Category: Articles

Despite much publicity in recent years that has suggested in unqualified terms that the first two or three years of life are critical in fostering healthy brain development and, in turn, healthy behavioral development, the reality is that we know very little about brain development in the human and even less about the role of experience in sculpting the developing brain. We know much less than the public has been led to believe over the past two years, and knowing as little as we do places profound constraints on our ability to intervene at an early age.

While we have data from many quarters—but notably from studies of deprivation—that clearly point to the importance of the first two to three years of life as playing a critical role in fostering healthy neural and psychological development, we have amazingly little data on exactly which aspects of experience are essential to development …

Infants of diabetic mothers (IDMs) are at increased risk for cognitive impairments, possibly due to alterations in fetal brain growth and development. The purpose of this longitudinal study is to evaluate the neural bases of cognitive impairments in IDMs. In this first phase, we evaluated neonatal brain function in 21 IDMs studied at term compared with 22 full-term, healthy control infants using event-related potentials (ERPs).

The ERP technique is an electrophysiologic method which can be used to study regional brain function and cognitive function. Brain activity was recorded over midline and lateral scalp sites while infants were presented with two sets of stimuli designed to evaluate auditory brain maturation cortical responses to speech and non-speech stimuli. Auditory recognition memory was evaluated using voice recordings of each infant’s mother and a stranger (both said “baby”). Each set of stimuli was edited to the same duration and peak sound level and represented …

Following the success of the pseudorabies project, the Network initiated a follow-up project to study the effects of stress on the formation of neural connections from the forebrain to the brainstem (the vital core components of the brain controlling functions essential for survival, including respiration, heart rhythm, blood pressure, eating, drinking, and sleep).

This study was designed to help determine how different early experiences in rats cause changes in how early connections between the forebrain and brainstem are established – either in how the connections are organized, or when the connections are formed. The experiment found that the underlying biological mechanisms for handling stress as adult rats change as a result of stressful experiences (handling and separation) encountered as pups. Rat pups that are repeatedly handled and separated from their mother exhibit altered adult behavioral, endocrine, and autonomic responses to stress, but the extent to which early handlingand/or maternal separation …

Face Recognition Study – The ability to recognize other faces and emotional expressions is a significant component of social cognition. This comparative study examines how particular areas of the brain may be involved in the development of this ability.

A Four-site Study on Face Recognition in Humans and Monkeys

In the mature brain, regions of the inferior temporal cortex (a part of the brain suspected to play a role in processing visual information) has been implicated in face recognition; and the amygdala has been implicated in the recognition of emotion.

This study seeks to determine when during development these parts of the brain start to be active in face and emotion recognition. In particular, the researchers are interested in the effects of early disturbances in these areas (physical disruptions, such as lesions, or social/emotional disruptions, such as social deprivation) on the development of the ability to recognize faces and emotions.…

Neuroimaging Studies of Previously Institutionalized Infants Adopted in the US – Although much media attention has focused on the abnormal behavioral development of children adopted from institutional orphanages, to date no one has examined how brain structure or function correlates with these abnormal behaviors. This study attempts to examine, using fMRI, the relation between brain structural and functional development and behavioral outcomes in children adopted from institutional orphanages.

IMAGING OF FORMERLY INSTITUTIONALIZED CHILDREN ADOPTED IN THE U.S.

Much is known about the outcomes of children who are adopted after being institutionalized, such as attentional, emotional, and behavioral disturbances. However, little is known about how institutionalization affects the structure and function of the brain, which in turn affects the observed behavioral outcomes.

This study examines whether observed aberrant behavior in previously institutionalized children correlates with MRI-based morphometry (the size and shape of brain structures) or patterns of brain activity detected using …

Our success in understanding how early socio-emotional relationships impact on subsequent brain-behavioral development will depend to a great degree on our assessment tools. To this end a second major effort of this initiative is focused on the development of tools that permit one to forge a linkage between brain and behavior.

It is our intent to develop a class of tools that range from molecular to molar, and that are geared to particular study groups, for example, normally developing children, children with disabilities (e.g., autism), rodents, non-human primates, and so forth.

At the molecular level, our studies focus on animals and perhaps human autopsy specimens that have been equated for age and developmental history. Here the latest advances in the tools of molecular biology prove indispensable (e.g., gene knockouts; high density arrays for gene sequencing; use of viruses to perturb normal patterns of gene and protein expression).

Moving more to …

A number of studies in non-human primates have suggested that the amygdala is essential for the normal production and interpretation of social signals. Network researchers conducted a study in rhesus monkeys that challenges this long-held belief. Adult monkeys with amygdala lesions appear to demonstrate normal social behavior, while infant monkeys with amygdala lesions in previous studies have demonstrated impairments in social behavior.

However, these abnormalities may not have been attributable to the absence of the amygdala, but may rather have been attributable to abnormal rearing conditions (isolation or peer-rearing) or to additional damage to structures surrounding the amygdala due to less sophisticated lesioning methods than are currently available. This study found that infant rhesus monkeys with very precise lesions of the amygdala who were reared with their mothers did develop species-appropriate social behaviors, indicating that the amygdala is not necessary for normal social development.

However, these animals did produce more …

Methods for Studying Brain-Behavior Relations – Part of the challenge of studying the effects of experience on the brain is the paucity of methods for examining the development of particular brain structures. These research projects focus on the development of methods that will allow us to look at how brain structures thought to be involved in particular aspects of behavioral development change with time and experience.

As interest in the brain increases among those studying behavioral development, the need for basic knowledge about brain development also grows. For those interested in emotional development and temperament, it is crucial to understand the development of the amygdala, a part of the brain that is believed to serve as the “seat” of emotion. The amygdala also plays a prominent role in regulating an individual’s ability to associate rewards with certain behaviors. Finally, the amygdala is critically involved in the recognition and interpretation of …

The Network has conducted several related studies in Rhesus monkeys that address how early social deprivation affects brain and behavioral development. Monkeys who were removed from their mothers at either 1 week of age or 4 weeks of age developed strikingly abnormal behaviors compared both to each other and to normal monkeys who left their mothers at 6 months, the usual time for maternal separation. Neuroanatomical studies of these monkeys have shown distinct differences in some areas related to social functioning. Other studies involve introducing monkeys separated at 1 week of age (who appear to lack any social drive after the separation) to a “supermom” (a female monkey known to adopt infants). These studies are showing that, while the behavioral abnormalities seen in these separated monkeys can be remediated by the introduction of a substitute mother, there appears to be a narrow window of opportunity for the reintroduction of maternal …