Deficit in Complex Sequence Processing after a Virtual Lesion of Left BA45

Although the contribution of Broca''s area to motor cognition is generally accepted, its exact role remains controversial. A previous functional imaging study has suggested that Broca''s area implements hierarchically organised motor behaviours and, in particular, that its anterior (Brodmann area 45, BA45) and posterior (BA44) parts process, respectively, higher and lower-level hierarchical elements. This function of Broca''s area could generalize to other cognitive functions, including language. However, because of the correlative nature of functional imaging data, the causal relationship between Broca''s region activation and its behavioural significance cannot be ascertained. To circumvent this limitation, we used on-line repetitive transcranial magnetic stimulation to disrupt neuronal processing in left BA45, left BA44 or left dorsal premotor cortex, three areas that have been shown to exhibit a phasic activation when participants performed hierarchically organised motor behaviours. The experiment was conducted in healthy volunteers performing the same two key-press sequences as those used in a previous imaging study, and which differed in terms of hierarchical organisation. The performance of the lower-order hierarchical task (Experiment #1) was unaffected by magnetic stimulation. In contrast, in the higher-order hierarchical task (Experiment #2, “superordinate” task), we found that a virtual lesion of the anterior part of Broca''s area (left BA45) delayed the processing of the cue initiating the sequence in an effector-independent way. Interestingly, in this task, the initiation cue only informed the subjects about the rules to be applied to produce the appropriate response but did not allow them to anticipate the entire motor sequence. A second important finding was a RT decrease following left PMd virtual lesions in the superordinate task, a result compatible with the view that PMd plays a critical role in impulse control. The present study therefore demonstrates the role of left BA45 in planning the higher-order hierarchical levels of motor sequences.     

Distinct Parietal and Temporal Pathways to the Homologues of Broca's Area in the Monkey

The homologues of the two distinct architectonic areas 44 and 45 that constitute the anterior language zone (Broca's region) in the human ventrolateral frontal lobe were recently established in the macaque monkey. Although we know that the inferior parietal lobule and the lateral temporal cortical region project to the ventrolateral frontal cortex, we do not know which of the several cortical areas found in those regions project to the homologues of Broca's region in the macaque monkey and by means of which white matter pathways. We have used the autoradiographic method, which permits the establishment of the cortical area from which axons originate (i.e., the site of injection), the precise course of the axons in the white matter, and their termination within particular cortical areas, to examine the parietal and temporal connections to area 44 and the two subdivisions of area 45 (i.e., areas 45A and 45B). The results demonstrated a ventral temporo-frontal stream of fibers that originate from various auditory, multisensory, and visual association cortical areas in the intermediate superolateral temporal region. These axons course via the extreme capsule and target most strongly area 45 with a more modest termination in area 44. By contrast, a dorsal stream of axons that originate from various cortical areas in the inferior parietal lobule and the adjacent caudal superior temporal sulcus was found to target both areas 44 and 45. These axons course in the superior longitudinal fasciculus, with some axons originating from the ventral inferior parietal lobule and the adjacent superior temporal sulcus arching and forming a simple arcuate fasciculus. The cortex of the most rostral part of the inferior parietal lobule is preferentially linked with the ventral premotor cortex (ventral area 6) that controls the orofacial musculature. The cortex of the intermediate part of the inferior parietal lobule is linked with both areas 44 and 45. These findings demonstrate the posterior parietal and temporal connections of the ventrolateral frontal areas, which, in the left hemisphere of the human brain, were adapted for various aspects of language production. These precursor circuits that are found in the nonlinguistic, nonhuman, primate brain also exist in the human brain. The possible reasons why these areas were adapted for language use in the human brain are discussed. The results throw new light on the prelinguistic precursor circuitry of Broca's region and help understand functional interactions between Broca's ventrolateral frontal region and posterior parietal and temporal association areas.     

