In our daily lives, we do not only process sensory information about single stimuli, but become consciously aware of many stimuli, perceive them as embedded in a context, and experience a rich diversity of sensations in multiple modalities. How is the brain able to perceive and to integrate or differentiate between sensory modalities? Here we apply techniques such as ensemble recordings (many-neuron recordings, using tetrodes, silicon probes and two-photon imaging) and optogenetics to examine how neurons and neuronal populations code sensory stimuli and make a difference between perceived versus unperceived stimuli, as gauged via behavioral report. Leading discoveries are that the visual cortex, seemingly dedicated to a single modality (vision) is susceptible to non-visual factors such as reward and auditory input.
Empirical neuroscience data, although very intriguing on their own, are often too complicated to explain by intuitive models drafted with pen-and-paper. Therefore, computational models of networks performing cognitive and perceptual tasks are needed. In this research line we focus on neuronal models of predictive coding, wherein perception is built on the brain generating ‘predictions’ (or representations) about what causes the sensory inputs received through our senses. We have developed a novel, scalable model of a deep neural network relying on predictive coding with Hebbian learning. Next challenges are to make the model more neurobiologically realistic, endowing it with cortex-like circuitry, and expand the model to include cognitive capacities and multisensory integration.
How does the brain transmit sensory information to the temporal lobe memory system to direct the storage of hippocampus-dependent long-term memories? We understand some basics of sensory processing and hippocampal memory, but do not grasp how the two are connected and communicate. We focus on how the visual, auditory and somatosensory cortices interact with the hippocampus and an intermediate, parahippocampal structure: the perirhinal cortex. Using chemogenetics and ensemble recordings, we study the role of the sensory cortical-hippocampal hierarchy in navigation, discrimination between spatial patterns (pattern separation), object recognition and memory retrieval. Recently, we discovered perirhinal neurons with spatially extended firing fields – informally dubbed ‘neighborhood cells’ in analogy to hippocampal place cells.
How does brain activity give rise to consciousness? What in the brain makes the difference when we perceive or do not perceive an object? a key tenet of my neuropresentationalist theory holds that conscious experience essentially provides the subject with a multimodally rich and spatially encompassing survey of its situation in the world, including its body. This has a function: it enables the subject to make complex decisions and plan its behavior. The neural architecture required to construct this survey is rich, comprising phenomena such as hierarchical and lateral connectivity in the cortex, phase coding, predictive representations and a multi-level organization of representational systems. To better understand the conscious state, we also study neuronal ensembles and multi-area interactions during sleep and anesthesia. Thus, our theoretical research is translated into practical experiments on perception, multisensory integration as well as computational modelling. Complementary research with clinical relevance comprises data analysis to better characterize the conscious state and alleviate symptoms in patients who are behaviorally impaired and/or locked-in.
Chairing the Cognitive and Systems Neuroscience group at the Swammerdam Institute for Life Sciences, I collaborate with staff members of the group, and many more scientists, to conduct the research as sketched above, coordinate teaching activities, support technical innovation, and guide PhD students in their projects. With Umberto Olcese I collaborate in several funded project
(Neurotechnology: INTENSE project, Consciousness: Templeton Initiative on Accelerating Research on Consciousness, Human Brain Project). Dr Jorge Mejias, Prof. Dr Sander Bohte and I work together on computational modelling in the Human Brain Project and the NWA-ORC grant ‘Perceptive Acting under Uncertainty’. With Dr Conrado Bosman I collaborate on the emergent development of multisensory integration early in life. I also work closely with Gerjan Huis in ‘t Veld (biotechnician), Dr Angelica da Silva Lantyer (Scientific Integration Manager Human Brain Project) and data analyst and PhD candidate Pietro Marchesi.
On May 3, 2021, a new popular-science book from Pennartz was released by Publishing House Prometheus: De Code van het Bewustzijn. Hoe de hersenen onze werkelijkheid vormgeven. (The Code of Consciousness, in Dutch; paperback, 352 pages, ISBN: 978 90 446 3191 3)
Cyriel Pennartz studied Biology at the Radboud University and University of Amsterdam with specializations in Neurobiology, Philosophy and Computational Neuroscience. He obtained his PhD degree in Neuroscience at the latter university. His PhD project examined the electrophysiology and plasticity of brain circuits involved in memory and motivation, focusing on the ventral striatum, and was partly conducted at the University of Tennessee (Memphis, U.S.A.). He next worked as Postdoctoral fellow in Computational Neuroscience at the Department of Physics of Computation of the California Institute of Technology with John Hopfield. Here he worked on neural network models of Reinforcement Learning. In 1994 he became tenured staff scientist and group leader at the Netherlands Institute for Brain Research, initially researching the physiology of the brain´s circadian clock. Working with Bruce McNaughton and Carol Barnes at the University of Arizona (Tucson, U.S.A.), he introduced in vivo ensemble recording techniques to the Netherlands and discovered replay of reward information in the ventral striatum during sleep.
In 2003 he was appointed Full Professor in Cognitive and Systems Neuroscience at the University of Amsterdam, where he is currently leads the Cognitive and Systems Neuroscience group. He merges experimental neuroscience, computational models of brain function and theory on perception, memory and consciousness. His work in experimental neuroscience is paired with technological innovations in multi-area electrophysiology, pharmacological and optogenetic interventions, advanced data analytics and computer simulations. Chief characteristics of his work are its multidisciplinarity and integrative approach, in which theory and computer models drive in-depth experimentation. Recently his work has been ramifying into the clinical domain, studying disorders of consciousness and memory, and into neurotechnology, developing new methods to combat consequences of stroke.
For general information about our Master track Cognitive Neurobiology and Clinical Neurophysiology and internships, please contact: C.A.BosmanVittini@uva.nl.
Are you seeking more specific information on Pennartz’ research lines or specific projects for internships or collaboration? Please contact me (C.M.A.Pennartz@uva.nl).