess the effect of demographic variables of age, gender, and education on its various measures. Materials and Methods: The study was conducted as part of the Iranian Brain Imaging Database (IBID) project. The sample consisted of 300 normal individuals in the age range of 20 to 70 years, with an equal number of participants in each age decade (#60). The sample was classified by five decades, including 20-30-year-olds, 31-40-year-olds, 41-50-year-olds, 51-60-year-olds, and 61-70-year-olds. Each age decade was divided equally between the genders. The Rey Auditory Verbal Learning Test (RAVLT), which was defined in terms of 10 scores on learning, recall, and recognition, was used to assess verbal learning and memory. Results: The correlation matrix among the variables shows that all three variables of age, gender, and education had a significant correlation with most RAVLT measures. Among the three demographic variables, age had the strongest correlation with most RAVLT scores. Three-way Analysis of Variance (ANOVA) showed that the effect of age and gender on memory and learning measures was significant. On the other hand, the effect of education on some measures was statistically significant. In addition, the mean and standard deviation of 10 RAVLT measures classified by gender and education years in the five age groups are provided. Conclusion: The findings show that while increasing age, verbal memory, and learning performance decline, women outperform men, and education affects some indicators of learning and memory. These findings emphasize the importance of using age-, gender- and education-related normative data in clinical, educational, and research settings

How do cannabis users mentally travel in time? Evidence from an fMRI study of episodic future thinking

Rationale Episodic future thinking (EFT) is a cognitive function that allows individuals to imagine novel experiences that may happen in the future. Prior studies show that EFT is impaired in different groups of substance users. However, there is no evidence regarding the neurobiological mechanisms of EFT in cannabis users. Objectives We aimed to compare brain activations of regular cannabis users and non-using controls during an EFT fMRI task. Exploratory analyses were also conducted to investigate the association between EFT and cannabis use variables (e.g., duration of use, age onset, frequency of use). Methods Twenty current cannabis users and 22 drug-naïve controls underwent an fMRI scanning session while completing a task involving envisioning future-related events and retrieval of past memories as a control condition. The EFT fMRI task was adapted from the autobiographical interview and composed of 20 auditory cue sentences (10 cues for past and 10 cues for future events). Participants were asked to recall a past or generate a future event, in response to the cues, and then rate their vividness after each response. Results We found that cannabis users compared to non-user controls had lower activation within the cerebellum, medial and superior temporal gyrus, lateral occipital cortex, and occipital fusiform gyrus while envisioning future events. Cannabis users rated the vividness of past events significantly lower than non-users (P < 0.005). There were marginal group differences for rating the vividness of future events (P = 0.052). Significant correlations were also found between the medial and superior temporal gyrus activities and behavioral measures of EFT and episodic memory. Conclusions Cannabis users, compared to drug-naïve controls, have lower brain activation in EFT relevant regions. Thus, any attempts to improve aberrant EFT performance in cannabis users may benefit from EFT training

Iron quantification in basal ganglia using quantitative susceptibility mapping in a patient with ALS: a case report and literature review

BackgroundQuantitative susceptibility mapping (QSM) is a magnetic resonance imaging (MRI) technique that can measure the magnetic susceptibility of tissues, which can reflect their iron content. QSM has been used to detect iron accumulation in cortical and subcortical brain regions. However, its application in subcortical regions such as the basal ganglia, particularly the putamen, is rare in patients with amyotrophic lateral sclerosis (ALS).Case presentation and literature reviewWe present the case of a 40-year-old male patient with ALS who underwent an MRI for QSM. We compared his QSM images with those of a control subject and performed a quantitative analysis of the magnetic susceptibility values in the putamen regions. We also reviewed the literature on previous QSM studies in ALS and summarized their methods and findings. Our QSM analysis revealed increased magnetic susceptibility values in the bilateral putamen of the ALS patient compared to controls, indicating iron overload. This finding is consistent with previous studies reporting iron dysregulation in subcortical nuclei in ALS. We also discussed the QSM processing techniques used in our study and in the literature, highlighting their advantages and limitations.ConclusionThis case report demonstrates the potential of QSM as a sensitive MRI biomarker for evaluating iron levels in subcortical regions of ALS patients. QSM can provide quantitative information on iron deposition patterns in both motor and extra-motor areas of ALS patients, which may help understand the pathophysiology of ALS and monitor disease progression. Further studies with larger samples are needed to validate these results and explore the clinical implications of QSM in ALS

A Different Olfactory Perception in Anosmic Patients: Evidence from Functional MRI

Olfactory system is a vital sensory system in mammals, giving them the ability to connect with their environment. Anosmia, or the complete loss of olfaction ability, which could be caused by injuries, is an interesting topic for inspectors with the aim of diagnosing patients. Sniffing test is currently utilized to examine if an individual is suffering from anosmia; however, functional Magnetic Resonance Imaging (fMRI) provides unique information about the structure and function of the different areas of the human brain, and therefore this noninvasive method could be used as a tool to locate the olfactory-related regions of the brain. In this study, by recruiting 31 healthy and anosmic individuals, we investigated the neural BOLD responses in the olfactory cortices following two odor stimuli, rose and eucalyptus, by using a 3T MR scanner. Comparing the two groups, we observed a network of brain areas being more active in the normal individuals when smelling the odors. In addition, a number of brain areas also showed an activation decline during the odor stimuli, which is hypothesized as a resource allocation deactivation. This study illustrated alterations in the brain activity between the normal individuals and anosmic patients when smelling odors, and could potentially help for a better anosmia diagnosis in the future

