Hyeonjeong Jeong

Multiple brain networks for visual self-recognition with different sensitivity for motion and body part.

Multiple brain networks may support visual self-recognition. It has been hypothesized that the left ventral occipito-temporal cortex processes ones own face as a symbol, and the right parieto-frontal network processes self-image in association with motion-action contingency. Using functional magnetic resonance imaging, we first tested these hypotheses based on the prediction that these networks preferentially respond to a static self-face and to moving ones whole body, respectively. Brain activation specifically related to self-image during familiarity judgment was compared across four stimulus conditions comprising a two factorial design: factor Motion contrasted picture (Picture) and movie (Movie), and factor Body part a face (Face) and whole body (Body). Second, we attempted to segregate self-specific networks using a principal component analysis (PCA), assuming an independent pattern of inter-subject variability in activation over the four stimulus conditions in each network. The bilateral ventral occipito-temporal and the right parietal and frontal cortices exhibited self-specific activation. The left ventral occipito-temporal cortex exhibited greater self-specific activation for Face than for Body, in Picture, consistent with the prediction for this region. The activation profiles of the right parietal and frontal cortices did not show preference for Movie Body predicted by the assumed roles of these regions. The PCA extracted two cortical networks, one with its peaks in the right posterior, and another in frontal cortices; their possible roles in visuo-spatial and conceptual self-representations, respectively, were suggested by previous findings. The results thus supported and provided evidence of multiple brain networks for visual self-recognition.

Face-specific and domain-general characteristics of cortical responses during self-recognition.

The ability of visual self-recognition in animals and infants is considered a hallmark of the domain-general cognitive representation of the self, which also underpins higher social ability. Cortical regions activated during self-face recognition in human adults have been accordingly expected to play the domain-general role in self-processing. However, there is no evidence of the involvement of this network in non-face domains. We compared cortical responses during face and name recognition of self, a friend, and an unfamiliar person, using functional magnetic resonance imaging (fMRI). Recognition of the self-face activated the right inferior frontal, precentral, supramarginal, and bilateral ventral occipitotemporal regions, consistent with previous findings, whereas these regions did not show self-specific activation during name recognition. During both face and name recognitions, increased activation for the friend and unfamiliar person than for the self was observed in the bilateral temporoparietal regions, and higher activation for the self and friend than for the unfamiliar person was observed in the medial cortical structures. These results suggest that the role of the self-specific networks during face recognition is not domain-general, but rather face-specific, and that the medial cortical structures, which are also implicated in self-referential processes, are not relevant to self-other distinction during face or name recognition. Instead, the reduced temporoparietal activation is a domain-general characteristic of the cortical response during self-recognition, which may reflect suppression of an automatic preparatory process for social interaction, possibly paralleling the disappearance of social behavior to the mirrored self-image at the emergence of self-recognition in animals and infants.

Cortical activation in the processing of passive sentences in L1 and L2: An fMRI study

The question of whether the bilingual brain processes a first and second language (L1 and L2, respectively) differently is a central issue in many psycholinguistic and neurolinguistic studies. This study used functional magnetic resonance imaging (fMRI) to investigate whether late bilinguals process structurally complex sentences in L1 and L2 in different cortical networks. For this purpose, we directly compared brain activity during the processing of active and passive sentences in both L1 and L2. We asked 36 healthy subjects to judge whether or not a presented sentence was semantically plausible. Both L1 and L2 activated the left hemispheric language-related regions such as the left inferior frontal, superior/middle temporal, and parietal cortices. However, we found different activation patterns between L1 and L2 in the processing of passive sentences. Passive sentences elicited greater activation than their active counterparts in the left pars triangularis, the premotor area, and the superior parietal lobule in Japanese, but not in English. Furthermore, there was a significant interaction between sentence type (active versus passive) and language (Japanese versus English) in the left pars orbitalis. The results of this study indicate that late bilinguals use similar cortical regions to comprehend both L1 and L2. However, when late bilinguals are presented with structurally complex sentences, the involvement of these regions differs between L1 and L2. These results suggest that, in addition to age of L2 acquisition and L2 proficiency, differences in grammatical construction affect cortical representation during the comprehension of L1 and L2.

Effect of syntactic similarity on cortical activation during second language processing: a comparison of English and Japanese among native Korean trilinguals.

