Finding the self? An event-related fMRI study

Researchers have long debated whether knowledge about the self is unique in terms of its functional anatomic representation within the human brain. In the context of memory function, knowledge about the self is typically remembered better than other types of semantic information. But why does this memorial effect emerge? Extending previous research on this topic (see Craik et al., 1999), the present study used event-related functional magnetic resonance imaging to investigate potential neural substrates of self-referential processing. Participants were imaged while making judgments about trait adjectives under three experimental conditions (self-relevance, other-relevance, or case judgment). Relevance judgments, when compared to case judgments, were accompanied by activation of the left inferior frontal cortex and the anterior cingulate. A separate region of the medial prefrontal cortex was selectively engaged during self-referential processing. Collectively, these findings suggest that self-referential processing is functionally dissociable from other forms of semantic processing within the human brain.     

Is Broca's area involved in the processing of passive sentences? An event-related fMRI study

We used functional magnetic resonance imaging (fMRI) to investigate whether activation in Broca's area is greater during the processing of passive versus active sentences in the brains of healthy subjects. Twenty Japanese native speakers performed a visual sentence comprehension task in which they were asked to read a visually presented sentence and to identify the agent or the patient in the sentence by pressing a button. We found that the processing of passive sentences elicited no greater activation than that of active sentences in Broca's area. However, passive sentences elicited greater activation than active sentences in the left frontal operculum and the inferior parietal lobule. Thus, our neuroimaging results suggest that deficits in the comprehension of passive sentences in Japanese aphasics are induced not by lesions to Broca's area, but to the left frontal operculum and/or the inferior parietal lobule.     

Is it really my turn? An event-related fMRI study of task sharing

Acting together with others is a fundamental human ability. This raises the possibility that we take others' actions into account whenever somebody acts around us. Event-related fMRI was used to identify brain regions responsive to changes in cognitive processing when one and the same go-nogo task is performed alone or together with a co-actor performing a complementary task. Reaction times showed that participants integrated the potential action of their co-actor in their own action planning. Increased activation in ventral premotor cortex was found when participants acted upon stimuli referring to their own action alternative, but only when their partner performed a complementary task. This suggests that knowing about the potential actions of a partner increases the relevance of stimuli referring to oneself. Acting in the presence of a co-actor was also associated with increased orbitofrontal activation, indicating that participants monitored their performance more closely to make sure it really was their turn. These results suggest that our default mode is to interact with others.     

Is it really my turn? An event-related fMRI study of task sharing

Abstract

Acting together with others is a fundamental human ability. This raises the possibility that we take others’ actions into account whenever somebody acts around us. Event-related fMRI was used to identify brain regions responsive to changes in cognitive processing when one and the same go–nogo task is performed alone or together with a co-actor performing a complementary task. Reaction times showed that participants integrated the potential action of their co-actor in their own action planning. Increased activation in ventral premotor cortex was found when participants acted upon stimuli referring to their own action alternative, but only when their partner performed a complementary task. This suggests that knowing about the potential actions of a partner increases the relevance of stimuli referring to oneself. Acting in the presence of a co-actor was also associated with increased orbitofrontal activation, indicating that participants monitored their performance more closely to make sure it really was their turn. These results suggest that our default mode is to interact with others.     

Is it about the self or the significance? An fMRI study of self-name recognition

Our own name, due to its high social relevance, is supposed to have a unique status in our information processing. However, demonstrating this phenomenon empirically proves difficult as famous and unknown names, to which self-name is often compared in the studies, may differ from self-name not only in terms of the ‘me vs. not-me’ distinction, but also as regards their emotional content and frequency of occurrence in everyday life. In this fMRI study, apart from famous and unknown names we used the names of the most important persons in our subjects' lives. When compared to famous or unknown names recognition, self-name recognition was associated with robust activations in widely distributed bilateral network including fronto-temporal, limbic and subcortical structures, however, when compared to significant other's name, the activations were present specifically in the right inferior frontal gyrus. In addition, the significant other's name produced a similar pattern of activations to the one activated by self-name. These results suggest that the differences between own and other's name processing may rather be quantitative than qualitative in nature.     

