Fritz Sommer

Friedrich T. Sommer, Ph.D.
Redwood Center for Theoretical Neuroscience
UC Berkeley
132 Barker, MC #3190
Berkeley, CA 94720-3190
phone (510) 643-1472
fax (510) 643-4952
<fsommer at berkeley dot edu>

Associate Adjunct Professor, Redwood Center for Theoretical Neuroscience & Helen Wills Neuroscience Institute, University of California, Berkeley
Faculty member (Privatdozent), Department of Computer Science, University of Ulm

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Research Interests

Many impressive capabilities of the brain are not yet understood, for example, abilities in perception to rapidly analyze cluttered visual scenes, spoken language, morse code or the virtually unlimited capacity of our long-term memory. My lab focusses on the question how neurons and networks in the brain collaborate to produce perception, memory and ultimately cognition. To study this question we use computational models of the brain and advanced techniques of data analysis. For a full list of the research publications, see the cv.

Recent Publications

K. Koeppsell, X. Wang, Y. Wei, V. Vaingankar, J. A. Hirsch, F. T. Sommer: Dynamical coding opens a novel channel for visual information to reach cortex. (2006) submitted

M. Rehn, F. T. Sommer: A network that uses few active neurones to code visual input predicts the diverse shapes of cortical receptive fields. Journal of Computational Neuroscience (2006) in press ps (postscript file: change pdf->ps)

F. T. Sommer, P. Kanerva: Can neural models of cognition benefit from the advantages of connectionism? Behavoral Brain Sciences (2006) in press pdf

M. Rehn, F. T. Sommer: Storing and restoring visual input with collaborative rank coding and associative memory. Neurocomputing 69 (10-12) (2006) 1219-1223 pdf

F. T. Sommer, T. Wennekers: Synfire chains with conductance-based neurons: internal timing and coordination with timed input. Neurocomputing 65-66 (2005) 449 - 454 pdf

D. George, F. T. Sommer: Computing with inter-spike inverval codes in networks of integrate and fire neurons. Neurocomputing 65-66 (2005) 414 - 420 pdf

L. M. Martinez, Q. Wang, R. C. Reid, C. Pillai, J.-M. Alonso, F. T. Sommer, J. A. Hirsch: Receptive field structure varies with layer in the primary visual cortex. Nature Neuroscience 8 (12) (2005) 372 - 379 pdf

A. Knoblauch, F. T. Sommer: Spike-timing dependent plasticity can form "zero-lag" links for cortical oscillations. Neurocomputing 52-54 (2004) 301 - 306 pdf

M. Rehn, F. T. Sommer: A network for the rapid formation of binary sparse representations of sensory input. Technical Report RNI-04-1 (2004)

G. Glatting, F. M. Mottaghy, J. Karitzky, A. Baune, F. T. Sommer, G. B. Landwehrmeyer, S. N. Reske: Improving binding potential analysis in [11C]raclopide PET studies using cluster analysis. Medical Physics 31 (4) (2004) 902-906 pdf

J. A. Hirsch, L. M. Martinez, C. Pillai, J.-M. Alonso, Q. Wang, F. T. Sommer: Functionally distinct inhibitory neurons at the first stage of visual cortical processing. Nature Neuroscience 6 (12) (2003) 1300 - 1308 pdf

F. T. Sommer, T. Wennekers: Models of distributed associative memory networks in the brain. Theory in Biosciences (122) (2003) 70 - 86 pdf

Eds: F. T. Sommer, A. Wichert: Exploratory analysis and data modeling in functional neuroimaging. MIT Press, Boston, MA (2003) link to publisher (table of contents, etc.)

A. Knoblauch, F. T. Sommer: Synaptic plasticity, conduction delays, and inter-areal phase relations of spike activity in a model of reciprocally connected areas. Neurocomputing (52-54) (2003) 301-306 pdf

V. Schmitt, R. Koetter, F. T. Sommer: The impact of thalamo-cortical projections on activity spread in cortex Neurocomputing (52-54) (2003) 919-924 pdf

Selected Publications by Theme

For a brief description of some of the research projects, see synopsis of research.

Computational models and analysis of the microscopic physiology in early visual stages

M. Rehn, F. T. Sommer: A network that uses few active neurons to code visual input predicts the diverse shapes of cortical receptive fields. (2006) to appear in Journal of Computational Neuroscience

M. Rehn, F. T. Sommer: Storing and restoring visual input with collaborative rank coding and associative memory. Neurocomputing 69 (10-12) (2006) 1219-1223 pdf

L. M. Martinez, Q. Wang, R. C. Reid, C. Pillai, J.-M. Alonso, F. T. Sommer, J. A. Hirsch: Receptive field structure varies with layer in the primary visual cortex. Nature Neuroscience 8 (12) (2005) 372 - 379 pdf

