Tests On Miner Show Brain Activity

(CBS/AP)  Although he's still in a partial coma, the sole survivor of the Sago Mine disaster is showing signs of brain activity.

Doctors say Randal McCloy has yet to fully awaken from a medically-induced coma. But they expect that — and the rest of his healing — to be a gradual, lengthy process.

McCloy remains in critical condition at West Virginia University's Ruby Memorial Hospital in Morgantown.

Neurosurgeon Julian Bailes says tests are showing a lot of activity on both sides of McCloy's brain. But Bailes says it's too early to interpret what the activity means.

Meanwhile, funerals for the

last two men (video)

killed in last week's explosion brought mourners from as far away as New York. Probes are underway into both the Sago Mine disaster and overall national mining safety.

There was no significant change Tuesday morning in the condition of McCloy, 26. He remained in critical condition at West Virginia University's Ruby Memorial Hospital in Morgantown.

McCloy has yet to fully awaken from a medically induced coma, but doctors did not express concern.

"I think we have no clear clue of the extent of his injury or the time of his recovery," Bailes said.

However, Bailes said tests showed a lot of activity on both sides of McCloy's brain.

"It is probably too early for us to tell what that means, but it is very important to us that he has a lot of brain activity," Bailes said.

But McCloy still has a fever of undetermined origins, doctors say, CBS' Aleen Sirgany reports.

Earlier, Dr. Larry Roberts of Ruby Memorial Hospital said a large step was taken toward healing.

"The ventilator to which he is still hooked up is no longer giving him mechanical breaths; he's doing all his own breathing," Roberts said.

A complete recovery may not be possible, outside experts say.

"Overall you're going to see a slowing of the patient's mental abilities ... cognitive problems, thinking, the speed at which you make decisions," Dr. Keith Siller, head of neurology at New York University Medical Center in New York, told CBS News' Tony Guida.