Previous MindTalks
Wintersemester 2023/2024
04.12.2023 | 16:00 - 17:30
Raum 2030, Cognium, Hochschulring 18
Coding of social odors in the hippocampus and beyond
Prof. Dr. Sami Hassan
While the hippocampus is a crucial brain region for social memory, the memory of conspecific interactions, the precise mechanisms underlying the integration of social sensory cues with contextual information for the formation of episodic social memories are still unclear. This seminar examines the mechanisms of social sensory information processing by the hippocampus and presents a series of experiments using high-resolution imaging of populations of hippocampal neurons in awake mice exposed to social and non-social odors. These experiments show for the first time specific and robust social olfactory responses to individual conspecifics by neurons in a small subregion of the hippocampus called CA2. Statistical analysis shows that these responses are flexibly modulated during associative learning with social odor and reward, and optogenetic experiments show that CA2 activity is important for this learning. Finally, the experiments show that the CA2 neuronal activity space contains a higher-order structure that allows generalization along the categories of reward and social relevance, a feature that we find to be critically altered in a genetic mouse model of neuropsychiatric disease. This finding positions the genetic mouse model as well as the experimental paradigm as a promising avenue to investigate innovative therapeutic modalities targeting abnormalities in social cognition associated with neuropsychiatric disorders.
11.12.2023 | 16:00 - 17:30
Raum 2030, Cognium, Hochschulring 18
Neural and behavioural mechanisms of attention in live social interactions
Prof. Dr. Louisa Kulke
Attention is affected by the social context we are in: Adults enjoy looking at other people when they watch television at home, but they will inhibit themselves from staring at strangers in a crowded elevator.
The current talk compares attention in live interactions, video-chats and videos. It shows, firstly, that eye movements significantly differ between live interactions and videos: Adults look significantly less at a stranger in a live social situations than in a video. This lack of gaze is not due to disinterest. Co-registration of eye-tracking and EEG allowed us to measure neural responses related to attention, showing comparable attentiveness in live social situations as when watching a videos, even though gaze patterns differ. This suggests that people inhibit their gaze to strangers in live social situations, even if they are interested in them.
People’s attention in social situations can depend on different factors. Firstly, it can depend on age. We could demonstrate that the social inhibition of gaze already exists in infancy and develops until early childhood. Secondly, it may depend on individual differences. We will summarize findings from clinical populations with autism and anxiety disorders. Thirdly, it can depend on the interaction partner, whose emotions may play a role. The talk will summarize findings regarding emotion effects in live interactions, videochats and videos. Furthermore, technology may play a role. We will present a study investigating gaze to android robots compared to humans.
In summary, attention is strongly influenced by social context and this effect develops with age.
18.12.2023 | 16:00 - 17:30
Raum 2030, Cognium, Hochschulring 18
The neuronal mechanisms of change detection and reaction times
Dr. Detlef Wegener
The ability to rapidly perceive and process changes in the external environment and to generate a fast and appropriate motor response is one of the crucial driving forces of animal evolution. For prey animals, it enhances the likelihood of escaping from predators, while for predators, it increases the chances of successfully capturing prey. As a consequence, the underlying physiological mechanisms have become increasingly refined throughout evolution. In some specialists, they have developed into nearly perfect form.
Consequently, the underlying neural mechanisms of change detection represent one of the fundamental encoding principles of nervous systems, including the brains of primates. Today's MIND-Talk focuses on describing the neural basis of motion change detection, from the level of individual cells in visual cortex to population coding. It is demonstrated that cognitive processes in the brain have a direct impact on change detection and crucially determine how quickly motor responses to such changes can occur. Although starting with the analysis of neuronal firing rates, the quest for the coding of change detection reveals the significant importance of the fine temporal dynamics of neural activity for comprehending the interaction among distinct neuron populations and, ultimately, for the behavior generated.
15.01.2024 | 16:00 - 17:30
Raum 2030, Cognium, Hochschulring 18
The more the merrier: Nature-inspired broadband visual stimuli improve sensory perception
Prof. Dr. Björn Kampa
Natural scenes are composed of complex distributions of visual features that drive neural response patterns and shape visual perception. However, most stimuli that are commonly used in vision research only reveal neural responses to single features, such as a specific stimulus orientation. How larger feature distributions affect neural responses and visual perception is therefore poorly understood. To address this question, we presented broadband visual stimuli with parametrically-controlled bandwidth of stimulus orientations and spatial frequencies to awake mice while recording the activity of neural populations in the primary visual cortex with two-photon imaging. Matching the orientation bandwidth of broadband stimuli to naturalistic images strongly increased neural responses and improved feature discrimination performance. Correspondingly, increasing orientation bandwidth also improved the performance of mice in a visual discrimination task. Our results strongly suggest that the visual system is tuned to the feature distributions of naturalistic visual inputs, with broader feature distributions driving more robust neural responses and enhanced visual perception.
