learning program
background
 
 
 
 
 
 
The basic hypothesis
The basic, still unproven, hypothesis underlying the Neurovers-IT project is that networks of living networks cultured on top of a Micro-Electrode array, can represent   a useful computational device. If this hypothesis proves to be true, such devices could have a broad range of possible applications
         

Structural change in neuronal cell cultures
Current neuro-physiological research uses imaging to identify the brain areas involved in specific behaviors and (more recently) to understand the correlation between the activity of different areas.   Molecular and genetic work focuses on the functioning of individual neurons and synapses. But to date there has been relatively little work on the functioning of natural neuronal networks in vivo . An alternative is to use cell cultures in vitro. This work has shown that neuronal cultures produce a rich pattern of electrical activity that matures over the life of the network. Pharmacological studies have demonstrated that the maturation of the network is correlated with neuronal electrical activity. Two European projects (NEUROBIT
<link to: http://www.neuro-it.net/pdf_dateien/neurobit_neuro-IT%20Bonn%20ver3.pdf >
and INPRO <link to: http://www.neuro-it.net/powerpoint/INPRO.PPT > )
and other groups have studied changes in network morphology and dynamic behavior over long periods of time. The results of these studies identify general tendencies common to all cultures but also show a high degree of variability. This supports the idea that morphology is "plastic" - but poses a major challenge for its use as a practical technology A number of groups have investigated the network dynamics associated with focal electrical stimulation and the way in which stimulation can reinforce specific stimulus-response circuits. At least one study has shown that where stimuli are delivered over an extended period, cultures weaken their response to familiar and strengthen the response to rare stimuli.   This kind of response may be interpreted as a learning mechanism allowing the storage of useful information.

         

Cell culturing technology
The studies just described would not be possible without modern cell culturing technology. In the past 30 years, in vitro systems have become a powerful tool for applications in basic research, drug screening and bio-sensing. In these systems neurons can be grown on top of Multi Electrode Arrays (MEAs) In vitro systems allow controlled electrical stimulation of the neuronal network and the capture of the signals it generates. The same equipment allows researchers to administer pharmacologically active molecules (neuro-transmitters, hormones and other neuro-modulators) to the culture, studying the effects on neuronal dynamics and plasticity. It should be noted however most current systems are designed for short-term studies. Automated support for unsupervised cell culturing is a recent development. Today, special serum-free media compositions, serum replacements, and neuroprotective supplements have made it possible to incubate cultures under relatively well-defined conditions and the use of sealed cultures has extended the life times of cultures of dissociated neurons to 18 months and beyond. This has made it possible to perform the kind of long term repeated measurements needed to investigate structural learning . New MEAs, developed by the EU NEUROBIT project, allow the segregation of neurons into inter-connected clusters. This allows researchers to compare the dynamics and computational capabilities of different neuronal populations and to investigate the conflicting requirements of integration and specialization. The recent development of a field-effect transistor (FET) with 16000 electrodes   and a 128 electrode CMOS chip with real-time recording and stimulation capabilities shows the potential of the technology.

 
         
   
         
       
         
         
         
  ©Neurovers-it Consortium 2007
webdesign paololafarina.com