Sinnesrennen zwischen motorisch gesteuerten Hirnregionen zur Koordinierung der Reaktione auf die Auenßenwelt

01/08/2021 to 31/07/2024

nteracting with the surrounding environment requires a fine balance
between following internal goals while maintaining sensitivity to external
events. Since the 1980’s, the main perspective in cognitive neuroscience
has been to study how the brain selects the appropriate behavior in reaction
to an external event. Thus, the primary experimental approach was to rely
on highly well controlled “trials” in which specific sensory task events occur
and specific behavioral outputs are measured. However, no matter how well
controlled intra-trial experimental events are, the trials themselves and their
first sensory stimuli necessarily come asynchronously to the ongoing internal
brain state. This creates what we call a “race condition” between the
processing of the new external information and the completion of internal
plans. In the present proposal, we will study this race condition in the visual
modality and with eye movements. We argue that before any orienting eye
movement response to the outside world can happen, an interruption of
internal ongoing processes must first take place. We will rigorously investigate the neurophysiological basis underpinning a very early and
automatic interrupt process caused by exogenous events. Our primary
hypothesis is that endowing neurons at the edge of the motor control
periphery with early visual sensitivity might help in handling the coordination
needed between whether to orient to the outside stimulus or whether to first
complete execution of an already planned movement. To that end, we will
study omnipause neurons (OPNs) located in the brainstem, which gate eye
movements by maintaining inhibition upon saccade burst neurons and only
allow saccades when they pause. We will show that OPNs, in fact, exhibit a
vast and intriguing repertoire of visual responses. Their inhibitory properties,
together with their visual sensitivity, make them the perfect candidate to
support interruption of ongoing oculomotor behavior before responding to
exogenous stimuli. On the other hand, sensory properties in a neighboring
structure, superior colliculus (SC), support orienting behaviour instead.
Understanding how a sensory race between OPNs and SC underlies flexible
motor behavior will provide a highly mechanistic description of exactly what
to expect in terms of the final motor response when external stimuli come
asynchronously to internal brain state. The transformative aspect of the
proposal is that it will strongly recast traditional interpretations of the
functional roles of late motor control structures in the lower brainstem.
Moreover, the concept of interruption explored in the proposal can clarify a
wide variety of neurophysiological observations related not only to
oculomotor control circuitry, but also to cognitive and perceptual processes,
providing deeper explanation of some of the most classic cognitive findings
in the attention literature, as well as findings related to decision processes
underlying overt orienting.