22.01.2024 | 16:00 - 17:30
Raum 2030, Cognium, Hochschulring 18
Dissecting mechanisms mediating neurotransmitter release from sensory cells in the gut epithelium
Prof. Dr. Cordelia Imig
Enteroendocrine cells (EECs) are sensory secretory cells in the gut epithelium that release peptide hormones and neurotransmitters in response to changes in the gut milieu. These cells are positioned at the interface between the body and the environment and therefore form an important relay station for sensory information transmitted along the microbiome-gut-brain-axis. Interestingly, mouse EECs express components of the neuronal molecular neurotransmitter release machinery and are positioned close to neuronal processes, indicating fast and directed cell-to-cell communication reminiscent of that at synaptic junctions between neurons in the brain. Our research goal is to dissect the molecular mechanisms that mediate signaling by distinct ECC subtypes and to thereby contribute to a better understanding of how EEC function regulates physiology, behaviour, and metabolism in health and disease.
29.01.2024 | 16:00 - 17:30
Haus der Wissenschaft, Sandstraße 4/5, Olbers-Saal
Wie wir Sprache in Alltagssituation besser verstehen: Vom gesunden Ohr bis zum Hörimplantat
Prof. Dr. Andreas Radeloff
Weshalb können wir unsere Gesprächspartner verstehen, selbst wenn deren Stimme leiser ist als die Umgebungsgeräusche? Wieso wissen wir sofort, wo das Telefon liegt, das gerade klingelt? Wie funktionieren Hörimplantate für ertaubte Menschen?
Das Hörvermögen ist einer unserer faszinierendsten Sinne und zugleich Grundlage für die akustische Kommunikation und Voraussetzung für den Lautspracherwerb. Der heutige Vortrag wird in allgemeinverständlicher Form verschiedene Aspekte rund um das gesunde und erkrankte Hörsystem erklären. Es werden aktuelle Behandlungsstrategien der Schwerhörigkeit bis hin zu implantierbaren Systemen aufgezeigt. Schließlich werden aktuelle Forschungsergebnisse zum Zusammenhang zwischen Schwerhörigkeit und Demenz erläutert und erklärt, wie jede/r das eigene Risiko vermindern kann.
Sommersemester 2023
05.06.2023 | 16:00 – 17:30
Haus der Wissenschaft, Sandstraße 4/5, Olbers-Saal
Gehirn auf der Kippe: Selbstorganisation zwischen Chaos und Ordnung und die Trickkiste der Physik
Prof. Dr. Stefan Bornholdt
Die Nervenzellen in unserem Kopf sind wie kleine geladene Colts: Jederzeit bereit zu „feuern“. Unser Gehirn besteht aus Milliarden davon, in einem dichten Signalnetz verbunden. Das ist Stoff für Alpträume, denn was wenn das Signalfeuer in Windeseile wächst, wer hält es auf?
Die alltägliche Erfahrung mit unserem Gehirn scheint beruhigenderweise eine andere zu sein: Wir können in Ruhe nachdenken, Musik genießen, oder einfach nur träumen, ohne dass die Aktivität unserer Nervenzellen je außer Kontrolle zu geraten scheint.
Was steckt hinter dieser unglaublichen Zähmung der Hirnzellen?
Einen Hinweis darauf gibt eine erstaunliche Beobachtung, die empfindliche Messungen erst seit wenigen Jahren sichtbar machen: Das Gehirn „knistert“ wenn es in Ruhe ist. Wenige Nervenzellen feuern hier und da, und im Lautsprecher klingt das dann etwa so wie ein gemütliches Lagerfeuer. Aus der Physik kennen wir solches Knistern, z.B. bei Erdbeben, beim langsamen Zerknüllen von Papier oder beim Übergiessen von Rice Krispies mit Milch. Die Modelle der Physik, die diese Phänomene beschreiben, scheinen auch auf das Gehirn zu passen. Dies gibt die entscheidende Fährte, um zu verstehen, wie das Gehirn „die Nerven behält“.
12.06.2023 | 16:00 - 17:30
Raum 2030, Cognium, Hochschulring 18
Interaction between sensory and motor systems during task engagement
Dr. Janelle Pakan
We are constantly learning from our experiences as we engage with the world around us. During this active learning our senses work together to build an external reality, which is also influenced by our ongoing behaviours. A major challenge in modern neuroscience is to elucidate how sensory and behavioural systems integrate and influence each other across distributed brain networks. How does contextual sensory stimulation transform to behavioural output and how does our behavioural output subsequently feedback to affect fundamental sensory processing? A vital step in understanding the functional principles of these neural circuits is to directly observe the activity of local circuit elements with high temporal and spatial resolution during sensation and action. To do this, my lab use in vivo two-photon calcium imaging in combination with virtual environments to examine principles of cortical plasticity in sensory and association brain regions across different levels of task engagement in mice.
19.06.2023 | 16:00 – 17:30
Raum 2030, Cognium, Hochschulring 18
The secret social life of fruit flies
Prof. Dr. Jan Clemens
Social communication is multi-modal - when we interact, we speak, gesticulate, and touch. However, how the sender produces these different signals in a coordinated manner, and how the receiver evaluates these dynamical multimodal signals is still unclear. We address this issue in the fruit fly which thanks to its complex social behavior and genetic toolbox is ideal for dissecting the neural basis underlying communication. During courtship, male flies produce two types of communication signals to woo the female: air-borne "song” is produced by moving the wing, while substrate-borne “vibrations” are transmitted via the legs to the substrate. In my talk, I will focus on how the male chooses between these different signal types in a context-dependent manner and I will briefly touch on these signals' specific behavioral effects in the female.
