A pinboard by
Sebastian Quezada

PhD student, Hudson Institute of Medical Research


My research interest is in the developmental human brain, but more specifically in how it folds.

When it is first formed in the uterus, the brain of the fetus starts as a simple structure with a smooth surface (like a marble ball), but as it develops in the second and third trimester, it not only starts growing, but also its cortex starts folding, to finally adopt the wrinkly , convoluted shape we know in the adult brain.

The correct folding pattern is very, very important for the future of the owner of this brain, because if it is not properly folded (i.e. the shape is not right) the person can suffer multiple issues, such as hearing, learning, motor and visual impairment, schizophrenia, epilepsy, mental retardation, cerebral palsy, behavioural issues and many more.

In general terms, the brain is pretty similar to an origami figure: it needs to be properly folded to be completely functional. However, instructions for such folding are not found in the bookstore as for origami. The instructions for the brain to fold are hidden inside the cells, and are part of our genes. However, regrettably, only initial understanding of these genes has been obtained, and also many genes affecting the right folding pattern remain unknown.

So, it is very important to understand and keep studying and discovering these important genes, so in the future we can keep our babies and children from suffering the consequences of a misfolded brain origami.


Gyrification brain abnormalities as predictors of outcome in anorexia nervosa.

Abstract: Gyrification brain abnormalities are considered a marker of early deviations from normal developmental trajectories and a putative predictor of poor outcome in psychiatric disorders. The aim of this study was to explore cortical folding morphology in patients with anorexia nervosa (AN). A MRI brain study was conducted on 38 patients with AN, 20 fully recovered patients, and 38 healthy women. Local gyrification was measured with procedures implemented in FreeSurfer. Vertex-wise comparisons were carried out to compare: (1) AN patients and healthy women; (2) patients with a full remission at a 3-year longitudinal follow-up assessment and patients who did not recover. AN patients exhibited significantly lower gyrification when compared with healthy controls. Patients with a poor 3-year outcome had significantly lower baseline gyrification when compared to both healthy women and patients with full recovery at follow-up, even after controlling for the effects of duration of illness and gray matter volume. No significant correlation has been found between gyrification, body mass index, amount of weight loss, onset age, and duration of illness. Brain gyrification significantly predicted outcome at follow-up even after controlling for the effects of duration of illness and other clinical prognostic factors. Although the role of starvation in determining our findings cannot be excluded, our study showed that brain gyrification might be a predictor of outcome in AN. Further studies are needed to understand if brain gyrification abnormalities are indices of early neurodevelopmental alterations, the consequence of starvation, or the interaction between both factors.

Pub.: 17 Sep '15, Pinned: 28 Jul '17

Sex differences in cortical volume and gyrification in autism.

Abstract: Male predominance is a prominent feature of autism spectrum disorders (ASD), with a reported male to female ratio of 4:1. Because of the overwhelming focus on males, little is known about the neuroanatomical basis of sex differences in ASD. Investigations of sex differences with adequate sample sizes are critical for improving our understanding of the biological mechanisms underlying ASD in females.We leveraged the open-access autism brain imaging data exchange (ABIDE) dataset to obtain structural brain imaging data from 53 females with ASD, who were matched with equivalent samples of males with ASD, and their typically developing (TD) male and female peers. Brain images were processed with FreeSurfer to assess three key features of local cortical morphometry: volume, thickness, and gyrification. A whole-brain approach was used to identify significant effects of sex, diagnosis, and sex-by-diagnosis interaction, using a stringent threshold of p < 0.01 to control for false positives. Stability and power analyses were conducted to guide future research on sex differences in ASD.We detected a main effect of sex in the bilateral superior temporal cortex, driven by greater cortical volume in females compared to males in both the ASD and TD groups. Sex-by-diagnosis interaction was detected in the gyrification of the ventromedial/orbitofrontal prefrontal cortex (vmPFC/OFC). Post-hoc analyses revealed that sex-by-diagnosis interaction was driven by reduced vmPFC/OFC gyrification in males with ASD, compared to females with ASD as well as TD males and females. Finally, stability analyses demonstrated a dramatic drop in the likelihood of observing significant clusters as the sample size decreased, suggesting that previous studies have been largely underpowered. For instance, with a sample of 30 females with ASD (total n = 120), a significant sex-by-diagnosis interaction was only detected in 50 % of the simulated subsamples.Our results demonstrate that some features of typical sex differences are preserved in the brain of individuals with ASD, while others are not. Sex differences in ASD are associated with cortical regions involved in language and social function, two domains of deficits in the disorder. Stability analyses provide novel quantitative insights into why smaller samples may have previously failed to detect sex differences.

Pub.: 07 Jul '15, Pinned: 28 Jul '17

Cerebral cortical gyrification: a preliminary investigation in temporal lobe epilepsy.

Abstract: To introduce a measure of global cortical folding in epilepsy by using stereology. Subtle developmental abnormalities associated with temporal lobe epilepsy may encompass brain morphologic changes such as an aberrant degree of cortical folding.Stereologic methods of volume and surface-area estimation were applied to in vivo MR brain-image data of a cohort of 20 temporal lobe epilepsy (TLE) patients (10 men, 10 women), and 20 neurologically normal controls (10 men, 10 women). Indices of cerebral gyrification and cerebral atrophy were generated. The impact of side of seizure onset, age at onset, history of febrile seizures, presence or absence of lesions, and presence or absence of secondarily generalized seizures on cerebral gyrification was assessed.Although no significant group mean difference was found in the degree of cerebral gyrification between patients and controls, five of 10 of male patients had an abnormal gyrification when compared with male controls. One female patient had a significant change in gyrification compared with female controls. In general, patients with TLE demonstrated a significant degree of global cerebral atrophy compared with controls. Clinical factors were not demonstrated to affect significantly any of the quantitative parameters.The results of this study suggest that an aberrant degree of global cerebral gyrification may occur in certain clinical groups of TLE patients. These findings have implications for general theories of developmental susceptibility in TLE.

Pub.: 14 Feb '07, Pinned: 28 Jul '17