Blindness and brain plasticity: contribution of mental imagery? An fMRI study

The purpose of this study was to study brain plasticity in the visual cortex, in six subjects totally blind from birth. The protocol we used was the same as that employed in a prior study on blindfolded sighted subjects (Brain Res., 924 (2002) 176). The production of mental images from animal names versus passive listening to abstract words, involved, in the early blind subjects as well as in the blindfolded sighted subjects of our control group, the superior occipital, inferior and superior parietal areas, premotor area, visual association. Activation foci in the somatosensory areas in the left hemisphere, as well as in the temporal and fusiform gyri were only visible in the blind subjects. The experiment, which was repeated after a short period of rest, demonstrated, this time again, predominant involvement of the dorsal pathway and activation of the primary visual area (in a region of interest). With respect to the ongoing debate on brain reorganization, our study shows that the primary visual area is activated in early blind subjects, and that activation persists in a mental imagery task involving no sensory input other than verbal instructions.     

Is the self special in the dorsomedial prefrontal cortex? An fMRI study

Abstract

In recent years, several neuroimaging studies have suggested that the neural basis of the self-referential process1 ¹In this article, we define self-“related” processing as a wide variety of information processing to address every stimulus related to the self, and self-“referential” processing as a type of self-related processing that especially needs to access self-representation composed of the self-concept, autobiographical memory and so on. is special, especially in the medial prefrontal cortex (MPFC). However, it remains controversial whether activity of the MPFC (and other related brain regions) appears only during the self-referential process. We investigated the neural correlates during the processing of references to the self, close other (friend), and distant other (prime minister) using fMRI. In comparison with baseline findings, referential processing to the three kinds of persons defined above showed common activation patterns in the dorsomedial prefrontal cortex (DMPFC), left middle temporal gyrus, left angular gyrus, posterior cingulate cortex and right cerebellum. Additionally, percent changes in BOLD signal in five regions of interest demonstrated the same findings. The result indicated that DMPFC was not special for the self-referential process, while there are common neural bases for evaluating the personalities of the self and others.     

Reaction time inhibition from subliminal cues: is it related to inhibition of return?

Task-irrelevant visual cues with near zero visibility proved apt to retard reaction time for the detection of supraliminal visual targets presented at the cued location. The time course of the effect was similar to that of the so-called inhibition-of return (IOR), which is assumed to be due to the withdrawal of attention from the inhibited location. However the present subliminal cues consistently failed to induce an RT facilitation prior to the RT inhibition, contrary to what would be expected if the cue were able to attract attention to the cued location. Since the RT inhibition from subliminal cues could not be attributed to the withdrawal of attention from the cued location, it can be argued that such cues acted both outside of consciousness and without the influence of attention. Therefore, the RT inhibitory effect seems best accounted for by an automatic, unconscious and attention-independent self-inhibition of response tendencies instructed by irrelevant information, akin to that postulated by (Eimer, M., & Schlaghecken, F. (1998). Effects of masked stimuli on motor activation: behavioural and electrophysiological evidence. Journal of Experimental Psychology Human Perception and Performance, 24, 1737-1747.) to explain the negative compatibility effect.     

Neural differentiation of lexico-syntactic categories or semantic features? event-related potential evidence for both

Event-related potentials (ERPs) were used to investigate whether processing differences between nouns and verbs can be accounted for by the differential salience of visual-perceptual and motor attributes in their semantic specifications. Three subclasses of nouns and verbs were selected, which differed in their semantic attribute composition (abstract, high visual, high visual and motor). Single visual word presentation with a recognition memory task was used. While multiple robust and parallel ERP effects were observed for both grammatical class and attribute type, there were no interactions between these. This pattern of effects provides support for lexical-semantic knowledge being organized in a manner that takes account both of category-based (grammatical class) and attribute-based distinctions.     

Does context matter in evaluations of stigmatized individuals? An fMRI study

The manner in which disparate affective responses shape attitudes toward other individuals has received a great deal of attention in neuroscience research. However, the malleability of these affective responses remains largely unexplored. The perceived controllability of a stigma (whether or not the bearer of the stigma is perceived as being responsible for his or her condition) has been found to polarize behavioral affective responses to that stigma. The current study uses functional magnetic resonance imaging to identify the neural correlates underlying the evaluation of stigmatized individuals (people who are homeless) when perceptions of the controllability of their condition are altered. Results demonstrated that perceivers engaged neural networks implicated in inferring intentionality (e.g. the medial prefrontal cortex) when they evaluated a homeless individual who was described as being responsible for becoming homeless. Conversely, neural networks associated with resolving strong affective responses (e.g. insula) were engaged when evaluating a homeless individual who was described as not being responsible for becoming homeless.     

