Studies of the functional characteristics of central neurons of the brain in a behavioral experiment

Abstract

The activity of central integrative brain neurons is associated with the overall assessment of functionally diverse signals of different sensory modalities which converge on these neurons via parallel inputs. Processing this information, these neurons take part in organizing the animal's various actions and in the mechanisms involved in switching from one action to another. Therefore, understanding of the functional characteristics of central brain neurons requires studies in which the dynamics of neuron activity are recorded continuously throughout a sequence of actions performed by an animal. Traditional methods of analyzing neuron activity, such as the construction of post- and peristimulus histograms and cross-correlation analysis, are inadequate for this purpose. These methods allow analysis to be applied to neuron spike activity only around each synchronization point Their use for studies of a developed program of animal actions unavoidably leads to a set of separate histograms providing no information on the dynamics of neuron activity corresponding to continuous behavior. A complex approach to studying the neuronal correlates of behavior is suggested, designed to overcome these difficulties. The method is based on the use of a developed behavioral program with recording of several neurons in parallel, with analysis of neuron activity using a relative time scale based on the duration of each sequentially performed action. Non-traditional methods of processing neuron spike activity were developed for analysis of the resulting data, including construction of relative histograms and multidimensional statistics methods. These approaches allowed us to study the dynamics of neuron activity continuously through all the stages of performance of a behavioral program and obtain data on the involvement of each group of those neurons which were studied in functionally different actions. This methodology was tested using studies of the functional characteristics of striatum neurons in monkeys. Comparable data were obtained on the individual responses of neurons and on the dynamics of their activity at different stages of the animals' performance of a multicomponent behavioral program. This revealed the lack of functional specialization in striatum neurons and different patterns of their involvement in motor and cognitive functions.