Using a novel recording system, we simultaneously recorded high-speed video of the courtship interactions alongside the song and vibration produced by the male. Statistical modelling of the male's signal choice suggests that the switch from song to vibration is induced by female stationarity, which we causally tested by optogenetically controlling female walking during courtship. To determine how this choice is implemented in the brain, we use optogenetics and find that the production of both signals is tightly integrated in the brain. All tested central neurons that drive song also drive vibrations with temporally complex and persistent dynamics. Combining these experimental data with a computational model, we propose a simple circuit motif that explains the complex signalling dynamics and their modulation by social cues. Lastly, I will present preliminary results from playback experiments that reveal distinct effects of song and vibration signals on female behavior.
Fällt wegen Krankheit leider aus
Dissecting mechanisms mediating neurotransmitter release from sensory cells in the gut epithelium
Prof. Dr. Cordelia Imig
Enteroendocrine cells (EECs) are sensory secretory cells in the gut epithelium that release peptide hormones and neurotransmitters in response to changes in the gut milieu. These cells are positioned at the interface between the body and the environment and therefore form an important relay station for sensory information transmitted along the microbiome-gut-brain-axis. Interestingly, mouse EECs express components of the neuronal molecular neurotransmitter release machinery and are positioned close to neuronal processes, indicating fast and directed cell-to-cell communication reminiscent of that at synaptic junctions between neurons in the brain. Our research goal is to dissect the molecular mechanisms that mediate signaling by distinct ECC subtypes and to thereby contribute to a better understanding of how EEC function regulates physiology, behaviour, and metabolism in health and disease.
Wintersemester 2022/2023
07.11.2022, 16:00-17:30, via Zoom
Learnable neural latent representations
Prof. Dr. Mackenzie Mathis
Mapping behavioral actions to neural activity is a fundamental goal of neuroscience. As our ability to record large neural and behavioral data increases, there is growing interest in modeling neural dynamics during adaptive behaviors to probe neural representations. In particular, neural latent embeddings can reveal underlying correlates of behavior, yet, we lack non-linear techniques that can explicitly and flexibly leverage joint behavior and neural data. Here, we fill this gap with a novel method, CEBRA, that jointly uses behavioral and neural data in a hypothesis- or discovery-driven manner to produce consistent, high-performance latent spaces. We validate its accuracy and demonstrate our tool's utility for both calcium and electrophysiology datasets, across sensory and motor tasks, and in simple or complex behaviors across species. It allows for single and multi-session datasets to be leveraged for hypothesis testing or can be used label-free. Lastly, we show that CEBRA can be used for the mapping of space, uncovering complex kinematic features, and rapid, high-accuracy decoding of natural movies from visual cortex.
05.12.2022, 18:00-19:30, via Zoom
Using large scale physiology to study the functional organization and dynamics of the mouse visual cortex
Prof. Dr. Saskia de Vries
An important open question in neuroscience is how sensory information is represented and transformed by circuits in the cortex. To study this we created the Allen Brain Observatory. This open dataset is a large-scale, systematic survey of physiological activity in the awake mouse cortex recorded using 2-photon calcium imaging. It consists of over 63,000 neurons recorded in over 1300 imaging sessions, surveying 6 cortical areas, 4 cortical layers, and 14 transgenically defined cell types (Cre lines). In this talk I will describe our analysis of this dataset revealing functional organization of visual responses across cortical areas and layers. Using the joint reliabilities of responses to multiple stimuli, we classify neurons into functional classes and validate this classification with models of visual responses. Further, I will show how inhibitory interneurons in the cortical circuit regulate network dynamics, balancing sensitivity and network stability.
12.12.2022, 16:00-17:30, Raum 2030, Cognium, Hochschulring 18
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Intervening in the brain of the blind: Challenges and future prospects
Prof. Dr. Eduardo Fernández Jover
Motivated by the success of cochlear implants for deaf patients, our group is developing a cortical visual neuroprosthesis designed to interface with the occipital cortex in order to restore a limited but useful sense of vision to profoundly blind patients. We will review the most important challenges regarding this neuroprosthetic approach and emphasize the need for basic human psychophysical research on the best way of presenting complex stimulating patterns through multiple microelectrodes.
We will present our recent results regarding the implantation and explantation of intracortical microelectrodes in blind volunteers (ClinicalTrials.gov identifier NCT02983370). Our results, although preliminary, demonstrate the safety and efficacy of chronic intracortical microstimulation via a large number of electrodes in humans, showing its high potential for restoring a functional vision in the blind. These findings support earlier findings in monkey experiments and suggest that several arrays of penetrating electrodes might form the basis for a cortically based solution for sight restoration in individuals with profound blindness.
We hope that advances in medical technologies, neuroscience, electronics, material science, and information and communication technologies, combined with the increase of intelligence in these visual neuroprosthetic devices, will encourage the development of new and improved custom-tailored neuroelectronic systems for restoring functional sight in many blind people.
