Figure 8.

Summary diagram of the inhibitory synaptic reorganization involving calretinin-immunoreactive cells and dendritic inhibitory interneurons in the non-sclerotic epileptic human hippocampus. Control: a part of the calretinin-positive cells are interneuron selective inhibitory cells in the human hippocampus targeting dendritic inhibitory cells and other calretinin-containing interneurons (green). Calretinin-containing neurons also form dendro-dendritic contacts with each other. The electrically coupled calretinin-positive cells can efficiently synchronize the action of dendritic inhibitory cells (dark blue) on pyramidal cell dendrites (orange). Epileptic, non-sclerotic: some calretinin-positive cells are degenerated resulting in an impairment of the calretinin-positive interneuron ensemble. This may lead to the asynchronous firing of the targeted dendritic inhibitory cells (light blue) which may cause a less effective inhibition of pyramidal cell dendrites. This may result in abnormally enhanced potentiation of excitatory inputs to principal cells.