Theoretical Neuroscience Podcast
This podcast focuses on topics in theoretical and computational neuroscience, targeting students and researchers in the field. It likely explores models of neural systems, brain function, and quantitative approaches to understanding the brain. The host, Gaute Einevoll, is a prominent neuroscientist, and the discussions are accessible to an academic audience. Episodes may cover current research, methodological advances, and theoretical frameworks in neuroscience.
Episoder
On the computational neuroscience legacy of Valentino Braitenberg - with Ad Aertsen - #43
The prominent and colorful neuroscientist Valentino Braitenberg was born 100 years ago. He co-founded the Max Planck Institute of Biological Cybernetics in Tübingen in Germany, where he made seminal contributions to neuroanatomy, synthetic psychology, and theories for cerebellar, fly vision and cortical function. He was celebrated at the recent Braitenberg*100 symposium which I attended together w
On neuronal identity and representational drift - with Timothy O'Leary - #42
A bursting neuron can maintain its firing-pattern identity throughout an animal's life, even though the ion-channel proteins underlying this identity are turned over on the timescale of days. Today's guest has proposed that neuronal identities are stored in the specific protein production rules, which are regulated by intracellular calcium signaling. And how can animals reliably perform a lear
On functional effects of neuronal heterogeneity - with David Dahmen - #41
Most neural network models till date have assumed all neurons to be identical, or at least that all neurons within a population are identical. In reality, no two neurons are completely the same. Is this due to unavoidable "biological noise" that the nervous system has to cope with, or can it be a useful feature included by design? The guest co-wrote the recent paper "How heterogeneity shapes dynam
On smelling your way to the fruit with ring models - with Katherine Nagel - #40
Fruit flies need a short-term (working) memory to keep their direction when they navigate their way to the fruit by smelling. Mean-field ring models was theoretically suggested to encode stimulus orientations 30 years and was observed in fruit-fly compass neurons 10 years ago. But how does odor input come into the picture to set the compass course? The group of the guest has studied the question
On modeling neural population activity with mean-field models - with Tilo Schwalger - #39
Starting with the work of pioneers like Wilson and Cowan in the 1970s, mean‑field models have become a dominant tool for modeling neural activity at the level of neuronal populations. Despite their popularity, most mean‑field models have been heuristic and not systematically derived from the underlying 'microscopic' dynamics of individual neurons. Today's guest has made important contributions
On extracting spiking network models from experiments - with Richard Gao - #38
While some models aim to explain qualitative features of brain activity, other aim to reproduce experimental data quantitatively. If so, model parameters must be adjusted to make the model predictions fit the experimental data. A complication is that in most neurobiological applications, there is not a unique best fit: many parameter combinations give equally good model fits. Recently, the gues
On reproducibility of modeling and 10 years with the Potjans-Diesmann network model - with Hans Ekkehard Plesser - #37
Reproducibility is key for scientific progress. If research results cannot be reproduced and trusted, other researchers cannot build on them. Reproducibility is a challenge also in computational neuroscience, and today's guest has worked on how this can be remedied, for example, through standardized model description and model sharing. He also recently organised a workshop celebrating a decade wit
On low-dimensional manifolds in motor cortex - with Sara Solla - #36
Historically, the analysis of neural recordings focused on responses of single neurons recorded by single-contact electrodes. Modern electrodes with multiple electrode contacts can instead record spikes (action potentials) from hundreds of neurons simultaneously. Manifold analysis of the overall population activity of these neurons has become a critical tool for interpretation of such data. The po
On modeling metabolic networks in the brain – with Polina Shichkova - #35
Neurons need particular sodium and potassium concentration gradients across their membranes to function. These gradients are set up by so-called ion pumps which require energy stored in ATP molecules to run. ATP is the common energy currency in the brain and is produced from nutrients delivered by the blood by a complicated set of chemical reactions known as a metabolic network. Today's guest has
On balanced neural networks - with Nicolas Brunel - #34
An important discovery that has come out of computational neuroscience, is that cortical neurons in vivo appear to receive so-called balanced inputs. In the balanced state the excitatory and inhibitory synaptic inputs to a neuron are about equal, and action potentials occur when a fluctuation temporarily makes the excitation dominate. The theory, for example, explains the observed irregular firing