The role of ventral premotor cortex in action execution and action understanding

The human ventral premotor cortex overlaps, at least in part, with Broca's region in the dominant cerebral hemisphere, that is known to mediate the production of language and contributes to language comprehension. This region is constituted of Brodmann's areas 44 and 45 in the inferior frontal gyrus. We summarize the evidence that the motor related part of Broca's region is localized in the opercular portion of the inferior frontal cortex, mainly in area 44 of Brodmann. According to our own data, there seems to be a homology between Brodmann area 44 in humans and the monkey area F5. The non-language related motor functions of Broca's region comprise complex hand movements, associative sensorimotor learning and sensorimotor integration. Brodmann's area 44 is also a part of a specialized parieto-premotor network and interacts significantly with the neighbouring premotor areas. In the ventral premotor area F5 of monkeys, the so called mirror neurons have been found which discharge both when the animal performs a goal-directed hand action and when it observes another individual performing the same or a similar action. More recently, in the same area mirror neurons responding not only to the observation of mouth actions, but also to sounds characteristic to actions have been found. In humans, through an fMRI study, it has been shown that the observation of actions performed with the hand, the mouth and the foot leads to the activation of different sectors of Broca's area and premotor cortex, according to the effector involved in the observed action, following a somatotopic pattern which resembles the classical motor cortex homunculus. On the other hand the evidence is growing that human ventral premotor cortex, especially Brodmann's area 44, is involved in polymodal action processing. These results strongly support the existence of an execution-observation matching system (mirror neuron system). It has been proposed that this system is involved in polymodal action recognition and might represent a precursor of language processing. Experimental evidence in favour of this hypothesis both in the monkey and humans is shortly reviewed.     

Cerebral Activations Related to Writing and Drawing with Each Hand

BackgroundWriting is a sequential motor action based on sensorimotor integration in visuospatial and linguistic functional domains. To test the hypothesis of lateralized circuitry concerning spatial and language components involved in such action, we employed an fMRI paradigm including writing and drawing with each hand. In this way, writing-related contributions of dorsal and ventral premotor regions in each hemisphere were assessed, together with effects in wider distributed circuitry. Given a right-hemisphere dominance for spatial action, right dorsal premotor cortex dominance was expected in left-hand writing while dominance of the left ventral premotor cortex was expected during right-hand writing.MethodsSixteen healthy right-handed subjects were scanned during audition-guided writing of short sentences and simple figure drawing without visual feedback. Tapping with a pencil served as a basic control task for the two higher-order motor conditions. Activation differences were assessed with Statistical Parametric Mapping (SPM).ResultsWriting and drawing showed parietal-premotor and posterior inferior temporal activations in both hemispheres when compared to tapping. Drawing activations were rather symmetrical for each hand. Activations in left- and right-hand writing were left-hemisphere dominant, while right dorsal premotor activation only occurred in left-hand writing, supporting a spatial motor contribution of particularly the right hemisphere. Writing contrasted to drawing revealed left-sided activations in the dorsal and ventral premotor cortex, Broca’s area, pre-Supplementary Motor Area and posterior middle and inferior temporal gyri, without parietal activation.DiscussionThe audition-driven postero-inferior temporal activations indicated retrieval of virtual visual form characteristics in writing and drawing, with additional activation concerning word form in the left hemisphere. Similar parietal processing in writing and drawing pointed at a common mechanism by which such visually formatted information is used for subsequent sensorimotor integration along a dorsal visuomotor pathway. In this, the left posterior middle temporal gyrus subserves phonological-orthographical conversion, dissociating dorsal parietal-premotor circuitry from perisylvian circuitry including Broca''s area.     

