Cognitive processing in literate and illiterate subjects: a review of some recent behavioral and functional neuroimaging data

The study of illiterate subjects, which for specific socio-cultural reasons did not have the opportunity to acquire basic reading and writing skills, represents one approach to study the interaction between neurobiological and cultural factors in cognitive development and the functional organization of the human brain. In addition the naturally occurring illiteracy may serve as a model for studying the influence of alphabetic orthography on auditory-verbal language. In this paper we have reviewed some recent behavioral and functional neuroimaging data indicating that learning an alphabetic written language modulates the auditory-verbal language system in a non-trivial way and provided support for the hypothesis that the functional architecture of the brain is modulated by literacy. We have also indicated that the effects of literacy and formal schooling is not limited to language related skills but appears to affect also other cognitive domains. In particular, we indicate that formal schooling influences 2D but not 3D visual naming skills. We have also pointed to the importance of using ecologically relevant tasks when comparing literate and illiterate subjects. We also demonstrate the applicability of a network approach in elucidating differences in the functional organization of the brain between groups. The strength of such an approach is the ability to study patterns of interactions between functionally specialized brain regions and the possibility to compare such patterns of brain interactions between groups or functional states. This complements the more commonly used activation approach to functional neuroimaging data, which characterize functionally specialized regions, and provides important data characterizing the functional interactions between these regions.     

Quantitative Anatomy: Power Beyond the Images

Positron emission tomography (PET) is a frontiermedical technology that, in contrast to the othercomputer-assisted technologies providing anatomicalpictures, produces functional images. I argue that PETalso opens up an avenue for shifting from images (asa tool for representation of biomedical data) back toanalysis of measurements (as a tool for quantificationof physiology). Admittedly, quantification of functionrequires structural constraints. I coined the emerginginterpretational framework quantitative anatomyin an attempt to conceptualize the PET merger betweenmeasuring and imaging, the two competing meansmedicine uses to examine the human body. Anatomyjustifies interpretations that fit the existingknowledge of a larger clinical audience, whilestatistical data possess an unexplored potential tointroduce mathematical rigor in the evaluation offunction, but are still a black box for the majorityof clinicians. This epistemological change is beingcarried out by PET users in action as well as indiscourse.     

Brain activity in adults who stutter: similarities across speaking tasks and correlations with stuttering frequency and speaking rate

Many differences in brain activity have been reported between persons who stutter (PWS) and typically fluent controls during oral reading tasks. An earlier meta-analysis of imaging studies identified stutter-related regions, but recent studies report less agreement with those regions. A PET study on adult dextral PWS (n = 18) and matched fluent controls (CONT, n = 12) is reported that used both oral reading and monologue tasks. After correcting for speech rate differences between the groups the task-activation differences were surprisingly small. For both analyses only some regions previously considered stutter-related were more activated in the PWS group than in the CONT group, and these were also activated during eyes-closed rest (ECR). In the PWS group, stuttering frequency was correlated with cortico-striatal-thalamic circuit activity in both speaking tasks. The neuroimaging findings for the PWS group, relative to the CONT group, appear consistent with neuroanatomic abnormalities being increasingly reported among PWS.     

一般流体智力的脑成像研究述评

对一般流体智力的脑成像研究有助于探明智力的脑机制。从结构成像与功能成像两个方面阐述了相关的研究。已有研究表明,一般流体智力与总的脑体积、额叶或其他多个脑区的灰质体积中等正相关。一般智力（g）因素负荷高的任务比负荷低的任务引发特定脑区更大的激活。较早的研究发现一般智力水平个体差异与脑区的激活呈负相关,但此后的一些研究却得到相反的结论。未来的研究应加强对个体差异的研究,将脑成像技术与EEG或ERP技术结合起来,整合多水平（心理测量、遗传学等）的研究结果,进一步阐明一般流体智力的脑机制     

人类工作记忆的某些神经影像研究

采用神经影像技术研究人类工作记忆的脑机理是目前一个十分活跃的研究领域。研究表明存在负责不同信息加工的工作记忆系统 ,如词语工作记忆、空间工作记忆等 ,其中词语工作记忆主要由大脑左半球参与 ,空间工作记忆主要由大脑右半球参与。前额叶在工作记忆中的作用相当复杂 ,包括对记忆信息的注意和抑制、管理、整合等功能。合理巧妙的实验设计、多种研究手段的综合应用必将使人类工作记忆的脑机理得到充分阐明。     

Processing Faces and Facial Expressions

This paper reviews processing of facial identity and expressions. The issue of independence of these two systems for these tasks has been addressed from different approaches over the past 25 years. More recently, neuroimaging techniques have provided researchers with new tools to investigate how facial information is processed in the brain. First, findings from traditional approaches to identity and expression processing are summarized. The review then covers findings from neuroimaging studies on face perception, recognition, and encoding. Processing of the basic facial expressions is detailed in light of behavioral and neuroimaging data. Whereas data from experimental and neuropsychological studies support the existence of two systems, the neuroimaging literature yields a less clear picture because it shows considerable overlap in activation patterns in response to the different face-processing tasks. Further, activation patterns in response to facial expressions support the notion of involved neural substrates for processing different facial expressions.     

