Geir Halnes
University of Oslo
Excitatory postsynaptic potentialPhysicsBiophysicsIonComputational neuroscienceArtificial intelligenceNeuroscienceInhibitory postsynaptic potentialMembrane potentialChemistryBiological systemBiological neuron modelNeuronExtracellularComputer scienceArtificial neural networkElectroencephalographyCable theoryComputational modelBiology
54Publications
13H-index
495Citations
Publications 47
Newest
#1Solveig Næss (University of Oslo)H-Index: 5
#2Geir Halnes (NMBU: Norwegian University of Life Sciences)H-Index: 13
Last. Torbjørn V. Ness (NMBU: Norwegian University of Life Sciences)H-Index: 12
view all 7 authors...
Electroencephalography (EEG) and magnetoencephalography (MEG) are among the most important techniques for non-invasively studying cognition and disease in the human brain. These signals are known to originate from cortical neural activity, typically described in terms of current dipoles. While the link between cortical current dipoles and EEG/MEG signals is relatively well understood, surprisingly little is known about the link between different kinds of neural activity and the current dipoles t...
4 CitationsSource
#1Marte J. Sætra (NMBU: Norwegian University of Life Sciences)H-Index: 2
#2Geir HalnesH-Index: 13
Last. Gaute T. EinevollH-Index: 37
view all 3 authors...
Computational modeling in neuroscience has largely focused on simulating the electrical activity of neurons, while ignoring other components of brain tissue, such as glial cells and the extracellular space. As such, most existing models can not be used to address pathological conditions, such as spreading depression, which involves dramatic changes in ion concentrations, large extracellular potential gradients, and glial buffering processes. We here present the electrodiffusive neuron-extracellu...
Source
#1Solveig Næss (NMBU: Norwegian University of Life Sciences)
#1Solveig Næss (NMBU: Norwegian University of Life Sciences)H-Index: 5
Last. Torbjørn V. Ness (NMBU: Norwegian University of Life Sciences)H-Index: 12
view all 7 authors...
Electroencephalography (EEG) and magnetoencephalography (MEG) are among the most important techniques for non-invasively studying cognition and disease in the human brain. These signals are known to originate from cortical neural activity, typically described in terms of current dipoles. While the link between cortical current dipoles and EEG/MEG signals is relatively well understood, surprisingly little is known about the link between different kinds of neural activity and the current dipoles t...
Source
#1Torbjørn V. NessH-Index: 12
#2Geir HalnesH-Index: 13
Last. Gaute T. Einevoll (NMBU: Norwegian University of Life Sciences)H-Index: 37
view all 5 authors...
Measurements of electric potentials from neural activity have played a key role in neuroscience for almost a century, and simulations of neural activity is an important tool for understanding such measurements. Volume conductor (VC) theory is used to compute extracellular electric potentials such as extracellular spikes, MUA, LFP, ECoG and EEG surrounding neurons, and also inversely, to reconstruct neuronal current source distributions from recorded potentials through current source density meth...
1 Citations
#1Marte J. Sætra (University of Oslo)H-Index: 2
#2Gaute T. Einevoll (NMBU: Norwegian University of Life Sciences)H-Index: 37
Last. Geir Halnes (NMBU: Norwegian University of Life Sciences)H-Index: 13
view all 3 authors...
In most neuronal models, ion concentrations are assumed to be constant, and effects of concentration variations on ionic reversal potentials, or of ionic diffusion on electrical potentials are not accounted for. Here, we present the electrodiffusive Pinsky-Rinzel (edPR) model, which we believe is the first multicompartmental neuron model that accounts for electrodiffusive ion concentration dynamics in a way that ensures a biophysically consistent relationship between ion concentrations, electric...
10 CitationsSource
#1Ada J. Ellingsrud (Simula Research Laboratory)H-Index: 2
#2Andreas Våvang Solbrå (University of Oslo)H-Index: 4
Last. Marie E. Rognes (Simula Research Laboratory)H-Index: 17
view all 5 authors...
Mathematical models for excitable cells are commonly based on cable theory, which considers a homogenized domain and spatially constant ionic concentrations. Although such models provide valuable insight, the effect of altered ion concentrations or detailed cell morphology on the electrical potentials cannot be captured. In this paper, we discuss an alternative approach to detailed modelling of electrodiffusion in neural tissue. The mathematical model describes the distribution and evolution of ...
9 CitationsSource
#1Geir Halnes (NMBU: Norwegian University of Life Sciences)H-Index: 13
#2Klas H. Pettersen (University of Oslo)H-Index: 18
Last. Gaute T. Einevoll (NMBU: Norwegian University of Life Sciences)H-Index: 37
view all 5 authors...
We review modelling of astrocyte ion dynamics with a specific focus on the implications of so-called spatial potassium buffering where excess potassium in the extracellular space (ECS) is transported away to prevent pathological neural spiking. The recently introduced Kirchhoff–Nernst–Planck (KNP) scheme for modelling ion dynamics in astrocytes (and brain tissue in general) is outlined and used to study such spatial buffering. We next describe how the ion dynamics of astrocytes may regulate micr...
2 CitationsSource
#1Ada J. EllingsrudH-Index: 2
Last. Marie E. Rognes (Simula Research Laboratory)H-Index: 17
view all 5 authors...
Mathematical models for excitable cells are commonly based on cable theory, which considers a homogenized domain and spatially constant ionic concentrations. Although such models provide valuable insight, the effect of altered ion concentrations or detailed cell morphology on the electrical potentials cannot be captured. In this paper, we discuss an alternative approach to detailed modelling of electrodiffusion in neural tissue. The mathematical model describes the distribution and evolution of ...
1 Citations
#1Geir Halnes (NMBU: Norwegian University of Life Sciences)H-Index: 13
#2Simen Tennøe (University of Oslo)H-Index: 5
Last. Kjetil Hodne (NMBU: Norwegian University of Life Sciences)H-Index: 12
view all 6 authors...
Pituitary endocrine cells fire action potentials (APs) to regulate their cytosolic Ca2+ concentration and hormone secretion rate. Depending on animal species, cell type, and biological conditions, pituitary APs are generated either by TTX-sensitive Na+ currents (INa), high-voltage activated Ca2+ currents (ICa), or by a combination of the two. Previous computational models of pituitary cells have mainly been based on data from rats, where INa is largely inactivated at the resting potential, and s...
3 CitationsSource
#1Tuomo Mäki-Marttunen (University of Oslo)H-Index: 11
#2Tobias Kaufmann (University of Oslo)H-Index: 35
Last. Ole A. Andreassen (University of Oslo)H-Index: 123
view all 23 authors...
The brain is the most complex of human organs, and the pathophysiology underlying abnormal brain function in psychiatric disorders is largely unknown. Despite the rapid development of diagnostic tools and treatments in most areas of medicine, our understanding of mental disorders and their treatment has made limited progress during the last decades. While recent advances in genetics and neuroscience have a large potential, the complexity and multidimensionality of the brain processes hinder the ...
13 CitationsSource