16.01.2023, 16:00-17:30, Raum 2030, Cognium, Hochschulring 18
This presentation will also be streamed via Zoom, please use the following link:
Aims and limits of behavioral pharmacology
Prof. Dr. Michael Koch
Behavioral Pharmacology takes advantage of the fact that most of the neurons in the central nervous system use chemical messengers (neurotransmitter molecules) to convey „information“ in neuronal networks. One of the aims of this discipline is – by experimentally manipulating „key players“ in neurotransmission, e.g. enzymes, transporters and receptors and quantifying behavioral changes – to understand the neurobiochemistry of these processes. Another aim is to translate the findings from the experiments that are mostly done in experimental animals to humans – thereby providing a rational basis of psychopharmacological treatment of mental disorders. The talk will mostly focus on two neuroprotective and -restorative „proof-of-principle“-approaches following brain lesions.
30.01.2023, 16:00-17:30, Olbers-Saal, Haus der Wissenschaft, Sandstr. 4/5, Bremen
Fake News und Gehirn: Gefahren und wie wir uns schützen können!
Prof. Dr. Markus Knauff
In einer Gesellschaft, in der die Gier nach Aufmerksamkeit die Ideale von Wahrheit und Wahrhaftigkeit verdrängt, haben Fake News ein leichtes Spiel. Bislang ist es der Politik nicht gelungen, dem Einhalt zu gebieten. Und Facebook, Twitter und Co. verdienen gut an der Verbreitung von Falschinformation. Wir müssen uns also selbst schützen. Dabei hilft uns, wenn wir besser verstehen, wie unser Gehirn Informationen verarbeitet. Was macht unser Gehirn so anfällig für Fehlinformation? Warum sind wir so schnell bereit, gezielte Desinformation zu glauben und zu verbreiten? Wie können wir uns vor gezielten Manipulationsversuchen schützen? Der Vortrag bietet zweierlei: Ergebnisse aus der kognitiven Grundlagenforschung, wie unser Gehirn wahre und falsche Informationen verarbeitet, und ganz praktische Tipps zum rationalen Umgang mit Nachrichten aus sozialen Netzwerken und Messenger Diensten.
Literaturtipp: Knauff, M. & Spohn, W. (2021) (Hrsg.). The Handbook of Rationality. Cambridge, MA: MIT Press.
06.02.2023, 16:00-17:30, Raum 2030, Cognium, Hochschulring 18
Organic mixed conductors - a new materials class for the Neurosciences?
Prof. Dr. Björn Lüssem
Efficient communication across the interface between biological tissue and microelectronics is a long-sought but thus far elusive goal. There is a gap between silicon-based microelectronics and biological tissue. Silicon is mechanically stiff, leading to inflammation and damage in soft and stretchable tissue. Silicon operates by manipulation of electrons and holes, whereas biological information is mainly transmitted via ionic signals.
Mixed organic semiconductors are a new materials class that sets out to bridge this gap. Mixed semiconductors conduct both, ions and electronic charge, and are thus an efficient transducer between biology and microelectronics. Furthermore, organic semiconductors are soft, stretchable, and bio-compatible, making them ideal candidates for wearable or implantable sensor systems.
Here, I will summarize recent progress that has been made in using mixed semiconductors for the neurosciences. An emphasis is put on the potential to sense both, electronic and chemical signals with high spatial and temporal resolution. Several challenges of the field are presented, in particular with respect to sensitivity, speed of measurements, and fabrication. I will review several approaches to overcome these limits and discuss first steps to establish mixed semiconductors as a new tool for the neurosciences.
Sommersemester 2022
16.05.2022, 16:00-17:30, Raum 2030, Cognium, Hochschulring 18
Co-constructing understanding – learning how to learn from infants as a new approach for teaching robots?
Prof. Dr. Britta Wrede
Will computers and robots be able to understand our world the way we humans do? From the beginning of their endeavor AI researchers have discussed if it is possible for a computer to become “…a mind, in the sense that computers can be literally said to understand and have other cognitive states” (Searle, 1980) – also known as “strong AI” - or if AI is just “… the science of making machines do things that would require intelligence if done by men” (Minsky), i.e. just simulate behavior that appears intelligent – also known as “weak AI”. Since then, many new arguments have arisen and new perspectives been formulated, pertaining among others to the scope of AI (narrow vs general), the need for embodiment, cultural emersion, or social interaction.
In my talk I will argue that in order for robots to be able to understand our world the way we do they need to be able to learn from our explanations just as children do. More specifically, they need the ability to jointly co-construct meaning by interacting with humans. Co-construction refers to a bi-directional process where mutual scaffolding and monitoring take place, generally in a task-oriented situation with a joint goal. I will present some results from our research on scaffolding in parent-child interactions and their modelling in HRI, enabling the robot to make sense of scaffolding behavior. More recently, for example in the TRR/SFB 318 “Constructing Explainability”, we are investigating how computers and robots can make their understanding of the world and the interaction transparent and meaningful to the user by explaining and other strategies, addressing attentional, emotional and many other strategies.
Our goal is to close the loop of scaffolding and monitoring to reciprocally enable humans and robots to jointly co-construct meaning in interaction. We believe that through these little steps a shared understanding of the world can be achieved between humans and robots.