On computational neurotechnology for the clinic - with Anthony Burkitt, Nada Yousif & Esra Neufeld - #33
How can computational neuroscience contribute to developing neurotechnology to help people with brain disorders and disabilities? This was the topic of a panel debate I hosted at the 34th Annual Computational Neuroscience Meeting in Florence in July this year. Electric or magnetic recording and/or stimulation are key clinical tools for helping patients, and the three panelists have all used comput
On IIT and adversarial testing of consciousness theories - with Christof Koch - #32
In an adversarial collaboration researchers with opposing theories jointly investigate a disputed topic by designing and implementing a study in a mutually agreed unbiased way. Results from adversarial testing of two well-known theories for consciousness, Global Neuronal Workspace Theory (GNWT) and Integrated Information Theory (IIT), were presented earlier this year. In this podcast one of the pr
On how to cure brain diseases - with Nicole Rust - #31
A promise of basic neuroscience research is that the new insights will lead to new cures for brain diseases. But has that happened so far? Today's guest, an accomplished professor of neuroscience, decided to investigate. Her book "Elusive cures: why neuroscience hasn't solved brain disorders - and how we can change that" came out this summer. Here she argues that we need to consider the brain as a
On co-dependent excitatory and inhibitory plasticity - with Tim Vogels - #30
Synaptic plasticity underlies several key brain functions including learning, information filtering and homeostatic regulation of overall neural activity. While several mathematical rules have been developed for plasticity both at excitatory and inhibitory synapses, it has been difficult to make such rules co-exist in network models. Recently the group of the guest has explored how co-dependent p
On the philosophy of simplification in computational neuroscience - with Mazviita Chirimuuta and Terrence Sejnowski - #29
Computational neuroscientists rely on simplification when they make their models. But what is the right level of simplification? When should we, for example, use a biophysically detailed model and when a simplified abstract model when modelling neural dynamics? What are the problems of simplifying too much, or too little? This was the topic of the panel discussion between a science philosopher (
On whole-cell modeling of bacteria - with Markus Covert - #28
A future computational neuroscience project could be to model not only the signal processing properties of neurons, but also all processes that keep a neuron alive for, say, a 100-year life span. In 2012 the group of the guest published the first such whole-cell model for a very simple bacterium (M. genitalia). In 2020 a model of the larger E. coli bacterium comprising 10.000 equations and 19.000
On construction and clinical use of multipurpose neuron models - with Etay Hay - #27
Numerous neuron models have been made, but most of them are "single-purpose" in that they are made to address a single scientific question. In contrast, multipurpose neuron models are made to be used to address many scientific questions. In 2011, the guest published a multipurpose rodent pyramidal-cell model which has been actively used by the community ever since. We talk about how such models ar
On the population code in visual cortex - with Kenneth Harris - #26
With modern electrical and optical measurement techniques, we can now measure neural activity in hundreds or thousands of neurons simultaneously. This allows for the investigation of population codes, that is, of how groups of neurons together encode information. In 2019 today's guest published a seminal paper with collaborators at UCL in London where analysis of optophysiological data from 10.000
On growing synthetic dendrites – with Hermann Cuntz - #25
The observed variety of dendritic structures in the brains is striking. Why are they so different, and what determine the branching patterns? Following the dictum "if you understand it, you can build it", the lab of the guest builds dendritic structures in a computer and explore the underlying principles. Two key principles seem to be to minimize (i) the overall length of dendrites and (ii) the pa
On neuroscience foundation models - with Andreas Tolias - #24
The term "foundation model" refers to machine learning models that are trained on vast datasets and can be applied to a wide range of situations. The large language model GPT-4 is an example. The group of the guest has recently presented a foundation model for optophysiological responses in mouse visual cortex trained on recordings from 135.000 neurons in mice watching movies. We discuss the desig
On human whole-brain models - with Viktor Jirsa - #23
A holy grail of the multiscale approach for physical brain modelling is to link the different scales from molecules, via cells and local neural networks, up to whole-brain models. The goal of the Virtual Brain Twin project, lead by today's guest, is to use personalized human whole-brain models to aid clinicians in treating brain ailments. The podcast discusses how such models are presently made us
