Spatial representations

…Research spans spatial representations, foveal and peripheral processing, attention, retinal anatomy, emmetropization and myopia. The laboratory combines human psychophysics, controlled retinal stimulation, computational modelling, precise eye and head tracking, retinal imaging and EEG during active vision. Researchers work within the Center for Visual Science and Brain and Cognitive Sciences, with collaborations in optics, neuroscience and ophthalmology. Applications comprise

The hippocampus is widely known for spatially-selective responses in individual cells. However, many of its cells do not have easily-interpretable spatial tuning curves or are selective for other task-relevant variables. To better understand the computations played by this structure, it may be necessary to look to population-level features of neural activity and the distributed computations they enable. Here, we focus on two such features: 1) a continuous neural manifold that maps spatial and task structure, 2) spatial representations that “sweep” ahead of the animal as it moves through the en

Animal brains and behaviours have evolved in the natural world – to allow different species to meet their daily life challenges. However, our understanding of how the brain deals with such diverse conditions stems from constrained laboratory experiments – where an animal exhibits one specific behaviour in one particular task. While this approach has revealed many instances of how the brain can encode isolated behaviours, it leaves the fundamental question unexplored: How does the brain actually represent the real world – in natural and multi-animal settings? To answer this, we caught wild Egyp

…or to code for space, suggested by spatially tuned cells (place cells, grid cells, etc.) recorded in nonhuman animals. In an attempt to reconcile the two views, we use a memory-augmented neural network in a reinforcement learning setup to solve a navigation task in a simulated maze. The key feature of the model is that it learns autonomously what and when to store into, and retrieve from, an external memory buffer. Once the mode

Throughout each day the brain captures snapshots of distinct experiences, forming episodic memories that often last a lifetime. This function depends on the hippocampus – a brain region that is evolutionarily conserved across vertebrates. My lab studies the relationship between hippocampal activity and episodic memory using a unique model organism – the black-capped chickadee. Chickadees are specialist food-caching birds that store thousands of food items at concealed locations in their environment and use memory later in time to retrieve their caches. I will describe our effort in designing b

…it has been unclear to what extent spatial representations are present in the primate brain and how to reconcile these representations with the known mnemonic function of this region. I will discuss a series of experiments that have examined neural activity in the hippocampus in monkeys performing behavioral tasks including

…dynamics underlying retrieval of spatial representations?We study the dynamics of recur

…Spatial representations (place, grid head direction cells) emerge with a similar timeline and so does memory replay, the spontaneous repetition of experience-related activity patterns. Memory replay is thought to be key to information communication between the hippocampus and neocortex. It is therefore important to assess the developmental timeline of

…in the encoding and retrieval of representations of distinct spatial environments and episodes. We explored the complexity of neural activity patterns (‘dimensionality’), to understand how multiple maps are maintained in sub-populations of neurons. High dimensionality suggests unique neural 'maps' for different environments, while low dimensionality indicates overlapping representations across episodes. Prior research has shown distinct spatial representations in hippocampal subfields CA1/ CA3, with increased dimensional

The spatial coding in the hippocampus (HPC) and its emergence during learning is well studied, but it is still unclear how the spatial information in the medial prefrontal cortex(mPFC) is changing between different learning stages. We recorded multiple unit activity using a combination of 24 movable tetrodes for the HPC and a Neuropixels silicon probe with 384 channels for the mPFC. We monitored the formation of spatial representations in both regions while the rat performed a spatial memory task on the radial eight-arm maze. The animal started in the center of the 8-arm maze and needed to loc

…this, we tracked how hippocampal CA1 spatial representations of a familiar environment change with t

During spatial navigation, hippocampal place cells rely on visual inputs to map space, but other sensory modalities, such as odour, can also be effectively used (doi: 10.1093/cercor/bht239). Although rodents are nocturnal and short-sighted, little is known about the role of other sensory modalities as substrates for place fields. Here, we recorded electrophysiologically from place cells in the hippocampal CA1 region of adult male rats while they explored a round empty field arena in darkness and in the absence of reliable tactile, olfactory, and visual cues. We compared place cell behaviour un

…study in hippocampal CA1 activity how spatial representations and neuronal dynamics are affected by environmental and task complexity and by rats’ prior learning experience. Each neuronal ensemble was recorded in four recording sessions: a session where a rat was exposed to a stationary rat-sized robot and a session with the robot slowly moving, were flanked by two sessions without the robot. Some rats were trained to avoid a location define