J. A. Hirsch, L. M. Martinez, C. Pillai, J.-M. Alonso, Q. Wang, F. T. Sommer: Functionally distinct inhibitory neurons at the first stage of visual cortical processing. Nature Neuroscience 6 (12) (2003) 1300 - 1308 pdf

Mechanisms of memory in realistic neural networks

Long-term memory

F. T. Sommer, T. Wennekers : Associative memory in networks of spiking neurons Neural Networks 14 (6-7) Special Issue: Spiking Neurons in Neuroscience and Technology (2001) 825 - 834 pdf

F. T. Sommer, T. Wennekers: Modeling studies on the computational function of fast temporal structure in cortical circuit activity Journal of Physiology - Paris 94 (5/6) (2000) 473-488 pdf

F. T. Sommer: On cell assemblies in a cortical column Neurocomputing (32-33) (2000) 517 - 522 pdf

T. Wennekers, F. T. Sommer: Gamma-oscillations support optimal retrieval in associative memories of two-compartment neurons Neurocomputing 26-27 (1999) 573 - 578 pdf

T.Wennekers, F.T.Sommer, G.Palm: Iterative Retrieval in Associative Memories by Threshold Control of Different Neural Models In: Supercomputers in Brain Research: From Tomography to Neural Networks World Scientific Publishing Comp (1995) 301-319

Short-term memory

A. Knoblauch, T. Wennekers, F. T. Sommer: Is voltage dependent synaptic transmission in NMDA receptors a robust mechanism for working memory? Neurocomputing (44-46) (2002) 19-24 pdf

U. Vollmer, F. T. Sommer: Coexistence of short and long term memory in a model network of realistic neurons Neurocomputing (38-40) (2001) 1031 - 1036 pdf

Large-scale integration of cortical representations

F. T. Sommer, T. Wennekers : Models of distributed associative memory networks in the brain Theory in Biosciences (122) (2003) 70 - 86 pdf

Associative memory in reciprocal cortico-cortical projections

F. T. Sommer, T. Wennekers : Associative memory in a pair of cortical cell groups with reciprocal projections Neurocomputing (38-40) (2001) 1575 - 1580 pdf

F. T. Sommer, T. Wennekers, G. Palm: Bidirectional completion of cell assemblies in the cortex Computational Neuroscience: Trends in Research 1998, Plenum Press, New York, (1998) ps

Large-scale integration relying on oscillations

A. Knoblauch, F. T. Sommer: Spike-timing dependent plasticity can form "zero-lag" links for cortical oscillations Neurocomputing (58-60) 185 - 190 (2004) pdf

A. Knoblauch, F. T. Sommer: Synaptic plasticity, conduction delays, and inter-areal phase relations of spike activity in a model of reciprocally connected areas Neurocomputing (52-54) (2003) 301-306 pdf

Models of macroscopic activity spread in cortex

V. Schmitt, R. Koetter, F. T. Sommer: The impact of thalamo-cortical projections on activity spread in cortex Neurocomputing (2003) (52-54) (2003) 919-924 pdf

R. Kötter and F. T. Sommer: Global relationship between anatomical connectivity and activity propagation in the cerebral cortex Phil. Trans. R. Soc. Lond. B (355) (2000) 127 - 134 pdf

F.T.Sommer, R. Kötter: Simulating a Network of Cortical Areas Using Anatomical Connection Data in the Cat Computational Neuroscience: Trends in Research 1997, Plenum Press, New York (1997) 511-517 ps

R. Koetter, P. Nielsen, J. Dyhrfjeld, F. T. Sommer, G. Northoff: Multi-level integration of quantitative neuroanatimical data Chapter in Computational Neuroanatomy: Principles and Methods. Ed.: G. A. Ascoli, Humana Press Inc., Totowa, NJ (2002)

Theory of sparse associative memory

Bayesian theory of autoassociative memory

F. T. Sommer, P. Dayan: Bayesian Retrieval in Associative Memories with Storage Errors IEEE Transactions on Neural Networks 9 (4) (1998) 705-713 pdf

Bidirectional sparse associative memory

F. T. Sommer, G. Palm: Improved Bidirectional Retrieval of Sparse Patterns Stored by Hebbian Learning Neural Networks 12 (2) (1999) 281 - 297 pdf

F. T. Sommer, G. Palm: Bidirectional Retrieval from Associative Memory Advances in Neural Information Processing Systems 10, MIT Press, Cambridge, MA (1998) 675 - 681 pdf

Analysis of recurrent sparse autoassociative memories

F.Schwenker, F.T.Sommer, G.Palm: Iterative Retrieval of sparsely coded associative memory patterns Neural Networks 9 (1996) 445-455 pdf

Analysis of sparse pattern recognition

G.Palm, F.T.Sommer: Information capacity in recurrent Mc.Culloch-Pitts networks with sparsely coded memory states Network 3 (1992) 177-186 pdf

