Over time, humans have developed the remarkable ability to use what they see to guide and control their motor actions, or voluntary movement of limbs and muscles, as well as their behaviour. For example, we are proficient not only in carrying out tasks such as picking up an object, but also in making decisions such as estimating how far our arm needs to stretch to reach the object.
This type of visual-motor control is routine, yet vital for an individual. What makes this coordination so precise is the fact that much of the brain is specialized for such control. Examining how the brain and nervous system control these actions forms the research focus of Dr. Aditya Murthy, an Associate Professor in the Centre for Neuroscience at the Indian Institute of Science, Bangalore.
When we need to respond to an object within the range of our eyesight, there are certain cognitive processes that happen in our brain. “The visual system needs to talk to the motor system, and the brain has to coordinate this process,” explains Dr. Murthy. In order to successfully execute a voluntary movement, such as grabbing an object placed in front of us, our brains may need to process a range of decisions. Some of these include the will to reach an object (volition), understanding the relation of the object with respect to our body (perception), developing mechanisms to obtain the object (selection), sending motor commands to muscles (initiation), feedback on motor movement (monitoring) and changing motor or muscle movements to improve accuracy (correction).
One of the ways Dr. Murthy’s lab studies ‘correction’ is using a robotic arm to administer a sudden jerk, and observing how the participant responds to and corrects for this change in movement in a trial, and anticipate this perturbation across trials. Such techniques help researchers understand the “nature of computation that the brain must perform in order to enable behaviours such as error correction and motor learning,” explains Dr. Murthy.
Other techniques used in the lab include Electromyography (EMG) and Trans-cranial Magnetic Stimulation (TMS). The lab members are using TMS to stimulate certain areas of the brain and observe the corresponding motor reactions. Using such non-invasive techniques gives researchers the opportunity to study brain structure and function in normal individuals as well as those with certain neurodegenerative disorders.
Dr. Murthy uses these techniques to investigate several important questions in the field of cognitive neuroscience today: How does the brain plan and control movements? What is the mechanism behind the hand-eye coordination? How can movement decisions be modified in real time? How can actions be modulated by past performance? According to Dr. Murthy, these questions have several implications for neurodegenerative disorders involving motor impairment.
“The basal ganglia is a brain structure involved in visual motor control that transforms visual input to motor output, and it gets infected in diseases like Parkinson’s disease, Huntington’s disease and Obsessive Compulsive Disorder,” he explains. “These are disorders of action control. Using research on visual-motor control, we can observe the differences between the healthy brain, the primate brain and the diseased brain.” Research carried out in Dr. Murthy’s lab has improved our understanding of such disorders that cause physical and mental defects.
For the past 18 years, Dr. Murthy has been studying how visual information that is processed by the nervous system gets converted into overt behaviour. Today, he and his students are working on understanding the basis of how motor actions are performed effortlessly in the hope that their findings may be used to develop robots that can mimic the range of human motor actions. Dr. Murthy explains, “Robots are very precise, and when we compare robots to human motor movements, we realize that human movements are somewhat messier. However, human movements are far more complicated and flexible. A human can juggle and do gymnastics, but there is no robot alive that can do the same.”
An upcoming field of study in India, cognitive neuroscience has advanced rapidly in the past decade. When Dr. Murthy established his lab in 2009 at IISc, it was one of three neuroscience labs at the Centre for Neuroscience. Over the years, with the help of generous government aid and support from IISc, the Centre has grown to house eleven labs pursuing cutting-edge neuroscience that have contributed greatly to advancing research in this area.
While talking about the challenges of running a lab in this field, Dr. Murthy states, “More flexibility in the typical undergraduate curriculum is required for students to be become truly comfortable to pursue interdisciplinary research that is characteristic of neuroscience today. But, the good thing about our field is that there are a lot of research areas that have not been investigated. And there are many different ways in which you can see the same problem.”