Language Universals Engage Broca's Area

It is well known that natural languages share certain aspects of their design. For example, across languages, syllables like blif are preferred to lbif. But whether language universals are myths or mentally active constraints—linguistic or otherwise—remains controversial. To address this question, we used fMRI to investigate brain response to four syllable types, arrayed on their linguistic well-formedness (e.g., blif≻bnif≻bdif≻lbif, where ≻ indicates preference). Results showed that syllable structure monotonically modulated hemodynamic response in Broca''s area, and its pattern mirrored participants'' behavioral preferences. In contrast, ill-formed syllables did not systematically tax sensorimotor regions—while such syllables engaged primary auditory cortex, they tended to deactivate (rather than engage) articulatory motor regions. The convergence between the cross-linguistic preferences and English participants'' hemodynamic and behavioral responses is remarkable given that most of these syllables are unattested in their language. We conclude that human brains encode broad restrictions on syllable structure.     

Temporal Reliability and Lateralization of the Resting-State Language Network

The neural processing loop of language is complex but highly associated with Broca''s and Wernicke''s areas. The left dominance of these two areas was the earliest observation of brain asymmetry. It was demonstrated that the language network and its functional asymmetry during resting state were reproducible across institutions. However, the temporal reliability of resting-state language network and its functional asymmetry are still short of knowledge. In this study, we established a seed-based resting-state functional connectivity analysis of language network with seed regions located at Broca''s and Wernicke''s areas, and investigated temporal reliability of language network and its functional asymmetry. The language network was found to be temporally reliable in both short- and long-term. In the aspect of functional asymmetry, the Broca''s area was found to be left lateralized, while the Wernicke''s area is mainly right lateralized. Functional asymmetry of these two areas revealed high short- and long-term reliability as well. In addition, the impact of global signal regression (GSR) on reliability of the resting-state language network was investigated, and our results demonstrated that GSR had negligible effect on the temporal reliability of the resting-state language network. Our study provided methodology basis for future cross-culture and clinical researches of resting-state language network and suggested priority of adopting seed-based functional connectivity for its high reliability.     

Motor and cognitive functions of the ventral premotor cortex

Recent data show that the ventral premotor cortex in both humans and monkeys has motor and cognitive functions. The cognitive functions include space perception, action understanding and imitation. The data also show a clear functional homology between monkey area F5 and human area 44. Preliminary evidence suggests that the ventral part of the lateral premotor cortex in humans may correspond to monkey area F4. A tentative map of the human lateral premotor areas founded on the reviewed evidence is presented.     

Localization of attachment area of the symbiotic Chlorella variabilis of the ciliate Paramecium bursaria during the algal removal and reinfection

Chlorella spp. and ciliate Paramecium bursaria share a mutual symbiosis. However, both alga-removed P. bursaria and isolated symbiotic algae can grow independently. Additionally, mixing them experimentally can cause algal reinfection through host phagocytosis. Although the symbiotic algal localization beneath the host cell cortex is a prerequisite phenomenon for maintenance of the relationship of their endosymbiosis, how and where the algae locate beneath the host cell cortex remains unknown. To elucidate this phenomenon, algal distribution patterns during algal removal and reinfection were observed. During algal removal, algae at the host anterior cortex were easier to remove than at the posterior and ventral or dorsal cortex areas. During algal reinfection, the algae after separation from the host digestive vacuoles tended to localize beneath the host ventral or dorsal cortex more readily than that at other cortices. Algae that reinfected trichocyst-removed paramecia didn’t show this localization. Trichocyst-discharge experiments clarified that trichocysts of the anterior cortex are difficult to remove. In 14 strains of P. bursaria, some of the paramecia lacked their symbiotic algae at the anterior cortex. These observations demonstrate that symbiotic algae of P. bursaria are difficult to localize at the anterior cortex and that they are easy to remove from the area.     

