Evolution of cortical neurons supporting human cognition

Human cognitive abilities are generally thought to arise from cortical expansion over the course of human brain evolution. In addition to increased neuron numbers, this cortical expansion might be driven by adaptations in the properties of single neurons and their local circuits. We review recent findings on the distinct structural, functional, and transcriptomic features of human cortical neurons and their organization in cortical microstructure. We focus on the supragranular cortical layers, which showed the most prominent expansion during human brain evolution, and the properties of their principal cells: pyramidal neurons. We argue that the evolutionary adaptations in neuronal features that accompany the expansion of the human cortex partially underlie interindividual variability in human cognitive abilities.

Verbal and General IQ Associate with Supragranular Layer Thickness and Cell Properties of the Left Temporal Cortex

The left temporal lobe is an integral part of the language system and its cortical structure and function associate with general intelligence. However, whether cortical laminar architecture and cellular properties of this brain area relate to verbal intelligence is unknown. Here, we addressed this using histological analysis and cellular recordings of neurosurgically resected temporal cortex in combination with presurgical IQ scores. We find that subjects with higher general and verbal IQ scores have thicker left (but not right) temporal cortex (Brodmann area 21, BA21). The increased thickness is due to the selective increase in layers 2 and 3 thickness, accompanied by lower neuron densities, and larger dendrites and cell body size of pyramidal neurons in these layers. Furthermore, these neurons sustain faster action potential kinetics, which improves information processing. Our results indicate that verbal mental ability associates with selective adaptations of supragranular layers and their cellular micro-architecture and function in left, but not right temporal cortex.

P–772 Blastocyst quality and perinatal outcomes in women undergoing single blastocyst transfer in frozen cycles

Study question

Is the morphological grading systems of a blastocyst associated with perinatal outcomes in women undergoing frozen-thawed single blastocyst transfer (SBT)?

Summary answer

Preferential transfer of a blastocyst based on their morphological grading systems appears to be supported by observed differences in perinatal outcomes.

What is known already

The transfer of a morphologically good quality blastocyst is associated with higher implantation and pregnancy rates as compared with a poor quality blastocyst. However to date, the association of the morphologic parameters of the blastocyst (developmental stage, inner cell mass (ICM), and trophectoderm (TE)) with the perinatal outcomes after blastocyst transfer remains unknown.

Study design, size, duration

A retrospective cohort study including 21,648 frozen-thawed SBT cycles from January 2013 to March 2019.

Participants/materials, setting, methods

6037 women with singleton delivery in Peking University Third Hospital were eligible for analysis. Multivariate logistic regression was used to test the risk of factors with the expression of crude odds ratios (OR) and adjusted OR (aOR) with 95% confidence intervals (CI).

Main results and the role of chance

Transfer of a blastocyst with grading lower than 3BB was associated with a higher chance of female baby (49% vs 43%, aOR = 1.27 (1.12, 1.43)) and a higher rate of cesarian section (C-section) (69% vs 65%, aOR = 1.17 (1.03, 1.34)). Compared with stage 4 blastocyst, transfer of a stage 3 blastocyst was associated with a higher chance of preterm delivery (PTD) (aOR = 1.77 (1.08, 2.90)). Both stage 3 and stage 6 blastocyst transfer was associated with a lower chance of female baby (aOR = 0.68 (0.48, 0.97), 0.66 (0.47, 0.93), respectively). Compared with grade A ICM blastocyst transfer, Grade B ICM and grade C ICM blastocyst transfer was associated with a lower chance of a female baby (adjusted OR = 0.84 (0.73, 0.96), 0.63 (0.48, 0.83), respectively) and a higher risk of large for gestational age (LGA) (aOR = 1.20 (1.01, 1.42), 1.46 (1.07, 1.98), respectively). Grade C ICM blastocyst transfer was associated with an increased risk of macrosomia (aOR = 1.66 (1.14, 2.42)).Grade B TE and grade C TE blastocyst transfer had a lower risk of gestational diabetes mellitus (GDM) (aOR = 0.76 (0.60, 0.98), 0.69 (0.50, 0.94), respectively) than grade A TE blastocyst transfer.

Limitations, reasons for caution

The main limitations of this study were its retrospective nature and the relative subjectivity of blastocyst scoring. The follow-up was conducted through a phone call and some patients might not report their obstetrical and neonatal outcomes, leading to a relatively lower rate of several obstetrical outcomes.

Wider implications of the findings: Transfer of a poor quality blastocyst is associated with a higher rate of C-section. The association between ICM grading and LGA and macrosomia would suggest that blastocysts with grade A ICM grading should be transferred preferentially and supports the use of current morphological grading systems for embryo prioritisation.

