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Elife. 2017 Sep 11;6. pii: e29648. doi: 10.7554/eLife.29648.

Removal of inhibition uncovers latent movement potential during preparation.

Author information

1
Department of Bioengineering, University of Pittsburgh, Pittsburgh, United States.
2
Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, United States.
3
Department of Otolaryngology, University of Pittsburgh, Pittsburgh, United States.
4
Department of Neuroscience, University of Pittsburgh, Pittsburgh, United States.

Abstract

The motor system prepares for movements well in advance of their execution. In the gaze control system, the dynamics of preparatory neural activity have been well described by stochastic accumulation-to-threshold models. However, it is unclear whether this activity has features indicative of a hidden movement command. We explicitly tested whether preparatory neural activity in premotor neurons of the primate superior colliculus has 'motor potential'. We removed downstream inhibition on the saccadic system using the trigeminal blink reflex, triggering saccades at earlier-than-normal latencies. Accumulating low-frequency activity was predictive of eye movement dynamics tens of milliseconds in advance of the actual saccade, indicating the presence of a latent movement command. We also show that reaching a fixed threshold level is not a necessary condition for movement initiation. The results bring into question extant models of saccade generation and support the possibility of a concurrent representation for movement preparation and generation.

KEYWORDS:

concurrent processing; eye movements; inhibitory gating; neuroscience; rhesus macaque; sensorimotor; superior colliculus; threshold

PMID:
28891467
PMCID:
PMC5650474
DOI:
10.7554/eLife.29648
[Indexed for MEDLINE]
Free PMC Article

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