In this study of native Korean trilinguals we examined the effect of syntactic similarity between first (L1) and second (L2) languages on cortical activation during the processing of Japanese and English, which are, respectively, very similar to and different from Korean. Subjects had equivalent proficiency in Japanese and English. They performed auditory sentence comprehension tasks in Korean, Japanese, and English during functional MRI (fMRI). The bilateral superior temporal cortex was activated during the comprehension of three languages. The pars triangularis of the left inferior frontal gyrus (IFG) was additionally activated for L2 processing. Furthermore, the right cerebellum, the pars opercularis of the left IFG, and the posteriomedial part of the superior frontal gyrus were activated during the English tasks only. We observed significantly greater activation in the pars opercularis of the left IFG, the right cerebellum, and the right superior temporal cortex during the English than Japanese task; activation in these regions did not differ significantly between Korean and Japanese. Differential activation of the pars opercularis of the left IFG and the right cerebellum likely reflects syntactic distance and differential activation in the right superior temporal cortex may reflect the prosodic distance between English from Korean and Japanese. Furthermore, in the pars oparcularis of the left IFG and the right cerebellum, significant negative correlation between the activation and duration of exposure was observed for English, but not for Japanese. Our research supports the notion that linguistic similarity between L1 and L2 affects the cortical processing of second language. Hum Brain Mapp, 2007.

Cortical mechanism of communicative speech production.

Communicative speech requires conformity not only to linguistic rules but also to behavior that is appropriate for social interaction. The existence of a special brain mechanism for such behavioral aspects of communicative speech has been suggested by studies of social impairment in autism, and it may be related to communicative vocalization in animals. We used functional magnetic resonance imaging (fMRI) to measure cortical activation while normal subjects casually talked to an actor (communication task) or verbally described a situation (description task) while observing video clips of an action performed by a familiar or an unfamiliar actor in a typical daily situation. We assumed that the communication task differed from the description task in the involvement of behavioral aspects of communicative speech production, which may involve the processing of interaction-relevant biographical information. Significantly higher activation was observed during the communication task than during the description task in the medial prefrontal cortex (polar and dorsal parts), the bilateral anterior superior temporal sulci, and the left temporoparietal junction. The results suggest that these regions play a role in the behavioral aspects of communicative speech production, presumably in understanding of the context of the social interaction. The activation of the polar part of the medial prefrontal cortex during the communication task was greater when the actor was familiar than when the actor was unfamiliar, suggesting that this region is involved in communicative speech production with reference to biological information. The precuneus was activated during the communication task only with the familiar actor, suggesting that this region is related to access to biographical information per se.

Cross-linguistic influence on brain activation during second language processing: An fMRI study

The goal of this study was to examine the effect of the linguistic distance between a first language (L1) and a second language (L2) on neural activity during second language relative to first language processing. We compared different L1–L2 pairs in which different linguistic features characterize linguistic distance. Chinese and Korean native speakers were instructed to perform sentence comprehension tasks in two L2s (English and Japanese) and their respective L1s. Activation while understanding English sentences relative to understanding sentences in L1 was greater for the Korean group than the Chinese group in the left inferior frontal gyrus, bilateral posterior superior temporal gyri, and right cerebellum. Activation while understanding Japanese sentences relative to understanding sentences in L1 was greater for the Chinese group than the Korean group in the anterior portion of the left superior temporal gyrus. The results demonstrated that the location of the L2–L1 processing-induced cortical activation varies between different L1–L2 pairs.

Self-face recognition in social context

The concept of “social self” is often described as a representation of the self‐reflected in the eyes or minds of others. Although the appearance of ones own face has substantial social significance for humans, neuroimaging studies have failed to link self‐face recognition and the likely neural substrate of the social self, the medial prefrontal cortex (MPFC). We assumed that the social self is recruited during self‐face recognition under a rich social context where multiple other faces are available for comparison of social values. Using functional magnetic resonance imaging (fMRI), we examined the modulation of neural responses to the faces of the self and of a close friend in a social context. We identified an enhanced response in the ventral MPFC and right occipitoparietal sulcus in the social context specifically for the self‐face. Neural response in the right lateral parietal and inferior temporal cortices, previously claimed as self‐face‐specific, was unaffected for the self‐face but unexpectedly enhanced for the friends face in the social context. Self‐face‐specific activation in the pars triangularis of the inferior frontal gyrus, and self‐face‐specific reduction of activation in the left middle temporal gyrus and the right supramarginal gyrus, replicating a previous finding, were not subject to such modulation. Our results thus demonstrated the recruitment of a social self during self‐face recognition in the social context. At least three brain networks for self‐face‐specific activation may be dissociated by different patterns of response‐modulation in the social context, suggesting multiple dynamic self‐other representations in the human brain. Hum Brain Mapp, 2011.

