Ultrastructural heterogeneity of layer 4 excitatory synaptic boutons in the adult human temporal lobe neocortex
Rachida Yakoubi,
Astrid Rollenhagen,
Marec von Lehe,
Dorothea Miller,
Bernd Walkenfort,
Mike Hasenberg,
Kurt Sätzler,
Joachim HR Lübke
Affiliations
Rachida Yakoubi
Institute of Neuroscience and Medicine INM-10, Research Centre Jülich GmbH, Jülich, Germany
Astrid Rollenhagen
Institute of Neuroscience and Medicine INM-10, Research Centre Jülich GmbH, Jülich, Germany
Marec von Lehe
Department of Neurosurgery, Knappschaftskrankenhaus Bochum, Bochum, Germany; Department of Neurosurgery, Brandenburg Medical School, Ruppiner Clinics, Neuruppin, Germany
Dorothea Miller
Department of Neurosurgery, Knappschaftskrankenhaus Bochum, Bochum, Germany
Bernd Walkenfort
Medical Research Centre, IMCES Electron Microscopy Unit (EMU), University Hospital Essen, Essen, Germany
Mike Hasenberg
Medical Research Centre, IMCES Electron Microscopy Unit (EMU), University Hospital Essen, Essen, Germany
Kurt Sätzler
School of Biomedical Sciences, University of Ulster, Londonderry, United Kingdom
Institute of Neuroscience and Medicine INM-10, Research Centre Jülich GmbH, Jülich, Germany; Department of Psychiatry, Psychotherapy and Psychosomatics, Faculty of Medicine, RWTH University Hospital Aachen, Aachen, Germany; JARA Translational Brain Medicine, Jülich/Aachen, Germany
Synapses are fundamental building blocks controlling and modulating the ‘behavior’ of brain networks. How their structural composition, most notably their quantitative morphology underlie their computational properties remains rather unclear, particularly in humans. Here, excitatory synaptic boutons (SBs) in layer 4 (L4) of the temporal lobe neocortex (TLN) were quantitatively investigated. Biopsies from epilepsy surgery were used for fine-scale and tomographic electron microscopy (EM) to generate 3D-reconstructions of SBs. Particularly, the size of active zones (AZs) and that of the three functionally defined pools of synaptic vesicles (SVs) were quantified. SBs were comparatively small (~2.50 μm2), with a single AZ (~0.13 µm2); preferentially established on spines. SBs had a total pool of ~1800 SVs with strikingly large readily releasable (~20), recycling (~80) and resting pools (~850). Thus, human L4 SBs may act as ‘amplifiers’ of signals from the sensory periphery, integrate, synchronize and modulate intra- and extracortical synaptic activity.
