Background  Interthalamic adhesion (ITA) or massa intermedia is a midline rod-like neural structure interconnecting the medial surfaces of two thalami. Its absence is considered as a midline defect associated with schizophrenia spectrum disorder. The present study aimed to determine the prevalence, location, and dimensions of the ITA in South Asian brains. Materials and Methods  One hundred midsagittal sections of adult cadaveric brains were examined for the presence or absence of ITAs, their location about the lateral wall of the third ventricle, and their dimensions. Results  ITA was found in 86 sections. In two cases, it was double. There was no significant relationship between the incidence of ITAs and sex ( p  > 0.05). The ITA was most commonly located in the anterosuperior quadrant. The horizontal diameter was 4.61 ± 1.17 mm, and the vertical diameter was 3.10 ± 0.78 mm. In all cases, the horizontal diameter was longer than the vertical. The average area of the ITA was significantly larger in females (17.56 ± 5.26 mm 2 ) than in males (13.62 ± 5.22 mm 2 ) ( p  = 0.025). Conclusion  Presence of ITA is common in South Asian brains, with usual location in the anterosuperior quadrant of the lateral wall of the third ventricle. The cross-sectional area of the ITA was significantly larger in females than in males. No correlation was found between the surface area of the ITA and the length of the third ventricle.

OBJECTIVE: Few studies have explored the morphology of massa intermedia (MI). The aim of the present study was to characterize it using magnetic resonance imaging (MRI).
METHODS: A total of 205 patients were enrolled in this study. Following initial examinations with conventional MRI sequences, thin-slice coronal and sagittal T2-weighted imaging was performed. For MI localization, the third ventricle was arbitrarily divided into nine areas on the midsagittal image.
RESULTS: MI was identified in 93% of the total patients-89% in male and 91% in female patients. Among them, 68% showed a single, styloid-shaped MI with variable thickness and cross sectional configuration, followed by broad and double MIs that were found in 18% and 10% patients, respectively. In the anteroposterior dimension, 99% of the MIs were identified in the middle third area, followed by the posterior third area. In the supero-inferior dimension, 95% of the MIs were identified in the middle third area, followed by the upper third area. With a significant difference, a broad MI was more frequently found in women than in men.
CONCLUSIONS: MIs are commonly located in the middle third of the third ventricle as a single commissure with high morphological variability. Compared to men, women may have a well-developed, broader MI.

With the explosion of neuroimaging, differences between male and female brains have been exhaustively analyzed. Here we synthesize three decades of human MRI and postmortem data, emphasizing meta-analyses and other large studies, which collectively reveal few reliable sex/gender differences and a history of unreplicated claims. Males\' brains are larger than females\' from birth, stabilizing around 11 % in adults. This size difference accounts for other reproducible findings: higher white/gray matter ratio, intra- versus interhemispheric connectivity, and regional cortical and subcortical volumes in males. But when structural and lateralization differences are present independent of size, sex/gender explains only about 1% of total variance. Connectome differences and multivariate sex/gender prediction are largely based on brain size, and perform poorly across diverse populations. Task-based fMRI has especially failed to find reproducible activation differences between men and women in verbal, spatial or emotion processing due to high rates of false discovery. Overall, male/female brain differences appear trivial and population-specific. The human brain is not \"sexually dimorphic.\"

The role of massa intermedia (MI) is poorly understood in humans. Recent studies suggest its presence may play a role in normal human neurocognitive function while prior studies have shown the absence of MI correlated with psychiatric disorders. There is growing evidence that MI is likely a midline white matter conduit, responsible for interhemispheric connectivity, similar to other midline commissures. MI presence was identified in an unrelated sample using the Human Connectome Project database. MI structural connectivity maps were created and gray matter target regions were identified using probabilistic tractography of the whole brain. Probabilistic tractography revealed an extensive network of connections between MI and limbic, frontal and temporal lobes as well as insula and pericalcarine cortices. Women compared to men had stronger connectivity via their MI. The presented results support the role of MI as a midline commissure with strong connectivity to the amygdala, hippocampus, and entorhinal cortex.

Massa intermedia (MI), also known as interthalamic adhesion is an inconsistent bridge connecting the two thalami. Recent studies suggest MI contains functional neuronal tissue and is responsible for interhemispheric communication. Absence of MI has been linked to cognitive differences and psychiatric disorders. However, MI is naturally absent in up to 35 percent of cases but its true prevalence during life in humans is unknown. High resolution anatomical MR studies of 1410 subjects aged 2 months to 93 years were reviewed and those with MI were identified. Prevalence and characteristics of MI were identified and grouped by gender and decade of life. MI was present in 87.3% of the studied subjects. Absence of MI was noted in as early as first decade of life as well as all decades of life, but its absence increased with age, suggesting additional factors during life as mediators. Females had 2.75 times higher likelihood of MI presence than males. Size of MI decreased with increasing age up to age 70. Size of MI was best predicted by third ventricular width and age mediating a larger MI with smaller third ventricular size and younger age. MI is present in 87.3% of the population as determined in this MRI study. Absence of MI is identifiable in very early years of life, suggesting a congenital cause. MI\'s prevalence, however, was also found to decrease with advancing age, suggesting a dynamic process of MI disappearance during life.

Massa intermedia (MI) is an inconsistent midline structure in the human brain that is absent in approximately 30% of the population. Absence of MI is seen more frequently in schizophrenia spectrum disorder and bipolar disorder. However, very little is known about the normal role of MI in the human brain. The purpose of this study was to investigate the role of human MI in cortical and subcortical cognitive processing as determined by differences between subjects with and without MI. Using the Human Connectome Project database, a cohort of randomly selected participants were selected to (1) identify presence, absence, and size of MI, and (2) explore possible cognitive process mediated by the presence of MI. Four hundred and two brains were included (216 females) in the final analysis. Four independent blind raters identified 360 brains with MI (202 females) and 42 without MI using anatomical T1-weighted MR scans. Presence of MI was significantly more prevalent in female participant (p = 0.005) and they had significantly larger size of MI (p = 0.001 and 0.000 for anteroposterior and craniocaudal dimensions, respectively). There were no statistically significant differences in the presence of MI with regards to age, race and ethnicity. Further analysis revealed gender, flanker test, and loneliness as predictor of the presence of MI in a Firth logistic regression model (p = 0.0004). This is the largest study of human MI to date. MI may contribute to interhemispheric cortical and subcortical connectivity with resulting subtle neuropsychological differences among individuals with a present versus absent MI.

BACKGROUND: Terminal deletion of chromosome 6q is a rare chromosomal abnormality associated with intellectual disabilities and various structural brain abnormalities. We present a case of 6q terminal deletion syndrome with unusual magnetic resonance imaging (MRI) findings in a neonate.
METHODS: The neonate, who was prenatally diagnosed with dilation of both lateral ventricles, was born at 38 weeks of gestation. MRI demonstrated abnormal membranous structure continuing to the hypertrophic massa intermedia in the third ventricle that had obscured the cerebrospinal fluid pathway, causing hydrocephalus. G-band analysis revealed a terminal deletion of 6q with the karyotype 46, XY, add(6)(q25.3) or del(6)(q26). He underwent ventriculoperitoneal shunt successfully, and his head circumference has been stable.
CONCLUSIONS: 6q terminal deletion impacts the molecular pathway, which is an essential intracellular signaling cascade inducing neurological proliferation, migration, and differentiation during neuronal development. In patients with hydrocephalus in association with hypertrophy of the massa intermedia, this chromosomal abnormality should be taken into consideration. This case may offer an insight into the pathogenesis of hydrocephalus in this rare chromosomal abnormality.