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At least 235 records · Page 13Linked to original sources
PubMed1998

Reduced after-hyperpolarization in rat piriform cortex pyramidal neurons is associated with increased learning capability during operant conditioning.

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 paradigm, the trained group was exposed to extensive training with rats learning to discriminate between 35 and 50 pairs of odours. Piriform cortex pyramidal neurons from 'trained', 'control' and 'naive' rats did not differ in their passive membrane properties and single spike characteristics. However, the after-hyperpolarizations (AHPs) that follow six-spike trains were reduced after 'extensive training' by 43% and 36% compared with 'control' and 'naive', respectively. This effect was not observed in the piriform cortex of another group of rats, in which hyperexcitability was induced by chemical kindling. In another experimental paradigm rats were trained only until they demonstrated 'rule learning', usually after discriminating between one and two pairs of odours ('mild training'). In this experiment, a smaller, yet significant, reduction (20%) in AHPs was observed. AHP reduction was apparent in most of the sampled neurons. AHP remained reduced up to 3 days after the last training session. 5 days or more after the last training session, AHP amplitude recovered to pre-training value and did not differ between 'trained' rats and the others. Accordingly, training suspension for 5 days or more resulted in slower learning of novel odours. We suggest that increased neuronal excitability, manifested as reduced AHP, is related to the ability of the cortical network to enter a 'learning mode' which creates favourable conditions for enhanced learning capability.

Animals↗
PubMed2005

Unconscious operant conditioning in the paradigm of brain-computer interface based on color perception.

This study investigate the mutual fine-tuning of ongoing EEG rhythmic features with RGB values controlling color shades of computer screen during neuro-feedback training. Fifteen participants had not been informed about the existence of neurofeedback loop (NF), but were guided only to look at the computer screen. It was found that during such unconscious NF training, a variety of color shades on the screen gradually changed from rather various types to the main one within the framework of color palette specified for each individual. This phenomenon was not observed in control experiments with simulated neuro-feedback. Individual color patterns induced on the screen during NF did not depend on the schema of connection between of EEG rhythms and RGB controller. It is suggested that the basic neurophysiological mechanism of described NF training consists of the directed selection of EEG patterns reinforced by comfortable color shades without conscious control.

Adult↗