Neural correlates of conscious and unconscious perception of self-faces

Priority of the “Self” is thought to be evolutionarily advantageous. However, evidence for this priority has been sparse. Capitalizing on a recently developed experimental tool (masked priming), able to reveal unconscious processes, I present new empirical data supporting, and further characterizing, the notion of self-specificity

4. Epidemics, Regulations, and Aristotle's Physics of Motion

The current polarization in public debate surrounding governmental regulatory responses to the Covid-19 pandemic is often portrayed as conflict between individual freedom and state control. A recurrent trope has been the likening of regulation in response to the Covid-19 pandemic to the condition described in Thomas Hobbes’s Leviathan, where citizens forego their individual freedom in exchange for protection by a mighty sovereign. In this sense, regulations introduced in response to the current pandemic have been viewed as threatening to expand state power and limit individual freedom. Whilst recognizing that epidemic-related regulations raise issues of state control and individual freedom, and hence resonate with Hobbes’s political theory, here I suggest that the polarization in this public debate also subtends epistemic uncertainty, and struggle over the locus of authority for knowledge and the relation of knowledge to action. In this respect, Hobbes is relevant to the current pandemic-debate also (and perhaps most significantly) for his reflection on human knowledge and action. Elements of Hobbes’s understanding of knowledge, as well as of the relation between knowledge and action, imply casting the human intellect in physical terms, and in particular in terms compatible with the Aristotelian physics of natural motion. I then bring this historical point to bear upon the current debate surrounding the Covid-19 pandemic, to suggest that the Hobbesian physics-inflected account of knowledge may offer a relevant—perhaps speculative, yet conceptually grounded and historically informed—perspective from which to reflect upon and responsibly assess, (dis)approve of, comply with, or challenge epidemic-related regulations. Keywords: Epidemic, Epidemic-related regulations, Hobbes, Bacon, Aristotle, Physic

3. The Non-Orientability of the Mechanical in Thomas Carlyle’s Early Essays

Thomas Carlyle’s early writings epitomise the critical stance towards the utilitarian culture of the age, which Carlyle condemns for glorifying the ‘outward’, i.e. the physical world of machinery, governed by automaticity and mechanical principles, at the expense of the ‘inward’, i.e. the spiritual realm of the human individual, whose hallmarks are instead free volition and agency, and to which automaticity and mechanical principles are foreign. By the 19th century, however, the distinction between human and machine was becoming increasingly problematic. Drawing from Thomas Carlyle’s essays “Signs of the Times” (1829) and “Characteristics” (1831), and from earlier physiological texts with which they engage—chiefly David Hartley’s Observations on Man (1749)—, I explore the tension between the understanding of the human in terms of free will and agency, and the physiological evidence that human thought and behaviour are partly automatic. I argue that the understanding of human nature as partly automatic destabilises Carlyle’s categories of ‘outward’ and ‘inward’ by disrupting their underlying assumption of a clear boundary between man and machine based on their functioning (the latter) or not (the former) according to mechanical principles, entailing instead a fluid connotation whereby the ‘mechanical’ is defined as much by identification with the ‘human’ as in opposition to it. I conclude by offering a geometric illustration of the destabilised inward-outward boundary through the metaphor of non-orientable surfaces (e.g. Möbius strip and Klein bottle), in which it is impossible to distinguish an inside and an outside.

Self-face enhances processing of immediately preceding invisible faces. Neuropsychologia 49

a b s t r a c t The self-face is thought to be an especially salient stimulus. Behavioral evidence suggests that self-face processing advantage is associated with enhanced processing of temporally adjacent subliminal stimuli. However, the neural basis of this self-related processing modulation has not been investigated. We studied self-face induced signal amplification through masked priming and repetition suppression (fMRI adaptation). Subjects performed a gender-categorization task on self-and non-self target faces preceded by subliminal (17 ms) prime faces. The relationship between prime and target was varied between task-incongruent (when prime and target belonged to a different gender) and task-congruent (when prime and target belonged to the same gender) pairs. We found that, in the presence of the visible self-face (but not of other non-self faces), a bilateral fronto-parietal network exhibited repetition suppression to subliminal prime faces belonging to the same gender (task-congruent) as the target, consistent with the notion that, in the presence of the selfface, subliminal stimuli access high-level processing systems. These results are in agreement with the notion of self-specific top-down amplification of subliminal task-relevant information, and suggest that the self-face, through its high salience, is particularly efficacious in focusing attention