Trial registration number

N/A

73 Is There A Real Relationship Between Body Mass Index and Vasovagal Syncope or is it Just Anecdote?

Introduction

Syncope is characterised by global cerebral hypoperfusion rapidly causing a transient loss of consciousness with loss of voluntary muscle tone and a subsequent spontaneous, prompt and complete recovery. It is often caused by Neurally mediated reflex syncope syndromes of which Vasovagal syncope (VVS) is the commonest form. The prodromal symptoms of VVS are explained by circulatory alterations (vasodilatation and bradycardia) and autonomic activation. Whilst many triggers and risk factors for such alterations are recognised, they are incompletely understood. Anecdotally, being “young and thin” is a risk factor but there is little published data evaluating the relationship between body weight and VVS. Whilst VVS can often be diagnosed on clinical history alone, further evaluation is warranted in some patients. The validated test to assess susceptibility to VVS is the head-up-tilt table (HUT) test. We set out to evaluate the relationship between Body Mass Index (BMI) and the outcome of HUT testing.

Methods

We reviewed the outcomes of 1193 patients attending for HUT testing at the University Hospitals of Leicester between December 2014 and October 2017. The protocol used was a 40 minute passive HUT (70 degree) followed by sublingual nitroglyserin. The parameters of height, weight, gender and test outcome were recorded prospectively and interrogated retrospectively.

Results

Of the 1193 patients, the passive HUT test was positive for VVS in 293 patients. These patients were then sub-grouped by BMI as set out in the table. The chances of VVS, as diagnosed by HUT testing are almost doubled in those with a (clinically underweight) BMI range 16-20. (p value 0.002-0.001)

Discussion

The presented data supports the anecdotal experience of many clinicians: that low BMI may be associated with an increased tendency to VVS. The physiological basis for this (if it is real) is not understood and requires further evaluation since it may have implications for future management strategies. Larger studies are required to further analyse this relationship to determine if BMI is an independent predictor or risk factor for VVS.

Fertility preservation in women with cancer and afterward

Women are surviving cancer in greater numbers. For this population, fertility becomes an important issue to be discussed before treatment to ensure maximal chances of fertility after treatment completion. Options for fertility preservation include egg or embryo freezing, ovarian tissue freezing, as well as gonadotropin releasing hormone analogs. The option for each individual patient will depend on the type of cancer, its aggressiveness and the time before treatment needs to commence, the type of treatment, the health of the patient, and whether the patient has a male partner.

A Type 1 Diabetes Genetic Risk Score Predicts Progression of Islet Autoimmunity and Development of Type 1 Diabetes in Individuals at Risk

OBJECTIVE

We tested the ability of a type 1 diabetes (T1D) genetic risk score (GRS) to predict progression of islet autoimmunity and T1D in at-risk individuals.

RESEARCH DESIGN AND METHODS

We studied the 1,244 TrialNet Pathway to Prevention study participants (T1D patients' relatives without diabetes and with one or more positive autoantibodies) who were genotyped with Illumina ImmunoChip (median [range] age at initial autoantibody determination 11.1 years [1.2-51.8], 48% male, 80.5% non-Hispanic white, median follow-up 5.4 years). Of 291 participants with a single positive autoantibody at screening, 157 converted to multiple autoantibody positivity and 55 developed diabetes. Of 953 participants with multiple positive autoantibodies at screening, 419 developed diabetes. We calculated the T1D GRS from 30 T1D-associated single nucleotide polymorphisms. We used multivariable Cox regression models, time-dependent receiver operating characteristic curves, and area under the curve (AUC) measures to evaluate prognostic utility of T1D GRS, age, sex, Diabetes Prevention Trial-Type 1 (DPT-1) Risk Score, positive autoantibody number or type, HLA DR3/DR4-DQ8 status, and race/ethnicity. We used recursive partitioning analyses to identify cut points in continuous variables.

RESULTS

Higher T1D GRS significantly increased the rate of progression to T1D adjusting for DPT-1 Risk Score, age, number of positive autoantibodies, sex, and ethnicity (hazard ratio [HR] 1.29 for a 0.05 increase, 95% CI 1.06-1.6; P = 0.011). Progression to T1D was best predicted by a combined model with GRS, number of positive autoantibodies, DPT-1 Risk Score, and age (7-year time-integrated AUC = 0.79, 5-year AUC = 0.73). Higher GRS was significantly associated with increased progression rate from single to multiple positive autoantibodies after adjusting for age, autoantibody type, ethnicity, and sex (HR 2.27 for GRS >0.295, 95% CI 1.47-3.51; P = 0.0002).

CONCLUSIONS

The T1D GRS independently predicts progression to T1D and improves prediction along T1D stages in autoantibody-positive relatives.