Conference PaperPDF Available

Visual backward masking in rats: a behavioral task for studying the neural mechanisms of visual awareness

Abstract

The neural mechanism of visual awareness has been primarily studied by contrasting neural activity between visible and invisible stimuli, in attempt to unveil the necessary and sufficient condition for neural representations to enter conscious vision. Visual illusions that render stimuli invisible (e.g., binocular rivalry, backward masking) are prominent behavioral paradigms. So far, majority of studies on visual awareness have been conducted on human and non-human primates. Although these studies greatly contributed to establishing specific brain region-dependent modulation of neural activity by awareness, the field would benefit from being able to conduct experiments on rodents. This advance would provide access to modern techniques such as optogenetic manipulation and two-photon imaging, etc. Here, for the first time, we report backward masking in rats. Backward masking is a visual illusion in which a target is rendered invisible by a visual mask that follows the target with a brief stimulus onset asynchrony (SOA). We first developed a head-fixed rat spherical treadmill system that is amicable to rats performing visual tasks with low contrast, short duration stimuli, which are required for testing backward masking. Rats were initially trained to discriminate a “go” target (vertical grating: 0.15cpd, 28deg visual angle) and a “no-go” target (horizontal grating: 0.075 cpd, 28deg visual angle) without the visual mask. They responded either by running or staying still on the treadmill during a brief time-window after stimulus presentation and were rewarded with drops of water for running in response to “go” target and punished with time-out penalty for running in response to a “no-go” target. Duration and contrast of target stimuli were gradually reduced to experimental parameters for the backward masking experiment (duration:16ms, luminance contrast:15%). After achieving threshold performance (d’ >1.5), backward masking experiments were conducted with SOAs at 16, 33, 49, 66, 83, 99, 116 ms. Plaids were used as visual mask (duration:33ms, luminance contrast:95%). In all 5 rats, smaller SOA led to statistically non-significant differences between hit and false-alarm ratio. In contrast, difference between hit and false alarm rate were significant for larger SOAs. Threshold SOAs at which masking occurred varied across rats (range: 33m -66ms). In conclusion, a visual stimulus can be rendered invisible with short SOAs, and hence, backward masking can be used to study the neural correlate of consciousness in rats.
5/9/14, 3:06 PMOasis, The Online Abstract Submission System
Page 1 of 3http://www.abstractsonline.com/submit/SubmitPrinterFriendlyVer…004%7D&MKey=%7B54C85D94%2D6D69%2D4B09%2DAFAA%2D502C0E680CA7%7D
Print this Page for Your Records Close Window
Control/Tracking Number: 2014-S-8540-SfN
Activity: Scientific Abstract
Current Date/Time: 5/9/2014 8:05:46 AM
Visual backward masking in rats: a behavioral task for studying the neural mechanisms of visual awareness
AUTHOR BLOCK: *M. WATANABE1, N. TOTAH1, K. KAISER2, S. LÖWE2, N. K. LOGOTHETIS1;
1Logothetis, Max Planck Inst. For Biol. Cybernetics, Tuebingen, Germany; 2Univ. of Tuebingen, Tuebingen, Germany
Abstract:
The neural mechanism of visual awareness has been primarily studied by contrasting neural activity between visible and
invisible stimuli, in attempt to unveil the necessary and sufficient condition for neural representations to enter conscious
vision. Visual illusions that render stimuli invisible (e.g., binocular rivalry, backward masking) are prominent behavioral
paradigms.
So far, majority of studies on visual awareness have been conducted on human and non-human primates. Although these
studies greatly contributed to establishing specific brain region-dependent modulation of neural activity by awareness, the
field would benefit from being able to conduct experiments on rodents. This advance would provide access to modern
techniques such as optogenetic manipulation and two-photon imaging, etc.
Here, for the first time, we report backward masking in rats. Backward masking is a visual illusion in which a target is
rendered invisible by a visual mask that follows the target with a brief stimulus onset asynchrony (SOA). We first developed a
head-fixed rat spherical treadmill system that is amicable to rats performing visual tasks with low contrast, short duration
stimuli, which are required for testing backward masking.
Rats were initially trained to discriminate a “go” target (vertical grating: 0.15cpd, 28deg visual angle) and a “no-go” target
(horizontal grating: 0.075 cpd, 28deg visual angle) without the visual mask. They responded either by running or staying still
on the treadmill during a brief time-window after stimulus presentation and were rewarded with drops of water for running in
response to “go” target and punished with time-out penalty for running in response to a “no-go” target.
Duration and contrast of target stimuli were gradually reduced to experimental parameters for the backward masking
5/9/14, 3:06 PMOasis, The Online Abstract Submission System
Page 2 of 3http://www.abstractsonline.com/submit/SubmitPrinterFriendlyVer…004%7D&MKey=%7B54C85D94%2D6D69%2D4B09%2DAFAA%2D502C0E680CA7%7D
OASIS Helpdesk
Powered by OASIS, The Online Abstract Submission and Invitation System SM
© 1996 - 2014 Coe-Truman Technologies, Inc. All rights reserved.
experiment (duration:16ms, luminance contrast:15%). After achieving threshold performance (d’ >1.5), backward masking
experiments were conducted with SOAs at 16, 33, 49, 66, 83, 99, 116 ms. Plaids were used as visual mask (duration:33ms,
luminance contrast:95%).
In all 5 rats, smaller SOA led to statistically non-significant differences between hit and false-alarm ratio. In contrast,
difference between hit and false alarm rate were significant for larger SOAs. Threshold SOAs at which masking occurred
varied across rats (range: 33m -66ms).
In conclusion, a visual stimulus can be rendered invisible with short SOAs, and hence, backward masking can be used to
study the neural correlate of consciousness in rats.
:
Presentation Preference (Complete): Nanosymposium Preferred
Linking Group (Complete): None selected
Nanosymposium Information (Complete):
Theme and Topic (Complete): D.05.b. Sensorimotor transformation: Behavior and whole animal ; D.04.n. Representation
of objects
Keyword (Complete): CONSCIOUSNESS ; VISUAL PERCEPTION ; VISION
Support (Complete):
Support: Yes
Grant/Other Support: : Grant/Other Support: Marie Curie Incoming International Fellowship (WHISKERATTENTION
project, grant number: PIIF-GA-2012-331122)
Special Requests (Complete):
Would you be interested in being considered for a dynamic poster?: No, I am not interested in presenting a Dynamic
Poster
Is the first (presenting) author of this abstract a high school or undergraduate student?: None
Religious Conflict?: No Religious Conflict
Additional Conflict?: No
Status: Finalized
5/9/14, 3:06 PMOasis, The Online Abstract Submission System
Page 3 of 3http://www.abstractsonline.com/submit/SubmitPrinterFriendlyVer…004%7D&MKey=%7B54C85D94%2D6D69%2D4B09%2DAFAA%2D502C0E680CA7%7D
ResearchGate has not been able to resolve any citations for this publication.
ResearchGate has not been able to resolve any references for this publication.