How can a current in the brain feel like a touch on a finger? · Grey Matter

The primary somatosensory cortex is laid out as a map of the body, and each small patch of it normally receives signals from one patch of skin.

How can a current in the brain feel like a touch on a finger?

The primary somatosensory cortex is laid out as a map of the body, and each small patch of it normally receives signals from one patch of skin. Exciting the neurons around an electrode tip produces activity that the brain reads as coming from that patch, so a man with a spinal cord injury felt pressure on specific fingers of his paralysed hand when arrays in the hand area were stimulated. The sensation is still artificial (often a tingle or a buzz), and stimulating several neighbouring electrodes together or in sequence is what makes it read as an edge or a stroke across the skin.