WHY A BRAIN CAPABLE OF LANGUAGE EVOLVED ONLY ONCE: PREFRONTAL CORTEX AND SYMBOL LEARNING

Abstract. Language and information processes are critical issues in scientific controversies regarding the qualities that epitomize humanness. Whereas some theorists claim human mental uniqueness with regard to language, others point to successes in teaching language skills to other animals. However, although these animals may learn names for things, they show little ability to utilize a complex framework of symbolic reference. In such a framework, words or other symbols refer not only to objects and concepts but also to sequential and hierarchical relationships with other symbols. This process is essential to human mental operations, including language, mathematics, and music. In humans, these operations may have coevolved with the prefrontal area of the cerebral cortex, which is proportionately much larger in humans than in other animals and more intricately linked with other areas of the brain. Analysis of the structure and function of the prefrontal area suggests that it is centrally involved in the operation of higher-order associative relationships involving the subordination of one set of associations to another. This alternate learning strategy apparently appeared at the cost of certain sensory, motor, or limbic abilities. The payoff was symbolic thinking. Humans thus are unique among species, not just for their highly developed language ability but for their odd style of thinking and learning.     

激活右腹外侧前额叶提高抑郁症患者对社会疼痛的情绪调节能力：一项TMS研究

负性人际交往经历和负性社会事件是抑郁症的重要诱导因素, 而社会功能受损是抑郁症患者的重要特征之一, 患者通常表现出对社会疼痛的情绪失调。为了提高抑郁症患者在负性社交情境中或面对负性社会事件时的情绪调节能力, 本研究采用经颅磁刺激技术(transcranial magnetic stimulation, TMS), 考察抑郁症患者在腹外侧前额叶(the ventrolateral prefrontal cortex, VLPFC)被激活后其情绪调节能力的改变。结果表明, 当右侧VLPFC被TMS激活且患者采用认知重评策略调节情绪时, 实验组患者(n = 64)比对照组患者(n = 63)在社会排斥情境下报告了更弱的负性情绪体验, 这说明激活右侧VLPFC可以有效提高患者对社会疼痛的外显性情绪调节能力。本研究是采用TMS提高抑郁症患者情绪调节能力的首次尝试, 实验发现不但支持了VLPFC与认知重评策略的因果关系, 还为临床改善抑郁症等社会功能障碍患者的情绪调节能力提供了明确的神经治疗靶点。后续研究还需探讨多疗程TMS刺激方案、改变社会疼痛的诱发方式、对比左右侧VLPFC的治疗效果、尝试使用其他的情绪调节策略, 进一步验证本研究的结论, 优化TMS治疗方案。     

背外侧前额叶对主动遗忘负性社会反馈的作用：针对抑郁症的TMS研究

抑郁症患者的负性心境可能源于其抑制功能障碍。患者在主动遗忘负性材料时无法有效调用背外侧前额叶(the dorsolateral prefrontal cortex, DLPFC)等负责抑制控制的额叶脑网络。同时, 患者对社会信息的加工比对非社会信息的加工存在更明显的认知神经障碍, 很难主动遗忘对自己不利的社会反馈信息。为了提高抑郁症患者对负性社会反馈的主动遗忘能力, 本研究采用经颅磁刺激技术(transcranial magnetic stimulation, TMS), 考察抑郁症患者在左侧(n = 32)或右侧DLPFC (n = 30)被激活后其记忆控制能力的改变。结果表明, 当患者的DLPFC被TMS激活时, 他们对社会拒绝的回忆正确率与健康对照组(n = 31)无差异, 且TMS激活右侧DLPFC还改善了患者对他人的社会态度。本研究是采用TMS提高抑郁症患者主动遗忘能力的首次尝试, 研究结果不但支持了DLPFC与记忆控制功能的因果关系, 还为临床治疗抑郁症、创伤后应激障碍、药物成瘾等患者的记忆控制缺陷提供了明确的神经靶点。     

EVidence for dorsolateral and orbital prefrontal cortical involvement in the expression of aggressive behavior

