Biomedical subjects

Eshel Ben-Jacob

Publications and source records attributed to Eshel Ben-Jacob.

21 records · Page 2Linked to original sources

PubMed2002

A method for spike sorting and detection based on wavelet packets and Shannon's mutual information.

Studying the dynamics of neural activity via electrical recording, relies on the ability to detect and sort neural spikes recorded from a number of neurons by the same electrode. We suggest the wavelet packets decomposition (WPD) as a tool to analyze neural spikes and extract their main features. The unique quality of the wavelet packets-adaptive coverage of both time and frequency domains using a set of localized packets, facilitate the task. The best basis algorithm utilizing the Shannon's information cost function and local discriminant basis (LDB) using mutual information are employed to select a few packets that are sufficient for both detection and sorting of spikes. The efficiency of the method is demonstrated on data recorded from in vitro 2D neural networks, placed on electrodes that read data from as many as five neurons. Comparison between our method and the widely used principal components method and a sorting technique based on the ordinary wavelet transform (WT) shows that our method is more efficient both in separating spikes from noise and in resolving overlapping spikes.

Action Potentials↗

PubMed2002

Long term behavior of lithographically prepared in vitro neuronal networks.

We measured the long term spontaneous electrical activity of neuronal networks with different sizes, grown on lithographically prepared substrates and recorded with multi-electrode-array technology. The time sequences of synchronized bursting events were used to characterize network dynamics. All networks exhibit scale-invariant Lévy distributions and long-range correlations. These observations suggest that different-size networks self-organize to adjust their activities over many time scales. As predictions of current models differ from our observations, this calls for revised models.

Electrodes↗

PubMed2002

Sub-micromorphology of the epicuticle of hornets: AFM studies.

The upper part of the hornet cuticle in the abdominal region reveals several structures. First, situated at intervals of 10 microm or more apart, there are depressions housing a peripheral photoreceptor (PP) and between every two of these, there are horizontal flats resembling an irregular polygon which are mostly elongated and about 100 microm2 in area. Upon each such terrace-like flat there are tile-shaped protuberances up to several micrometres in length and mostly running parallel to one another, covering the entire surface. Between every two such terraces there is a 'step' of up to 1.4 microm in height. Both the 'tiles' and 'steps' terminate in front of the distal part of each PP, which is a recessed and smooth region. Secondly, in other regions of the cuticle one can note other surface configurations such as: (a) a paucity of 'tiles'; (b) no 'tiles' at all but a chessboard-like pattern, the 'squares' of which contain rectangles recessed to various depths, interspersed among 'plaques' that are not recessed and may even protrude; and (c) anfractuous (characterized by windings and turnings) flats that are intermittently criss-crossed by grooves. In addition to the above, most of the cuticle also displays numerous setae (i.e. small hairs). We suppose that all the described structures and configurations either contribute to enlargement of the cuticular surface, or act as an optical grid, thereby enhancing the absorption of light. We further speculate that for hornets in flight, situations may arise where part of the above mentioned structures orientates perpendicular to the sunlight and this entire orientation acts to direct the solar energy toward and into the PP so as to enable greater utilization of light as an energy source.

Abdomen↗