Multijoint movement control: the importance of interactive torques C. Ketcham, N. Dounskaia, G. Descending command issues. How the mesencephalic locomotor region recruits hindbrain neurons I. Kagan, M. Role of basal ganglia-brainstem systems in the control of postural muscle tone and locomotion K. Takakusaki, J. Oohinata-Sugimoto et al. Locomotor role of the corticoreticular-reticulospinal-spinal interneuronal system K. Matsuyama, F. Cortical and brainstem control of locomotion T.
Drew, S. Prentice, B. Direct and indirect pathways for corticospinal control of upper limb motoneurons in the primate R.
Lemon, P. Kirkwood et al. Supraspinal sensorimotor interactions. Arousal mechanisms related to posture and locomotion: 1. Descending modulation E. Garcia-Rill, Y. Homma, R. Arousal mechanisms related to posture and locomotion: 2.
Ascending modulation R. Skinner, Y. Homma, E. Switching between cortical and subcortical sensorimotor pathways T. Isa, Y. Cerebellar interactions and control mechanisms. Cerebellar activation of cortical motor regions: comparisons across mammals T.
Yamamoto, Y. Nishimura et al. Task-dependent role of the cerebellum in motor learning J. Role of the cerebellum in eyeblink conditioning V. Integration of multiple motor segments for the elaboration of locomotion: role of the fastigial nucleus of the cerebellum S. Role of the cerebellum in the control and adaptation of gait in health and disease W. Thach, A. Eye-head-neck coordination. Current approaches and future directions to understanding control of head movement B. The neural control of orienting: role of multiple-branching reticulospinal neurons S.
Yoshimura, K. Role of the frontal eye fields in smooth gaze tracking K. Fukushima, T. Yamanobe et al.
Cortical and brainstem control of locomotion.
The role of cross-striolar and commissural inhibition in the vestibulocollic reflex Y. Functional synergies among neck muscles revealed by branching patterns of single, long descending motor-tract axons Y. Sugiuchi, S. Kakei et al. Control of orienting movements: role of multiple tectal projections of the lower brainstem A.
Grantyn, A. The reference system, which is probably stored in interconnecting networks at a high level of the CNS Ito, ; Bloedel and Bracha, ; Thach, ; McFadyen and Belanger, , serves to minimize impairments of posture and locomotion. Third, we hypothesize that descending commands from the cognitive and emotive portions of the higher CNS, and activity of both locomotion-inducing sites and posture-control sites are constantly compared with that of the reference system Fig. Such a system incorporates both anticipatory and reactive control processes.
Note that the authors' model incorporates that component of reactive control that is responsive to corollary discharges of descending output signals, at all levels from the locomotor centers to the spinal cord. Such central feedback combined with peripheral feedback at the cerebral cortical level enables the animal conscious perception of its kinesthetic aspects of volitional and automatic adjustments of ongoing locomotion Gandevia, Fourth, it follows from the above that an integration center must participate in a comparator function: comparing top - down locomotor command signals with bottom - up feedback signals revealing the current state of locomotion.
Top-down signals may originate in either cognitive or emotive brain structures Mogenson et al. For example, the nucleus accumbens, an older part of the striatum, receives input signals from limbic structures, including the hippocampus. It is a major site for initiation of motivation-driven locomotion Mogenson et al. Bottom-up signals contribute to reactive control of posture and locomotion Arshavsky et al.
Fifth, the integration center's efferent output is distributed by way of executing centers see Fig. The latter's function is to ensure that motor signals are sent to a number of different muscle-control systems such that multiple body segments are activated in a coordinated manner. These output signals guarantee that appropriate and timely forces are applied to relevant joints Mori et al. The conversion from Qp to Bp locomotion. Downward and upward arrowheads on each line represent descending and ascending signals to and from each motor segment.
Note the changes in the height of the reward. See the text for further details. Reproduced from Nakajima et al. The executing centers of Fig. These pathways mediate the descending command signals that activate a number of spinal MN columns, each of which innervates a specific set of muscles that operates on a specific motor segment.
Neuroscientists identify brain circuit that integrates head motion with visual signals
The descending command signals comprise those needed to activate spinal pattern generators that bring about the step cycle of each single limb Rossignol, , commissural INs that coordinate left- and right-limb motor segments Matsuyama et al. Some of the output signals also modulate brainstem and spinal circuitry involved in the elaboration of postures that support the execution of locomotion Mori et al.
Didier Le Ray, Locomotion is a basic motor function generated and controlled by genetically defined neuronal networks.
The pattern of muscle synergies is generated in the spinal cord, whereas neural centers located above the spinal cord in the brainstem and the forebrain are essential for initiating and controlling locomotor movements. One such locomotor control center in the brainstem is the mesencephalic locomotor region MLR , first discovered in cats and later found in all vertebrate species tested to date. Over the last years, we have investigated the cellular mechanisms by which this locomotor region operates in lampreys.
The lamprey MLR is a well-circumscribed region located at the junction between the midbrain and hindbrain. Stimulation of the MLR induces locomotion with an intensity that increases with the stimulation strength. Glutamatergic and cholinergic monosynaptic inputs from the MLR are responsible for excitation of reticulospinal RS cells that in turn activate the spinal locomotor networks.
The inputs are larger in the rostral than in the caudal hindbrain RS cells.
In addition to its inputs to RS cells, the MLR activates a well-defined group of muscarinoceptive cells in the brainstem that feeds back strong excitation to RS cells in order to amplify the locomotor output. Finally, the MLR gates sensory inputs to the brainstem through a muscarinic mechanism. It appears therefore that the MLR not only controls locomotor activity but also filters sensory influx during locomotion.
Locomotion is the ability to sit down and stand up, get up and down from the floor, or move and walk around in the environment. Activities such as walking, getting in and out of vehicles, on and off furniture, and maintaining balance are affected by loss of locomotion ability. In order to move around, we require adequate muscle, motor control, and balance. Our legs and feet support the rest of our body and provide the force to propel us forward. Age related musculo-skeletal conditions cause loss of locomotion ability.
In the case of arthritis joint mobility is limited, leading to reduced range of leg and lower body movement. The ability to maintain balance is also reduced, resulting in an increased risk of falling. Because muscle strength in the lower body such as the legs decreases with an increase in age, the arms are more frequently used to support the body when, for instance, sitting down and standing up.