[visionlist] PhD position at MPI Tuebingen: Causal studies of awareness with mice visionPosted: July 12, 2017
PhD Position – Max Planck Institute for Biological Cybernetics (Tübingen, Germany)
The Max Planck Institute for Biological Cybernetics offers a PhD student position under the supervision of Dr. Masataka Watanabe in the department of Prof. Nikos Logothetis (Department of Physiology of Cognitive Processes).
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. So far, majority of studies have been conducted on human and non-human primates and the field would benefit from being able to conduct experiments on rodents, which would grant access to modern experimental methods.
The main goal of the project is to extend the study of visual awareness with mice to further understand its neural mechanism by applying techniques such as optogenetic manipulation, high-density neural recording and high-density electric microstimulation. We have two lines of research, where the first builds on a conventional approach utilizing optical illusions that render stimuli invisible, and the second, taking a more radical approach where we attempt to “rewire” a split-brain for full monitoring and manipulation of interhemispheric interaction necessary for bilateral integration of visual awareness.
1) Investigating the causal role of visual areas on awareness with backward masking and optogenetic silencing
We have behavioral evidence that visual backward masking takes effect in rats and mice and will use it to investigate the neural mechanism of visual awareness. 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). The existence of the illusory effect in rodents proves that, as in humans and macaques, elongated neural activity after target offset is required for neural representation to enter visual consciousness. Together with high-density neural recordings under backward masking, we apply optogenetic silencing of visual areas to investigate its causal role on awareness. Results from V1 shows that it does not have a critical role. We are working on higher visual areas such as the postrhinal and perirhinal cortex, where we have successfully recorded visually evoked activity that shows interesting dissociations in neural preference (e.g. preference to visual objects) compared to lower vision, that are yet to be established in rodent vision.
For details of the initial V1 project (submitted), see the SfN abstract below,
2) Investigating the neural code for visual hemifield integration with “rewired” split-brain mice
To investigate the neural mechanisms of bilateral integration of visual awareness, we attempt to “rewire” two cortical hemispheres in split-brain mice. Firstly, we train mice to conduct a bilateral matching task (we have confirmation that mice can perform random dot symmetry detection), and then conduct corpus callosotomy. After confirmation that ability to conduct such tasks are absent, we attempt to rewire split hemispheres to regain minimal behavioral performance. Rewiring of split hemispheres allows us to monitor and modulate all cortical neuronal information exchange between the hemispheres. First generation hemispheric rewiring will be conducted by high-density chronic recording and closed loop micro-stimulation. Rewiring utilizes “bundled microwire chronic electrodes” for tracking neurons for months and high-density low current microstimulation to evoke naturalistic and sparse spatiotemporal action potentials in responses to contralateral neural firing. The experimental configuration not only can tackle the necessary neural information exchange for integration of two streams of awareness, but also allows us to causally test which properties of neural information (e.g. firing rate, spike timing, neural fluctuation) is critical by means of modulating the neural code via artificial rewiring of hemispheres.
For more details and background, please take a look at the talk I gave in UC Berkeley,
Applicants should have a master degree in neuroscience, biology, or experimental psychology. Candidates with a background in engineering, physics, or related fields are also encouraged to apply their skills to the analysis of neurophysiological data, but these applicants should also have interest in our ultimate goal of understanding behavior and cognition. Prior experience working with behaving rats or mice, programming (MATLAB), and a mathematical or computational background are all highly desirable in applicants, but not all required. English language fluency is required, but German language fluency is not required for laboratory work or classes. Students will join the International Max Planck Research School for Systems and Cognitive Neuroscience / Graduate Training Center of Neuroscience at the University of Tübingen (http://ift.tt/2pcwPPS). The positions are fully funded for 3 years with extension for additional years possible.
Applications should include a CV, a brief (up to 500 word) personal statement about research interests and goals after the PhD, and 2 letters of reference. These may be submitted by email to Dr. Masataka Watanabe (firstname.lastname@example.org)
Masataka Watanabe, PhD
Research Group Leader
Department of Physiology of Cognitive Processes
Max Planck Institute for Biological Cybernetics