30.05.2022, 16:00-17:30, Raum 2030, Cognium, Hochschulring 18
Primary visual cortex and beyond
PD Dr. Dirk Jancke
How are neuronal processing delays compensated in primary visual cortex? How are different parameters multiplexed and stimulus traces created at early steps of cortical processing? How plastic is the functional layout of this area and how are natural scenes represented across populations of neurons? I will address these questions from the viewpoint of wide-field optical imaging, a recording method that captures cortical activity at mesoscopic scale. In combination with classical (TMS) and modern perturbation methods (here serotonergic modulation via optogenetics) I will outline further ongoing research directions of our lab that exploit optical imaging technologies to reveal the complexity of visual processing dependent on brain state and behavioral context
20.06.2022, 16:00-17:30, Olbers-Saal, Haus der Wissenschaft, Sandstr. 4/5, Bremen
Auf dem Weg zur Erfassung physiologischer Vorgänge bei neuro-degenerativen Erkrankungen
Prof. Dr. Matthias Günther
Das Gehirn ist ein wichtiges und zugleich faszinierendes Organ des Menschen. Sogenannte neuro-degenerative Erkrankungen stellen allerdings eine massive Bedrohung der Leistungsfähigkeit dieses Organs dar. Neben vielen anderen Faktoren spielt dabei die Blutversorgung eine große Rolle und es wurde erkannt, dass einige dieser neuro-degenerativen Erkrankungen (wie z.B. Alzheimer-Erkrankung) zu einem frühen Zeitpunkt mit Veränderungen der Gefäßstruktur der kleinsten Gefäße, der Kapillaren, einhergeht. Dabei spielt die Blut-Hirn-Schranke eine wichtige Rolle, die als Barriere das Hirngewebe kontrolliert mit Nährstoffen und Sauerstoff versorgt, Schadstoffe fernhält und Abfallstoffe entsorgen kann.
Im Rahmen eines internationalen Forschungsprojektes, das vom Fraunhofer-Institut MEVIS in Bremen geleitet wird, sollen Methoden entwickelt und getestet werden, mit denen die Blut-Hirn-Schranke nicht invasiv untersucht werden kann. Ziel ist es, frühzeitige Veränderungen in dieser wichtigen Hirngefäßstruktur sichtbar zu machen und damit ein wichtiges Hilfsmittel zur Erforschung von Therapien für z.B. Alzheimer-Erkrankungen zur Verfügung zu haben. Im Vortrag werden anhand des Forschungsprojekts und erster Ergebnisse die wissenschaftlichen Grundlagen vereinfacht erläutert und ein Einblick in die aktuelle Forschung gegeben.
27.06.2022, 16:00-17:30, Raum 2030, Cognium, Hochschulring 18
This presentation will also be streamed via Zoom, please use the following link:
Machine Listening
Prof. Dr. Haizhou Li
Der Excellence Chair Prof. Dr. Haizhou Li wird ein Forschungsprogramm vorstellen, in dem ein biologisch inspiriertes Modell für das maschinelle Zuhören entworfen, implementiert und überprüft werden wird, das die Fähigkeit des menschlichen Zuhörens nachempfindet. Die Forschergruppe verfolgt dazu einen anthropomorphen Ansatz, um die Herausforderungen des maschinellen Zuhörens mit dem modernen Paradigma erklärbarer künstlicher Intelligenz zu adressieren. Dieser anthropomorphe Ansatz besteht aus einer kognitiven Schleife, welche die Eingabeseite der Sprachakquisition mit der Ausgabeseite des Sprachverstehens in beide Richtungen miteinander koppelt. Der Ansatz verspricht eine enorme Verbesserung für den Einsatz sprachbasierter Technologien in realen Szenarien, wie bei der auditorischen Aufmerksamkeit in Cocktail-Party Szenarien, der Spracherkennung in Multisprecherszenarien und dem Hören bei Robotern. Die Forschung markiert einen Wendepunkt für Architekturen der Sprachverarbeitung, die bis heute auf einer einfachen gerichteten Verarbeitung von Ein- nach Ausgabe basieren.
04.07.2022, 16:00-17:30, Olbers-Saal, Haus der Wissenschaft, Sandstr. 4/5, Bremen
Vortrag muss leider krankheitsbedingt verschoben werden!
Fake News und Gehirn: Gefahren und wie wir uns schützen können!
Prof. Dr. Markus Knauff
In einer Gesellschaft, in der die Gier nach Aufmerksamkeit die Ideale von Wahrheit und Wahrhaftigkeit verdrängt, haben Fake News ein leichtes Spiel. Bislang ist es der Politik nicht gelungen, dem Einhalt zu gebieten. Und Facebook, Twitter und Co. verdienen gut an der Verbreitung von Falschinformation. Wir müssen uns also selbst schützen. Dabei hilft uns, wenn wir besser verstehen, wie unser Gehirn Informationen verarbeitet. Was macht unser Gehirn so anfällig für Fehlinformation? Warum sind wir so schnell bereit, gezielte Desinformation zu glauben und zu verbreiten? Wie können wir uns vor gezielten Manipulationsversuchen schützen? Der Vortrag bietet zweierlei: Ergebnisse aus der kognitiven Grundlagenforschung, wie unser Gehirn wahre und falsche Informationen verarbeitet, und ganz praktische Tipps zum rationalen Umgang mit Nachrichten aus sozialen Netzwerken und Messenger Diensten.
