科研之友
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摘要
Key points In the primary taste cortex, two populations of neurons have been identified whose activity either correlates or anticorrelates with tastant concentration. The relative contribution of each population to signalling the perceived intensity of taste is unknown. To resolve this issue, we recorded activity from neurons in primary taste cortex while rats made choices that depended on NaCl concentration cues to obtain water reward. Two neural ensemble's neural activity anticorrelated with NaCl concentration, but differed according to their response to water as one ensemble tracked the solution's osmotic pressure. A third neural ensemble's activity was correlated with NaCl concentration and had the strongest relationship to the rat's choices, suggesting a central role in signalling the perceived intensity of NaCl solutions. A fourth neural ensemble responded only to water, but some of these neurons were influenced by behavioural context because they responded differently to water presented as a cue versus reward. Abstract The gustatory cortex (GC) is important for perceiving the intensity of tastants but it remains unclear as to how single neurons in the region carry out this function. Previous studies have shown that taste-evoked activity from single neurons in GC can be correlated or anticorrelated with tastant concentration, yet whether one or both neural responses signal intensity is poorly characterized because animals from these studies were not trained to report the intensity of the concentration that they tasted. To address this issue, we designed a two-alternative forced choice (2-AFC) task in which freely licking rats distinguished among concentrations of NaCl and recorded from ensembles of neurons in the GC. We identified three neural ensembles that rapidly (<300 ms or similar to 2 licks) processed NaCl concentration. For two ensembles, their NaCl evoked activity was anticorrelated with NaCl concentration but could be further distinguished by their response to water; in one ensemble, water evoked the greatest response while in the other ensemble the lowest tested NaCl concentration evoked the greatest response. However, the concentration sensitive activity from each of these ensembles did not show a strong association with the behaviour of the rat in the 2-AFC task, suggesting a lesser role for signalling tastant intensity. Conversely, for a third neural ensemble, its neural activity was well correlated with increases in NaCl concentration, and this relationship best matched the intensity perceived by the rat. These results suggest that this neuronal ensemble in GC whose activity monotonically increases with concentration plays an important role in signalling the intensity of the taste of NaCl.
- 出版日期2012-7