Dynamics of the human alpha rhythm: evidence for non-linearity?

OBJECT: For a better understanding of the physiological mechanisms responsible for alpha rhythms it is important to know whether non-linear processes play a role in their generation. We used non-linear forecasting in combination with surrogate data testing to investigate the prevalence and nature of alpha rhythm non-linearity, based on EEG recordings from humans. We interpreted these findings using computer simulations of the alpha rhythm model of Lopes da Silva et al. (1974). METHODS: EEGs were recorded at 02 and O1 in 60 healthy subjects (30 males; 30 females; age: 49.28 years; range 11-84) during a resting eyes-closed state. Four artefact-free epochs (2.5 s; sample frequency 200 Hz) from each subject were tested for non-linearity using a non-linear prediction statistic and phase-randomized surrogate data. A similar type of analysis was done on the output of the alpha model for different values of input. RESULTS: In the 480 (60 subjects, 2 derivations, 4 blocks) epochs studied, the null hypothesis that the alpha rhythms can result from linearly filtered noise, could be rejected in 6 cases (1.25%). The alpha model showed a bifurcation from a point attractor to a limit cycle at an input pulse density of 615 pps. Non-linearity could only be detected in the model output close to and beyond this bifurcation point. The sources of the non-linearity are the sigmoidal relationships between average membrane potential and output pulse density of the various cells of the neuronal populations. CONCLUSION: The alpha rhythm is a heterogeneous entity dynamically: 98.75% of the epochs (type I alpha) cannot be distinguished from filtered noise. Apparently, during these epochs the activity of the brain has such a high complexity that it cannot be distinguished from a random process. In 1.25% of the epochs (type II alpha) non-linearity was found which may be explained by dynamics in the vicinity of a bifurcation to a limit cycle. There is thus experimental evidence from the point of view of dynamics for the existence of the two types of alpha rhythm and the bifurcation predicted by the model.     

Grammatical processing without semantics? An event-related brain potential study of preschoolers using jabberwocky sentences

Behavioral studies have demonstrated that children develop a nearly adult-like grammar between 36 and 42 months, but few studies have addressed how the child's brain processes semantic versus syntactic information. In previous research, Silva-Pereyra and colleagues showed that distinct event-related potentials (ERPs) are elicited by semantic and syntactic violations in sentences in children as young as 30, 36, and 48 months, following the patterns displayed by adults. In the current study, we examined ERPs to syntactic phrase structure violations in real and jabberwocky sentences in 36-month-old children. Jabberwocky sentences are sentences in which content (open-class) words are replaced by pseudowords while function (closed-class) words are retained. Results showed that syntactically anomalous real sentences elicited two positive ERP effects: left-distributed effects from 500 to 750 msec and 1050 to 1300 msec, whereas syntactically anomalous jabberwocky sentences elicited two negative ERP effects: a left-distributed effect from 750 to 900 msec and a later broadly distributed effect from 950 to 1150 msec. The results indicate that when preschoolers process real English sentences, ERPs resembling the positive effects previously reported for adults are noted, although at longer latencies and with broader scalp distributions. However, when preschoolers process jabberwocky sentences with altered lexical-semantic content, a negative-going ERP component similar to one typically associated with the extraction of meaning is noted.     

Why are smiles contagious? An fMRI study of the interaction between perception of facial affect and facial movements

In human communication there is often a close relationship between the perception of an emotionally expressive face and the facial response of the viewer himself. Whereas perception and generation of facial expressions have been studied separately with functional imaging methods, no studies exist on their interaction. We combined the presentation of emotionally expressive faces with the instruction to react with facial movements predetermined and assigned. fMRI was used in an event related design to examine healthy subjects while they regarded happy, sad, or neutral faces and were instructed to simultaneously move the corners of their mouths either (a). upwards or (b). downwards, or (c). to refrain from movement. The subjects' facial movements were recorded with an MR-compatible video camera. Movement latencies were shortened in congruent situations (e.g. the presentation of a happy face and combined with upward movements) and delayed in non-congruent situations. Dissonant more than congruent stimuli activated the inferior prefrontal cortex and the somatomotor cortex bilaterally. The congruent condition, in particular when seeing a happy face, activated the medial basotemporal lobes (hippocampus, amygdala, parahippocampal region). We hypothesize that this region facilitates congruent facial movements when an emotionally expressive face is perceived and that it is part of a system for non-volitional emotional facial movements.     

