Comparing the neural correlates of affective and cognitive theory of mind using fMRI: Involvement of the basal ganglia in affective theory of mind

Theory of Mind (ToM) is the ability to infer other people’s mental states like intentions or desires. ToM can be differentiated into affective (i.e., recognizing the feelings of another person) and cognitive (i.e., inferring the mental state of the counterpart) subcomponents. Recently, subcortical structures such as the basal ganglia (BG) have also been ascribed to the multifaceted concept ToM and most BG disorders have been reported to elicit ToM deficits. In order to assess both the correlates of affective and cognitive ToM as well as involvement of the basal ganglia, 30 healthy participants underwent event-related fMRI scanning, neuropsychological testing, and filled in questionnaires concerning different aspects of ToM and empathy. Directly contrasting affective (aff) as well as cognitive (cog) ToM to the control (phy) condition, activation was found in classical ToM regions, namely parts of the temporal lobe including the superior temporal sulcus, the supplementary motor area, and parietal structures in the right hemisphere. The contrast aff > phy yielded additional activation in the orbitofrontal cortex on the right and the cingulate cortex, the precentral and inferior frontal gyrus and the cerebellum on the left. The right BG were recruited in this contrast as well. The direct contrast aff > cog showed activation in the temporoparietal junction and the cingulate cortex on the right as well as in the left supplementary motor area. The reverse contrast cog > aff however did not yield any significant clusters. In summary, affective and cognitive ToM partly share neural correlates but can also be differentiated anatomically. Furthermore, the BG are involved in affective ToM and thus their contribution is discussed as possibly providing a motor component of simulation processes, particularly in affective ToM.     

Language deficits in pre-symptomatic Huntington's disease: evidence from Hungarian

A limited number of studies have investigated language in Huntington’s disease (HD). These have generally reported abnormalities in rule-governed (grammatical) aspects of language, in both syntax and morphology. Several studies of verbal inflectional morphology in English and French have reported evidence of over-active rule processing, such as over-suffixation errors (e.g., walkeded) and over-regularizations (e.g., digged). Here we extend the investigation to noun inflection in Hungarian, a Finno-Ugric agglutinative language with complex morphology, and to genetically proven pre-symptomatic Huntington’s disease (pre-HD). Although individuals with pre-HD have no clinical, motor or cognitive symptoms, the underlying pathology may already have begun, and thus sensitive behavioral measures might reveal already-present impairments. Indeed, in a Hungarian morphology production task, pre-HD patients made both over-suffixation and over-regularization errors. The findings suggest the generality of over-active rule processing in both HD and pre-HD, across languages from different families with different morphological systems, and for both verbal and noun inflection. Because the neuropathology in pre-HD appears to be largely restricted to the caudate nucleus and related structures, the findings further implicate these structures in language, and in rule-processing in particular. Finally, the need for effective treatments in HD, which will likely depend in part on the ability to sensitively measure early changes in the disease, suggests the possibility that inflectional morphology, and perhaps other language measures, may provide useful diagnostic, tracking, and therapeutic tools for assessing and treating early degeneration in pre-HD and HD.     

右侧基底节损伤遗忘症患者的知觉性启动效应与语义性启动效应的分离与定位

采用偏好、自由联想、字根补笔和字辨认等4项任务观察一例单纯性右侧基底节损伤遗忘症患者和两组正常对照的启动效应。结果发现：（1）该患者知觉性启动效应障碍,而语义性启动效应正常。认为知觉性启动效应的神经学基础可能在基底节。（2）该患者知觉性启动效应与语义性启动效应分离。认为神经组织的损伤可导致不同形式启动效应的分离,提出内隐记忆或启动效应的不同形式可能存在不同的神经学基础。     

Parallel associative processing in the dorsal striatum: segregation of stimulus-response and cognitive control subregions

Although evidence suggests that the dorsal striatum contributes to multiple learning and memory functions, there nevertheless remains considerable disagreement on the specific associative roles of different neuroanatomical subregions. We review evidence indicating that the dorsolateral striatum (DLS) is a substrate for stimulus–response habit formation – incremental strengthening of simple S–R bonds – via input from sensorimotor neocortex while the dorsomedial striatum (DMS) contributes to behavioral flexibility – the cognitive control of behavior – via prefrontal and limbic circuits engaged in relational and spatial information processing. The parallel circuits through dorsal striatum interact with incentive/affective motivational processing in the ventral striatum and portions of the prefrontal cortex leading to overt responding under specific testing conditions. Converging evidence obtained through a detailed task analysis and neurobehavioral assessment is beginning to illuminate striatal subregional interactions and relations to the rest of the mammalian brain.     

厌恶加工的神经基础

厌恶是由令人不愉悦、反感的事物诱发的情绪。根据刺激类型的不同, 厌恶可以分为不同的类型。脑岛和基底节是厌恶加工的主要脑区, 前扣带回、杏仁核、丘脑、内侧前额叶也参与厌恶加工。对已有研究的总结发现, 不同类型的厌恶、不同感觉通道的厌恶加工可能具有不同的神经基础。在未来的研究中, 应当注重研究厌恶加工的认知机制、神经基础以及与厌恶相关的神经递质等问题。     

Open and closed cortico-subcortical loops: A neuro-computational account of access to consciousness in the distractor-induced blindness paradigm

How the brain decides which information to process ‘consciously’ has been debated over for decades without a simple explanation at hand. While most experiments manipulate the perceptual energy of presented stimuli, the distractor-induced blindness task is a prototypical paradigm to investigate gating of information into consciousness without or with only minor visual manipulation. In this paradigm, subjects are asked to report intervals of coherent dot motion in a rapid serial visual presentation (RSVP) stream, whenever these are preceded by a particular color stimulus in a different RSVP stream. If distractors (i.e., intervals of coherent dot motion prior to the color stimulus) are shown, subjects’ abilities to perceive and report intervals of target dot motion decrease, particularly with short delays between intervals of target color and target motion.We propose a biologically plausible neuro-computational model of how the brain controls access to consciousness to explain how distractor-induced blindness originates from information processing in the cortex and basal ganglia. The model suggests that conscious perception requires reverberation of activity in cortico-subcortical loops and that basal-ganglia pathways can either allow or inhibit this reverberation. In the distractor-induced blindness paradigm, inadequate distractor-induced response tendencies are suppressed by the inhibitory ‘hyperdirect’ pathway of the basal ganglia. If a target follows such a distractor closely, temporal aftereffects of distractor suppression prevent target identification. The model reproduces experimental data on how delays between target color and target motion affect the probability of target detection.