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Learning-related cellular modifications were studied in the rat piriform cortex. Water-deprived rats were divided to three groups: 'trained' rats were trained in a four-arm maze to discriminate positive cues in pairs of odours, 'control' rats were 'pseudo-trained' by random water rewarding, and 'naive' rats were water-deprived only. In one experimental(More)
Learning-related cellular modifications were studied in the rat piriform cortex after operand conditioning. Rats were trained to discriminate positive cues in pairs of odors. In one experimental paradigm, rats were trained to memorize 35-50 pairs of odors ("extensive training"). In another paradigm, training was continued only until rats acquired the rule(More)
We studied the role of acetylcholine (ACh) in creating learning-related long-lasting modifications in the rat cortex. Rats were trained to discriminate positive and negative cues in pairs of odors, until they demonstrated rule learning and entered a mode of high capability for learning of additional odors. We have previously reported that pyramidal neurons(More)
We studied the effect of olfactory learning on the dendritic spine density of pyramidal neurons in the rat piriform (olfactory) cortex. Rats were trained to distinguish between two pairs of odours in an olfactory discrimination task. Three days after training completion, rats were killed and layer II pyramidal neurons identified by Golgi impregnation were(More)
Learning-related modifications in predisposition for long-term potentiation (LTP) and long-term depression (LTD) were studied in brain slices of the rat piriform cortex following olfactory learning. Rats were trained to discriminate between pairs of odors until they demonstrated rule learning. We have previously shown that such training is accompanied by(More)
High pressure induces CNS hyperexcitability while markedly depressing synaptic transmitter release. We studied the effect of pressure (up to 10.1 MPa) on the parallel fibre (PF) synaptic response in biplanar cerebellar slices of adult guinea pigs. Pressure mildly reduced the PF volley amplitude and to a greater extent depressed the excitatory field(More)
In the metathoracic ganglion (T3) of the cockroach, extracellular potassium activity (aK) was measured with ion-sensitive microelectrodes and intracellular recordings were simultaneously made from giant axons (GAs) during high frequency stimulation of the connectives. Blockade of spike conduction through T3 was associated with intraganglionic aK rises of(More)
1. Previous studies have shown that hyperbaric pressure depresses synaptic transmission and have suggested that the effect is primarily on transmitter release. The present study analysed the effects of pressure at a crustacean neuromuscular junction. Changes in pressure were compared to changes in extracellular calcium concentration [Ca2+]o with respect to(More)
1. Propagation of action potentials at high frequency was studied in a branching axon of the lobster by means of simultaneous intracellular recording both before and after the branch point. 2. Although the branching axon studied has a geometrical ratio close to one (perfect impedance matching) conduction across the branch point failed at stimulation(More)
1. The ionic mechanisms involved in block of conduction of action potentials following high frequency stimulation were studied in a branching axon of the lobster Panulirus penicillatus. 2. A 2-3 mM increase in extracellular K concentration (normal concentration 12 mM) produced block of conduction into both daughter branches. 3. While conduction block(More)