J. van Pelt

Long-term multielectrode registration of neuronal firing activity from rat cerebral cortex tissue in-vitro

Activity-dependent processes are involved in neurite outgrowth and synaptogenesis. The authors expect that during neural network formation neuronal morphogenesis and synaptic connectivity are reciprocally dependent on the emerging bioelectric activity in the network. The authors want to study whether and how bioelectric activity is involved in the formation of network structure. A multielectrode recording facility has been constructed for the long-term registration of action potentials of individual neurons during network development in both organotypic and dissociated rat cerebral cortex tissue cultures. Long-term recordings of action potentials with good signal-to-noise ratios have been obtained. Experiments to correlate these activity levels with quantitative data on neuronal morphological development are in progress. Uncorrelated periodic fluctuations at a time scale of about ten minutes have been observed.

Activity patterns of cultured neural networks on micro electrode arrays

A hybrid neuro-electronic interface is a cell-cultured micro electrode array, acting as a neural information transducer for stimulation and/or recording of neural activity in the brain or the spinal cord (ventral motor region or dorsal sensory region). It consists of an array of micro electrodes on a planar substrate, the electrodes being covered by a network of cultured neurons. The cultured neuron network layer acts as a natural host for in vivo neural connections. Besides this function, live neural networks can become spontaneously active and have the capability of information processing, as minibrains. One may envisage future applications of these intermediary networks as front-end signal processors. The paper presents results on spatio-temporal activity patterns and their characterization in neural networks, cultured from dissociated rat visual cortex. Cultures lasted 43 days in vitro on multi electrode plates with 60 electrode sites and started activity after about seven days. Firing rates increase with time thereafter. Typical pacemaker-and-burst firing patterns are seen, the time characteristics of which change over days, typically.

Minimal requirements for long-term serum-free culturing of electrically active dissociated neurons in a monolayer

A method is presented for culturing dissociated fetal rat cerebral cortex and other brain areas. These cultures meet the following requirements: (1) they are maintained in a serum-free medium, (2) the cultured cells form a near monolayer allowing optimal access and visibility, (3) neurons survive up to at least six weeks, while (4) showing a high incidence of spontaneous action potential discharges. The dissociated neurons are grown on coverslips in a serum-free medium conditioned by astrocytes. Development of the cultures as monolayers was dependent on basic polymers, which prevent neuronal aggregation. Long-term survival and health (as indicated by abundant spontaneous action potential discharges) depended on insulin, transferrin, lipoic acid, vitamins A and E, albumin, and conditioning of the medium by astrocytes. Series of more than 300 nearly identical cultures can be routinely produced from one litter of rats, for use in morphological, biochemical and electrophysiological assays without adaptation.