Subjective Somatosensory Experiences Disclosed by Focused Attention: Cortical-Hippocampal-Insular and Amygdala Contributions

In order to explore the neurobiological foundations of qualitative subjective experiences, the present study was designed to correlate objective third-person brain fMRI measures with subjective first-person identification and scaling of local, subtle, and specific somatosensory sensations, obtained directly after the imaging procedure. Thus, thirty-four volunteers were instructed to focus and sustain their attention to either provoked or spontaneous sensations of each thumb during the fMRI procedure. By means of a Likert scale applied immediately afterwards, the participants recalled and evaluated the intensity of their attention and identified specific somatosensory sensations (e.g. pulsation, vibration, heat). Using the subject''s subjective scores as covariates to model both attention intensity and general somatosensory experiences regressors, the whole-brain random effect analyses revealed activations in the frontopolar prefrontal cortex (BA10), primary somatosensory cortex (BA1), premotor cortex (BA 6), precuneus (BA 7), temporopolar cortex (BA 38), inferior parietal lobe (BA 39), hippocampus, insula and amygdala. Furthermore, BA10 showed differential activity, with ventral BA10 correlating exclusively with attention (r(32) = 0.54, p = 0.0013) and dorsal BA10 correlating exclusively with somatosensory sensation (r(32) = 0.46, p = 0.007). All other reported brain areas showed significant positive correlations solely with subjective somatosensory experiences reports. These results provide evidence that the frontopolar prefrontal cortex has dissociable functions depending on specific cognitive demands; i.e. the dorsal portion of the frontopolar prefrontal cortex in conjunction with primary somatosensory cortex, temporopolar cortex, inferior parietal lobe, hippocampus, insula and amygdala are involved in the processing of spontaneous general subjective somatosensory experiences disclosed by focused and sustained attention.     

Horseradish peroxidase study of connections of the hippocampal (mediodorsal) cortex ofOphisaurus apodus

Sources of afferent projections of the hippocampal (mediodorsal) cortex were detected in lizards (Ophisaurus apodus) by the retrograde horseradish peroxidase transport method. Labeled neurons after injection of the enzyme were most numerous in the anterior dorsolateral thalamic nucleus, mammillary body, superior nucleus raphe, dorsal cortex (ipsilaterally), and the hippocampal cortex of the contralateral hemisphere. Fewer neurons projecting into the hippocampal cortex were found in these same structures on the side opposite to that of the injection, and also in the ventromedial zone of the telencephalon (olfactory tubercle, the nucleus of Broca's diagonal band, and the nucleus accumbens), the preoptic region of the hypothalamus, and the ventrotegmental region of the midbrain. Endings of efferent fibers from the hippocampal cortex were found in the septum, thalamus, hypothalamus (mainly on the side of injection of the enzyme), and also in the hippocampal and dorsal cortex of both hemispheres. The results show that afferent and efferent connections of the lizard's hippocampal cortex are similar to those of mammals.     

Wernicke's area homologue in chimpanzees (Pan troglodytes) and its relation to the appearance of modern human language

Human language is distinctive compared with the communication systems of other species. Yet, several questions concerning its emergence and evolution remain unresolved. As a means of evaluating the neuroanatomical changes relevant to language that accompanied divergence from the last common ancestor of chimpanzees, bonobos and humans, we defined the cytoarchitectonic boundaries of area Tpt, a component of Wernicke''s area, in 12 common chimpanzee brains and used design-based stereologic methods to estimate regional volumes, total neuron number and neuron density. In addition, we created a probabilistic map of the location of area Tpt in a template chimpanzee brain coordinate space. Our results show that chimpanzees display significant population-level leftward asymmetry of area Tpt in terms of neuron number, with volume asymmetry approaching significance. Furthermore, asymmetry in the number of neurons in area Tpt was positively correlated with asymmetry of neuron numbers in Brodmann''s area 45, a component of Broca''s frontal language region. Our findings support the conclusion that leftward asymmetry of Wernicke''s area originated prior to the appearance of modern human language and before our divergence from the last common ancestor. Moreover, this study provides the first evidence of covariance between asymmetry of anterior and posterior cortical regions that in humans are important to language and other higher order cognitive functions.     