Iranian Brain Imaging Database: A Neuropsychiatric Database of Healthy Brain

Introduction: The Iranian Brain Imaging Database (IBID) was initiated in 2017, with 5 major goals: provide researchers easy access to a neuroimaging database, provide normative quantitative measures of the brain for clinical research purposes, study the aging profile of the brain, examine the association of brain structure and function, and join the ENIGMA consortium. Many prestigious databases with similar goals are available. However, they were not done on an Iranian population, and the battery of their tests (e.g. cognitive tests) is selected based on their specific questions and needs. Methods: The IBID will include 300 participants (50% female) in the age range of 20 to 70 years old, with an equal number of participants (#60) in each age decade. It comprises a battery of cognitive, lifestyle, medical, and mental health tests, in addition to several Magnetic Resonance Imaging (MRI) protocols. Each participant completes the assessments on two referral days. Results: The study currently has a cross-sectional design, but longitudinal assessments are considered for the future phases of the study. Here, details of the methodology and the initial results of assessing the first 152 participants of the study are provided. Conclusion: IBID is established to enable research into human brain function, to aid clinicians in disease diagnosis research, and also to unite the Iranian researchers with interests in the brain

Larger Volume and Different Activation of the Brain in Response to Threat in Military Officers

Introduction: Military missions involve stressful and life-threatening situations; however, soldiers should have a healthy cognition on the battlefield despite their high-stress levels. This is an ability that should be gained during prior military training. Successful and influential training is suggested to be associated with structural and functional improvements of the brain. Methods: This study investigated the pattern of brain activation while observing videos relevant to life-threatening situations, in addition to brain structure. Accordingly, the obtained data were compared between 20 military members and 26 healthy controls. The study participants were all male, aged between 19 to 24 years, right-handed, studying BSc, and from the same socioeconomic status. Results: The obtained data presented a larger volume in a total number of 1103 voxels of the brain (in 5 brain areas) in the military group. Furthermore, the military group suggested higher brain activation in the visual processing areas of the brain when observing real combat videos; however, this increment was mostly in the areas associated with motor processing and executive functions in the controls. Conclusion: This study indicated that military training is associated with positive structural changes in the brain. Besides, it provided a different brain activation in response to stressful situations. These findings highlighted the importance of qualified military training

Genetic and environmental influences on brain structure and biochemistry in the elderly: data from the &#8206;older Australian twins study

This thesis examines the relative influence of genetic and environmental factors on brain structure and &#8206;biochemistry in late life. Human life expectancy has been extended in recent decades. However, maintaining &#8206;physical and mental health in the elderly is a substantial public health challenge. Healthy brain functioning is one &#8206;of the major criteria for healthy ageing, and several features have correlations with this, including brain volume, &#8206;brain white matter hyperintensity (WMH) and brain metabolites. Both brain development and age-related &#8206;changes are under the influence of genetic and environmental factors, and twin studies provide a robust natural &#8206;experiment within which relative estimates of these influences can be made.&#8206;The participants in this work were from the Older Australian Twins Study (OATS), a large study of elderly &#8206;twins, with a mean age of 72.1 years. Using data from OATS, the influences of genetic and environmental factors &#8206;on human brain volume, WMH volume and metabolites concentration in the elderly were estimated. For this, &#8206;structural equation modeling was performed to compare MRI data from identical (monozygotic) and fraternal &#8206;&#8206;(Dizygotic) twins, in Mx GUI program. Later, the influences of age and sex on the heritability of the above &#8206;phenotypes, along with the &#8206;existence of common genetic factors between them were examined.&#8206;Estimations showed significant heritability of the brain volume, WMH volume and brain biochemistry in the &#8206;elderly. Brain volume heritability decreased with age, but WMH volume heritability increased. No significant sex &#8206;difference was observed in the heritability of brain metabolites and WMH volumes, whereas heritability of brain &#8206;volume was higher in male. Also, common genetic factors were observed between the volumes and WMHs of &#8206;different brain regions and also between the brain metabolites.&#8206;The results of this thesis showed that the human brain is largely under the influence of genetic factors in late life, &#8206;but that this influence may diminish with age, particularly in brain volume. Also, sex was observed as a factor &#8206;moderating the influence of genes on the brain. Given the diminishing influence of genetic factors with age, this &#8206;thesis suggests that healthy ageing may be optimized by enrichment of environmental conditions.&#8206

The Digit Span Test: Normative Data for the Iranian Normal Population

Background: The digit span test (DST) is one of the most widely used neuropsychological tools to measure two neurocognitive functions of working memory and attention. Objectives: This study aimed to collect Iranian normative data on DST and examine the association between three demographic variables and performance in DST. Materials & Methods: As part of the Iranian brain imaging database (IBID) project, the present study was conducted in 2017-2018 on three hundred normal people aged 20 to 70. They were recruited using convenience sampling in Tehran City, Iran. Each decade consisted of 60 participants, and the gender proportion was equal. Five decades of age, gender and education were the independent variables. The dependent variables were DST scores (the longest digit sequence and total digit span). Results: Age and education had a significant negative and positive correlation with both subtests (P=0.01), respectively; however, no significant correlation was observed between gender and DST scores (P>0.05). According to multivariate analysis of variance, the interaction of age, gender and education did not lead to a significant difference in the DST scores (P=0.309). In addition, The Tukey post hoc test showed that participants under 40 had significantly higher DST scores than older participants (P<0.05).  Conclusion: The demographic variables have a significant association with the working memory and attention performance of the normal Iranian population, and it is necessary to interpret DST scores using regional normative data