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Biomedical signals from many sources including hearts, brains and endocrine systems pose a challenge to researchers who may have to separate weak signals arriving from multiple sources contaminated with artifacts and noise. The analysis of these signals is important both for research and for medical diagnosis and treatment. The applications of Independent(More)
1. In the mollusc Tritonia escape swimming is produced by a network of central pattern generator (CPG) neurons. The purpose of this study was to determine which neurotransmitters might be involved in the swim system. 2. Injection of serotonin (5HT) into whole animals elicited swimming followed by a long-lasting inhibition of swimming. In isolated brain(More)
'Independent component analysis' is a technique of data transformation that finds independent sources of activity in recorded mixtures of sources. It can be used to recover fluctuations of membrane potential from individual neurons in multiple-detector optical recordings. There are some examples in which more than 100 neurons can be separated(More)
Independent Component Analysis (ICA) blindly separates mixtures of signals into individual components. Here we used ICA to isolate spike trains from individual neurons recorded optically in the Tritonia diomedea isolated brain. ICA removed several types of artifacts, allowed us to view an approximation of the membrane potential as opposed to the usual(More)
To understand the relationship between memory storage sites in the brain and learned changes in behavior, the learned behavior must be characterized. However, even simple types of learning may be quite complex. Repeated elicitation of the Tritonia swim produced multiple changes in the response. Several types of acquisition curves were observed in a single(More)
The role of nonassociative learning processes in determining whether or not a chemical stimulus will elicit the Tritonia diomedea swimming response was examined in a variety of conditioning experiments. Iterative presentation of a chemical stimulus resulted in a reduced swimming probability (SP). By the criteria of Thompson and Spencer (Thompson RF, Spencer(More)
When repeatedly elicited, the oscillatory escape swim of the marine mollusc Tritonia diomedea undergoes habituation of the number of cycles per swim. Because the neural circuit for this behavior is reasonably well understood, a cellular analyses of habituation in Tritonia is feasible. Since such a study must ultimately relate cellular correlates to(More)
Physiological studies of learning and memory often require reduced nervous system preparations that can be trained by stimulation of neural pathways in a manner that mimics behavioral training. In the isolated brain preparation of the seaslug Tritonia, fictive swimming can be activated with a few electrical pulses applied to the cut end of a nerve, and(More)
Independent component analysis (ICA) was used to separate action potential trains recorded with voltage-sensitive dyes in the isolated brain preparation of the seaslug Tritonia. It was assumed that the membrane potential of each neuron was an approximately independent source and that detectors (photodiodes) recorded linear mixtures of sources. These(More)
We found neurons that can change the sign of their response to hyperpolarizing inputs depending on the amplitude of that input. After small hyperpolarizations, neurons showed a transient depolarization or post-inhibitory-rebound (PIR) while larger hyperpolarizing inputs lead to a post-inhibitory hyperpolarization (PIH). PIR is sometimes sufficient to(More)