Literaturtipp: Knauff, M. & Spohn, W. (2021) (Hrsg.). The Handbook of Rationality. Cambridge, MA: MIT Press.
11.07.2022, 16:00-17:30, Raum 2030, Cognium, Hochschulring 18
Exploring the brain with functional digital twins
Prof. Dr. Fabian Sinz
Deep neural networks have set new standards in modeling the responses of large scale populations of neurons to natural stimuli, yielding models that can accurately predict the response of thousands of neurons to novel stimuli. This allows us to treat the model as a functional digital twin of the neural circuit and probe neurons in ways that would not be feasible experimentally. With that, we can derive new hypotheses about the neural circuits that can then be verified in subsequent experiments. In this talk, I will give an overview over the models and their application in understanding the computational properties of visual cortex.
Wintersemester 2021/2022
06. Dezember 2021, 16:30-18:00, Raum 2030, Cognium, Hochschulring 18
Voltage imaging with genetically encoded voltage indicators: Development and application
Prof. Dr. Daan Brinks
Technologies that allow high-speed imaging of cellular dynamics are central to our ability to ask and answer new questions in cell biology and neuroscience. Here, I will focus on voltage imaging: the optical recording of membrane potentials and their fast dynamics in excitable cells. I will touch upon the development of pooled high throughput screens, high-speed microscopes, targeted gene expression schemes and improved near-infrared voltage indicators, which enabled simultaneous in vivo recordings of supra- and subthreshold voltage dynamics in multiple neurons in the hippocampus of behaving mice. I will discuss recent developments in our lab expanding the palette of available tools and applications for voltage imaging in vitro and in vivo, and touch upon recent functional transcriptomics work that enhances the potential of voltage imaging as a diagnostic tool.
17. Januar 2022, 16:30-18:00, Zoom
Computation spike by spike - hardware and wetware
Prof. Dr. Alberto Garcia-Ortiz and Prof. Dr. Klaus Pawelzik
Recent advances in machine learning with deep neural networks (DNNs) show impressive performances in solving difficult problems. However, current DNN approaches are still inefficient when compared with their biological counterparts. It appears that evolution has found solutions that are still superior to the current technical implementations. Spiking neural networks (SNN) could offer an alternative to standard CNNs. Like the brain, SNN can operate reliably using mechanisms that are inherently non-reliable. Beside robustness, SNN have further advantages like the possibility of higher energy efficiency and more efficient asynchronous parallelization.
However, current implementations of SNNs require hundreds of cores with large and complex circuits. We present an alternative approach, the ‘Spike-by-Spike’ (SbS) networks, which represent a compromise between computational requirements and biological realism that preserves essential advantages of biological networks while allowing a much more compact technical implementation. To fully exploit the robustness and efficiency of SbS, dedicated hardware architectures are required. By combining optimized hardware architectures with stochastic and approximate processing approaches, this new approach aims to improve the performance of neural networks and their energy consumption by at least one order of magnitude.
24. Januar 2022, 16:30-18:00, Zoom
Decoding higher order cognition from invasive brain signals
Prof. Dr. Christian Herff
The decoding of higher order cognition directly from recordings of neural activity in the brain could enable a new generation of prosthetic devices. Accurate information about memory processes, reward perception and attempted speech and motor activity will allow targeted interventions and next-level human-computer interaction. In this presentation, I will present work with neurological patients that have electrodes implanted deep into their brains for clinical procedures. By piggybacking on these clinical routines, we are able to record high-fidelity neural activity across a variety of brain areas and align them to cognitive tasks. Through the application of machine learning, we are able to decode higher-order cognition from these recordings and process the output in real-time.
Sommersemester 2021
10. Mai 2021, 16:00-18:00
A reservoir of decision strategies in the mouse frontal cortex
Dr. Zach Mainen
A decision is an exclusive commitment to one of several alternative actions. A decision strategy is an algorithm for how to decide: what things to pay attention to and how to process them. For example, some decision strategies are based on direct responses to observable stimuli ('model free') while others require inferences about hidden states ('model based'). Decision strategies, like attentional processes, should imply commitment of neural processing resources, but the nature and limits of those resources are not well understood. We've been exploring these issues by recording large neural ensembles in the frontal cortex of mice performing a foraging task that admits several possible strategies for deciding when to leave a foraging site. We formulate a model based on temporal integration and reset that unifies an ensemble of strategies (including both model-based and model-free) into a single algorithmic family. We find that at any given time, not just one but the entire family of strategies can be simultaneously decoded from these neural ensembles. Surprisingly, the ability to read out a particular strategy is independent of whether it is currently being deployed behaviorally. Such multiplexing of decision computations may allow for more flexible combination and switching of strategies. These findings suggest that actual decisions reveal only the tip of an iceberg of decision-relevant computations being executed within the brain. This work is led by Fanny Cazettes and in collaboration with Alfonso Renart.
