FeaGatSu · Feature-gating in superior colliculus
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2018-06-01 → 2020-05-31
- EU contribution
- €172,800
- Participants
- 1
- Scheme
- MSCA-IF-EF-ST
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Results in brief
Feature-gating in superior colliculus
Mice, like humans, use vision to interact with their environment, e.g., a sudden, expanding shadow above their head, mimicking an approaching predator, triggers innate freezing or escape behavior. Mice also rely on vision when hunting. These visually-guided innate behaviors are mediated by the activation of neural circuits going through the superior colliculus (Fig. 1). Wide-field neurons of the superior colliculus are known to be involved in innate fear and hunting behaviors and respond to stimuli mimicking an approaching or passing-by predator or prey. They receive direct input from the retina and integrate the visual information along their massive dendritic trees. We investigated how wide-field neurons of the mouse superior colliculus combine signals from the retina to detect salient features that are important for the animal’s survival in three steps. First, we characterized the visual features wide-field neurons respond to. Second, we identified the visual features relayed by the retinal ganglion cells to wide-field neurons. Third, we determined the computational rules that allow wide-field neurons to effectively extract visual features that represent prey or predator from the retinal signals. This was achieved by labeling and recording from wide-field neurons and their retinal inputs using a combination of genetic tracing and two-photon microscopy of a fluorescent indicator that lights up when cells respond to a stimulus. We found that 10 types of retinal ganglion cells provide input to wide-field neurons, with each anatomical type (Fig. 2, left) providing a unique signal in response to a visual stimulus (Fig. 2, right). These responses are combined along the dendrites of wide-field neurons. We found that signals in the dendritic tips can be represented by the sum of the retinal inputs. However, at the soma, such a simple summation of the retinal inputs fails to represent the output of wide-field neurons (Fig. 3). Further investigation of this complex signal integration will advance our understanding of signal processing in central neurons and eventually aid intervention in neural processing disorders.
Data: CORDIS, © European Union
Project objective
Imagine a huge elephant rushing towards you; your first instinct is – run! This innate escape response is triggered by visual cues, here, a fast expanding object, and crucially depends on the extraction of few relevant features. The processing of visual information starts in the retina where more than 40 types of retinal ganglion cells extract salient features from the visual scene. Information about these features is sent to downstream brain areas. A central node where retinal signals are integrated is the superior colliculus. This evolutionary-conserved brain area controls innate behaviors, directly linking the outputs of the retina with the activation of motor outputs and behavior. In mice, escape behaviors can be initiated upon activation of a single cell type of superior colliculus, wide-field neurons. They receive inputs from a subset of retinal ganglion cell types and respond preferentially to two distinct visual stimuli, slow moving dots and quickly expanding disks, each known to trigger defensive behaviors. However, the computational strategy used by collicular neurons to process feature-selective retinal inputs remains unknown. In the proposed project, I will identify the mechanisms by which retinal features are integrated in collicular wide-field neurons. I will combine transsynaptic viral circuit tracing with two-photon calcium imaging to identify and characterize the feature-selective inputs from retinal ganglion cells (in-vitro) and functional outputs of wide-field neurons (in-vivo). The results of these experiments will allow me to deduce how the output features of wide-field neurons arise from the retinal inputs using computational modeling and neural decoding techniques. This will reveal the circuit and computational principles by which retinal feature-selectivity drives complex circuit function in central brain regions.
Original text from CORDIS.
Participants
- VIB VZW · ZWIJNAARDE - GENTCoordinatorBelgium
Links
Data: CORDIS, © European Union