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A neural net was used to analyse samples of natural images and text. For the natural images, components resemble derivatives of Gaussian operators, similar to those found in visual cortex and inferred from psychophysics 4]. While the results from natural images do not depend on scale, those from text images are highly scale dependent. Convolution of one of(More)
We show that a form of synaptic plasticity recently discovered in slices of the rat visual cortex (Artola et al. 1990) can support an error-correcting learning rule. The rule increases weights when both pre-and postsy-naptic units are highly active, and decreases them when pre-synaptic activity is high and postsynaptic activation is less than the threshold(More)
Spike detection and spike sorting techniques are often difficult to assess because of the lack of ground truth data (i.e., spike timings for each neuron). This is particularly important for in vitro recordings where the signal to noise ratio is poor (as is the case for multi-electrode arrays at the bottom of a cell culture dish). We present an analysis of(More)
Calculations of the sensitivity of the saturation recovery and inversion recovery pulse sequences used in nuclear magnetic resonance imaging show the former to be superior in discriminating between tissues with the same proton density but different T1's. Two other pulse sequences, which are combinations of the above, have also been analyzed. These have(More)
A biologically inspired technique for detecting onsets in sound is presented. Outputs from a cochlea-like filter are spike coded, in a way similar to the auditory nerve (AN). These AN-like spikes are presented to a leaky integrate-and-fire neuron through a depressing synapse. Onsets are detected with essentially zero latency relative to these AN spikes.(More)
Signals from extracellular electrodes in neural systems record voltages resulting from activity in many neurons. Detecting action potentials (spikes) in a small number of specific (target) neurons is difficult because many neurons, both near and more distant, contribute to the signal at the electrode. We consider some nearby neurons as target neurons(More)
We discuss spike detection for noisy neuronal data. Robust spike detection techniques are especially important for probes which have fixed electrode sites that cannot be independently manipulated to isolate signals from specific neurons. Low signal-to-noise ratio (SNR) and similarity of spectral characteristic between the target signal and background noise(More)