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Thalamocortical development of parvalbumin neurons in normal and periventricular leukomalacia brains
1Division of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, NCNP, Tokyo, Japan.
Insights
This study reveals how parvalbumin (PA) expression in the developing brain relates to cognitive functions in preterm children. Altered PA levels indicate specific impacts on brain development and thalamocortical connections.
Area of Science:
- Neuroscience
- Developmental Biology
- Pediatrics
Background:
- Preterm birth can lead to cognitive and learning disorders due to disruptions in higher brain functions.
- Understanding the functional development of the cerebral hemisphere is crucial for identifying these disturbances.
Purpose of the Study:
- To investigate the functional development of the cerebral hemisphere in relation to cognition and learning disorders in preterm-born children.
- To examine the expression patterns of parvalbumin (PA) during early brain development.
Main Methods:
- Utilized parvalbumin (PA) immunohistochemistry in human subjects ranging from 21 gestational weeks (GW) to 11 years of age.
- Observed the appearance and spread of PA-immunoreactive neurons in various brain regions, including the thalamus and cortex.
- Correlated PA expression patterns with the presence and type of periventricular leukomalacia (PVL) in preterm infants.
Main Results:
- PA-immunoreactive neurons appeared sequentially in the RNT, globus pallidus, VPoL, and VPoM from 24 GW.
- PA expression was detected in the primary somatosensory and auditory cortices by 38 GW, forming dense bands by 1 month of age.
- Decreased PA expression was observed in cortices with diffuse PVL, while increased PA expression was noted in those with focal PVL.
Conclusions:
- Developmental changes in PA expression correlate with thalamocortical connection development and functional maturation of cortical neurons.
- Accelerated PA expression may be induced by extra-uterine stimuli in preterm infants.
- Reduced PA levels in preterm children suggest impairment of thalamocortical neurons, potentially underlying cognitive deficits.
Abstract:
To clarify disturbances in higher brain functions including cognition and learning disorders in preterm-born children, we investigated the functional development of the cerebral hemisphere, using parvalbumin (PA) immunohistochemistry in human subjects aged from 21 GW to 11 years of age. PA-immunoreactive neurons first appeared in the RNT at 24 GW, spread to the globus pallidus, and then to the VPoL and VPoM. At 38 GW, PA-immunoreactive neurons first appeared in layer 4 of the primary somatosensory cortex and auditory cortex, and comprised a dense band in layers 4 to 5 at 1 month of age. The developmental changes and course of PA expression in the early developmental stage corresponded to development of the thalamocortical connection and then to the functional development of cortical neurons. In preterm cases, PA expression was decreased in the cerebral cortices that corresponded to widespread or diffuse type PVL, but was increased in those with focal type PVL. These results indicate that accelerated expression of PA was induced by extra-uterine stimuli and a reduction of PA reflects the impairment of thalamocortical neurons.