On 40 years with the Hopfield network model - with Wulfram Gerstner - #22
In 1982 John Hopfield published the paper "Neural networks and physical systems with emergent collective computational abilities" describing a simple network model functioning as an associative and content-addressable memory. The paper started a new subfield in computational neuroscience and led to the influx of numerous theoretical scientists, in particular physicists, to the field. The podcast g
On models for short-term memory - with Pawel Herman - #21
The leading theory for learning and memorization in the brain is that learning is provided by synaptic learning rules and memories stored in synaptic weights between neurons. But this is for long-term memory. What about short-term, or working, memory where objects are kept in memory for only a few seconds? The traditional theory held that here the mechanism is different, namely persistent firing
On neuro-AI on the boat - part 2 of 2 - with Cristina Savin, Tim Vogels, Mikkel Lepperød, Paul Middlebrooks - #20
In September Paul Middlebrooks, the producer of the podcast BrainInspired, and I were both on a neuro-AI workshop on a coast liner cruising the Norwegian fjords. We decided to make two joint podcasts with some of the participants where we discuss the role of AI in neuroscience. In this second part we discuss the topic with Cristina Savin and Tim Vogels and round off with a brief discussion with Mi
On neuro-AI on the boat - part 1 of 2 - with Ken Harris, Andreas Tolias, Mikkel Lepperød, Paul Middlebrooks - #19
In September Paul Middlebrooks, the producer of the podcast BrainInspired, and I were both on a neuro-AI workshop on a coast liner cruising the Norwegian fjords. We decided to make two joint podcasts with some of the participants where we discuss the role of AI in neuroscience. In this first part we talk with Mikkel Lepperod, the main organizer about the goal of the workshop, and with Ken Harris a
On electric brain signals - solo episode - #18
Most of what we have learned about the functioning of the living brain has come from extracellular electrical recordings, like the measurement of spikes, LFP, ECoG and EEG signals. And most analysis of these recordings has been statistical, looking for correlations between the recorded signals and what the animal/human is doing or being exposed to. However, starting with the neuron rather than t
On dendritic function - with Yiota Poirazi - #17
The most prominent visual characteristic of neurons is their dendrites. Even more than 100 years after their first observation by Cajal, their function is not fully understood. Biophysical modeling based on cable theory is a key research tool for exploring putative functions, and today's guest is one the leading researchers in this field. We talk about of passive and active dendrites, the kind o
On consciousness - with Christof Koch - #16
The greatest mystery of all is why a group of atoms, like the ones constituting me, can feel anything. The mind-brain problem has puzzled philosophers for millennia. Thanks to pioneers like Christof Koch, consciousness studies have recently become a legitimate field of scientific inquiry. In this vintage episode, recorded in February 2021, we discuss many aspects of the phenomenon, including an
On the simulation tool NEURON - with Michael Hines - #15
Computational neuroscientists use many software tools, and NEURON has become the leading tool for biophysical modeling of neurons and neural network. Today's guest has been the leading developer of NEURON since the infancy almost 50 years ago. We talk about how the tool got started and the development up until today's modern version of the software, including CoreNEURON optimized for parallel exe
On the molecular memory code - with Sam Gershman - #14
The idea that memories are stored in molecules was popular in the middle of the 20th century. However, since the discovery of long-term potentiation (LTP) in the 1970s, the dominant view has been that our memories are stored in synapses, that is, in the connections between neurons. Today, there are signs that the interest in molecular memory is returning, and the guest has presented a theory sugge
On quantum biology - with Johnjoe McFadden - #13
Is quantum physics important in determining how living systems, including brains, work? Today's guest is a professor of molecular genetics at the University of Surrey in England and explores this question in the book "Life at the edge: The coming of age of quantum biology". In this "vintage" episode, recorded in late 2019, we talk about how quantum physics is or may be key in photosynthesis, smel
On modeling of signaling pathways inside the neuron - with Avrama Blackwell - #12
Most computational neuroscientists investigate electric dynamics in neurons or neural networks, but there is also computations going on inside neurons. Here the key dynamical variables are concentrations of numerous different molecules, and the signaling is typically done in cascades of chemical reactions, called signaling pathways. Today's guest is an expert in this kind of modelling and is parti
