What is the role of the hippocampus and associated areas such as the entorhinal cortex and medial septum in spatial navigation: do theta oscillations have a significant effect on navigation spatial and could this shed light on the underlying neuronal mechanisms? The hippocampus has been associated with memory formation and consolidation, through studies of lesions in patients who underwent bilateral medial temporal lobectomy, such as the famous amnesiac HM. In 1971, with the discovery of place cells by O'Keefe and Dostrovsky, spatial navigation was recognized as one of the primary navigation mechanisms. of the major roles of the hippocampus, with their 1978 book "The Hippocampus as a Cognitive Map", O'Keefe and Nadel's hypothesis has since exerted great influence in the field. The term "place cell" generally refers to pyramidal neurons in the hippocampus that show increased activity when an animal, usually a rodent, is at a particular location on an experimental track or arena. The regions in which cells fire are called place fields. Place cells are thought to be active in response to sensory signals and particularly complex stimuli. This suggests that place cell function depends on sensory input and integration. Counterintuitively, place cell activation is not static with respect to an objective or relative place field location, because when transferred to a new environment, any particular place cell can be activated by a completely independent or “remapped” location field. This suggests that place cells integrate information with a contextual component and a metric component linking sensory and distance data. (Jeffery, 2007)By examining areas with cortical inputs in the hippocampus, Moser and others in 2005 discovered another cell type in the dorsomedial entorhinal cortex (dME...... middle of paper.. ....toric interference model based on the theta phase difference and interference between soma and dendritic processes that results in periodic spatial activity derived from the temporal signal (Burgess N, Barry C, O'Keefe 2007 and Giacomo, Zilli 2007) and the attractor model based on network dynamics, with reciprocal firing of grid cells as the basis for periodicity. As the importance of theta cannot yet be effectively determined in humans. , elucidating the mechanism of grid periodicity will have lasting implications for the direction of research and may require a critical rethinking of many currently accepted models. The selected papers explore this in two ways: The first paper examines the effects of. the removal of theta on the periodicity of grid cells and the second seeks to determine whether the presence of theta is necessary for a normal grid cell. activity.