How prenatal stress and early birth affect the baby's brain

What is the primary hypothesis of this study regarding prenatal maternal stress and preterm infants?

The study hypothesizes that prenatal exposure to maternal stress reduces functional connectivity of the amygdala with subcortical, limbic, and frontal regions in preterm infants.

Source: Prenatal stress alters amygdala functional connectivity in preterm neonates · DOI · quote verified

What general pattern of positive and negative connectivity does the amygdala show across all neonatal study groups?

The amygdala shows positive functional connectivity with subcortical structures like the hypothalamus, thalamus, insula, and brainstem, and negative connectivity with cortical structures like the precuneus, cuneus, and occipital lobe.

Source: Prenatal stress alters amygdala functional connectivity in preterm neonates · DOI · quote verified

What were the defining gestational age, birth weight, and scan timing characteristics of the preterm infants in Cohort 1?

Cohort 1 included very preterm neonates born under 32 weeks gestation with a birth weight between 500 and 1500 g, who were scanned without documented prenatal stress exposure at term equivalent age (40-44 weeks).

Source: Prenatal stress alters amygdala functional connectivity in preterm neonates · DOI · quote verified

How was prenatal stress exposure operationally defined and collected for Cohort 2?

Prenatal stress was defined as a binary classification (present/absent) based on a documented clinical diagnosis of maternal depression and/or anxiety in the medical chart, obtained retrospectively.

Source: Prenatal stress alters amygdala functional connectivity in preterm neonates · DOI · quote verified

What maternal pharmacologic treatment led to exclusion from Cohort 2?

Maternal pharmacologic treatment for depression and/or anxiety led to exclusion from Cohort 2.

Source: Prenatal stress alters amygdala functional connectivity in preterm neonates · DOI · quote verified

Compared to term controls, what alterations in amygdala connectivity did very preterm neonates exhibit in Cohort 1?

Very preterm neonates showed significantly reduced amygdala connectivity with the brainstem, insula, hypothalamus, and thalamus, along with increased (less negative) connectivity to the occipital lobe.

Source: Prenatal stress alters amygdala functional connectivity in preterm neonates · DOI · quote verified

What alterations in left amygdala connectivity were found in extremely preterm neonates exposed to prenatal stress compared to non-exposed peers?

Extremely preterm neonates with prenatal stress exposure exhibited significantly reduced left amygdala connectivity to the brainstem, the fusiform, the hypothalamus, and the thalamus.

Source: Prenatal stress alters amygdala functional connectivity in preterm neonates · DOI · quote verified

Why is the absence of observed connectivity between the amygdala and the medial prefrontal cortex/anterior cingulate notable in this study?

This connection is highly sensitive to early life adversity in older populations, but it remains poorly characterized and undergoes major positive-to-negative reorganization during the neonatal and early infancy period.

Source: Prenatal stress alters amygdala functional connectivity in preterm neonates · DOI · quote verified

What did the exploratory combined analysis reveal about the synergistic relationship between preterm birth and prenatal stress?

It showed a step-wise decrease in thalamo-amygdala connectivity, where term controls had the highest connectivity, followed by non-stressed preterms, and stressed preterms had the lowest connectivity.

Source: Prenatal stress alters amygdala functional connectivity in preterm neonates · DOI · quote verified

What cellular mechanisms do preclinical models suggest link prenatal stress to disrupted brain development?

Preclinical models suggest that prenatal stress disrupts GABAergic progenitor migration and impairs synaptogenesis, which are also processes disrupted by preterm birth.

Source: Prenatal stress alters amygdala functional connectivity in preterm neonates · DOI · quote verified

What head motion exclusion thresholds were used during functional image preprocessing?

The researchers removed blocks of fMRI data with a displacement greater than 1.5 mm or a rotation greater than 2 degrees, requiring at least 2.5 minutes of remaining data.

Source: Prenatal stress alters amygdala functional connectivity in preterm neonates · DOI · quote verified

Were there significant group differences in motion (average frame-to-frame displacement) within Cohort 1 or Cohort 2?