On synaptic learning rules for spiking neurons - with Friedemann Zenke - #11
Today's AI is largely based on supervised learning of neural networks using the backpropagation-of-error synaptic learning rule. This learning rule relies on differentiation of continuous activation functions and is thus not directly applicable to spiking neurons. Today's guest has developed the algorithm SuperSpike to address the problem. He has also recently developed a biologically more plausib
On large-scale modeling of mouse primary visual cortex - with Anton Arkhipov - #10
Over the last ten years or so, the MindScope project at the Allen Institute in Seattle has pursued an industrylab-like approach to study the mouse visual cortex in unprecedented detail using electrophysiology, optophysiology, optical imaging and electron microscopy. Together with collaborators at Allen, today's guest has worked to integrate of these data into large-scale neural network, and in th
On origins of computational neuroscience and AI as scientific fields - with Terrence Sejnowski (vintage) - #9
Today's guest is a pioneer both in the fields of computational neuroscience and artificial intelligence (AI) and has had a front seat during their development. His many contributions include, for example, the invention of the Boltzmann machine with Ackley and Hinton in the mid 1980s. In this "vintage" episode recorded in late 2019 he describes the joint births of these adjacent scientific fields
On reverse engineering of the roundworm C.elegans - with Konrad Kording - #8
Today's guest has argued that the present dominant way of doing systems neuroscience in mammals (large-scale electric or optical recordings of neural activity combined with data analysis) will be inadequate for understanding how their brain works. Instead, he proposes to focus on the simple roundworm C.elegans with only 302 neurons and try to reverse engineer it by means of optical stimulation and
On topological data analysis and Hopfield-like network models - with Carina Curto - #7
Over the last decade topological analysis has been established as a new tool for analysis of spiking data. Today's guest has been a pioneer in adapting this mathematical technique for use in our field and explains concepts and example applications. We also also talk about so-called threshold-linear network model, a generalization of Hopfield networks exhibiting a much richer dynamics, where Carin
On central pattern generators in the spinal cord - with Henrik Lindén - #6
Not all interesting network activity occurs in cortex. Networks in the spinal cord, the long thin tubular structure extending downwards from the neck, is responsible for setting up rhythmic motor activity needed for moving around. How do these so-called central pattern generators work? Today's guest has, together with colleagues in Copenhagen, developed a neuron-based network theory for how these
On how vision works - with Li Zhaoping - #5
We know a lot about of how neurons in the primary visual cortex (V1) of mammals respond to visual stimuli. But how does the vast information contained in the spiking of millions of neurons in V1 give rise to our visual percepts? The guest's theory is that V1 acts as a "saliency detector" directing the gaze to the most important object in the visual scene. Then V1 in collaboration with higher visu
On multi-area cortex models - with Sacha van Albada - #4
A key goal of computational neuroscience is to build mathematical models linking single-neuron activity to systems-level activity. The guest has taken some bold steps in this direction by developing and exploring a multi-area model for the macaque visual cortex, and later also a model for the human cortex, using millions of simplified spiking neuron models. We discuss the many design choices, th
On the neural code - with Arvind Kumar - #3
It is widely thought that spikes (action potentials) are the main carrier of information in the brain. But what is the neural code, that is, what aspects of the spike trains carry the information? The detailed temporal structure or maybe only the average firing rate? And is there information in the correlation between spike trains in populations of similar neurons? The guest has thought about t
On biophysics of computation – with Christof Koch - #2
Starting from the pioneering work of Hodgkin, Huxley and Rall in the 1950s and 60s, we have a well-founded biophysics-based mathematical understanding of how neurons integrate signals from other neurons and generate action potentials. Today's guest wrote the classic book "Biophysics of Computation" on the subject in 1998. We discuss its contents, what has changed in the last 25 years, and also tou
On models of the mind - with Grace Lindsay - #1
The book "Models of the Mind" published in 2021 gives an excellent popular account of the history and questions of interest in theoretical neuroscience. I could think of no other person more suitable to invite for the inaugural episode of the podcast than its author Grace Lindsay. In the podcast we discuss highlights from the book as well as recent developments and the future of our field.
