Prefrontal Neurons Predict Choices during an Auditory Same-Different Task

Department of Psychological and Brain Sciences, Center for Cognitive Neuroscience, Dartmouth College, Hanover, NH 03755, USA.
Current Biology (Impact Factor: 9.57). 10/2008; 18(19):1483-8. DOI: 10.1016/j.cub.2008.08.054
Source: PubMed


The detection of stimuli is critical for an animal's survival [1]. However, it is not adaptive for an animal to respond automatically to every stimulus that is present in the environment [2-5]. Given that the prefrontal cortex (PFC) plays a key role in executive function [6-8], we hypothesized that PFC activity should be involved in context-dependent responses to uncommon stimuli. As a test of this hypothesis, monkeys participated in a same-different task, a variant of an oddball task [2]. During this task, a monkey heard multiple presentations of a "reference" stimulus that were followed by a "test" stimulus and reported whether these stimuli were the same or different. While they participated in this task, we recorded from neurons in the ventrolateral prefrontal cortex (vPFC; a cortical area involved in aspects of nonspatial auditory processing [9, 10]). We found that vPFC activity was correlated with the monkeys' choices. This finding demonstrates a direct link between single neurons and behavioral choices in the PFC on a nonspatial auditory task.

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Available from: Yale Cohen, Sep 17, 2014
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    • "The neural responses to the target and standard sounds were nearly unaffected by the cat's behavioral choice. Our present results suggest that the role of PU, as the major input site of the basal ganglia, might primarily be to provide sensory evidence and reward association to other brain areas, such as prefrontal cortex [5] [50] and premotor cortex [51], to encode the output of the decision process. However, it is worth noting that we only collected a small quantity of units (n = 16 in reward unit group) in the analysis of effects of behavioral choice, because the cats have been well trained with the use of the two discrimination tasks and seldom showed a miss or false alarm response. "
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    • "For example, VLPFC neurons were modulated during non-spatial auditory discrimination but showed no modulation during spatial auditory discrimination (Cohen et al., 2009). Further recordings over a large region of PFC which Cohen termed “vPFC” during categorization and decision making paradigms, demonstrate that prefrontal neuronal activity is correlated with behavioral choices (Russ et al., 2008b; Lee et al., 2009), although the location of these prefrontal neurons does not appear to overlap entirely with the ventrolateral PFC regions previously shown to be auditory responsive (Romanski et al., 2005). Nonetheless, inactivation studies are needed to determine whether VLPFC is essential in the performance of working memory or decision making tasks. "
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    • "Beyond the auditory cortex, do latter processing stages (e.g., the monkey ventral prefrontal cortex and human inferior frontal cortex) process categories for even more complex sounds? A reexamination of previous findings from our lab (Russ et al., 2008b; Tsunada et al., 2011) indicated important differences in neural categorization between the lateral belt and the ventral prefrontal cortex (Figure 3). We found that, at the population level, the category sensitivity for speech sounds in the prefrontal cortex was weaker than that in the lateral belt although neural activity in the prefrontal cortex transmitted a significant amount of categorical information. "
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