Decreased premotor cortex volume in victims of urban violence with posttraumatic stress disorder

Background

Studies addressing posttraumatic stress disorder (PTSD) have demonstrated that PTSD patients exhibit structural abnormalities in brain regions that relate to stress regulation and fear responses, such as the hippocampus, amygdala, anterior cingulate cortex, and ventromedial prefrontal cortex. Premotor cortical areas are involved in preparing to respond to a threatening situation and in representing the peripersonal space. Urban violence is an important and pervasive cause of human suffering, especially in large urban centers in the developing world. Violent events, such as armed robbery, are very frequent in certain cities, and these episodes increase the risk of PTSD. Assaultive trauma is characterized by forceful invasion of the peripersonal space; therefore, could this traumatic event be associated with structural alteration of premotor areas in PTSD?

Methodology/Principal Findings

Structural magnetic resonance imaging scans were acquired from a sample of individuals that had been exposed to urban violence. This sample consisted of 16 PTSD patients and 16 age- and gender-matched controls. Psychometric questionnaires differentiated PTSD patients from trauma-exposed controls with regard to PTSD symptoms, affective, and resilience predispositions. Voxel-based morphometric analysis revealed that, compared with controls, the PTSD patients presented significant reductions in gray matter volume in the ventral premotor cortex and in the pregenual anterior cingulate cortex.

Conclusions

Volume reduction in the premotor cortex that is observed in victims of urban violence with PTSD may be associated with a disruption in the dynamical modulation of the safe space around the body. The finding that PTSD patients presented a smaller volume of pregenual anterior cingulate cortex is consistent with the results of other PTSD neuroimaging studies that investigated different types of traumatic events.     

Neural Dynamics of Learning Sound—Action Associations

A motor component is pre-requisite to any communicative act as one must inherently move to communicate. To learn to make a communicative act, the brain must be able to dynamically associate arbitrary percepts to the neural substrate underlying the pre-requisite motor activity. We aimed to investigate whether brain regions involved in complex gestures (ventral pre-motor cortex, Brodmann Area 44) were involved in mediating association between novel abstract auditory stimuli and novel gestural movements. In a functional resonance imaging (fMRI) study we asked participants to learn associations between previously unrelated novel sounds and meaningless gestures inside the scanner. We use functional connectivity analysis to eliminate the often present confound of ‘strategic covert naming’ when dealing with BA44 and to rule out effects of non-specific reductions in signal. Brodmann Area 44, a region incorporating Broca''s region showed strong, bilateral, negative correlation of BOLD (blood oxygen level dependent) response with learning of sound-action associations during data acquisition. Left-inferior-parietal-lobule (l-IPL) and bilateral loci in and around visual area V5, right-orbital-frontal-gyrus, right-hippocampus, left-para-hippocampus, right-head-of-caudate, right-insula and left-lingual-gyrus also showed decreases in BOLD response with learning. Concurrent with these decreases in BOLD response, an increasing connectivity between areas of the imaged network as well as the right-middle-frontal-gyrus with rising learning performance was revealed by a psychophysiological interaction (PPI) analysis. The increasing connectivity therefore occurs within an increasingly energy efficient network as learning proceeds. Strongest learning related connectivity between regions was found when analysing BA44 and l-IPL seeds. The results clearly show that BA44 and l-IPL is dynamically involved in linking gesture and sound and therefore provides evidence that one of the mechanisms required for the evolution of human communication is found within these motor regions.     

Levodopa Effects on Hand and Speech Movements in Patients with Parkinson’s Disease: A fMRI Study

Levodopa (L-dopa) effects on the cardinal and axial symptoms of Parkinson’s disease (PD) differ greatly, leading to therapeutic challenges for managing the disabilities in this patient’s population. In this context, we studied the cerebral networks associated with the production of a unilateral hand movement, speech production, and a task combining both tasks in 12 individuals with PD, both off and on levodopa (L-dopa). Unilateral hand movements in the off medication state elicited brain activations in motor regions (primary motor cortex, supplementary motor area, premotor cortex, cerebellum), as well as additional areas (anterior cingulate, putamen, associative parietal areas); following L-dopa administration, the brain activation profile was globally reduced, highlighting activations in the parietal and posterior cingulate cortices. For the speech production task, brain activation patterns were similar with and without medication, including the orofacial primary motor cortex (M1), the primary somatosensory cortex and the cerebellar hemispheres bilaterally, as well as the left- premotor, anterior cingulate and supramarginal cortices. For the combined task off L-dopa, the cerebral activation profile was restricted to the right cerebellum (hand movement), reflecting the difficulty in performing two movements simultaneously in PD. Under L-dopa, the brain activation profile of the combined task involved a larger pattern, including additional fronto-parietal activations, without reaching the sum of the areas activated during the simple hand and speech tasks separately. Our results question both the role of the basal ganglia system in speech production and the modulation of task-dependent cerebral networks by dopaminergic treatment.     

