Houston ( CNN ) -- Doctors at the Houston hospital where U.S. Rep. Gabrielle Giffords was transferred said that while she remains in intensive care , she has surprised them with the progress she has already made . Giffords , 40 , who was shot in the head at a public event in Arizona on January 8 , was transferred Friday to Memorial Hermann-Texas Medical Center . It was thought the congresswoman would begin rehabilitation at The Institute for Rehabilitation and Research ( TIRR ) Memorial Hermann , but officials said she was taken instead to the hospital 's trauma center for evaluation and treatment . `` She 's not quite ready for rehabilitation yet , '' Dr. Dong Kim of Memorial Hermann told CNN on Thursday . Kim would not elaborate , but on Friday , Dr. John Holcomb told reporters that Giffords has fluid on her brain . `` There 's a little fluid collection that the docs have put a drain into , around her brain , and that drain is still in place , '' he said . `` With that drain in place , she ca n't leave the ICU . '' He said Giffords will remain in the hospital while `` this drain business '' is sorted out and doctors make sure no infection is developing . During that time , she will undergo rehabilitation in the intensive care unit , as she was at Tucson , Arizona 's University Medical Center . That rehabilitation was under way on Saturday , Dr. Gerard Francisco , the hospital 's medical director , told reporters . `` She 's doing very well , '' he said . The exercises involve moving , sitting and standing , he said . `` We 're still in that phase of discovering what she can and can not do so we can come up with the best combination of therapy . '' Giffords `` surprised us , '' he said . `` She did not need as much assistance as we anticipated . '' Doctors had said earlier that Giffords has been able to stand with assistance . `` She 's activating her muscles even more than what I had anticipated , '' Francisco said . Giffords has a breathing tube in her neck and can not talk , but Francisco said he believes she is trying to communicate . She is very responsive to others , and follows commands . He said doctors were particularly encouraged by Giffords ' bringing her left leg , which was dangling off the side of the bed , up onto the bed . Giffords has good movement and muscle tone on her left side , he said , and some on her right side as well , although not as much as the left . She was shot in the left side of her brain , which controls her right side . Arizona doctors said Giffords ' transfer went flawlessly . Dr. Randall Friese of the UMC trauma center said that at some points as she traveled through the streets of Tucson , Giffords could hear applause from those who turned out to honor her . `` She responded very well to that , '' he said , smiling and even tearing up a bit . `` It was very emotional . '' Six people died in the shooting at a Tucson supermarket earlier this month , including a federal judge and a 9-year-old girl . A total of 19 people were shot . Giffords is the only one who remains hospitalized . Police said they believe suspect Jared Lee Loughner , 22 , targeted Giffords in the attack . Loughner is in custody and facing federal charges . Despite reaching a series of milestones , Giffords has a long road ahead , doctors have said . Once she enters rehabilitation , the process is expected to take four to six months . CNN 's Elizabeth Cohen contributed to this report .
Doctor : Giffords `` does not need as much assistance as we had anticipated '' She will remain in ICU while fluid is drained off her brain . The rehabilitation process is expected to take 4 to 6 months .