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@PHDTHESIS{Nabbefeld:964006,
author = {Nabbefeld, Gerion},
othercontributors = {Kampa, Björn M. and Musall, Simon Fritjof},
title = {{S}ignatures of cortical multisensory integration in mice
performing a novel visuotactile evidence accumulation task},
school = {RWTH Aachen University},
type = {Dissertation},
address = {Aachen},
publisher = {RWTH Aachen University},
reportid = {RWTH-2023-08096},
pages = {1 Online-Ressource : Illustrationen, Diagramme},
year = {2022},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University 2023; Dissertation, RWTH Aachen University, 2022},
abstract = {Much effort has been focused on studying how the brain
processes information from our individual senses. However,
the neural mechanisms, that allow the effortless integration
of unisensory inputs into multisensory percepts, are largely
unknown. To study how neural circuits integrate visual and
tactile information, we developed a multisensory
discrimination task for head-fixed mice. Here, two sequences
of visual, tactile or combined visuotactile stimuli are
presented on both sides of the mouse, which has to indicate
the higher-rate target-side to obtain a water reward. To
ensure integration of sensory information over the entire
stimulus period, a short delay was added before the
response. Mice achieved high accuracy in all conditions,
with improved performance in the multisensory condition.
This behavioral task gave us the opportunity to investigate
the neural circuits that allow mice to synergistically use
both the visual and tactile sensory information to solve the
behavioral task. We then used widefield imaging to measure
cortex-wide activity in transgenic mice expressing the
Ca2+-indicator GCaMP6s in all cortical excitatory neurons.
Here, we found that multisensory stimuli evoked higher
neuronal activity compared to unisensory stimulation. This
was most evident in the rostrolateral association area RL
and parts of medial frontal cortex (mFC), which reliably
responded to both visual and tactile stimuli. To better
isolate sensory responses from co-occurring task- or
behavior-related activity, we used a linear encoding model.
Including a multisensory interaction-term significantly
improved the predictions of cortical activity. With this
approach we identified two key features of sensory evoked
responses, depending on the stimulus condition. First, in
unisensory trials mice display cross-modal inhibition. Here,
in addition to the main sensory responses in the
corresponding sensory cortex, robust inhibition of activity
in the non-matching sensory cortex was found. Second, we
found additional superadditive responses in multisensory
trials, likely representing the absence of cross-modal
inhibition as well as increased activity in areas RL and
mFC. To understand how sensory information is used to guide
behavioral decisions, we first investigated which brain
areas displayed activity that reliably reflected the target
stimulus side. Here, the medial motor cortex more faithfully
reflected the target-side in tactile trials, while secondary
visual areas were more reliable in visual trials. In
multisensory trials, both regions accurately reflected the
target-side, likely resulting in higher certainty and
improved performance in multisensory trials. Finally, using
a choice-decoder we identified choice-related neural
activity in the anterolateral motor cortex (ALM), as well as
in licking-related regions of the primary motor and
somatosensory cortex. With this approach, we found no clear
modality-specific differences, suggesting that the same
neural circuits form decisions in all stimulus conditions.
Our results demonstrate that multisensory stimulation cause
widespread cortical activation in mice, which leads to
improved task performance. Here, cross-modal inhibition in
unisensory trials and superadditive multisensory integration
especially in RL and mFC were found in multisensory trials,
likely aiding mice in performing the individual task
condition. Sensory information is then accumulated over the
stimulus period in secondary visual areas and medial motor
cortex and this information converges in the secondary motor
cortex to form modality-unspecific decisions. These findings
give us a much deeper understanding of how the brain
processes and generalizes sensory information in order to
guide behavioral decisions.},
cin = {162320 / 160000},
ddc = {570},
cid = {$I:(DE-82)162320_20140620$ / $I:(DE-82)160000_20140620$},
pnm = {GRK 2416 - GRK 2416: MultiSenses-MultiScales: Neue Ansätze
zur Aufklärung neuronaler multisensorischer Integration
(368482240)},
pid = {G:(GEPRIS)368482240},
typ = {PUB:(DE-HGF)11},
doi = {10.18154/RWTH-2023-08096},
url = {https://publications.rwth-aachen.de/record/964006},
}
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