Multiple sounds degrade the frequency representation in monkey inferior colliculus

Abstract

<jats:title>Abstract</jats:title><jats:p>How the brain encodes information about simultaneously occurring stimuli is largely unknown, especially if those stimuli recruit largely overlapping populations of neurons. One hypothesis is that tuning curves might sharpen or shift to limit the number of stimuli driving any given neuron. To investigate this possibility, we recorded the activity of neurons in the inferior colliculus while monkeys localized either one or two simultaneous sounds that differed in frequency. Although monkeys were quite capable of performing this task (~90% correct), comparison of frequency tuning in single versus dual sound trials revealed frequency selectivity was degraded in the dual-sound case. Frequency tuning curves broadened, and frequency modulation of firing rate was attenuated in dual sound conditions. These tuning curve changes led to a slightly worse performance on dual sound trials by a maximum-likelihood decoder trained to predict the presented condition only from held-out spike counts. These results do not support that changes in frequency response functions could be used to overcome the overlap problem in the representation of simultaneous sounds, and suggest recent evidence of alternations in firing rate between rates corresponding to each of the two stimuli may be a more promising line of research.</jats:p>

Experimental investigation on tensile strength of novel metal matrix composite of aluminium alloy 5083 with SiC and eggshell powder reinforcement

“…The limitations of this work is the stir casting process done without any mould preheating, lack of heat treatment of cast material and lack of processing of the reinforcement materials [48]. This could be considered and included in the future studies [49]. Also, novel sustainable production methods for metal matrix composite production other than stir-casting can be employed to study the effectiveness of the composites produced in the upcoming works.…”