Distinctions between dorsal and ventral premotor areas: anatomical connectivity and functional properties

The dorsal and ventral premotor areas, together with the primary motor cortex, are believed to have major roles in preparing and executing limb movements. Recent studies have expanded our knowledge of the dorsal and ventral premotor areas, which occupy the lateral part of area 6 in the frontal cortex. It is becoming clear that these two premotor areas, through involvement in distinct cortical networks, take part in unique aspects of motor planning and decision making. New lines of evidence also implicate the lateral premotor areas in planning motor behavior and selecting actions.     

Organizing activity of Fgf8 on the anterior telencephalon

The anterior part of the embryonic telencephalon gives rise to several brain regions that are important for animal behavior, including the frontal cortex (FC) and the olfactory bulb. The FC plays an important role in decision‐making behaviors, such as social and cognitive behavior, and the olfactory bulb is involved in olfaction. Here, we show the organizing activity of fibroblast growth factor 8 (Fgf8) in the regionalization of the anterior telencephalon, specifically the FC and the olfactory bulb. Misexpression of Fgf8 in the most anterior part of the mouse telencephalon at embryonic day 11.5 (E11.5) by ex utero electroporation resulted in a lateral shift of dorsal FC subdivision markers and a lateral expansion of the dorsomedial part of the FC, the future anterior cingulate and prelimbic cortex. Fgf8‐transfected brains had lacked ventral FC, including the future orbital cortex, which was replaced by the expanded olfactory bulb. The olfactory region occupied a larger area of the FC when transfection efficiency of Fgf8 was higher. These results suggest that Fgf8 regulates the proportions of the FC and olfactory bulb in the anterior telencephalon and has a medializing effect on the formation of FC subdivisions.     

Understanding Others' Regret: A fMRI Study

Previous studies showed that the understanding of others'' basic emotional experiences is based on a “resonant” mechanism, i.e., on the reactivation, in the observer''s brain, of the cerebral areas associated with those experiences. The present study aimed to investigate whether the same neural mechanism is activated both when experiencing and attending complex, cognitively-generated, emotions. A gambling task and functional-Magnetic-Resonance-Imaging (fMRI) were used to test this hypothesis using regret, the negative cognitively-based emotion resulting from an unfavorable counterfactual comparison between the outcomes of chosen and discarded options. Do the same brain structures that mediate the experience of regret become active in the observation of situations eliciting regret in another individual? Here we show that observing the regretful outcomes of someone else''s choices activates the same regions that are activated during a first-person experience of regret, i.e. the ventromedial prefrontal cortex, anterior cingulate cortex and hippocampus. These results extend the possible role of a mirror-like mechanism beyond basic emotions.     

Lipid pathway alterations in Parkinson's disease primary visual cortex

Background

We present a lipidomics analysis of human Parkinson''s disease tissues. We have focused on the primary visual cortex, a region that is devoid of pathological changes and Lewy bodies; and two additional regions, the amygdala and anterior cingulate cortex which contain Lewy bodies at different disease stages but do not have as severe degeneration as the substantia nigra.

