Colloquium du DEC

PROGRAMME 2024-2025

2024-2025 PROGRAM

15 octobre 2024
Sam Gilbert (UCL, UK): "Outsourcing memory to the external environment: Cognitive offloading, value-based decision making, and metacognition"

This talk will summarise a line of experimental work, both laboratory-based and naturalistic, investigating how people use external tools and reminders to help them remember. The key questions are: 1) how do people decide between storing information in internal memory or external reminders; 2) how does this process change across the lifespan; 3) how does it relate to underlying brain activity; and 4) what are the downstream consequences for memory? I will argue that cognitive offloading is experimentally tractable and guided by metacognitive processes. Computational modelling suggests that it can also be seen as a form of value-based decision making. These results suggest real-world interventions that could improve people’s adaptive use of cognitive tools.
 

19 novembre 2024
Dean Mobbs (California Institute of Technology, USA)

The natural world presents a myriad of dangers that can threaten an organism's survival. This diversity of threats is matched by a set of universal and species-specific defensive behaviors which are often subsumed under the emotions of fear and anxiety. A major issue in the field of affective science, however, is that these emotions are often conflated and scientists fail to reflect the ecological conditions that gave rise to them. I attempt to clarify these semantic issues by describing the link between ethologically defined defensive strategies and fear. This, in turn, provides a clearer differentiation between fears, the contexts that evoke them, and how they are organized within defensive survival circuits.

10 décembre 2024
Giorgio Vallortigara (Università Di Trento, Italy) : "The cognitive neurobiology of numerousness"

What underlies the ability to deal with numbers and where did it come from? It has been hypothesized that our ability to accurately represent the number of objects in a set (numerousness), and to carry out numerical comparisons and arithmetic, developed from an evolutionarily conserved system for approximating numerical magnitude. Non-symbolic number cognition based on an approximate sense of magnitude has been documented in a variety of species. However, we know little about its origins (i.e., to what extent experience would shape it) and of its neural and molecular bases. To address the first issue we performed single cell recordings in awake young domestic chicks. We found neurons selective to number in the caudal nidopallium (a higher associative area with functional similarities to the mammalian prefrontal cortex), which suggest that an approximate sense of magnitude can be an inborn feature in the avian brain. To address the issue of circuitry and molecular bases of the sense of magnitude we made use of zebrafish, that in recent years became established as ideal developmental and behavioral genetic model system. Using a combination of early gene expression and in-situ hybridization we identified for the first time a small region in the caudal part of the dorso-central division of the zebrafish pallium that shows selective activation upon change in numerousness of visual stimuli. As pallial regions are implicated in number cognition in mammals and birds, these findings support the existence of an evolutionarily conserved system for approximating magnitudes and provide an avenue for exploring its underlying molecular and genetic correlates.

Giorgio Vallortigara is Professor of Neuroscience and Director of the Animal Cognition and Neuroscience Laboratory at the Centre for Mind/Brain Sciences of the University of Trento, Italy.

Among his research interest is the study of brain and behavioural asymmetries in a comparative and evolutionary perspective. He first discovered functional brain asymmetry in fish and amphibians. He also studied the mechanisms underlying the use of geometry in spatial navigation and the origins of number and object cognition in the animal brain. Professor Vallortigara’s most recent work has focused also on the investigation of brain asymmetry and numerical cognition in insects.

On these topics he has published more than 400 refereed papers, that have received more than 30,000 citations overall (h-index=96; source Google Scholar). He has contributed also to several books chapters, and is the author with L.J. Rogers and R.J. Andrew of the monograph “Divided Brains” (Cambridge University Press, 2013). He recently published the books “Born Knowing”by MIT Press (2021) and “The Origins of Consciousness” by Routledge (2024). His work has been rated several times in the Faculty of 1000 Biology and widely described in general science books of animal behaviour, cognitive science and neuroscience. He has been the recipient of several honors and prizes, including, among others, two ERC Advanced Grants, the Geoffrey de St. Hilaire Prize for Ethology, and a doctorate honoris causa from the University of Ruhr in Germany.
 

11 février 2025
Martin Giurfa (Sorbonne University, France): "Exploring cognition in miniature brains: from concepts, numbers and awareness in honey bees"

Despite having a 1mm3 brain, bees achieve remarkable cognitive feats, which include category and concept learning. They are also capable of numerosity judgments, which include a concept of zero and numerical-distance and numerical-size effects. In a novel exploration of their numeric capacities, we focused on the SNARC effect and showed that bees order numbers from left to right according to their magnitude and that the location of a number on that line varies with the reference number previously trained. Thus, this form of numeric representation is common to nervous system with distant evolutionary origins. The numeric sense of bees has, however some limitations that make it different from that of humans. Symbolic matching experiments in which different groups of bees were trained to match a sign (N or T) to a given numerosity (2 or 3) or vice versa revealed that learning the association was possible although reversing it (i.e. from number-to-sign if trained on sign-to-number, and vice versa) was not possible. This failure reveals a limitation in the symbolic representation of numbers in these insects.  

