In another question Everybody has a brain implant. What measures can a criminal take to escape justice? I assumed that a brain implant would be possible in the future for surveillance.
In this question I would like to explore the actual feasibility of such an implant from a biological stance.
My plan is to have a bionic implant that forms (or detects the firing of) synapses over a substantial area of the surface of the primary visual cortex (V1). In effect it becomes part of the brain.
My limited understanding is that V1 actually has an image distributed across its surface. This is what will get transmitted by the implant to the outside of the skull. Thus a movie of a person's visual experiences will be available for monitoring either live or in retrospect. Ignoring the technicalities of the electronic transmission through the skull, is the biology plausible with the neuroscience of the next 100 or so years? If not V1, what else could be tapped into?
My research so far has turned up the following:
V1 has a very well-defined map of the spatial information in vision. For example, in humans, the upper bank of the calcarine sulcus responds strongly to the lower half of visual field (below the center), and the lower bank of the calcarine to the upper half of visual field. In concept, this retinotopic mapping is a transformation of the visual image from retina to V1. The correspondence between a given location in V1 and in the subjective visual field is very precise: even the blind spots are mapped into V1. In terms of evolution, this correspondence is very basic and found in most animals that possess a V1. In humans and animals with a fovea in the retina, a large portion of V1 is mapped to the small, central portion of visual field, a phenomenon known as cortical magnification. Perhaps for the purpose of accurate spatial encoding, neurons in V1 have the smallest receptive field size of any visual cortex microscopic regions.