No, there were no significant differences in average frame-to-frame displacement when comparing term controls to very preterm neonates, or when comparing stressed to non-stressed extremely preterm neonates.

Source: Prenatal stress alters amygdala functional connectivity in preterm neonates · DOI · quote verified

Why did the researchers apply a standard MNI gray matter mask warped to a neonatal template instead of native segmentations?

Because the gray matter in the standard MNI template is larger, warping it ensures full gray matter coverage even when registration or segmentation errors occur.

Source: Prenatal stress alters amygdala functional connectivity in preterm neonates · DOI · quote verified

What baseline differences in gestational age and birth weight were present in Cohort 2, and how were they addressed?

Preterm neonates without prenatal stress exposure had significantly lower gestational age and birth weight than those with stress; the researchers addressed this by independently covarying for both variables, which did not change the main findings.

Source: Prenatal stress alters amygdala functional connectivity in preterm neonates · DOI · quote verified

Why did the researchers use a single representative infant brain as a registration template rather than an average template of all neonate brains?

A single representative brain has well-defined tissue interfaces that minimize errors during non-linear registration, unlike blurred average templates.

Source: Prenatal stress alters amygdala functional connectivity in preterm neonates · DOI · quote verified

What is a major limitation of how prenatal maternal stress was operationalized in this study?

Prenatal stress was defined using a binary clinical chart review for depression/anxiety diagnoses, making it difficult to separate general prenatal stress from maternal psychiatric illness or capture undocumented stressors.

Source: Prenatal stress alters amygdala functional connectivity in preterm neonates · DOI · quote verified

Why was the combined-cohort connectivity analysis presented only as 'exploratory'?

The two cohorts were imaged on different scanner systems and differed in postmenstrual age at scan, introducing complex, non-linear scanner and age effects that are difficult to model.

Source: Prenatal stress alters amygdala functional connectivity in preterm neonates · DOI · quote verified

Did the study identify any significant main effects of sex or sex-by-group interactions on amygdala functional connectivity?

No significant main effects of sex or sex-by-group interactions were found, although this may have been due to power limitations.

Source: Prenatal stress alters amygdala functional connectivity in preterm neonates · DOI · quote verified

Which specific covariates of no interest were regressed out of the fMRI time-series data?

Linear and quadratic drift, six rigid-body motion parameters, mean cerebrospinal fluid (CSF) signal, mean white matter signal, and overall global signal were regressed.

Source: Prenatal stress alters amygdala functional connectivity in preterm neonates · DOI · quote verified

How was the reference time course calculated for the amygdala seed to determine whole-brain connectivity?

It was computed by averaging the fMRI time course across all voxels within the defined amygdala region in individual space, which was then correlated with every other voxel in the gray matter.

Source: Prenatal stress alters amygdala functional connectivity in preterm neonates · DOI · quote verified

How was the whole-brain fMRI connectivity analysis corrected for multiple statistical comparisons?

Corrected using cluster-level correction via Monte Carlo simulations (AFNI's 3dClustSim), establishing a threshold cluster size of 4768.2 mm³.

Source: Prenatal stress alters amygdala functional connectivity in preterm neonates · DOI · quote verified

Which shared subcortical regions showed reduced amygdala functional connectivity in both preterm birth (Cohort 1) and prenatal stress (Cohort 2)?

Both cohorts demonstrated reduced amygdala connectivity to similar deep subcortical structures, specifically the brainstem, the hypothalamus, and the thalamus.

Source: Prenatal stress alters amygdala functional connectivity in preterm neonates · DOI · quote verified

What scanners were used for Cohort 1 and Cohort 2 imaging, respectively?

Cohort 1 was scanned using a 3T Siemens TIM Trio MR system, and Cohort 2 was scanned using a 3T Siemens Verio Clinical system.

Source: Prenatal stress alters amygdala functional connectivity in preterm neonates · DOI · quote verified

How does the literature describe the normal developmental trajectory of amygdala-mPFC connectivity from childhood to adolescence?

It is characterized by a developmental reorganization, moving from positive connectivity in childhood to negative connectivity in adolescence.

Source: Prenatal stress alters amygdala functional connectivity in preterm neonates · DOI · quote verified