Analyzing the Auditory Scene: Neurophysiologic Evidence of a Dissociation Between Detection of Regularity and Detection of Change

Detecting regularity and change in the environment is crucial for survival, as it enables making predictions about the world and informing goal-directed behavior. In the auditory modality, the detection of regularity involves segregating incoming sounds into distinct perceptual objects (stream segregation). The detection of change from this within-stream regularity is associated with the mismatch negativity, a component of auditory event-related brain potentials (ERPs). A central unanswered question is how the detection of regularity and the detection of change are interrelated, and whether attention affects the former, the latter, or both. Here we show that the detection of regularity and the detection of change can be empirically dissociated, and that attention modulates the detection of change without precluding the detection of regularity, and the perceptual organization of the auditory background into distinct streams. By applying frequency spectra analysis on the EEG of subjects engaged in a selective listening task, we found distinct peaks of ERP synchronization, corresponding to the rhythm of the frequency streams, independently of whether the stream was attended or ignored. Our results provide direct neurophysiological evidence of regularity detection in the auditory background, and show that it can occur independently of change detection and in the absence of attention

Subcortical processing in auditory communication

The voice is a rich source of information, which the human brain has evolved to decode and interpret. Empirical observations have shown that the human auditory system is especially sensitive to the human voice, and that activity within the voice-sensitive regions of the primary and secondary auditory cortex is modulated by the emotional quality of the vocal signal, and may therefore subserve, with frontal regions, the cognitive ability to correctly identify the speaker's affective state. So far, the network involved in the processing of vocal affect has been mainly characterised at the cortical level. However, anatomical and functional evidence suggests that acoustic information relevant to the affective quality of the auditory signal might be processed prior to the auditory cortex. Here we review the animal and human literature on the main subcortical structures along the auditory pathway, and propose a model whereby the distinction between different types of vocal affect in auditory communication begins at very early stages of auditory processing, and relies on the analysis of individual acoustic features of the sound signal. We further suggest that this early feature-based decoding occurs at a subcortical level along the ascending auditory pathway, and provides a preliminary coarse (but fast) characterisation of the affective quality of the auditory signal before the more refined (but slower) cortical processing is completed

Amygdala and auditory cortex exhibit distinct sensitivity to relevant acoustic features of auditory emotions

Discriminating between auditory signals of different affective value is critical to successful social interaction. It is commonly held that acoustic decoding of such signals occurs in the auditory system, whereas affective decoding occurs in the amygdala. However, given that the amygdala receives direct subcortical projections that bypass the auditory cortex, it is possible that some acoustic decoding occurs in the amygdala as well, when the acoustic features are relevant for affective discrimination. We tested this hypothesis by combining functional neuroimaging with the neurophysiological phenomena of repetition suppression (RS) and repetition enhancement (RE) in human listeners. Our results show that both amygdala and auditory cortex responded differentially to physical voice features, suggesting that the amygdala and auditory cortex decode the affective quality of the voice not only by processing the emotional content from previously processed acoustic features, but also by processing the acoustic features themselves, when these are relevant to the identification of the voice's affective value. Specifically, we found that the auditory cortex is sensitive to spectral high-frequency voice cues when discriminating vocal anger from vocal fear and joy, whereas the amygdala is sensitive to vocal pitch when discriminating between negative vocal emotions (i.e., anger and fear). Vocal pitch is an instantaneously recognized voice feature, which is potentially transferred to the amygdala by direct subcortical projections. These results together provide evidence that, besides the auditory cortex, the amygdala too processes acoustic information, when this is relevant to the discrimination of auditory emotions

Metaphor and music emotion: Ancient views and future directions

Music is often described in terms of emotion. This notion is supported by empirical evidence showing that engaging with music is associated with subjective feelings, and with objectively measurable responses at the behavioural, physiological, and neural level. Some accounts, however, reject the idea that music may directly induce emotions. For example, the 'paradox of negative emotion', whereby music described in negative terms is experienced as enjoyable, suggests that music might move the listener through indirect mechanisms in which the emotional experience elicited by music does not always coincide with the emotional label attributed to it. Here we discuss the role of metaphor as a potential mediator in these mechanisms. Drawing on musicological, philosophical, and neuroscientific literature, we suggest that metaphor acts at key stages along and between physical, biological, cognitive, and contextual processes, and propose a model of music experience in which metaphor mediates between language, emotion, and aesthetic response