Processing of emotional vocalizations in bilateral inferior frontal cortex

Abstract

a b s t r a c tA current view proposes that the right inferior frontal cortex (IFC) is particularly responsible for attentive decoding and cognitive evaluation of emotional cues in human vocalizations. Although some studies seem to support this view, an exhaustive review of all recent imaging studies points to an important functional role of both the right and the left IFC in processing vocal emotions. Second, besides a supposed predominant role of the IFC for an attentive processing and evaluation of emotional voices in IFC, these recent studies also point to a possible role of the IFC in preattentive and implicit processing of vocal emotions. The studies specifically provide evidence that both the right and the left IFC show a similar anterior-to-posterior gradient of functional activity in response to emotional vocalizations. This bilateral IFC gradient depends both on the nature or medium of emotional vocalizations (emotional prosody versus nonverbal expressions) and on the level of attentive processing (explicit versus implicit processing), closely resembling the distribution of terminal regions of distinct auditory pathways, which provide either global or dynamic acoustic information. Here we suggest a functional distribution in which several IFC subregions process different acoustic information conveyed by emotional vocalizations. Although the rostro-ventral IFC might categorize emotional vocalizations, the caudo-dorsal IFC might be specifically sensitive to their temporal features.

Whispering - The hidden side of auditory communication

“…In response to voiced vocalizations, activity was found in rACC, which is usually involved in inferring the emotional state of another individual (Frühholz et al, 2009;Frühholz et al, 2016a;Szameitat et al, 2010). Whispered vocalizations elicited activity in the OFC and the IFC, which are involved in the cognitive evaluation of vocalizations (Frühholz and Grandjean, 2013b), especially under demanding task conditions (Leitman et al, 2010). The IFC might be also involved in retrieving information from long term semantic memory (Binder et al, 2009), such that the impoverished sound quality of whispered vocalization is enriched with acoustic memory information from previous encounters with whispered voices or from prototypical information from voiced emotional vocalizations.…”

“…These bottom-up and the top-down connections might be required to decode the affective value from whispered voices due to their impoverished acoustic quality. The auditory cortex might send the analysis of the sparsely available acoustic information to the frontal cortex, which consequently might provide increased cognitive evaluation (Frühholz and Grandjean, 2013b;Leitman et al, 2010) and enrichment by voice memory information to support top-down predictions on acoustic decoding on the auditory cortex (Bar, 2009). This temporal bottom-up transfer of acoustic information and the frontal top-down influence might be an iterative process until an accurate decision can be made on whispered vocalizations.…”

“…We also determined activity in subregions of the STC consisting of STG and STS (Frühholz and Grandjean, 2013a). During the main experiment (see below) we also determined activity in frontal lobe subregions especially of the inferior frontal gyrus (IFG) and orbitofrontal cortex (OFC) that are central for the decoding of vocalizations (Frühholz and Grandjean, 2013b).…”

“…The inferior frontal cortex (IFC) shows activity and functional connectivity to the auditory cortex if acoustic cue salience in emotional voices decreases (Leitman et al, 2010), pointing to an enhanced cognitive evaluation in the IFC under challenging acoustic conditions (Frühholz and Grandjean, 2013b). The IFC might also enrich the perception of impoverished sounds by retrieving acoustic memory information from long-term, stored prototype emotional vocalizations (Binder et al, 2009).…”

Bilateral dorsal and ventral fiber pathways for the processing of affective prosody identified by probabilistic fiber tracking

“…Ventral and dorsal pathways, for example, are supposed to originate in multiple STG seed regions (Friederici, 2011;. Furthermore, these pathways probably terminate in the anterior as well as in the posterior IFG (Fruhholz and Grandjean, 2013b), serving to evaluate (Schirmer and Kotz, 2006) and to categorize vocalizations (Romo et al, 2004), respectively. Thus, especially the use of multiple temporal and frontal seed and target regions might help to more comprehensively describe the extended structural temporofrontal neural network underlying the processing of affective prosody.…”