Forebrain Control of Locomotion
Many behaviors in humans and animals are expressed as different kinds of locomotive movements: walking, jogging, dancing, swimming, etc. On one hand, locomotion is a highly automatic movement. The neural mechanisms that determine the order of muscular contractions and the coordination of limb movements during locomotion reside in the spinal cord.
On the other hand, the spinal mechanism lacks the distant information about the outside world and information about the purpose of locomotion. However, the basic pattern of locomotion may have numerous volitional variations to adapt it to the peculiarities of the environment and to the changing needs of a subject. This adaptation is possible due to the involvement of the higher brain motor centers. For example, when walking in natural environments, humans and animals must control the transfer and placement of their feet accurately in order to avoid numerous obstacles and irregularities. It is the activity of supraspinal, higher brain centers that modifies locomotion based on visual information.
The overall aim of this project is to understand the neuronal mechanisms of the forebrain that are involved in the adaptation of locomotion to the visually perceived features of the environment.
In our experiments, we test subjects during simple over-ground walking on an even surface when locomotion can proceed successfully even in the dark or with closed eyes, and we test them during walking along a horizontal ladder where vision is required for accurate foot placement on the cross-pieces. We record kinematic and dynamic parameters of limb, head, and body movements, the activity of limb muscles, and the neuronal activity of the motor thalamus and motor and parietal cortices. We then compare body mechanics, the activity of muscles, and the activity of brain areas in these two tasks to discover the parameters that are associated specifically with stepping under visual control.
In the analysis of biomechanics of complex locomotion behaviors we collaborate with the laboratory of Dr. Boris Prilutsky at the Georgia Institute of Technology in Atlanta, Georgia. Together we conduct experiments in Phoenix during which we record the whole-body kinematics and dynamics of subjects while they walk along a cluttered pathway, along series of elevated platforms, or along a narrow strip. We also record the activity of the motor region of the cerebral cortex the same time.
Our studies of the forebrain control of locomotion are leading to a better understanding of neuronal mechanisms of the forebrain for control of visually guided locomotion. The results may have significant clinical applications. In forebrain stroke patients, the choice of rehabilitation strategies for locomotion deficits depends largely on understanding the role of direct forebrain control of locomotion in relation to spinal mechanisms.