Learning second language vocabulary: Neural dissociation of situation-based learning and text-based learning

Second language (L2) acquisition necessitates learning and retrieving new words in different modes. In this study, we attempted to investigate the cortical representation of an L2 vocabulary acquired in different learning modes and in cross-modal transfer between learning and retrieval. Healthy participants learned new L2 words either by written translations (text-based learning) or in real-life situations (situation-based learning). Brain activity was then measured during subsequent retrieval of these words. The right supramarginal gyrus and left middle frontal gyrus were involved in situation-based learning and text-based learning, respectively, whereas the left inferior frontal gyrus was activated when learners used L2 knowledge in a mode different from the learning mode. Our findings indicate that the brain regions that mediate L2 memory differ according to how L2 words are learned and used.

The representation of social interaction in episodic memory: A functional MRI study

The representation of social interaction in episodic memory is a critical factor for the successful navigation of social relationships. In general, it is important to separate episodic memory during social interaction from episodic memory during the self-generation of action events. Different cortical representations have been associated with social interaction vs. self-generated episodic memory. Here we clarified the cortical representation of the effect of context (social vs. solitary) on episodic memory by comparing it with the generation effect (self vs. other) on episodic memory. Each participant learned words while engaged in a sentence generation and a reading task, and subsequently each participant was scanned with functional magnetic resonance imaging (fMRI) while they performed a recognition task using the words that had been learned. The experiment was comprised of four conditions and we looked at two situations that involved a social context and non-social (solitary) context task. In the learning session before entering the MRI, two participants collaborated in a social context either generating (social-contextual self-generation condition: SS) or reading (social-contextual other-generation condition: SO) a sequence of sentences alternately to construct a meaningful story narrative. In the non-social context, the participants generated (non-social-contextual self-generation condition: NS) or read (non-social-contextual other-generation condition: NO) a sequence of sentences individually. The stimuli for the recognition session consisted of learned words and novel words. Activation for social context retrieval was identified in the right medial prefrontal cortex (mPFC), and activation for self-generated retrieval was identified in the left mPFC and the left middle cingulate cortex. These results indicate that dissociable regions within the medial prefrontal cortices contribute to the processes involved in the representation of social interaction, including social context and self-generation in the retrieval of episodic memory.

Extraction of Situational Meaning by Integrating Multiple Meanings in a Complex Environment: A Functional MRI Study

Humans extract behaviorally significant meaning from a situation by integrating meanings from multiple components of a complex daily environment. To determine the neural underpinnings of this ability, the authors performed functional magnetic resonance imaging of healthy subjects while the latter viewed naturalistic scenes of two people and an object, including a threatening situation of a person being attacked by an offender with an object. The authors used a two‐factorial design: the object was either aversive or nonaversive, and the offenders action was either directed to the person or elsewhere. This allowed the authors to examine the neural response to object aversiveness and person‐directed intention separately. A task unrelated to threat was also used to address incidental (i.e., subconscious or unintentional) detection. Assuming individual differences in incidental threat detection, the authors used a functional connectivity analysis using principal components analysis of intersubject variability. The left lateral orbitofrontal cortex and medial prefrontal cortex (MPFC) were specifically activated in response to a threatening situation. The threat‐related component of intersubject variability was extracted from these data and showed a significant correlation with personality scores. There was also a correlation between threat‐related intersubject variability and activation for object aversiveness in the left temporal pole and lateral orbitofrontal cortex; person‐directed intention in the left superior frontal gyrus; threatening situations in the left MPFC; and independently for both factors in the right MPFC. Results demonstrate independent processing of object aversiveness and person‐directed intention in the left temporal‐orbitofrontal and superior frontal networks, respectively, and their integration into situational meaning in the MPFC. Hum Brain Mapp, 2009.