Building sensory and abstract representations
To make sense of the world around us, we use our sensory organs (our eyes, ears, nose, mouth and skin) to gather information. This information is sent to specialised regions in a part of the brain called the neocortex, which combines these sensory inputs and extracts important features to create internal representations. These sensory representations are what account for our perception of the external world and influence how we act upon it.
At SWC, we are working to understand the mechanisms by which the neocortex generates sensory representations. Our research primarily focuses on the visual areas of the neocortex as we can precisely control visual input in our experiments.
We use multiple methods including two-photon imaging, whole cell recordings and anatomical approaches to uncover how single neurons and networks of neurons result in representations of external stimuli in the neocortex. We measure how neurons connect to each other and how they form subnetworks that encode sensory features of the environment.
The Margrie, Hofer and Mrsic-Flogel labs are working to comprehensively dissect the organisation of circuits in the visual cortex with respect to different classes of excitatory projection neurons and inhibitory interneurons. The aim of this research is to integrate these data into a comprehensive model of single neurons and networks during sensory processing and provide the basis for understanding how dynamical modes arise from circuit architecture. This work involves close collaboration with computational researchers at GCNU.
The Mrsic-Flogel lab is working closely with the Znamenskiy lab* at the Francis Crick Institute to determine how object depth is computed from optic flow signals and which cortical areas and projection pathways implement this computation.
The Hofer lab is investigating cortical areas that process visual motion to determine how they distinguish movement in the environment from self-generated optic flow, and is testing how the thalamus contributes to this computation. The Hofer lab is also testing the theory that high-order thalamus acts as a switchboard to prioritise and differentially route visual information to target areas depending on behavioural relevance.
The Margrie lab is collaborating with the Burgess lab* to test how visual information is integrated with head direction signals to generate egocentric and allocentric representations of the visual environment.
The Branco lab is studying how sensory stimuli are analysed and identified as threats by midbrain circuits. In collaboration with the Branco lab, the Hofer lab is investigating how, through thalamic inhibition, these midbrain circuits can be regulated by and coordinated with cortical pathways during visual processing.
*Petr Znamenskiy and Neil Burgess are both part of our affiliates programme at SWC.
In addition to sensory representations of the world around us, we also need representations for more abstract concepts such as space and knowledge.
In 1978, John O’Keefe proposed a theory that the hippocampus and associated areas function as a cognitive map for spatial memory, forming an inner GPS in the brain. This theory of hippocampal function explained the finding of place cells and predicted the discovery of grid and head direction cells.
At SWC, we are working to expand on this theory to further understand how animals navigate. We are also exploring how such representations are used in learning and also how animals represent social information.
The O’Keefe lab is working towards identifying the mechanisms by which different sensory and internal inputs give rise to place cell formation, and determining the contribution of spatial representations in navigation.
The team are testing the theory that the hippocampus generates a goal-directed vector to the goal from the animal’s current location, by identifying how this goal vector is represented in place cell activity during navigation on the honeycomb maze. The O’Keefe lab is also working closely with the Branco lab to look at the neuronal activity in an associated area called the retrosplenial cortex during escape-to-shelter behaviour.
As part of the affiliates programme at SWC, Neil Burgess is testing predictions of an important recent generalisation of the spatial theories about place cell and grid cell firing. The theory proposes that states and transitions representing arbitrary bodies of knowledge are represented by place and grid cells respectively. Grid cell firing patterns are thought to be eigenvectors of the transition matrix, making precise predictions for their firing patterns in both spatial and non-spatial tasks.
The Burgess lab is also working with the Margrie lab and Branco lab to investigate the role of retrosplenial cortex circuits in coordinate transformation during spatial memory. They are focusing on escape behaviour and also exploiting new technologies that allow neural measurements during bodily translation or rotation.
Furthermore, the Hofer lab is testing the hypothesis that the thalamus facilitates coordinate transformations between areas and they are investigating the underlying circuit mechanisms.
The Saxe lab is exploring how neural representations change across a distributed network of interconnected brain areas during learning. The team are also investigating the neural representations underlying task switching, multitasking and abstraction.
The Duan lab is exploring how information about other individuals is represented in the brain, as for social animals individuals rarely act in isolation but instead interact with multiple others.
The Isogai and O’Keefe labs are also researching the neural mechanisms by which social information is represented in the brain, specifically the amygdala and hypothalamus, and how this representation is used to select from a repertoire of specific social behaviours. The Isogai lab is studying odour signals, called pheromones, and trying to understand how they give rise to the representation of social information including sex, age, and reproductive and social status, as well as how this representation drives the decision to engage in social interactions such as parenting, aggression and mating.