I feel therefore I am?

"The importance of sensory signals in activating the excitatory area is demonstrated by the effect of cutting the brain stem above the point where the fifth cerebral nerves enter the pons. These nerves are the highest nerves entering the brain that transmit significant numbers of somatosensory signals into the brain. When all these input sensory signals are gone, the level of activity in the brain excitatory area diminishes abruptly, and the brain proceeds instantly to a state of greatly reduced activity, approaching a permanent state of coma. But when the brain stem is transected below the fifth nerves, which leaves much input of sensory signals from the facial and oral regions, the coma is averted."
Guyton 11th edition, Elsiever, pg 729

I wonder if you could continue to think with absolutely no sensory input. Then, could you have output by just thinking, in the absence of all input? So much for "cognito ergo sum"