…While integration of spatial information into episodic memories has been studied in great detail, how social information is encoded in the brain has received less attention. Emerging evidence suggests that the hippocampus area CA2 plays an essential role for social recognition memories, and previous studies show that silencing area CA2 impairs social recognition in mice. To determine how social, spatial and object information is computed in the different areas of the hippocampus, we recorded

Rodents show pronounced local field potential (LFP) oscillations in the theta frequency range (7-12Hz in rodents) during exploration. Theta frequencies are thought to take part in memory processing by ensuring accurate sequences of neuron firing to facilitate plasticity processes. Many principal neurons in the parahippocampal areas, such as grid cells and place cells, show pronounced theta modulation. Grid cells in the medial entorhinal cortex (MEC) are theta modulated during active wakefulness, with power and frequency correlating to e.g. running speed or environmental familiarity. Suppressin

…and memories, and that abstract and spatial representations rely on a common neural fabric. I will argue that this might represent a novel example of “cortical recycling”, where the neuronal machine

The hippocampus is a key player in learning and memory. Research into this brain structure has long emphasized its plasticity and flexibility, though recent reports have come to appreciate its remarkably stable firing patterns. How novel information incorporates itself into networks that maintain their ongoing dynamics remains an open question, largely due to a lack of experimental access points into network stability. Development may provide one such access point. To explore this hypothesis, we birthdated CA1 pyramidal neurons using in-utero electroporation and examined their functional featu

…In the hippocampus, spatial representations are known to remain stable, but have also been shown to drift over long periods of time. We hypothesized that experience, more than the passage of time, is the driving force behind memory plasticity. We compared the stability of place cells in the hippocampus of mice traversing two similar, familiar tracks for different durations. We found that the more time spent in an environment,

…inputs combine to generate the brain’s spatial representations. In the first study (Campbell et al., 2018), we focused on the medial entorhinal cortex (MEC) and its set of navigationally-relevant cell types, including grid cells, border cells, and speed cells. We discovered that attractor dynamics could explain an array of initially puzzling MEC responses to virtual reality manipulations. This theoretical framewo

A complete neuroscience requires multi-level theories that address phenomena ranging from higher-level cognitive behaviors to activities within a cell. Unfortunately, we don't have cognitive models of behavior whose components can be decomposed into the neural dynamics that give rise to behavior, leaving an explanatory gap. Here, we decompose SUSTAIN, a clustering model of concept learning, into neuron-like units (SUSTAIN-d; decomposed). Instead of abstract constructs (clusters), SUSTAIN-d has a pool of neuron-like units. With millions of units, a key challenge is how to bridge from abstract c

Highly-social animals, like humans, live with many individuals, and interact with each other at times, locations and manner of their choosing. However, neurophysiological investigations of social responses are rarely conducted in such rich settings. To determine how the brain represents social information in a naturalistic setting – when the animals’ behavior is not experimentally constrained to a particular task – we constructed a bat cave for a colony of 5–10 bats of both sexes. The bats lived there 24×7, free to engage in any behaviors. Every day we conducted a ~3 hour experimental session,

The medial enthorhinal cortex (MEC) is a core brain region involved in spatial navigation, and provides navigational information to the downstream hippocampus. Neurons in the MEC respond to an animal's location and heading direction in an environment, as well as boundaries and an animals' distance from objects. Other studies have demonstrated that MEC neurons respond to more than navigation, illustrating the flexibility of the region in adjusting response profiles in different contexts. However, it remains poorly understood under what conditions and at what time-scale changes in MEC coding occ

Goal-directed navigation requires precise estimates of spatial relationships between current position and future goal, as well as planning of an associated route or action. While neurons in the hippocampal formation can represent the animal’s position and nearby trajectories, their role in determining the animal’s destination or action has been questioned. We thus hypothesize that brain regions outside the hippocampal formation may play complementary roles in navigation, particularly for guiding goal-directed behaviours based on the brain’s internal cognitive map. In this seminar, I will first

…suggesting that analogies based on spatial representations might be particularly effective to improve mathematics learning. Since fostering mathematics learning also involves addressing psychosocial factors such as the development of mathematical anxiety, providing social incentives to learn, and fostering engagement and motivation, I will argue that one area