Amirhossein Manzouri

• Master of Engineering
• Research Engineer at Karolinska Institutet

There is limited convergence in neuroimaging investigations into volumes of subcortical brain regions in social anxiety disorder (SAD). The inconsistent findings may arise from variations in methodological approaches across studies, including sample selection based on age and clinical characteristics. The ENIGMA-Anxiety Working Group initiated a gl...

Skill learning induces changes in estimates of gray matter volume (GMV) in the human brain, commonly detectable with magnetic resonance imaging (MRI). Rapid changes in GMV estimates while executing tasks may however confound between-and within-subject differences. Fluctuations in arterial blood f low are proposed to underlie this apparent task-rela...

The objective of this study is to introduce a new quantitative data-driven analysis (QDA) framework for the analysis of resting-state fMRI (R-fMRI) and use it to investigate the effect of adult age on resting-state functional connectivity (RFC). Whole-brain R-fMRI measurements were conducted on a 3T clinical MRI scanner in 227 healthy adult volunte...

BACKGROUND: Biomarkers of psychiatric treatment response remain elusive. Functional magnetic resonance imaging (fMRI) has shown promise, but low reliability has limited the utility of typical fMRI measures (e.g., average brain signal) as harbingers of treatment success. Notably, although historically considered a source of “noise,” temporal brain s...

To investigate the impact of adult age on the brain functional connectivity, whole-brain resting-state functional magnetic resonance imaging (R-fMRI) data were acquired on a 3T clinical MRI scanner in a cohort of 227, right-handed, native Swedish-speaking, healthy adult volunteers (N=227, aged 18-74 years old, male/female=99/128). The dataset is ma...

Biomarkers of psychiatric treatment response remain elusive. Functional magnetic resonance imaging (fMRI) has shown promise, but low reliability has limited the utility of typical fMRI measures as harbingers of treatment success. Strikingly, temporal variability in brain signals has already proven a sensitive and reliable indicator of individual di...

Purpose The objective of this study is to introduce a new quantitative data-driven analysis (QDA) framework for the analysis of resting-state fMRI (R-fMRI) and use it to investigate the effect of adult age on resting-state functional connectivity (RFC). Methods Whole-brain R-fMRI measurements were conducted on a 3T clinical MRI scanner in 227 heal...

Purpose: The objective of this study is to introduce a new quantitative data-driven analysis (QDA) framework for the analysis of resting-state fMRI (R-fMRI) and use it to investigate the effect of adult age on resting-state functional connectivity (RFC). Methods Whole-brain R-fMRI measurements were conducted on a 3T clinical MRI scanner in 227 hea...

Referrals for gender dysphoria (GD), characterized by a distressful incongruence between gender identity and at-birth assigned sex, are steadily increasing. The underlying neurobiology, and the mechanisms of the often-beneficial cross-sex hormone treatment are unknown. Here, we test hypothesis that own body perception networks (incorporated in the...

Individuals with gender incongruence (GI) experience serious distress due to incongruence between their gender identity and birth-assigned sex. Sociological, cultural, interpersonal, and biological factors are likely contributory, and for some individuals medical treatment such as cross-sex hormone therapy and gender-affirming surgery can be helpfu...

Individuals with gender dysphoria experience life-threatening distress due to incongruence between their gender identity and birth-assigned sex. Hormone therapy can be effective for reducing body incongruence, but responses vary, and there is no reliable way to predict therapeutic outcomes. We use clinical and MRI data before cross-sex hormone ther...

Gender identity is a core aspect of self-identity and is usually congruent with birth-assigned sex and own body sex-perception. The neuronal circuits underlying gender identity are unknown, but greater awareness of transgenderism has sparked interest in studying these circuits. We did this by comparing brain activation and connectivity in transgend...

Measuring brain morphology with non-invasive structural magnetic resonance imaging is common practice, and can be used to investigate neuroplasticity. Brain morphology changes have been reported over the course of weeks, days, and hours in both animals and humans. If such short-term changes occur even faster, rapid morphological changes while being...

The neuropeptide oxytocin plays a prominentrole in social and emotional cognition. Findings suggest thatexogenous intranasal oxytocin administrationfacilitatesemotion recognitionin humans,butindividual and contextual differences mayhave moderating effects.A major caveat in this line of work is that it is predominantly based on young males, which li...

Transgender persons experience incongruence between their gender identity and birth‐assigned sex. The resulting gender dysphoria (GD), is frequently treated with cross‐sex hormones. However, very little is known about how this treatment affects the brain of individuals with GD,nor do we know the neurobiology of GD. We recently suggested that discon...

