For months, the public knew of Rep. Gabrielle Giffords’s recovery only through other people. Her astronaut husband. Her protective chief of staff. The army of doctors and specialists who have shepherded her through multiple surgeries and day after day of grueling physical therapy.

But now it is Giffords herself offering the most convincing evidence yet of a remarkable rehabilitation, seven months after she was shot in the head by a would-be assassin who killed six bystanders and injured more than a dozen others.

On Monday, the Arizona Democrat flew on a commercial jet from Houston to Washington, where she surprised her colleagues by showing up to vote — her first vote since the Jan. 8 shooting. After a meal with her staff Tuesday, Giffords boarded a plane back to Houston, where she is still undergoing five days a week of intensive outpatient physical therapy.

The simple one-day journey provided new insights into her progress since the incident that left her with a significant brain injury, friends and specialists said Tuesday.

“In the beginning she could hardly get one word out,” recalled Richard Carmona, a family friend and former surgeon general who is not treating Giffords but has kept tabs on her recovery. Now, “she can speak and put a sentence together. Sometimes, she’s a little slower and a little more thoughtful.”

The mobility on the right side of her body was damaged, much like a stroke patient’s, he said. But she can now walk largely un­assisted. Her improvement has been “really quicker and better than anybody expected,” he said.

Giffords is undergoing three types of rehabilitation, Carmona said: physical therapy to strengthen her right side, occupational therapy to help her with day-to-day tasks such as using a knife and fork, and cognitive therapy including reading and word games. All are “meant to strengthen all the functions that were diminished or lost,” he said.

Giffords still struggles to communicate, a limitation that sometimes leaves her frustrated, friends said. But they said they do not doubt her cognitive abilities and are confident that she understood the debt issue when she voted Monday.

“I guess the most astonishing thing has been how her cognitive abilities seem never to have been affected in the first place. Her ability to know what is going on around her is complete,” said Michael McNulty, her friend and campaign chairman, who has visited with Giffords about every few weeks since she moved from her district in Tucson to Houston, where her husband is based. “She continues to have a lot of speech therapy. And she will continue to until she returns to her eloquent self.”

On Sunday, Giffords asked her husband, Mark Kelly, to call Rep. Debbie Wasserman Schultz (D-Fla.), a close friend, to find out if the decision on the debt ceiling would be so close that her vote could be pivotal, Wasserman Schultz said. Though the vote wasn’t as close as was expected at the time, Giffords decided to come anyway because she felt so strongly about the issue and wanted to raise the debt limit.

Many people who are shot in the head never survive, let alone regain so much of their abilities, said several specialists who observed Giffords during the Monday night vote. They credited her recovery so far to a combination of luck in terms of how the bullet traveled through her brain, the top-notch medical care she received, and hard work on the part of Giffords and her friends and family. They say the next year could bring further improvements.

“What we saw was someone who years ago would have been dead or very impaired, saying thanks and walking and showing some amount of comprehension,” said Jam Ghajar, a clinical professor of neurological surgery at Weill Cornell Medical College who is president of the Brain Trauma Foundation. “She’s made a terrific recovery. Certainly she’s an inspiration to medical personnel for what can happen if you take good care of somebody.”

The fact that Giffords clearly was acknowledging other people, responding to their body language and reacting with her own facial expressions indicates that she had retained higher-thinking abilities, making her aware of her surroundings and what she was doing, according to Darryl Kaelin, chief of the division of physical medicine and rehabilitation at the University of Louisville.

“She was head-nodding and responding to comments,” Kaelin said. “She clearly has some level of understanding.”

Friends say Giffords’s recovery has happened in sharp bursts — “quantum leaps,” said Bill Nugent, a friend from Tucson. He said he watched Giffords on television Monday night and was surprised by how much her condition has improved since her foray back to her hometown in June.

Nugent, who owns the Shanty bar, has long been convinced that Giffords will return to her post and perhaps aim higher — he has a “Giffords for U.S. Senate” sign.

“We’re not giving her a choice,” he joked. “I think she’ll be back with a vengeance.”

Giffords’s office said the congresswoman has not decided if she will run for reelection or for Senate.

As her Monday night appearance showed, she is not yet whole. She was thinner than before, her bandaged right arm hanging limply at her side. A scar is prominent on her forehead just below her hair, which is cropped short as it grows back.

She waved briskly with her left hand, her eyes and face animated. She recognized her colleagues, dispensing hugs and kind words. She mouthed “Thank you” and whispered in her colleagues’ ears. And without delay, she voted yes on a bill that her staff said she viewed as the most important to come up since the shooting.

On Tuesday afternoon, she decided not to join her husband when he and the rest of the crew of the space shuttle Endeavour went to the White House to meet with the president. “She decided to go home because she didn’t want to be late for therapy tomorrow,” said Pia Carusone, her chief of staff.

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