Cerebral Cortex Research

There are four workgroups in this laboratory:

Workgroup of Quantitative Functional Anatomy, led by Dr. Gábor Nyiri
Workgroup of in vitro physiology led by Dr. Attila Gulyás
Workgroup of in vivo physiology led by Dr. Viktor Varga
Workgroup of computational neuroscience led by Dr. Szabolcs Káli

Excerpt from the Guidebook of the Institute 2015.

Workgroup of Quantitative Functional Anatomy

The sophisticated cognitive functions of the human & mammalian brain reside in complex connections of cells in the central nervous system. In order to understand how the brain works, we need to find the connections among the different brain areas. Research in our group is directed towards understanding the behavioural consequences of the activity or inactivity of those connections. We try to decipher which transmitters & receptors are used there, and how their receptors distribute & function in their synapses. Using viral tracings, optogenetic behavioural techniques, quantitative high-resolution neuroanatomical light and electron microscopic methods, we primarily focus on the role of connections that target cortical, hippocampal and forebrain areas and on the roles they play in healthy & diseased states of the brain.

Workgroup webpage: http://koki.hu/~nyiri/

Workgroup members:

Workgroup of in vitro physiology

Neuronal network activity is generated through the interaction of excitatory and inhibitory neurons. To understand dynamics, two aspects of network behavior have to be studied: control and coding. Studying how different inhibitory neurons behave during distinct network states we can understand control. Monitoring the activity of large populations of principal neurons during different network states can help to understand the rules of coding.

We use an improved in vitro slice preparation that upon pharmacological manipulations can switch among different activity patterns similar to physiological (gamma oscillation, sharp-wave ripples) and pathological (epileptic) in vivo patterns. This arrangement allows selective and quick manipulation of the network's behavior and parallel multichannel recording of network activity (field potentials and multiunit) as well as recording of cellular output (loose-patch recording of action potentials) and input (voltage and current clamp) from identified neurons or pairs of neurons.

We study:

• How do different inhibitory neurons integrate convergent synaptic inputs and generate action potentials during different network activity patterns?
• How do different cell types balance the activity of excitatory neurons as a function of network activation and synchrony?
• Using 2-photon microscopy we started to image large population of principal neurons to understand their collective behavior during different states and during the transition among these states.
• We are in the process of setting up an in vivo head-restrained 2-photon imaging system, where the same questions can be studied in parallel with the in vitro approach.

Workgroup webpage: http://www.koki.hu/~gulyas/

Workgroup members:

Workgroup of in vivo physiology

In order to adapt to an ever-changing environment we have to store only relevant information that is key to our survival. Subcortical modulation, by influencing all stages of cortical information processing, is indispensable for the selection, storage and recall of information. Our lab aims to unravel the operational principles of subcortical modulation by studying how the hippocampus, the center of the brain's episodic memory circuitry, is influenced by subcortical modulators. We focus on the connection between the hippocampus and two of its main modulatory inputs, the medial septum and the median raphe. The former is thought to be pivotal for orchestrating the activity of hippocampal coding neuronal assemblies whereas the latter may affect the storage of certain types of information.

We deploy in vivo patch clamp recording in unanesthetized animals as well as the registration of large populations of neurons in freely moving mice by high channel count silicone electrode arrays. To decipher causal relationships between modulatory and hippocampal circuits we manipulate modulator neurons by light-addressable proteins. By high temporo-spatial resolution behavioral tracking we can explore the behavioral correlates of subcortical modulation.

Our ultimate goal is to get closer to the understanding of the process through which the collection of stimuli that bombards us in every moment of our life is transformed into life-changing experiences.

Workgroup members:

Workgroup of computational neuroscience

The brain is a highly complex, nonlinear system, whose operation needs to be understood over a wide range of spatial and temporal scales. Although a huge amount of data about the nervous system has been collected using a large variety of experimental approaches, making sense of these results and especially connecting the different scales is almost impossible through purely intuitive approaches and qualitative theories. Computational neuroscience offers a range of quantitative tools which allow us to describe the data in a succinct manner, to formulate our hypotheses about neural function clearly and precisely, and to link different scales and levels of organization through the application of mechanistic models. Models are on the one hand constrained by experimental data and, on the other hand, provide novel predictions which are testable using experimental methods.

Our workgroup uses various mathematical and simulation tools to study the dynamics and functions of both single neurons and networks in the hippocampus, often in combination with experiments conducted in the lab. Some of the main focus areas of our group are the following:

• synaptic integration and nonlinear processing in neuronal dendrites
• the origin and functions of population dynamics which are characteristic of the hippocampus, including theta and gamma oscillations and sharp wave-ripple events
• the storage and retrieval of spatial and memorial representations in the hippocampus
• fitting of neuronal parameters based on experimental data, and quantification of the expected precision of parameter inference

We also participate in the European Human Brain Project, where we are involved in the construction and testing of large-scale data-driven models of the hippocampus. This is a pilot project for collaborative, reproducible modeling using the tools of the Brain Simulation Platform of the HBP.

Workgroup members: