Contralateral Sounds Research Articles

Auditory interneurones in the mesothoracic ganglion of crickets

Auditory interneurone responses in the mesothoracic ganglion of the cricket Gryllus bimaculatus were investigated with special regard to temporal features of the calling song. Units representing five response types were found. One type codes verse syllables and intensity. The second codes syllables of highfrequency verses. The third responds as a pulse marker. The fourth shows adaptation and the response pattern depends on the verse frequency. The fifth fires a burst at verse onset. Responses of mesothoracic units recorded in two other cricket species do not differ markedly from those of Gryllus bimaculatus. Particularly, no tuning is found to species-specific differences in their calling songs. The stimulus direction can affect the threshold in different ways: dependence at all frequencies, dependence only between 3 and 6 kHz, and independence are found. The dependence is mainly expressed by a higher threshold for contralateral sounds. The mesothoracic branching of a few neurones was demonstrated by extracellular CoS-staining. These cells pass through the ganglion as connective fibres giving off small branches into the ventro-medial and dorso-medial neuropiles.

Plasticity of binaural interaction. I. Effect of early auditory deprivation

Plasticity of binaural interaction. I. Effect of early auditory deprivation

Information processing in the inferior colliculus of cat using high frequency acoustical stimulation and direct electrical stimulation of the osseous spiral laminae

In studies of the single unit neural response of the inferior colliculus which attempt to avoid the effects of neural volleying by using high frequency acoustical stimuli and direct electrical stimulation of nervous processes in the osseous spiral laminae of the cochlea, we have observed that, given knowledge of a neuron's characteristic frequency, the necessary and sufficient stimulus is either f . t . i = a constant, or f . t . τ = a constant, where f is bandwidth, t is duration, i is interaural intensity differences, and τ is interaural differences in time of signal arrival. The first stimulus form ( f . t . i ) is always effective in producing a neural response and predominates over the second stimulus form ( f . t . τ ) in eliciting a response. Most neurons are sensitive to lateralizing stimuli, i.e., to i (contralateral) vs i (ipsilateral) and to τ (contralateral) vs τ (ipsilateral). We have also observed that the effect of changes in i is usually correlated more with diminution in the absolute value of the contralateral input than the ipsilateral, perhaps indicating a “priming” effect and leading to the view that the inferior colliculus is biased toward the reception of contralateral sounds. Any of these effects may be registered neuronally in at least three different ways - (1) by changes in averaged spike count height at a set time; (2) by changes in latency of a set averaged spike count peak; or (3) by changes in total spike count.