HOUSTON, Texas – 3 Nov 10
Trinity Student Keeps an Eye on the Prize
By: Heather L. Ogletree
Remember that dizzy disorientation experienced as a child spinning in circles? Remember that feeling of force felt on a roller coaster ride? Envision being catapulted at speeds of 18,000 miles per hour with a total thrust of 7.8 million pounds, and you may start to understand what an astronaut experiences in their journey to and from space.
This summer, Meghan Appelbaum was paired by the Undergraduate Student Research Project (USRP) with NASA Mentor Scott Wood to participate in a project entitled, “Dynamic Visual Acuity as a diagnostic test for vestibulo-ocular reflex function.” During her 10 week experience, she conducted visual acuity tests on 13 subjects on a rotating chair at NASA’s Johnson Space Center in Houston in order to develop a new test which examines how well astronauts can see and react to visual targets when exposed to challenging motions like G transitions.
Dr. Wood explained, “The vestibular organs in our inner ear help us sense motion, and reflexively move our eyes to help vision during fast head movements. If these reflexes aren’t working normally, such as following adaptation to space, it can be difficult to read and respond to displays when experiencing vibrations during a landing because vision alone may not be fast enough to keep up.”
During the tests, Appelbaum and Wood used a rotator to rapidly oscillate subjects back and forth while viewing a computer-generated display. Subjects were asked to recognize the orientation of the letter “C” as quickly and accurately as possible. The letter briefly flashed on the screen, and could appear in any one of eight orientations (e.g., facing rightward, upward, etc.), as well as in random locations on the computer display. The subjects’ responses were recorded using a joystick either with or without motion, and with different presentation times and sizes of the visual targets.
“It is really quite fun conducting tests on people, and I loved getting to meet people from different areas,” said Appelbaum.
Through their tests, Appelbaum found that subjects were more accurate and it took less time to locate targets in the horizontal plane rather than when targets were presented above or below the line of sight. “This supports the fact that the [Vestibulo-Ocular Reflex] is used to help your vision...in the same plane of the movement,” said Appelbaum.
Dr. Wood added, “These reflexes move the eyes in the same plane as the motion, and therefore crewmembers may have more difficulty recognizing displays located along other directions.”
Appelbaum continued, “Hopefully this test can now be used as a pre and post-flight diagnostic test for the astronauts. We know it is a good measure of both accuracy and reaction time so we can use it to pinpoint any specific problems the astronauts may be having with their vestibulo-ocular reflex upon return to Earth.”
As a neuroscience major at Trinity University in San Antonio, Appelbaum was a little apprehensive about her internship. Appelbaum stated, “As an undergrad I was a little insecure at first, but that went away on the first day when I met my mentor, Dr. Scott Wood, and everyone else in the lab.”
In the future, Appelbaum intends to attend graduate school and hopes to one day come back to NASA to work as a Biomedical Flight Controller.
“I have thoroughly enjoyed seeing the background behind the research,” noted Appelbaum. “You never realize how much thought and effort goes into a project until you are a part of it. I have wanted to work for NASA since I was 16 years old, and this internship has definitely strengthened that desire.”