Statistical and dimensional analysis of the neural representation of the acoustic biotope of the frog.

The field of investigation is the neural representation of acoustic stimuli occurring in the natural environment of the frog. The point of departure is the description of a stimulus ensemble consisting of natural sounds: the acoustic biotope. A relation of statistical and dimensional structure of the acoustic biotope is indicated. The animal used in the neurophysiological experiments is the grass frog, Rana temporaria L.; microelectrode recordings are made in the auditory midbrain. A method is described to determine the existence of a relation between acoustic stimulus and neural events. The form of this relation has been investigated by first- and second-order stimulus-event correlation. While the first one does not give significant results, the second one leads to the spectrotemporal receptive field of the neuron for natural stimuli. Questions are formulated to estimate the value of this receptive field as a functional descriptor of the neuron. Finally, an outline is sketched for a synthetic construction of the bioacoustic space from neuroacoustic subspaces.