The Neurophysiology of Functionally Meaningful Categories: Macaque Ventrolateral Prefrontal Cortex Plays a Critical Role in Spontaneous Categorization of Species-Specific Vocalizations

Dartmouth College, Hanover, NH 03755, USA.
Journal of Cognitive Neuroscience (Impact Factor: 4.09). 10/2005; 17(9):1471-82. DOI: 10.1162/0898929054985464
Source: PubMed


Neurophysiological studies in nonhuman primates have demonstrated that the prefrontal cortex (PFC) plays a critical role in the acquisition of learned categories following training. What is presently unclear is whether this cortical area also plays a role in spontaneous recognition and discrimination of natural categories. Here, we explore this possibility by recording from neurons in the PFC while rhesus listen to species-specific vocalizations that vary in terms of their social function and acoustic morphology. We found that ventral prefrontal cortex (vPFC) activity, on average, did not differentiate between food calls that were associated with the same functional category, despite having different acoustic properties. In contrast, vPFC activity differentiated between food calls associated with different functional classes and specifically, information about the quality and motivational value of the food. These results suggest that the vPFC is involved in the categorization of socially meaningful signals, thereby both extending its previously conceived role in the acquisition of learned categories and showing the significance of using natural categorical distinctions in the study of neural mechanisms.

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Available from: Katherine A Maclean, Aug 14, 2014
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    • "For instance, compared to A1, secondary auditory areas in primates respond with longer latencies, higher stimulus selectivity, and can be robustly driven by band-pass noise, frequency-modulated sweeps, and species-specific vocalizations (Rauschecker et al. 1995; Rauschecker 1998; Tian et al. 2001; Wang et al. 2005; Kajikawa et al. 2008). Many of these secondary processing areas ultimately project to specific areas of prefrontal cortex (Hackett et al. 1999; Romanski et al. 1999; Romanski and Goldman-Rakic 2002; Romanski 2003) that are likely involved in even higher level processing such as stimulus categorization (Gifford et al. 2005; Cohen et al. 2006). The auditory cortex thus appears, and is often assumed to be, designed to perform increasingly complex and integrative computations as information flows from primary to secondary regions and, ultimately, to frontal areas. "
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    ABSTRACT: Neural responses in the auditory cortex have historically been measured from either anesthetized or awake but non-behaving animals. A growing body of work has begun to focus instead on recording from auditory cortex of animals actively engaged in behavior tasks. These studies have shown that auditory cortical responses are dependent upon the behavioral state of the animal. The longer ascending subcortical pathway of the auditory system and unique characteristics of auditory processing suggest that such dependencies may have a more profound influence on cortical processing in the auditory system compared to other sensory systems. It is important to understand the nature of these dependencies and their functional implications. In this article, we review the literature on this topic pertaining to cortical processing of sounds.
    Brain Topography 02/2015; 28(3). DOI:10.1007/s10548-015-0428-4 · 3.47 Impact Factor
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    • "Similarly, the monkey ventral prefrontal cortex encodes abstract categories. We have found that neurons in the ventral prefrontal cortex represent categories for food-related calls based on the transmitted information (e.g., high quality food vs. low quality food) (Gifford et al., 2005; Cohen et al., 2006). A more recent study found that neural activity in the monkey prefrontal cortex categorically represents the number of auditory stimuli (Nieder, 2012). "
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    ABSTRACT: Categorization enables listeners to efficiently encode and respond to auditory stimuli. Behavioral evidence for auditory categorization has been well documented across a broad range of human and non-human animal species. Moreover, neural correlates of auditory categorization have been documented in a variety of different brain regions in the ventral auditory pathway, which is thought to underlie auditory-object processing and auditory perception. Here, we review and discuss how neural representations of auditory categories are transformed across different scales of neural organization in the ventral auditory pathway: from across different brain areas to within local microcircuits. We propose different neural transformations across different scales of neural organization in auditory categorization. Along the ascending auditory system in the ventral pathway, there is a progression in the encoding of categories from simple acoustic categories to categories for abstract information. On the other hand, in local microcircuits, different classes of neurons differentially compute categorical information.
    Frontiers in Neuroscience 06/2014; 8(8):161. DOI:10.3389/fnins.2014.00161 · 3.66 Impact Factor
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    • "Neurons in prefrontal cortex exhibit strong category selectivity and likely contribute to the behavioral response (i.e. motor output) [8,76,86,87]. "
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    ABSTRACT: Humans and animals readily generalize previously learned knowledge to new situations. Determining similarity is critical for assigning category membership to a novel stimulus. We tested the hypothesis that category membership is initially encoded by the similarity of the activity pattern evoked by a novel stimulus to the patterns from known categories. We provide behavioral and neurophysiological evidence that activity patterns in primary auditory cortex contain sufficient information to explain behavioral categorization of novel speech sounds by rats. Our results suggest that category membership might be encoded by the similarity of the activity pattern evoked by a novel speech sound to the patterns evoked by known sounds. Categorization based on featureless pattern matching may represent a general neural mechanism for ensuring accurate generalization across sensory and cognitive systems.
    PLoS ONE 10/2013; 8(10):e78607. DOI:10.1371/journal.pone.0078607 · 3.23 Impact Factor
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