Hippocampus and Spatial Memory

The hippocampus is a brain structure located inside the temporal lobe. It forms a part of the limbic system and plays an important role in the formation, consolidation and retrieval of episodic memories. It has been shown that repetitive activation of excitatory synapses in the hippocampus causes an increase in synaptic strength that last for hours or days designated as long-term potentiation (LTP). It is widely believed that LTP provides an important key to understand the cellular and molecular mechanisms by which memories and formed and stored. Sensory information enters the hippocampus mainly through the perforant pathway consisting of the axons of neurons in layer II and III of the entorhinal cortex. The perforant path axons terminate on the dendrites of the dentate gryus granular cells. Then information flow through the hippocampus from the dentate gyrus to the CA3, the CA1 and the subiculum, forming hippocampal intrinsic trisynaptic circuit. In addition to its “traditional” role in learning and memory, the hippocampus is also involved in neuroimmunity. Lesion of hippocampus alters immunity and neuronal functions in the hippocampus are modulated by a variety of immune active molecules.