New Discoveries about the Auditory Medial Olivocochlear System
Matthew Fischl, Alia Pederson, Rebecca Voglewede, Hui Cheng, Jordan Drew et al.
(see article e0382242024)
Perceiving sounds requires quick and precise neuron responses to distinct features of sound. We know that auditory neurons in the cochlear nucleus (CN) and brainstem are equipped to process fast acoustic signals and that medial olivocochlear (MOC) neurons provide inhibition in the cochlea to help contribute to CN neuron processing of sound. But MOC neurons modulate the cochlea on a slow timescale, suggesting that there must be mechanisms in place that reduce MOC inhibition to promote auditory neuron speed and precision. To shed more light on this, Fischl et al. probed the relative timing of excitation and inhibition onto mouse MOC neurons. They did this using a novel in vitro slice preparation that kept the ascending auditory nerve root as well as the CN and its projecting axons intact, but still allowed for patch-clamp electrophysiology recordings of genetically identifiable MOC neurons. The authors found that inhibition of the MOC could be fast when localized to the CN. Robust data analyses revealed that this rapid inhibition had variable onset and delayed and desynchronized MOC activity. This would ensure that the MOC system does not inhibit the cochlea during rapid sounds that require precise neuron responses and instead is only engaged during slower and more sustained background sounds. These findings advance our understanding of the MOC system using innovative techniques and analyses to make discoveries that are informative for the field.
The Role of the Gustatory Cortex in Food Decisions and Consumption
Ahmad Jezzini and Camillo Padoa-Schioppa
(see article e2150232024)
The gustatory cortex (GC) is thought to be important for food-related decision-making and eating behavior, but there is a need for more insight into the role it plays. Jezzini and Padoa-Schioppa recorded from the GC in nonhuman primates as they chose between different flavors of juice. They found that GC neurons activated differently to represent the flavor, quantity, and subjective value of the juices animals selected in each trial. The variables represented in GC always depended on the animal's choice, suggesting that neurons in GC did not contribute to value comparison per se. Importantly, GC responses are not purely sensory. This is supported by the fact that many GC neurons represented the subjective value, as opposed to some physical property of the juices such as the sugar concentration. The findings from this study are a breakthrough in our understanding of a poorly understood brain region. Furthermore, this work advances our understanding of mechanisms for food-based decisions and consumption.
Footnotes
This Week in The Journal was written by Paige McKeon