Towards a functional neural systems model of developmental stuttering

This paper overviews recent developments in an ongoing program of brain imaging research on developmental stuttering that is being conducted at the University of Texas Health Science Center, San Antonio. This program has primarily used H₂¹⁵O PET imaging of different speaking tasks by right-handed adult male and female persistent stutterers, recovered stutterers and controls in order to isolate the neural regions that are functionally associated with stuttered speech. The principal findings have emerged from studies using condition contrasts and performance correlation techniques. The emerging findings from these studies are reviewed and referenced to a neural model of normal speech production recently proposed by Jürgens [Neurosci. Biobehav. Rev. 26 (2002) 235]. This paper will report (1) the reconfiguration of previous findings within the Jürgens Model; (2) preliminary findings of an investigation with late recovered stutterers; (3) an investigation of neural activations during a treatment procedure designed to produce a sustained improvement in fluency; and (4) an across-studies comparison that seeks to isolate neural regions within the Jürgens Model that are consistently associated with stuttering. Two regions appear to meet this criterion: right anterior insula (activated) and anterior middle and superior temporal gyri (deactivated) mainly in right hemisphere. The implications of these findings and the direction of future imaging investigations are discussed.

Educational objectives: The reader will learn about (1) recent uses of H₂¹⁵O PET imaging in stuttering research; (2) the use of a new neurological model of speech production in imaging research on stuttering; and (3) initial findings from PET imaging investigations of treated and recovered stutterers.     

Lexical retrieval constrained by sound structure: the role of the left inferior frontal gyrus

Positron emission tomography was used to investigate two competing hypotheses about the role of the left inferior frontal gyrus (IFG) in word generation. One proposes a domain-specific organization, with neural activation dependent on the type of information being processed, i.e., surface sound structure or semantic. The other proposes a process-specific organization, with activation dependent on processing demands, such as the amount of selection needed to decide between competing lexical alternatives. In a novel word retrieval task, word reconstruction (WR), subjects generated real words from heard non-words by the substitution of either a vowel or consonant. Both types of lexical retrieval, informed by sound structure alone, produced activation within anterior and posterior left IFG regions. Within these regions there was greater activity for consonant WR, which is more difficult and imposes greater processing demands. These results support a process-specific organization of the anterior left IFG.     

From rat sexual behavior to schizophrenia: a tribute to Professor Emeritus Knut Larsson

In July of 2002 Knut Larsson celebrated his 80th birthday. He could by then have looked back at a long and distingusihed career in the field of biological psychology. His research on sexual behavior had contributed to a basic understanding of many behavioral, endocrine and neural phenomena associated with or underlying sexual activity. Instead of looking back at his past achievements, Knut has preferred to look forward, constantly trying to find ways to stimulate interest in his own field and in biological psychology in general. This issue is a humble contribution to the noble end of enhancing the standing of biological psychology, particularly in Scandinavia. Foremost, however, it is a homage to a man of outstanding vision and intellectual integrity: Knut Larsson.     

Different corticostriatal patterns of L-DOPA utilization in patients with untreated schizophrenia and patients treated with classical antipsychotics or clozapine

Positron emission tomography (PET) has been shown to be of great importance in elucidating the mechanism of action of antipsychotic drugs. In psychotic patients L-[11C]DOPA PET has been used to demonstrate some differences in dopaminergic activity compared with that in healthy volunteers. Ten healthy volunteers were investigated with PET and L-[11C]DOPA. Ten drug-free patients with psychosis, nine stable schizophrenics treated with clozapine, and nine stable patients treated with classical antipsychotics were also investigated with L-[11C]DOPA. Principal-component analysis was employed for the analysis of L-[11C]DOPA Ki values across a number of corticostriatal brain regions. These data revealed a significant three-component model with clear-cut separation between healthy controls and patients with unmedicated schizophrenia. Stable optimal treatment with either classical neuroleptics or clozapine partially, albeit differentially, reversed the aberrant patterns seen in drug-free schizophrenia. It can thus be concluded that schizophrenia is associated with abnormal patterns of L-[11C]DOPA utilization in corticostriatal systems. Treatment with clozapine or classical neuroleptics induces partial, albeit differential, normalization of the abnormal patterns seen in untreated schizophrenia.