Finally, I will provide results comparing the bees' performance under delay vs. trace conditioning protocols, which in humans have been coupled to the use of distractors to determine whether awareness of the relationship between a conditioned stimulus (CS) and a distant unconditioned stimulus (US) is necessary for learning to occur. Our results show that, like in humans, providing distractors during delay conditioning has no effect on learning and memory formation. However, when the same distractors are provided during trace conditioning, i.e. when the CS and the US are separated by a gap, learning fails, thus showing the necessity of awareness for building the CS-US relationship in this learning form. 

Overall, these results indicate that a miniature brain is not a limitation for mediating relevant cognitive traits such as concept formation, numerosity and awareness. Current investigations focus on uncovering the neural solutions implemented by bees to achieve these performances to determine similarity and differences with the neural architectures existing in vertebrates. This comparative approach will provide crucial insights to understand the evolutionary origins of cognitive skills.
 

4 mars 2025
Ali Boyle (The London School of Economics and Political Science) : "Evolutionary accounts of episodic memory: what are the rules of the game?"

If episodic memory is an adaptation, what is its evolutionary function? Several answers have recently been suggested: perhaps episodic memory plays an adaptive role in learning, future-directed thought, or social cognition – or perhaps it has no evolutionary function at all. These answers are often presented as rivals; those defending one account typically also present arguments against competing accounts. 

In this paper, I take a step back from this debate, and ask: what should an evolutionary account of episodic memory do? A tempting, if flat-footed, answer is that it should explain why episodic memory is here, and why it is the way it is. Indeed, objections to evolutionary accounts typically argue that they fail to explain episodic memory’s existence or to explain one or more of its distinctive features. Whilst they are not unreasonable, these desiderata are often deployed in a way that assumes an overly simplistic account of episodic memory’s evolutionary history. I argue that if episodic memory is an adaptation, it most likely emerged through a gradual, step-wise evolutionary process by way of transitional forms, and it may have multiple evolutionary functions. As such, the explanatory demands that can reasonably be made of any given function are reduced. However, I suggest that this points toward some more challenging desiderata for an account of episodic memory’s origins. 

8 avril 2025
Karl Gegenfurtner (Giessen university, Germany) : "City of lights – city of lighting: Luminance and heterochromatic brightness"

Just about a century ago, luminance was established by the C.I.E. as the standard measure of light intensity. I will trace its historic origins in Paris at the turn of the 20th century, the great successes of luminance in standardizing lighting, and its shortcomings in adequately capturing heterochromatic brightness.

This presentation explores advances in modeling heterochromatic brightness, leveraging psychophysical tasks, neural correlates, and real-world lighting experiments. Central to this work is a robust ranking task in which observers evaluated the brightness of diverse color patches. The task reliably captured heterochromatic brightness judgments, revealing that a non-linear model, based on the maximum value of three weighted primaries (MaxRGB), consistently outperformed traditional metrics such as luminance, radiance, and CIE-derived color appearance models.

These findings align with results from steady-state visual evoked potential (SSVEP) experiments, which highlight distinct neural responses to luminance and heterochromatic brightness at different temporal frequencies. Further validation comes from experiments with tunable LED lamps, confirming the model's relevance across real-world lighting conditions. The results also include large-scale online data collection, demonstrating that brightness rankings remain robust even under less controlled environments.

These findings not only refine our understanding of brightness perception but also advocate for models better aligned with human visual experiences, echoing the innovative spirit of Paris’s historic contributions to vision science.

27 mai 2025
Smadar Ovadia-Caro (University of Haifa)

3 juin 2025
Mackenzie Mathis (Brain Mind Institute & Neuro X Institute, École Polytechnique Fédérale de Lausanne, Geneva, Switzerland): "Changing neural dynamics during motor learning"

The neural activity of the brain is intimately coupled to the dynamics of the body. Yet how our hierarchical sensorimotor system dynamically orchestrates the generation of movement while adapting to incoming sensory information remains unclear. To tackle this question, we have developed a series of deep learning tools that have enabled us to measure 3D kinematics and jointly model neural and behavioral dynamics. In this talk, I will briefly discuss these tools and then show how our lab uses them to dissect the neural contributions to motor control and learning. Specifically, we developed joystick-based tasks for mice where they must learn to rapidly adapt to changes in the environment. Using large-scale 2P-imaging in the cortex, we find functional grouping of neurons that have specific computational motifs that act as a substrate for learning.

17 juin 2025
Natalie Boll-Avetisyan (University of Potsdam)

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