Own body perception, and differentiating and comparing one's body to another person's body, are common cognitive functions that have relevance for self‐identity and social interactions. In several psychiatric conditions, including anorexia nervosa, body dysmorphic disorder, gender dysphoria, and autism spectrum disorder, self and own body perceptio...

The neurobiology of sexual preference is often discussed in terms of cerebral sex dimorphism. Yet, our knowledge about possible cerebral differences between homosexual men (HoM), heterosexual men (HeM) and heterosexual women (HeW) are extremely limited. In the present MRI study, we addressed this issue investigating measures of cerebral anatomy and...

Group differences in cortico-cortical covariations of Cth from the precuneus ROI. The scale is is logarithmic and shows log10(P); Warm colors indicate positive contrast and thus greater covariation in HoM than controls (HeM and HeW). Clusters calculated at p < .05 after Monte Carlo correction are superimposed on a standard MRI brain (TIF)

Hormone levels in HoM (n = 30). (DOCX)

Correlation between Kinsey scores and cortical thickness. Sagittal view of the standard brain MRI (atlas retrieved from the FreeSurfer program’s pipeline), showing regions in which Kinsey scores were significantly correlated with Cth. Scale is logarithmic and shows–log10(P), with warm colors positive correlations (thicker cortex, higher Kinsey scor...

Scores in a test of social functions. (DOCX)

Brain morphology change over the course of weeks, days, and hours, and can be detected by non-invasive structural magnetic resonance imaging. Rapid morphological changes at scanning has yet not been investigated. In a randomized within-group study, high-resolution anatomical images were acquired during passive viewing of pictures or a fixation cros...

Although frequently discussed in terms of sex dimorphism, the neurobiology of sexual orientation and identity is unknown. We report multimodal magnetic resonance imaging data, including cortical thickness (Cth), subcortical volumes, and resting state functional magnetic resonance imaging, from 27 transgender women (TrW), 40 transgender men (TrM), a...

Findings suggest that intranasal administration of oxytocin improves emotion recognition. The brain mechanisms underlying these effects, however, are underexplored. A major caveat in this line of work is that it is almost exclusively based on young males, which limits current knowledge and potential for generalizability across gender and age. Adopt...

Findings suggest that intranasal administration of oxytocin improves emotion recognition. The brain mechanisms underlying these effects, however, are underexplored. A major caveat in this line of work is that it is almost exclusively based on young males, which limits current knowledge and potential for generalizability across gender and age. Adopt...

Both transgenderism and homosexuality are facets of human biology, believed to derive from different sexual differentiation of the brain. The two phenomena are, however, fundamentally unalike, despite an increased prevalence of homosexuality among transgender populations. Transgenderism is associated with strong feelings of incongruence between one...

The neurobiology of sexual orientation is frequently discussed in terms of cerebral sex dimorphism (defining both functional and structural sex differences). Yet, the information about possible cerebral differences between sex-matched homo and heterosexual persons is limited, particularly among women. In this multimodal MRI study, we addressed thes...

Transgender individuals experience incongruence between their gender identity and birth-assigned sex. The resulting gender dysphoria (GD), which some gender-incongruent individuals experience, is theorized to be a consequence of atypical cerebral sexual differentiation, but support for this assertion is inconsistent. We recently found that GD is as...

Methods: FreeSurfer software was employed to measure cortical thickness and subcortical structural volumes. Axonal connections, indexed by fractional anisotropy, (FA) were measured with diffusion tensor imaging, and functional connectivity with resting state fMRI. Results: Compared to men, CAIS women displayed a "female" pattern by having thicke...

Gender dysphoria (GD) is characterized by incongruence between onés gender assigned at birth and the gender that one identifies with. The biological mechanisms of GD are unclear, especially in female-to-male transsexuals (FtM-TR). Here, we investigate whether distinct structural and functional patterns along cerebral midline networks processing own...

MRI diffusion tensor imaging (DTI) studies of white matter integrity in behavioral variant frontotemporal dementia have consistently shown involvement of frontal and temporal white matter, corresponding to regional loss of cortical volume. Volumetric imaging has a suboptimal sensitivity as a diagnostic tool and thus we wanted to explore if DTI is a...

White matter changes (WMC) are the focus of intensive research and have been linked to cognitive impairment and depression in the elderly. Cumbersome manual outlining procedures make research on WMC labor intensive and prone to subjective bias. We present a fast, fully automated method for WMC segmentation using a cascade of reduced support vector...

Background and purpose: Volumetric measurements on structural MR images are an established method to investigate pathology-related volume changes in cortex. Manual volumetric methods have sometimes been referred to as the reference standard for quality control of automatic volumetric methods. While some automatic methods, like VBM, may rely on a t...