G.Palm, F.T.Sommer: Information and pattern capacities in neural associative memories with feedback for sparse memory patterns In: Neural Network Dynamics, Springer New York (1992). Eds.: J.G.Taylor, E.R.Caianello, R.M.J.Cotterill, J.W.Clark, 3-18

Analysis of local learning rules

G.Palm, F.T.Sommer: Associative data Storage and Retrieval in Neural Nets In: Models of Neural Networks III, Springer New York (1996) Eds: E.Domany, J.L.van Hemmen, K.Schulten, 79-118 ps

Book, PhD-Thesis (in german)

F. T. Sommer: Theorie neuronaler Assoziativspeicher - Lokales Lernen und iteratives Retrieval von Information Verlag Hänsel-Hohenhausen (1993) ISBN 3-89349-901-6 ps

Neuroimaging

Edited book

Eds: F. T. Sommer, A. Wichert: Exploratory analysis and data modeling in functional neuroimaging MIT Press, Boston, MA (2003) link to publisher (table of contents, etc.)

General issues of Neuroimaging

F. T. Sommer, J. A. Hirsch, A. Wichert: Theories, data analysis and simulation models in neuroimaging - an overview In Exploratory analysis and data modeling in functional neuroimaging. Eds.: F.T. Sommer and A. Wichert, MIT Press, Boston, MA (2003) pdf

V. Schmitt, A. Wichert, J. Grothe, F. T. Sommer: The brain positioning software In: A practical guide of neuroscience databases and associated tools, Ed. R. Koetter, Kluwer, NY (2002)

Unsupervised method of detecting functional activity in Neuroimaging

A. Wichert, B. Abler, J. Grothe, H. Walter, F. T. Sommer: Exploratory analysis of event-related fMRI demonstrated in a working memory study In Exploratory analysis and data modeling in functional neuroimaging. Eds.: F.T. Sommer and A. Wichert, MIT Press, Boston, MA (2003) pdf

A. Wichert, H. Walter, G. Groen, A. Baune, J. Grothe, A. Wunderlich, F. T. Sommer: Detection of delay selective activity during a working memory task by explorative data analysis Neuroimage (13) (2001) 282

A. Baune, F. T. Sommer, M. Erb, D. Wildgruber, B. Kardatzki, G. Palm, W. Grodd: Dynamical Cluster Analysis of Cortical fMRI Activation NeuroImage 6 (5) (1999) 477 - 489 pdf

Analysis techniques in Positron Emission Tomography

G. Glatting, F. M. Mottaghy, J. Karitzky, A. Baune, F. T. Sommer, G. B. Landwehrmeyer, S. N. Reske: Improving binding potential analysis in [11C]raclopide PET studies using cluster analysis. Medical Physics 31 (4) (2004) 902-906 pdf

A. Baune, A. Wichert, G. Glatting, F. T. Sommer: Dynamical cluster analysis for the detection of microglia activation in Artificial Neural Nets and Genetic Algorithms. Eds. V. Kurkova, N. C. Stelle, R. Neruda, M. Karny. Springer, Wien (2001) 442 - 445

J. Ruckgaber, G. Glatting, J. Karitzky, A. Baune, F. T. Sommer, B. Neumaier, S. N. Reske: Clusteranalyse in der Positronen-Emissions-Tomographie des Hirns mit C-11-PK11195 Nuklearmedizin (40) (2001) A95

Neural associative memories in information technology

G. Palm, F. Schwenker, F. T. Sommer, A. Strey: Neural associative memory In Associative Processing and Processors, Eds. A. Krikelis and C. C. Weems, IEEE CS Press, Los Alamitos, CA, USA (1997) 307-326 ps

F.T.Sommer, F.Schwenker, G.Palm: Assoziative Speicher als Module in informationsverarbeitenden Systemen In: Contributions to the Workshop Aspekte Neuronalen Lernens, Eds. L.Cromme, J. Wille, T. Kolb Tech Report, TU Cottbus M-01/1995 (1995)

G.Palm, F.Schwenker, F.T.Sommer: Associative memory and sparse similarity preserving codes In: From Statistics to Neural Networks: Theory and Pattern Recognition Applications, Ed. V.Cherkassky, Springer NATO ASI Series F, New York (1994) 282-302

Teaching Courses, Workshops and Conferences

Workshops and conferences:

• COSYNE 2007: Workshop chair
• NIPS 2005: Program chair for Neuroscience
• CNS 2002 workshop: Neural assemblies
• NIPS 2000 workshop: Explorative analysis and data modeling in functional neuroimaging

Graduate teaching (US):

• Theoretical and computational neuroscience (2003, 2005; teaching participation at course MCB262/PSYCH290P, UC Berkeley)

Graduate teaching (semester courses held at University of Ulm):

• Information retrieval and associative memory
• Computational Neuroscience
• Theoretical methods for the interpretation of medical functional imaging data
• Information Retrieval
• Associative memories: conventional and neuronal
• Neural Cell Assemblies