The brain consists of approximately a hundred thousand million neurons, each of them connecting to approximately ten thousand other neurons. They receive and transmit electro-physical pulses (action potentials) that either excite or inhibit other cells, depending on the neurotransmitter that is used for transmission. The connectivity in the network that they form changes over time, depending on the past activity, which is thought to be crucial for learning and memory.


Physics of the brain starts at the single cell level. At this level the dynamics is nonlinear as ion channels responsible for the rate of change of the voltage across the membrane depend nonlinearly on the voltage across the cell membrane. Large ensembles of cells may be active rhythmically, as measured by fMRI, MEG or EEG. The brain rhythms emerge from the functional connectivity between cells in the network and external inputs to these cells. Brain rhythms, including their synchronization and desynchronization, form an important and possibly fundamental part of the orchestration of perception, movement and conscious experience. Synchronization and desynchronization of multicellular domains represent transitions, which are potentially fundamental for proper functioning of the brain. In various neurological disorders, these processes are disturbed, resulting in e.g. epilepsy, Parkinson’s disease or movement disorders.


This, in a nutshell, has been the playground for mathematicians, physicists and neurophysiologists at the Lorentz institute during the Brain Wave workshop. On a daily basis there were more than 45 participants. Over the whole week there were 65 participants. About 50 of them from the Netherlands, 50so different fields. Special days have been devoted to the mathematics and physics of neuronal networks that are thought to be responsible for epilepsy and Parkinson’s disease. These sessions attracted more than average attention. Round tables took place to discuss recent developments in neuroscience. Several new ideas and views for further research came up:


Terman and Rubin presented their work on modeling the neuronal substrate

of Parkinson’s disease and in particular the effect of deep-brain stimulation

to releave the symptoms of Parkinson’s disease.

• In the past there was the question whether rhythmic activity (in particular

gamma-activity) was the result of intrinsic properties of the inhibitory network

(ING-model) or whether the gamma activity arises due to the external

input to the excitatory cells, which are coupled to the inhibitory cells (PING).

Presumably, the solution is that both mechanisms are responsible and that

the ING and PING are compatible with the top-down and bottom-up contributions, respectively, to generate the gamma rhythm.

• The role of Ca2+ induced Ca2+ release in the mitochondrial network is relevant.

Ca2+ handling is an important element in pathology of diseases such

as diabetes, neurodegeneration and Parkinson’s disease.

• The channel-rhodopsin technique to manipulate specific cell types might be

a good tool to study rhythmic activity as it allows onset and/or offset of

particular cells in the neuronal network architecture. It has been decided at

the conference to work this point out and to incorporate it in a FOM proposal.


The atmosphere at the workshop was more than enthusiastic. The boat trip was a great success, not only because of the beautiful weather, but also due to the mutual friendly behaviour of the participants. The contribution of the staff of the Lorentz center is invaluable. The constant smile of Auke Planjer is a joy for everybody. We are graceful for the support of the Lorentz Center and for our sponsors: BMTI (UT), Donders Institute (RUN), NDNS+ and MRI.