CHICAGO (CBS) — Sen. Mark Kirk’s staff has released the first photo of the senator since he suffered a stroke in January.

The photo shows the senator sitting at a desk. His right arm is resting on the table top, while his left arm is down to his side.

Kirk suffered the stroke in mid-January and he underwent surgery at Northwestern Memorial Hospital. He has been undergoing intensive physical therapy at the Rehabilitation Institute of Chicago since mid-February.

U.S. Rep. John Shimkus (R-Ill.) met with Kirk in March. At the time, The Chicago Sun-Times quoted Shimkus as saying that mentally, Kirk is sharp, and already would be capable of casting “knowledgeable votes” in the Senate.

Doctors have said Kirk should make a full mental recovery, though they expect him to have limited movement on his left side.

Dr. Richard L. Harvey, Medical Director of the Rehabilitation Institute of Chicago (RIC) Center for Stroke Rehabilitation on Tuesday said: “Senator Kirk remains fully engaged in all aspects of his rehabilitation program. He is mentally sharp, and meets with his staff nearly every day to discuss policy issues and global current events. Senator Kirk is working very hard in daily therapy sessions to increase his strength and mobility, and has walked more than 10 miles in total since his arrival at RIC. In addition he is climbing stairs and getting in and out of vehicles. We are quite pleased with his ongoing recovery.”

Physicians have said Kirk suffered an ischemic stroke, the most common type. According to the American Stroke Association’s website, ischemic strokes account for about 87 percent of all cases. They are the result of an obstruction within a blood vessel that supplies blood to the brain, caused by fatty deposits in the blood vessels.

Kirk, a North Shore Republican, was elected to the U.S. Senate in 2010, winning the seat once held by President Barack Obama. Before that, he spent 10 years in the U.S. House.