Selective Responses to Tonic Descending Commands by Temporal Summation in a Spinal Motor Pool

Wang, Wei Chun; McLean, David L.

doi:10.1016/j.neuron.2014.06.021

Cited by 73 publications

(67 citation statements)

References 69 publications

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“…A classical caveat with Ca 2+ -based measurements of neuronal activity is to determine whether the signal represents spiking or subthreshold activity. Electrophysiological recordings coupled with Ca 2+ imaging of the same neuron (with the same Ca 2+ indicator than the one used in the present study) revealed that a 0.09 increase in ΔF/F is associated with spiking [53], [54], and this is consistent with recent observations in salamanders (see [31]). This would indicate that most RS cells illustrated in e.g.…”

Section: Discussionsupporting

confidence: 93%

Interfacing a salamander brain with a salamander-like robot: Control of speed and direction with calcium signals from brainstem reticulospinal neurons

Ryczko

Thandiackal

Ijspeert

2016

2016 6th IEEE International Conference on Biomedical Robotics and Biomechatronics (BioRob)

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Abstract-An important topic in designing neuroprosthetic devices for animals or patients with spinal cord injury is to find the right brain regions with which to interface the device. In vertebrates, an interesting target could be the reticulospinal (RS) neurons, which play a central role in locomotor control. These brainstem cells convey the locomotor commands to the spinal locomotor circuits that in turn generate the complex patterns of muscle contractions underlying locomotor movements. The RS neurons receive direct input from the Mesencephalic Locomotor Region (MLR), which controls locomotor initiation, maintenance, and termination, as well as locomotor speed. In addition, RS neurons convey turning commands to the spinal cord. In the context of interfacing neural networks and robotic devices, we explored in the present study whether the activity of salamander RS neurons could be used to control off-line, but in real time, locomotor speed and direction of a salamander robot. Using a salamander semiintact preparation, we first provide evidence that stimulation of the RS cells on the left or right side evokes ipsilateral body bending, a crucial parameter involved during turning. We then identified the RS activity corresponding to these steering commands using calcium (Ca

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Section: Discussionsupporting

confidence: 93%

Interfacing a salamander brain with a salamander-like robot: Control of speed and direction with calcium signals from brainstem reticulospinal neurons

Ryczko

Thandiackal

Ijspeert

2016

2016 6th IEEE International Conference on Biomedical Robotics and Biomechatronics (BioRob)

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“…In contrast, asymmetric processing of pitch is straightforward to implement given central vestibular architecture. Pitch information is represented in the brain by distinct nose-up and nose-down channels — independent populations of vestibular neurons with direct projections to movement generation centers [27; 28; 29; 10; 30; 31; 32; 33]. Thus, functional asymmetries between the nose-up and nose-down channels could mediate asymmetric sensitivity.…”

Section: Discussionmentioning

confidence: 99%

Control of Movement Initiation Underlies the Development of Balance

2017

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Summary Balance arises from the interplay of external forces acting on the body and internally generated movements. Many animal bodies are inherently unstable, necessitating corrective locomotion to maintain stability. Understanding how developing animals come to balance remains a challenge. Here we study the interplay between environment, sensation, and action as balance develops in larval zebrafish. We first model the physical forces that challenge underwater balance and experimentally confirm that larvae are subject to constant destabilization. Larvae propel in swim bouts that, we find, tend to stabilize the body. We confirm the relationship between locomotion and balance by changing larval body composition, exacerbating instability and eliciting more frequent swimming. Intriguingly, developing zebrafish come to control the initiation of locomotion, swimming preferentially when unstable, thus restoring preferred postures. To test the sufficiency of locomotor-driven stabilization and the developing control of movement timing, we incorporate both into a generative model of swimming. Simulated larvae recapitulate observed postures and movement timing across early development, but only when locomotor-driven stabilization and control of movement initiation are both utilized. We conclude the ability to move when unstable is the key developmental improvement to balance in larval zebrafish. Our work informs how emerging sensorimotor ability comes to impact how and why animals move when they do.

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“…The mechanisms responsible for recruiting Mauthner versus non-Mauthner escape circuits are still unclear, but presumably arise from a combination of their integrative properties and the nature of input from upstream visual processing centers [45]. One possibility is that visual inputs are evenly distributed among spinal projecting neurons.…”

Section: Discussionmentioning

confidence: 99%

Visual Threat Assessment and Reticulospinal Encoding of Calibrated Responses in Larval Zebrafish

2017

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Summary All visual animals must decide whether approaching objects are a threat. Our current understanding of this process has identified a proximity-based mechanism where an evasive maneuver is triggered when a looming stimulus passes a subtended visual angle threshold. However, some escape strategies are more costly than others and so it would be beneficial to additionally encode the level of threat conveyed by the predator's approach rate to select the most appropriate response. Here, using naturalistic rates of looming visual stimuli while simultaneously monitoring escape behavior and the recruitment of multiple reticulospinal neurons, we find that larval zebrafish do indeed perform a calibrated assessment of threat. While all fish generate evasive maneuvers at the same subtended visual angle, lower approach rates evoke slower, more kinematically variable escape responses with relatively long latencies as well as the unilateral recruitment of ventral spinal projecting nuclei (vSPNs) implicated in turning. In contrast, higher approach rates evoke faster, more kinematically stereotyped responses with relatively short latencies, as well as bilateral recruitment of vSPNs and unilateral recruitment of giant fiber neurons in fish and amphibians called Mauthner cells. In addition to the higher proportion of more costly, shorter latency Mauthner-active responses to greater perceived threats, we observe a higher incidence of freezing behavior at higher approach rates. Our results provide a new framework to understand how behavioral flexibility is grounded in the appropriate balancing of trade-offs between fast and slow movements when deciding to respond to a visually perceived threat.

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Selective Responses to Tonic Descending Commands by Temporal Summation in a Spinal Motor Pool

Cited by 73 publications

References 69 publications

Interfacing a salamander brain with a salamander-like robot: Control of speed and direction with calcium signals from brainstem reticulospinal neurons

Interfacing a salamander brain with a salamander-like robot: Control of speed and direction with calcium signals from brainstem reticulospinal neurons

Control of Movement Initiation Underlies the Development of Balance

Visual Threat Assessment and Reticulospinal Encoding of Calibrated Responses in Larval Zebrafish

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