Numerous studies have implicated the role of the prefrontal cortex in the expression of aggressive behavior. However, the nature of this relationship remains poorly understood. As such, the purpose of this article is to review both the animal and human literature pertaining to prefrontal cortical functioning and aggression in an attempt to help clarify this relationship. Particular attention is paid to differentiating the functions of the dorsolateral and the orbital regions of the prefrontal cortex in the expression of aggression. Evidence was garnered from four different types of studies: 1) those examining aggressive behavior in animals following ablations to the prefrontal cortex; 2) those examining aggressive behavior in humans following surgical and accidental lesions to the prefrontal cortex; 3) those examining prefrontal cortical functioning in individuals with psychiatric disorders characterized by aggression; and 4) those relating prefrontal cortical functioning to human aggressive behavior in laboratory situations. The general conclusion of this article is that the dorsolateral region of the prefrontal cortex is more likely to be involved in the expression of physical aggression whereas the orbital region is more likely to be involved in the expression of what is termed herein “disinhibited-nonaggressive” behavior. © 1995 Wiley-Liss, Inc.     

Neuronal changes in normal human aging and Alzheimer's disease

This article discusses age-related changes in brain weight, total number of cortical neurons, cortical dendrites, spine, and synapse density. The conclusion is that the present outlook is less grim than it was 30 years ago. Age-related reduction appears to be specific to brain region and cortical layer rather than a general feature. In addition, we describe a different pattern of changes that occur in Alzheimer's disease patients. This review concludes that the association cortices in particular are affected in aging and Alzheimer's disease and that the primary visual and somatosensory cortices are relatively spared.     

Corporal Punishment by American Parents: National Data on Prevalence, Chronicity, Severity, and Duration, in Relation to Child and Family Characteristics

We present data on corporal punishment (CP) by a nationally representative sample of 991 American parents interviewed in 1995. Six types of CP were examined: slaps on the hand or leg, spanking on the buttocks, pinching, shaking, hitting on the buttocks with a belt or paddle, and slapping in the face. The overall prevalence rate (the percentage of parents using any of these types of CP during the previous year) was 35% for infants and reached a peak of 94% at ages 3 and 4. Despite rapid decline after age 5, just over half of American parents hit children at age 12, a third at age 14, and 13% at age 17. Analysis of chronicity found that parents who hit teenage children did so an average of about six times during the year. Severity, as measured by hitting the child with a belt or paddle, was greatest for children age 5–12 (28% of such children). CP was more prevalent among African American and low socioeconomic status parents, in the South, for boys, and by mothers. The pervasiveness of CP reported in this article, and the harmful side effects of CP shown by recent longitudinal research, indicates a need for psychology and sociology textbooks to reverse the current tendency to almost ignore CP and instead treat it as a major aspect of the socialization experience of American children; and for developmental psychologists to be cognizant of the likelihood that parents are using CP far more often than even advocates of CP recommend, and to inform parents about the risks involved.     

Cumulative estrogen exposure and prospective memory in older women

This study looked at cumulative lifetime estrogen exposure, as estimated with a mathematical index (Index of Cumulative Estrogen Exposure (ICEE)) that included variables (length of time on estrogen therapy, age at menarche and menopause, postmenopausal body mass index, time since menopause, nulliparity and duration of breastfeeding) known to influence estrogen levels across the life span, and performance on prospective and retrospective memory measures in a group of 50 postmenopausal women (mean age=69.3years) who, if they were current or former users of estrogen therapy, had started therapy within 5years of menopause. The ICEE was found to be a significant predictor of performance on the Prospective Memory task (F(1)=4.21, p=.046, η(p)(2)=.084). No significant relationship was noted between the ICEE and performance on measures of retrospective memory. The results suggest that the level of cumulative lifetime exposure to estrogen a woman has influences her prospective memory performance later in life and that the influence of reproductive and biological markers of endogenous estrogen exposure are relevant factors to consider when studying the effect of estrogen therapy on cognitive functioning in postmenopausal women. In addition, the finding that performance on a measure of prospective memory, but not performance on measures of retrospective memory, was associated with the ICEE adds further support to the theory that the frontal cortex may be especially sensitive to estrogen.     