31. Mai 2021, 16:00-18:00
The neurobiology of confidence: from statistics to neurons
Dr. Torben Ott
How confident are you? As humans, aware of our subjective sense of confidence, we can readily answer. Knowing your level of confidence helps to optimize both routine decisions such as whether to go back and check if the front door was locked and momentous ones like finding a partner for life. Yet the inherently subjective nature of confidence has limited investigations by neurobiologists. We have developed a conceptual framework that roots subjective confidence in a statistical computation that can be behaviorally studied in non-human animals, thus enabling to study its neural basis. In an economic decision task, we asked humans and rats to invest time into choices based on ambiguous sensory evidence. Both humans and rats invest time according to their degree of confidence, the probability that their choice was correct. Single neurons in rat orbitofrontal cortex encode statistical decision confidence and predict two confidence-guided behaviors: trial-by-trial time investment serving as confidence reports and learning of choices across trials, thereby revealing abstract representations of decision confidence in rat frontal cortex. This work paves the way for interrogating the neural circuits that mediate confidence-based economic decisions and sheds light on the neural basis of metacognitive abilities.
21. Juni 2021, 16:00-18:00
From vision to navigation and back
Prof. Dr. Matteo Carandini
Vision provides crucial guidance to navigation, and this guidance is a key function of the visual system. The communication between visual system and navigation system, however, appears to operate also in the opposite direction, with navigation strongly influencing vision. We recorded from populations of neurons in mice that navigate virtual environments and found modulation by spatial position in neurons throughout the visual cortex, including primary visual cortex (but not in its thalamic afferents). These navigational signals correlate with those in the hippocampus, and reflect the animal’s own estimate of position acquired through both vision and idiothetic cues. They are perhaps strongest in the parietal cortex, where cells respond to vision only during navigation. Position signals, therefore, appear remarkably early in the visual system and permeate its operation. Various properties of these signals, including modulation by hippocampal theta oscillations, suggest that they originate in the hippocampus or associated regions of the navigational system. This talk centers on work by Aman Saleem, Julien Fournier, and Mika Diamanti.
5. Juli 2021, 16:00-18:00
How failures in protein folding can lead to neurodegenerative diseases
Prof. Dr. Janine Kirstein
How can we use a nematode to understand the manifestation and progression of neurodegenerative diseases? On a cellular level, humans do not differ much from much simpler organisms. We use the nematode C. elegans to understand how mutations that lead to aberrant protein structures such as amyloid fibrils cause neurodegenerative diseases. The nematode can be easily genetically manipulated and we have expressed the Abeta peptide (Aβ1-42) in the neurons and used fluorescence lifetime imaging to visualize and also quantify the aggregation of Aβ1-42 as the animal ages. Notably, using our new AD model, we could map for the first time in any living animal the onset of Aβ aggregation. Aβ1-42 starts to form amyloid fibrils in a subset of cholinergic neurons of the anterior head ganglion, the six IL2 neurons. Targeted depletion of Aβ1-42 in these IL2 neurons led to a systemic delay of Aβ pathology and restored neuronal function. We are currently studying what renders specific neurons more susceptible for Aβ1-42 aggregation and assess the potential of molecular chaperones as therapeutic strategy to interfere with the pathological aggregation cascade of Aβ1-42.
12. Juli 2021, 16:00-18:00
What the mouse eye tells the brain and how the brain processes this visual message
Dr. Katrin Franke
To provide a compact and efficient input to the brain, sensory systems separate the incoming information into parallel feature channels. In the visual system, parallel processing starts in the retina. Here, the image is decomposed into multiple retinal ganglion cell (RGC) types, each selective for a specific set of visual features like motion, contrast or edges. Recent work in mice provides a thorough classification of RGCs, revealing that the retina sends approx. 40 distinct information channels to the brain. However, how (i) visual features arise within the retinal network, (ii) are integrated in downstream brain areas and (iii) relate to behavior remains poorly understood. In my talk, I will present recent work addressing these questions by focusing on color – a single visual feature and an important aspect of natural scenes. Specifically, we followed the neural representation of color across all retinal layers to primary visual cortex in mice and linked our findings to the statistics of mouse natural scenes and available behavioral data. With this, we hope to increase our understanding of how specific sensory features are processed across neural hierarchies to drive behavior – a central question in neuroscience.
Wintersemester 2020/2021
16.11.2020, 16:00-18:00
Zeugenaussagen vor Gericht – über die Wahrheit und die Wahrheit über den Irrtum
Dr. Frank Maurer
Kern jeder richterlichen Tätigkeit ist, Zeugen zu hören und deren Aussage zu bewerten, Wahrheit zu erkennen, Lüge aufzudecken und Irrtum auszuschließen. In fast jedem Prozess werden Zeugen gehört, Zeugen sind das am meisten verwendete Beweismittel. Das Problem aber ist: Menschen sind nicht dafür gemacht, gute Zeugen zu sein. Ihr Auge ist keine Videokamera, ihr Gehirn kein Videorekorder. Der Mensch ist - soweit er als Zeuge auftritt - eine biologische Fehlkonstruktion.
Dieser MindTalk wirft einen Blick hinter die Kulissen bei Gericht und zeigt praxisnah, was Zeugen überhaupt leisten können und was Wahrnehmung, Aufmerksamkeit, Selektion und beschränkte Simultankapazität damit zu tun haben.
