UCSF

Coordinated neuronal activity plays an important role in information processing and transmission in the brain. With current research predominantly focuses on understanding the properties and functions of neuronal coordination within cortical areas, however, whether coordinated neuronal ensembles (cNEs) are unique to cortical local networks or extend to neuronal populations in other brain regions, such as the auditory thalamus, remains unknown. Additionally, questions persist regarding whether information carried by cNEs is effectively transmitted to downstream areas compared to single neurons. In this study, we use single-unit recordings in female Sprague-Dawley rats to investigate the properties and functions of groups of neurons exhibiting coordinated activity in the auditory thalamus – the medial geniculate body (MGB). We reliably identify cNEs, which are groups of neurons that fire synchronously, in the MGB. We demonstrate that cNEs in the MGB have enhanced information encoding properties and are stable between spontaneous and evoked activity. These MGB cNE properties are similar to what is observed in the cNEs in the primary auditory cortex (A1), suggesting that ensembles serve as a ubiquitous mechanism for organizing local networks, playing a fundamental role in sensory processing within the brain. Furthermore, spikes from MGB neurons synchronized with other cNE members exhibit higher efficacy in driving A1 neuron firing compared to spikes unrelated to cNE activities. This increased efficacy of cNE spikes is target-specific and cell-type specific, rather than resulting in a general increase in the firing rate across all A1 neurons. These findings support the concept of a neuronal ensemble as a functional unit for encoding and transmitting information in the forebrain processing.