Methodology/Principal Findings

Using liquid chromatography mass spectrometry lipidomics techniques for an initial screen of 200 lipid species, significant changes in 79 sphingolipid, glycerophospholipid and cholesterol species were detected in the visual cortex of Parkinson''s disease patients (n = 10) compared to controls (n = 10) as assessed by two-sided unpaired t-test (p-value <0.05). False discovery rate analysis confirmed that 73 of these 79 lipid species were significantly changed in the visual cortex (q-value <0.05). By contrast, changes in 17 and 12 lipid species were identified in the Parkinson''s disease amygdala and anterior cingulate cortex, respectively, compared to controls; none of which remained significant after false discovery rate analysis. Using gas chromatography mass spectrometry techniques, 6 out of 7 oxysterols analysed from both non-enzymatic and enzymatic pathways were also selectively increased in the Parkinson''s disease visual cortex. Many of these changes in visual cortex lipids were correlated with relevant changes in the expression of genes involved in lipid metabolism and an oxidative stress response as determined by quantitative polymerase chain reaction techniques.

Conclusions/Significance

The data indicate that changes in lipid metabolism occur in the Parkinson''s disease visual cortex in the absence of obvious pathology. This suggests that normalization of lipid metabolism and/or oxidative stress status in the visual cortex may represent a novel route for treatment of non-motor symptoms, such as visual hallucinations, that are experienced by a majority of Parkinson''s disease patients.     

Projection areas and branching patterns of the tympanal receptor cells in migratory locusts,Locusta migratoria and Schistocerca gregaria

Summary In Locusta migratoria and Schistocerca gregaria, the projection areas and branching patterns of the tympanal receptor cells in the thoracic ganglia were revealed. Four auditory neuropiles can be distinguished on each side of the ventral cord, always located in the anterior part of the ring tract in each neuromere (two in the meta-, one in the meso-, and one in the prothoracic ganglion). Some of the receptor fibres ascend to the suboesophageal ganglion. There are distinct subdivisions within the auditory, frontal metathoracic and mesothoracic neuropiles. The arrangement of the terminal arborisations of the four types of tympanal receptor cells according to their different frequency-intensity responses is somatotopic and similar in the two ganglia. Here the receptor cells of type-1 form a restricted lateroventral arborisation. Cells of type-4 occupy the caudal part with a dorsorostral extension. Cells of type-2 and -3 arborise in a subdivision between both. Most of the stained low-frequency receptors (type-1, -2, and -3) terminate either in the metathoracic or, predominantly, in the mesothoracic ganglion. In contrast, the high-frequency cells (type-4) ascend to the prothoracic ganglion. The receptor fibres of the different types of receptor cells differ in diameter.Abbreviations aRT anterior part of the ring tract - cf characteristic frequency - MVT median ventral tract - SEG suboesophageal ganglion - SMC supramedian commissure - VMT ventral median tract - VIT ventral intermediate tract Supported by the Deutsche Forschungsgemeinschaft; part of program A7 in Sonderforschungsbereich 305 (Ecophysiology)     

The neural correlates of emotional prosody comprehension: disentangling simple from complex emotion

Background

Emotional prosody comprehension (EPC), the ability to interpret another person''s feelings by listening to their tone of voice, is crucial for effective social communication. Previous studies assessing the neural correlates of EPC have found inconsistent results, particularly regarding the involvement of the medial prefrontal cortex (mPFC). It remained unclear whether the involvement of the mPFC is linked to an increased demand in socio-cognitive components of EPC such as mental state attribution and if basic perceptual processing of EPC can be performed without the contribution of this region.

Methods

fMRI was used to delineate neural activity during the perception of prosodic stimuli conveying simple and complex emotion. Emotional trials in general, as compared to neutral ones, activated a network comprising temporal and lateral frontal brain regions, while complex emotion trials specifically showed an additional involvement of the mPFC, premotor cortex, frontal operculum and left insula.

Conclusion

These results indicate that the mPFC and premotor areas might be associated, but are not crucial to EPC. However, the mPFC supports socio-cognitive skills necessary to interpret complex emotion such as inferring mental states. Additionally, the premotor cortex involvement may reflect the participation of the mirror neuron system for prosody processing particularly of complex emotion.