Connecting Circuits for Supraspinal Control of Locomotion

Abstract

Locomotion is regulated by distributed circuits and achieved by the concerted activation of body musculature. While the basic properties of executive circuits in the spinal cord are fairly well understood, the precise mechanisms by which the brain impacts locomotion are much less clear. This Review discusses recent work unraveling the cellular identity, connectivity, and function of supraspinal circuits. We focus on their involvement in the regulation of the different phases of locomotion and their interaction with spinal circuits. Dedicated neuronal populations in the brainstem carry locomotor instructions, including initiation, speed, and termination. To align locomotion with behavioral needs, brainstem output structures are recruited by midbrain and forebrain circuits that compute and infer volitional, innate, and context-dependent locomotor properties. We conclude that the emerging logic of supraspinal circuit organization helps to understand how locomotor programs from exploration to hunting and escape are regulated by the brain.

Dynamic control of visually-guided locomotion through cortico-subthalamic projections

“…Coordinated movement, and in particular locomotion, is enabled by distributed spinal and brain circuits. Although the executive mechanisms for locomotion are implemented in the spinal cord (Goulding, 2009;Grillner, 2003;Kiehn, 2016Kiehn, , 2006, locomotion is importantly regulated by supraspinal circuitry (Ferreira-Pinto et al, 2018;Kim et al, 2017;Ryczko and Dubuc, 2013).…”

Functional MRI Reveals Locomotion-Control Neural Circuits in Human Brainstem

“…All these regions play roles in locomotion. CN and PPN neurons send signals to the spinal cord by recruiting neurons in the medulla oblongata [ 26 ] or project directly to the spinal cord to control locomotion [ 6 ]. The middle parts of the pons-medulla junction area correspond to raphe nuclei in the pons and medulla oblongata, and the lateral parts mainly cover subgroups of nucleus reticularis.…”

“…Gait performance is related to the risk of dementia [ 1 ] and falls in the elderly [ 2 ] that lead to heavy burdens, and can be damaged by critical brain illnesses such as Parkinson’s disease [ 3 ] and stroke [ 4 ]. In the mesencephalic locomotor region (MLR) of vertebrates, the cuneiform nucleus (CN) supports defensive forms of locomotion, such as high-speed running to escape from dangerous contexts, whereas the pedunculopontine nucleus (PPN) may mediate slow, exploratory locomotion [ 5 , 6 ]. Descending dopaminergic projections from the substantia nigra to MLR possibly play a role in the locomotor deficits in Parkinson’s disease [ 7 ].…”

Expanding our horizons: central pattern generation in the context of complex activity sequences

“…This set of experiments thus highlights a caveat of warming/ cooling experiments, namely that it may not be the CPG itself that is manipulated to produce the predicted change, but instead neurons that excite or inhibit the CPG. Perhaps an analogy would be stimulation of the descending brain pathways that trigger locomotion in vertebrates; increased stimulation of these pathways can increase the rate and even alter the form of locomotion, presumably by increasing excitation of spinal cord CPGs (Cabelguen et al, 2003;Ferreira-Pinto et al, 2018;Lennard and Stein, 1977). Warming or cooling HVC in Bengalese finches, besides altering the motif duration, can alter the number of syllables of one type (Fig.…”