Could you tell me where you heard that, or saw that? And the marker signal does not turn people into necromorphs. Issac had no idea what was in his head, (through drawings as well as the neural access machine) but his brain was able to organise the symbols in such a way as the scientist could extrapolate what they were.instructions and blueprints, from there the markers are made, same person might not have worked out the microbe code, yet another will, and this is then all pieced together in a marker project. And also those that do piece together what the symbols 'are', its others around them that piece the puzzle together. But in most cases people just decend into madness and have no idea why. If you've ever seen stargate universe, where chloe was genetically altered by aliens, she could understand equations without really knowing what they ment. The difference in who can see the symbols and who can piece together what is happening, is down to the individual. This causes things such as paranio, sleeplessness, erratic behaviour, hallucinations to outright psychopathy. This causes damage and malfunctioning in the neural pathways of the brains as the organism is mentally trying to work out what is going on. The effects on the brain are caused by the instructions the signal has embedded in it.

It's not so much about IQ either, and this is shown in the expanded media better. The marker does not lower the IQ of people.

Dead space marker symbols