A
hologram is the image of an object in
three dimensions created and reproduced by the use of
lasers.
Holography is a method for recording and using such images. Holograms are remarkable in that, unlike normal photographs, every part of them contains the complete image but in reduced detail. Thus a small square cut from a hologram can be laser-illuminated to reveal the whole scene originally holographed, albeit with a loss of resolution. This feature made the hologram attractive to proponents of the thesis of distribution of the function of the brain who argued that memories are like holograms, not being located in a single precise engram - as claimed by the advocates of localization of function, but distributed perhaps across the whole of the cortex. Although intriguing, the holographic model of memory storage failed to gain general acceptance.
Current views favour D. O. Hebb's "Cell Assembly" concept, in which memories are stored in the connection between a group of neurons.
Ref: Cambridge Dict of Philosophy