Attachment: a biological basis for the therapeutic relationship?

When faced with loss, illness, distress, or threat, we tend to seek out an attachment figure from which we can obtain comfort and protection. The attachment theory, an evolutionary biosocial theory of development, postulates that the propensity to make strong emotional bonds to a differentiated and preferred person, conceived as stronger and or wiser, is a basic component of the human nature, distinct from feeding and sexuality. Attachment behaviour is present in germinal form in the neonate and continues to be present "from the cradle to the grave". On the basis of day-to-day experience of the responsiveness and accessibility of caregivers, children build internal working models of attachment figures and of themselves. Expectations about the likely behaviour of others, initially preverbal, characterize the approach of the individual to other persons. Internal working models are successively modified on the basis of recent experience. The therapeutic relationship can be viewed as the seeking of a secure base, from which the patient and the therapist, in a joint effort, explore the patient's attachment history and the painful feelings associated with it. The therapist, responsive to the patient's verbal and non-verbal attachment signals, is viewed as a supplementary attachment figure.     

How is cognitive control of a simple mental image achieved? An fMRI study

The aim of this study was to determine the brain regions associated with suppressing the image of an object. We used functional magnetic resonance imaging (fMRI) during five mental tasks (imagining, suppressing, erasing, free thinking and resting) performed by the subjects. The analysis showed that the suppressing, erasing and imagining conditions all activated the parietal and prefrontal regions to a different extent. These results suggest that the regions associated with cognitive control were also activated while a simple mental process was performed. Additionally, the results showed that the parietal lobe is the key region for the suppression of a mental image.     

Common networks for selective auditory attention for sounds and words? An fMRI study with implications for attention rehabilitation

Purpose: In an fMRI study the functional networks involved in auditory selective attention for sounds and words were investigated. Methods: 24 healthy volunteers (12 male, 12 female) had to respond to a category of targets (animal sounds vs. musical instruments, spoken names of instruments vs. animals; 6 targets, 12 nontargets) presented via headphones. Results: Under both the sound and word condition besides left superior and middle temporal lobe activation there was bilateral activity in the superior frontal (including the anterior cingulate cortex ACC), middle and inferior frontal and inferior parietal lobes. Under both conditions we also found cerebellar activity. In general there was a high overlap of the related attention networks for both conditions. Conclusions: The activation patterns revealed a high overlap across stimulus conditions with only slight modulation caused by the quality of the auditory material. For rehabilitation of attention deficits after brain damage this implicates that a single training procedure might address a common network for selective attention deficits under different stimulus conditions.     

Default distrust? An fMRI investigation of the neural development of trust and cooperation

The tendency to trust and to cooperate increases from adolescence to adulthood. This social development has been associated with improved mentalizing and age-related changes in brain function. Thus far, there is limited imaging data investigating these associations. We used two trust games with a trustworthy and an unfair partner to explore the brain mechanisms underlying trust and cooperation in subjects ranging from adolescence to mid-adulthood. Increasing age was associated with higher trust at the onset of social interactions, increased levels of trust during interactions with a trustworthy partner and a stronger decline in trust during interactions with an unfair partner. Our findings demonstrate a behavioural shift towards higher trust and an age-related increase in the sensitivity to others’ negative social signals. Increased brain activation in mentalizing regions, i.e. temporo-parietal junction, posterior cingulate and precuneus, supported the behavioural change. Additionally, age was associated with reduced activation in the reward-related orbitofrontal cortex and caudate nucleus during interactions with a trustworthy partner, possibly reflecting stronger expectations of trustworthiness. During unfair interactions, age-related increases in anterior cingulate activation, an area implicated in conflict monitoring, may mirror the necessity to inhibit pro-social tendencies in the face of the partner’s actual levels of cooperation.