30.11.2020, 16:00-18:00
Attention recognition: Key to adaptive cognitive systems
Prof. Dr. Tanja Schultz und Dr. Felix Putze
The digital revolution is changing our world. Among the various promises of the near future are articifial intelligent technologies that provide just the right assistance when we need it. However, current digital assistants like navigation systems make us realize how difficult it is to strike a balance between support and distraction.
Getting this right requires technical cognitive systems that observe and interpret our daily activities, ultimately providing support when needed, while keeping our focus on the task despite natural and technological distractions.
In our talk, we will describe research and development at the Cognitive Systems Lab (CSL) towards such adaptive cognitive systems. We will show how modeling attention from neural and physiological data can help to create adaptive systems and will discuss several facets of attention which play a crucial role in everyday life. Furthermore, we will argue that humans usually rely on ambiguous cues and therefore cognitive systems should as well, processing a range of biosignals and integrate multiple modalities over time to reliably estimate a user's attention.
Several end-to-end systems and applications will be described that were developed within the framework of collaborative projects such as SmartHelm and EASE, in which the CSL team explores biosignals from speech, muscle and brain activities using machine learning methods to interpret user states and traits in everyday situations.
14.12.2020, 16:00-18:00
Neuronal architectures for affective brains
Dr. Wulf Haubensak
Neuroscience is undergoing two revolutions: circuit technologies allow to experimentally deconstruct neuronal network mechanisms of behavior, at the same time large brain and genomic databases create opportunities for computational mining of the neurogenetic organization of the brain. We fuse both approaches to explore the emotional brain, from genetic to systems levels.
Brains generate internal models of the world to interpret and guide interactions with the environment. Using circuit neuroscience, we delineated a cortico-limbic network that encodes subjective stimulus salience (‘how important?’) and affective valence (‘good or bad?’) at different hierarchies. We find that bottom-up salience signals in the amygdala instruct bodily feedback from the insular cortex to control affective memory and behavior. This network recruits ‘gut feelings’ into decisions, particularly when knowledge is scarce and integrates spatial signals to safeguard environmental interactions.
From the past 60 million years to the emergence of human societies, human ancestors faced increasing complex habitats, requiring ever more elaborate behavioral strategies. Computational reconstruction of human cognitive evolution allows to trace neurogenetic signatures of functional selection in affective networks and puts the circuit mechanisms identified above into evolutionary context.
11.01.2021, 16:00-18:00
Similarity-based processes in judgement and decision making
Prof. Dr. Bettina von Helversen
Similarity plays a fundamental role in how people make sense of the world. People group similar objects together and use similarity to infer how to respond to unknown objects or situations. Specifically, research on category learning and generalization assumes that people categorize new objects based on their similarity to past instances activated in memory. In addition to similarity-based processes, however, people also establish rules. These rules denote the relationship between an objects’ attributes and group membership (i.e. animals that fly tend to be birds) in categorization decisions or a quantitative criterion (i.e. larger animals tend to have higher lifespans) in quantitative judgment. Similarity and rule-based processes are often treated as two independent strategies or modules people recruit depending on the affordances of the task. However, evidence suggests that both processes interact. In the talk I give an overview of our research on how similarity and rule-based processes jointly determine responses in judgments and categorization decisions and how (dis)-similarity may fuel the formation of rules.
25.01.2021, 16:00-18:00
Cortical mechanisms for visual perception and restoring them in blindness
Prof. Dr. Pieter Roelfsema
I will argue that early visual cortex plays a crucial role in visual cognition – i.e. in tasks where we reason about what we see. Early visual cortex acts as a cognitive blackboard for read and write operations by higher visual areas, which can thereby efficiently exchange information. Inhibiting these interactions gives rise to selective deficits in visual perception. Elementary processes such as contrast detection are unimpaired. However, more complex tasks, which depend on the segregation of a figure from the background are impaired. Our results inspire new approaches to create a visual prosthesis for the blind, by creating a direct interface with the visual cortex. I will discuss how high-channel-number interfaces with the visual cortex might be used to restore a rudimentary form of vision in blind individuals.
08.02.2021, 16:00-18:00
Where are the switches in the brain? Neural mechanisms of selective attention in experiment and theory
Prof. Dr. Andreas Kreiter und Dr. Udo Ernst
Human and non-human primates' brains are capable of performing a wide variety of quickly changing, often attention-dependent tasks in complex environments. Unlike digital computers, they do not have a software, i.e., different programs executed by the same central processing unit, which are called and executed according to current needs. Instead, complex networks of neurons throughout the brain can serve different purposes of information processing. To perform different tasks at different times, these networks need to be reconfigured accordingly at a time scale of seconds or less. However, networks of neurons do not have switch-like elements to change their connectivity pattern. Using a combination of experimental and theoretical results, we will argue that states of oscillatory synchronization between changing subsets of neurons modulate the pattern of effective connectivity within neuronal networks. We will show that such dynamic changes result in different functional circuits that route information depending on the behavioral task and selective attention, and discuss (putative) control mechanisms which are capable to establish and maintain appropriate network configurations.