Age differences in neural activity related to mentalizing during person perception

ABSTRACT

Mentalizing, or thinking about others’ mental states, shapes social interactions. Older adults (OA) have reduced mentalizing capacities reflected by lower medial prefrontal cortex (mPFC) activation. The current study assessed if OA’ lower mPFC activation reflects less spontaneous mentalizing during person perception. Younger adults (YA) and OA viewed ingroup White and outgroup Black and Asian faces and completed a mentalizing task during fMRI. Afterward, they completed a task in which they inferred mental states from faces. Using an mPFC region defined by the mentalizing task, OA had lower activity than YA during person perception. OA’ mPFC activity toward faces positively related to their mentalizing outside the scanner. The extent of OA’ lower mPFC activation during person perception may depend on their actual detection of mental states in faces. Further, YA’, but not OA’, mPFC activity distinguished between outgroups. OA’ lower mentalizing-related mPFC activity may reduce their ability to individuate outgroup members.     

Numbsense of shape,texture, and objects after left parietal infarction: A case report

Numbsense is a phenomenon, wherein patients can correctly respond to somatosensory stimuli at a higher rate than expected by chance, but cannot perceive the same stimuli consciously. Previously, numbsense has been reported in tactile localization of stimuli on the patient’s own body. Here, we describe a patient with numbsense that involved touched objects. The patient could not recognize the majority of somatosensory stimuli after left parietal infarction, but could correctly select shape, texture, and object stimuli more frequently than expected by chance.     

额叶与非额叶脑肿瘤患者分心记忆和符号数字作业的比较研究

本文以95例额叶、颞叶和顶枕叶脑肿瘤患者为被试,探讨了脑肿瘤部位同分心记忆和符号数字的关系。结果表明,额叶患者的故事意义分的分心消耗值显著高于正常人,其词的分心回忆和分心消耗值显著差于颞叶组,表明额叶在分心作业中较颞叶参与较多。右顶叶也有涉及分心注意较多的趋势,提示大脑前部可能与分心注意关系较密切。“符号数字”作业中,则“写”的作业有颞叶组好于额叶组,“说”的作业颞叶组好于顶枕组的趋势。     

Preliminary evidence for selective cortical responses to music in one-month-old infants

Prior studies have observed selective neural responses in the adult human auditory cortex to music and speech that cannot be explained by the differing lower-level acoustic properties of these stimuli. Does infant cortex exhibit similarly selective responses to music and speech shortly after birth? To answer this question, we attempted to collect functional magnetic resonance imaging (fMRI) data from 45 sleeping infants (2.0- to 11.9-weeks-old) while they listened to monophonic instrumental lullabies and infant-directed speech produced by a mother. To match acoustic variation between music and speech sounds we (1) recorded music from instruments that had a similar spectral range as female infant-directed speech, (2) used a novel excitation-matching algorithm to match the cochleagrams of music and speech stimuli, and (3) synthesized “model-matched” stimuli that were matched in spectrotemporal modulation statistics to (yet perceptually distinct from) music or speech. Of the 36 infants we collected usable data from, 19 had significant activations to sounds overall compared to scanner noise. From these infants, we observed a set of voxels in non-primary auditory cortex (NPAC) but not in Heschl's Gyrus that responded significantly more to music than to each of the other three stimulus types (but not significantly more strongly than to the background scanner noise). In contrast, our planned analyses did not reveal voxels in NPAC that responded more to speech than to model-matched speech, although other unplanned analyses did. These preliminary findings suggest that music selectivity arises within the first month of life. A video abstract of this article can be viewed at https://youtu.be/c8IGFvzxudk .

Research Highlights

• Responses to music, speech, and control sounds matched for the spectrotemporal modulation-statistics of each sound were measured from 2- to 11-week-old sleeping infants using fMRI.
• Auditory cortex was significantly activated by these stimuli in 19 out of 36 sleeping infants.
• Selective responses to music compared to the three other stimulus classes were found in non-primary auditory cortex but not in nearby Heschl's Gyrus.
• Selective responses to speech were not observed in planned analyses but were observed in unplanned, exploratory analyses.

     

Would a neuroscience of violence aid in understanding legal culpability?

Defense attorneys in criminal cases are beginning to argue that their clients were biologically predisposed to committing their crimes and therefore were less responsible for their behavior. Indeed, if our brains cause our behavior, and our brains are the way they are because of genetic composition, insults, disease, and life experiences, it becomes difficult to argue that any punishment as justified retribution for behavior is cogent. In this essay, I address the question of whether understanding the neuroscience behind human behavior should alter our legal notion of responsibility. We will examine this query in greater detail, using violence as a case study, asking whether understanding the neuroscience underlying violent behavior impacts our notion of personal or legal culpability. I shall argue that it does not. I proceed by first briefly sketching what we know about human violence and the biology behind it. Then I turn to a quick discussion of psychopaths, their connections to violence, and what we think we know about the biology of their brains. Finally, I come to the question of whether we should consider violent people with specific brain abnormalities as mad or bad, which will feed into the question of whether such people are responsible for their criminal behavior. I conclude with some very general and very brief speculations on what this discussion has to tell us about nature of being human.     

Developmental imaging genetics: Linking dopamine function to adolescent behavior

Adolescence is a period of development characterized by numerous neurobiological changes that significantly influence behavior and brain function. Adolescence is of particular interest due to the alarming statistics indicating that mortality rates increase two to three-fold during this time compared to childhood, due largely to a peak in risk-taking behaviors resulting from increased impulsivity and sensation seeking. Furthermore, there exists large unexplained variability in these behaviors that are in part mediated by biological factors. Recent advances in molecular genetics and functional neuroimaging have provided a unique and exciting opportunity to non-invasively study the influence of genetic factors on brain function in humans. While genes do not code for specific behaviors, they do determine the structure and function of proteins that are essential to the neuronal processes that underlie behavior. Therefore, studying the interaction of genotype with measures of brain function over development could shed light on critical time points when biologically mediated individual differences in complex behaviors emerge. Here we review animal and human literature examining the neurobiological basis of adolescent development related to dopamine neurotransmission. Dopamine is of critical importance because of (1) its role in cognitive and affective behaviors, (2) its role in the pathogenesis of major psychopathology, and (3) the protracted development of dopamine signaling pathways over adolescence. We will then focus on current research examining the role of dopamine-related genes on brain function. We propose the use of imaging genetics to examine the influence of genetically mediated dopamine variability on brain function during adolescence, keeping in mind the limitations of this approach.