Building on the primary focus of the Institute of Developmental Neuroscience, the investigation of the emergence and significance of oscillatory brain activity in perinatal age, a new project branch has emerged with a focus on adolescent brain development.

It is not only in the early stages of development that the brain shows increased plasticity; the adolescent phase is also characterized by this. During adolescence, mature behavioral functions begin to emerge, especially in cognitive areas. This is accompanied by a renewed reconstruction of structural and functional patterns, particularly in the prefrontal cortex.

The aim of this research project is to elucidate the underlying mechanisms of this reconstruction and its contribution to the development of functional as well as dysfunctional cognitive abilities. To this end, we measure the changes in brain activity, both at the oscillatory and neuronal level, simultaneously in the prefrontal cortex and hippocampus from childhood to adulthood in animal models and relate these to morphological changes in different cell populations in the brain. In addition, the developmental stage of cognitive abilities is examined at different ages using certain behavioral tests and combined with electrophysiological measurements as well as optogenetic manipulations of neuronal activity in order to obtain information about a causal relationship.

Specific neuronal populations that make a critical contribution to the identified mechanisms will be analysed in gene expression analyses using RNA sequencing in both naïve and animal models of psychiatric disorders. This comprehensive strategic approach contributes to a better understanding of the sensitivity of the juvenile phase to the symptomatic onset of psychiatric disorders.

Neuronal activity in the developing brain has several unique characteristics. It is characterized by long periods of electrical silence alternating with sporadic bursts of activity, by highly correlated and extremely low neuronal firings, and is only weakly modulated by the behavioral state.

Equally unique are the dynamics with which neurons interact and communicate at both microscopic and macroscopic levels. To understand how the logic of neuronal interactions develops during ontogeny, we study the functional development of the prefrontal and primary sensory cortex, the hippocampus and the subcortical nuclei.

Using various analytical and experimental approaches, we investigate the microcircuitry and long-distance communication between these brain areas and their relevance for the development of cognitive abilities.

The occurrence of cognitive deficits is characteristic of various neuropsychiatric disorders. These deficits are based on changes in functional connectivity and communication in prefrontal-hippocampal networks. Clinical descriptions of these diseases have provided evidence that these dysfunctions may have their origin in early development, long before the first disease-relevant symptoms are identifiable. Using mouse models that reflect the multifactorial aetiology of psychiatric diseases (e.g. the genetic and environmental (GE) model), we have been able to show that the initiation of functional communication in prefrontal-hippocampal networks is already disrupted in the course of early development. Accordingly, our team is working on characterising the cellular mechanisms underlying the impaired maturation of prefrontal-hippocampal networks in neuropsychiatric diseases.

Early sensory processing is essential for the functional development of sensory brain areas. However, it is not known whether early sensory experience influences the development of cognitive abilities. To answer this question, we use the olfactory system as one of the earliest developed senses.

The olfactory system is functional at birth and newborn rodents use olfactory information for learning and cue-guided behaviours that are crucial for their survival. Moreover, unlike input from other sensory modalities, olfactory information directly reaches cortical areas without thalamic relay.

Therefore, the olfactory system is tightly coupled to the hippocampal formation and the frontal cortex, key structures for cognitive abilities such as memory and decision making. We investigate the maturation of cognitive areas related to the olfactory system and the consequences of developmental disorders of olfactory activity for cognitive abilities.