Motor control

…yet poorly understood question of motor control: How can rhythmic movements, such as walking, be generated and stopped at any point in the cycle while posture is preserved? Since conventional models of spinal motor function rely on alternation between flexor and extensor modules, which are limited to just two phases, this question exposes the essential shortcoming of the conventional understanding: How ca

…interpretations, evolutionary claims, motor control and the limits of low-dimensional descriptions, along with work on restoring movement after spinal-cord injury.

…angular variables for working memory, motor control, and navigation. Theories have proposed that such representations are maintained by a class of recurrently connected networks called ring attractor networks. These networks rely on large numbers of neurons to maintain continuous and stable representations and to accurately integrate incoming signals. The head direction system of the fruit fly, however, seems to achieve these properties with a remarkably small network. These findings challenge our understanding of ring attr

Most walking animals can maintain motor control after limb injury or amputation, where coordinating movements of a drastically altered body requires dynamic interactions between the nervous system, the biomechanics of the body, and the physical environment. Until recently, it has been challenging to link neural and biomechanical models to investigate adaptive motor recovery because it requires coupling neural control in closed-loop with the environment. Further, while previous approaches have been able to simulate walking in biomechanically realistic bodies, the joint kinematics and ground rea

Artifical neural network (ANN) approaches to motor control commonly adopt generic architectures like fully connected multi-layer perceptrons (MLPs) and recurrent neural networks (RNNs). As such architectures contain few inductive biases, it is common to require priors in the form of rewards, training curricula, imitation data, or trajectory generators. In nature, animals are born with priors in the form of their nervous system's architecture, which has been shaped by evolution to confer innate ability and efficient learning. For instance, a horse can walk within hours of birth and quickly impr

Understanding the neuromechanical principles of collective motor behaviors is a longstanding question at the intersection between neuroscience, motor control and fluid mechanics. Striking examples of these behaviors include the patterns formed by fishes swimming or birds flying in schooling formations. What is the advantage of schooling? What central vs peripheral control mechanisms are involved in these emergent behaviors? Modeling the closed loop interaction between the neural and mechanical components describing collective behaviors is a complex task. It requires accurate modeling and si

Understanding how the brain encodes movements is vital for motor control. Research suggests that this involves comparing proprioceptive inputs from the body with an internal model of expected movement. When these signals match, vestibular signals---which would otherwise stabilize the head against movements---are suppressed, allowing voluntary movement to occur. This mechanism implies that integrating proprioceptive and vestibular inputs is crucial for effective coordination. While previous studies indicate the involvement of multiple brain areas, with the PIVC at the forefront, the mechanisms

Motor control is a complex, high-dimensional task. It has been suggested that the brain may reduce the dimensionality of this control problem by using a set of motor primitives (or muscle synergies) that encode frequently used patterns of muscle co-activations in the time and/or weight-domain (Bizzi et al., 1991; Kutch and Valero-Cuevas, 2012; Bizzi and Cheung, 2013; Alessandro et al., 2013). In this project we investigate how motor primitives may affect the learning of movement in motor cortex. We model motor cortex as a recurrent neural network (RNN) and compare two potential output scenario

For motor control, the activities of local neural nets need to be coordinated, which can be attained via direct synaptic connections. Phylogenetically, the main purpose of the brain is the active interaction with the environment which suggests the presence of an alternative neural coordination mechanism, namely one that is mediated by a feedback loop involving the outside world. In this context we study the coordination of otherwise isolated neural clusters via 'force coupling', viz exclusively through the reactive forces of the body. Coordination arises when a given neural net reacts to the

…is in learning, decision-making and motor control, as manifested in the PD symptoms such as rigidity, slowness of movements, tremor and poor behavioural flexibility. Following DA loss, the un

The human brain quickly adapts to a changing environment, often faster than can be explained by synaptic plasticity. One of the main candidates to account for such rapid changes is neuromodulation. We explore how modulation can assist a recurrent neural network to accommodate a range of variations of the tasks it is initially trained on. There are a number of approaches allowing for rapid acquisition of new tasks, for example, the neuronal gain modulation model [1]. However, we found that by affecting the input-output function of a neuron such an approach can neither address the variation of a

…The intricate orchestration of motor control is governed by the cortico-basal ganglia- thalamocortical loops, with recent investigations highlighting the pivotal role of basal ganglia downstream projections to pedunculopontine nucleus (PPN) in regulating specific motor programs. Despite these advancements, the precise mechanisms through which the basal ganglia networks selectively control these functional motor modules remain incompletely elucidated. Our findings in mouse reveal that th

…for touch-based shape perception and motor control. However, the spatiotemporal dynamics of how tactile information is remapped from the somatotopic reference frame in the primary somatosensory cortex to the spatiotopic reference frame remains unclear. This study investigated how hand position in space or posture influences cortical somatosensory processing. Twenty-two healthy subjects received electrical stimulation to the right thumb (D1) or little finger (D5) in three position conditions: palm down on right side of the body