Dorsolateral prefrontal cortex mediates working memory processes in motor skill learning

Neuroimaging studies have shown that the dorsolateral prefrontal cortex (DLPFC) is recruited during motor skill learning, which suggests the involvement of the DLPFC in working memory (WM) processes, such as selection and integration of motor representations temporarily stored in WM. However, direct evidence linking activation of the DLPFC to WM storage and manipulation during motor skill learning in real-time is rare. In this study, we conducted two experiments to investigate the causal role of DLPFC activity in WM storage and manipulation during motor skill learning under low and high WM-demand conditions. Participants received continuous theta burst stimulation (cTBS) and sham stimulation (crossover design) over the left DLPFC (experiment 1) or right DLPFC (experiment 2). Before and after stimulation, participants in both experiments performed a sequential finger-tapping (SFT) task containing repeated sequence (low-WM demand) and non-repeated sequence (high-WM demand) conditions which are used to study WM processes. The number of correct sequences (NoCS) and reproduction error rate were analyzed. Learning gains in NoCS improved significantly with the practice for both sequence types in the presence of either stimulation type. Compared to sham stimulation, cTBS over the left DLPFC resulted in significantly reduced learning gains in NoCS for non-repeated sequences. These results suggest that the left DLPFC contributes to WM manipulation during motor skill learning.     

Building phrases in language production: An MEG study of simple composition

Although research on language production has developed detailed maps of the brain basis of single word production in both time and space, little is known about the spatiotemporal dynamics of the processes that combine individual words into larger representations during production. Studying composition in production is challenging due to difficulties both in controlling produced utterances and in measuring the associated brain responses. Here, we circumvent both problems using a minimal composition paradigm combined with the high temporal resolution of magnetoencephalography (MEG). With MEG, we measured the planning stages of simple adjective–noun phrases (‘red tree’), matched list controls (‘red, blue’), and individual nouns (‘tree’) and adjectives (‘red’), with results indicating combinatorial processing in the ventro-medial prefrontal cortex (vmPFC) and left anterior temporal lobe (LATL), two regions previously implicated for the comprehension of similar phrases. These effects began relatively quickly (∼180 ms) after the presentation of a production prompt, suggesting that combination commences with initial lexical access. Further, while in comprehension, vmPFC effects have followed LATL effects, in this production paradigm vmPFC effects occurred mostly in parallel with LATL effects, suggesting that a late process in comprehension is an early process in production. Thus, our results provide a novel neural bridge between psycholinguistic models of comprehension and production that posit functionally similar combinatorial mechanisms operating in reversed order.     

Neural processing of intentional biological motion in unaffected siblings of children with autism spectrum disorder: An fMRI study

Despite often showing behaviorally typical levels of social cognitive ability, unaffected siblings of children with autism spectrum disorder have been found to show similar functional and morphological deficits within brain regions associated with social processing. They have also been reported to show increased activation to biological motion in these same regions, such as the posterior superior temporal sulcus (pSTS), relative to both children with autism and control children. It has been suggested that this increased activation may represent a compensatory reorganization of these regions as a result of the highly heritable genetic influence of autism. However, the response patterns of unaffected siblings in the domain of action perception are unstudied, and the phenomenon of compensatory activation has not yet been replicated. The present study used functional magnetic resonance imaging to determine the neural responses to intentional biological actions in 22 siblings of children with autism and 22 matched controls. The presented actions were either congruent or incongruent with the actor’s emotional cue. Prior studies reported that typically developing children and adults, but not children with autism, show increased activation to incongruent actions (relative to congruent), within the pSTS and dorsolateral prefrontal cortex. We report that unaffected siblings did not show a compensatory response, or a preference for incongruent over congruent trials, in any brain region. Moreover, interaction analyses revealed a sub-region of the pSTS in which control children showed an incongruency preference to a significantly greater degree than siblings, which suggests a localized deficit in siblings. A sample of children with autism also did not show differential activation in the pSTS, providing further evidence that it is an area of selective disruption in children with autism and siblings. While reduced activation to both conditions was unique to the autism sample, lack of differentiation to incongruent and congruent intentional actions was common to both children with ASD and unaffected siblings.