…limited sample sizes of imaging case-control studies. We focused instead on brain structural correlates of genetic disposition to dyslexia in large-scale population data. In over 30,000 adults (UK Biobank), higher polygenic disposition to dyslexia was associated with lower head and brain size, and especially reduced volume and/or altered fiber density in networks involved in motor control, language and vision (Fig. 1). However, individual genetic variants disposing to dyslexia

Dopamine transmission is involved in reward processing and motor control, and its impairment plays a central role in numerous neurological disorders. Despite its strong pathophysiological relevance, the molecular and structural organization of the dopaminergic synapse remains to be established. We used targeted labeling and fluorescence-activated sorting to purify striatal dopaminergic synaptosomes. Our data reveal the adhesion of dopaminergic varicosities to glutamatergic, GABAergic, or cholinergic synapses in tripartite structures we named “dopamine hub synapses.” We provide the proteome of

…the neural mechanisms underpinning motor control in the domain of social interaction remain poorly understood, especially at single cell or population level. Our previous studies demonstrated that both monkeys and humans adapt their behaviour when acting in a dyadic context, and that macaques, as humans, leverage on a “we-representation”, suggesting phylogenetically preserved neural processes. At neural level, we showed in macaque dorsal premotor (PMd/F2) cortex the existence of a population of cells, preferentia

Precise motor control relies on appropriate connections between subcerebral projection neurons (SCPN) in cerebral cortex and targets in brainstem and spinal cord. While cortical innervation of the spinal cord is crucial for skilled movement, input into the brainstem additionally fine-tunes movement and motor planning. The brainstem receives cortical input either through: 1) cortico-brainstem neurons (CBN) innervate brainstem directly without reaching into the spinal cord, 2) corticospinal neurons (CSN) project to the spinal cord while also branching in brainstem. Distinguishing between these t

Spinal cord injury immediately impairs movement control and other essential physiological functions. Evidence has shown that a large-scale network including spinal and supraspinal structures is recruited after SCI to promote functional recovery. Orexins (hypocretins), known for promoting wakefulness, arousal, and reward-seeking behaviours, also influence muscular tone, locomotion initiation, and skilled performance, exerting a multi-systemic effect on motor control predisposing for movement execution. Despite the potential relevance of orexin transmission in motor recovery after CNS damage, th

Complex behavioral tasks like grasping require precise and accurate motor control. This demands an intricate interplay between proprioceptive processing and motor command generation within the sensorimotor system. While the task-driven modeling approach has proven successful in capturing sensory representations, adapting it to model the sensorimotor system has remained a challenge. Here, we investigate the potential of deep reinforcement learning to capture sensorimotor representations. By training artificial agents to imitate natural grasp movements using imitation learning, we develop stimul

Flour beetles such as Tribolium castaneum are devastating pests of dry stored grain products, causing up to 19% loss of these commodities in the Global South. Little is known about how the nervous systems of these animals coordinate effective movement. We therefore employed novel behavioural assays combined with whole-animal and leg tracking to assess how larvae move over different types of terrain. We found that larvae move most efficiently over fibrous substrates (e.g. paper), consistent with the beetle’s original habitat of tree bark. Locomotion over flat terrain primarily involves movement

…is a common target for treating PD's motor symptoms. However, we have little understanding of STN pathology in PD. We aimed to examine the cellular and functional pathology of the STN in PD using both rodent and post-mortem human brain tissue. First, we show bidirectional motor control by STN using optogenetic modulation, where inhibition of the STN increases movement and STN activation decreases movement. We also examined the effect of bidirectional optogenetic m

Goal-directed action control relies on the prefrontal cortex (PFC), where distinct subsections collaborate in functional networks. The extent to which the network favors a hierarchical system, characterized by early convergence within the PFC, versus a shallow brain hypothesis, featuring numerous parallel circuits from the cortex to downstream targets, remains elusive (Suzuki et al. 2023). Employing optogenetic modulation, behavioral assessments, and fMRI, we investigate the impact of PFC subarea-stimulation on motor control and whole-brain activation patterns. We quantified error rate and rea

Several studies highlight motivation's crucial role in motor decision-making for maximizing potential rewards. However, how explicit rewards impact the neural dynamics of decision-making processes and their effects on neural organization at the network level, is still unexplored. To address this gap, we analyzed neuronal activity recorded from the premotor cortex (PMd) of three monkeys while performing a modified version of the stop signal task. In this task, the motivation to either act or inhibit action was manipulated using Cues that informed about different reward contexts. We conducted an

…It plays an important role in motor control, integrating inputs from upstream structures in the basal ganglia, before sending organised projections to a wide range of targets in the midbrain, brainstem and thalamus. Here we present a detailed in silico model of the mouse SNr, including its afferent inputs. The electrophysiological and morphological properties of SNr neurons are characterised in acute brain slices via whole cell patch-clamp and morphological reconstruction. Using reconstructed morpholog