Meta-analytic evidence for a novel hierarchical model of conceptual processing

Conceptual knowledge plays a pivotal role in human cognition. Grounded cognition theories propose that concepts consist of perceptual-motor features represented in modality-specific perceptual-motor cortices. However, it is unclear whether conceptual processing consistently engages modality-specific areas. Here, we performed an activation likelihood estimation (ALE) meta-analysis across 212 neuroimaging experiments on conceptual processing related to 7 perceptual-motor modalities (action, sound, visual shape, motion, color, olfaction-gustation, and emotion). We found that conceptual processing consistently engages brain regions also activated during real perceptual-motor experience of the same modalities. In addition, we identified multimodal convergence zones that are recruited for multiple modalities. In particular, the left inferior parietal lobe (IPL) and posterior middle temporal gyrus (pMTG) are engaged for three modalities: action, motion, and sound. These “trimodal” regions are surrounded by “bimodal” regions engaged for two modalities. Our findings support a novel model of the conceptual system, according to which conceptual processing relies on a hierarchical neural architecture from modality-specific to multimodal areas up to an amodal hub

P6 Left posterior inferior parietal cortex causally supports the retrieval of action knowledge

Introduction: Conceptual knowledge is central to numerous cognitive abilities, such as word comprehension. The left posterior inferior parietal lobe (pIPL) is consistently activated in neuroimaging studies on conceptual processing regardless of the concepts” content, suggesting that it represents a multimodal hub for conceptual knowledge. For example, we previously showed that left pIPL is engaged during the retrieval of both sound and action features of word meaning. However, as neuroimaging is correlational, it remains unknown whether left pIPL plays a causal role in multimodal conceptual processing. Objectives: We aimed to determine whether left pIPL is functionally relevant for the processing of action and/or sound features of concepts, and to what extent such causal involvement depends on the task. Materials & methods: We applied 10 Hz online repetitive transcranial magnetic stimulation (rTMS; 4 pulses at 100% resting motor threshold) over left pIPL or sham rTMS, while 26 participants performed three different tasks—lexical decision, sound judgment, and action judgment—on words that exhibited a high or low association with sounds and actions (e.g. “telephone” is a high sound–high action word). Results: A repeated-measures ANOVA on sham-normalized accuracies showed a 3-way interaction of task, sound association, and action association. Step-down analyses (using marginal means) revealed that rTMS over left pIPL selectively impaired response accuracy for action judgments on low sound–low action words, as compared to sham stimulation (t = −3.18, p = 0.006; Bonferroni-corrected) (Fig. 1). Accuracy during lexical decisions or sound judgments was not significantly affected by TMS. Response times were also not significantly altered. Conclusion: Our results indicate that left pIPL is causally involved in the processing of action features of concepts selectively when these are task-relevant. TMS seems to have increased action-related activity in the pIPL, leading to a higher likelihood to judge an object as action-related. The fact that high-sound words were not affected suggests that sound features enable compensation for disruption of action processing via sound-action coupling. The absence of TMS effects during lexical decisions indicates that left pIPL specifically supports tasks that require access to conceptual knowledge. The lack of a significant impairment of sound judgments might reflect that (1) left pIPL is not causally involved in sound feature retrieval; (2) pIPL stimulation concomitantly affected nearby action-relevant regions, leading to a predominant disruption of action features; or (3) other sound-relevant regions compensated for the perturbation by increasing their functional contribution

Left posterior inferior parietal cortex causally supports the retrieval of action knowledge

Conceptual knowledge is central to human cognition. The left posterior inferior parietal lobe (pIPL) is implicated by neuroimaging studies as a multimodal hub representing conceptual knowledge related to various perceptual–motor modalities. However, the causal role of left pIPL in conceptual processing remains unclear. Here, we transiently disrupted left pIPL function with transcranial magnetic stimulation (TMS) to probe its causal relevance for the retrieval of action and sound knowledge. We compared effective TMS over left pIPL with sham TMS, while healthy participants performed three different tasks—lexical decision, action judgment, and sound judgment—on words with a high or low association to actions and sounds. We found that pIPL-TMS selectively impaired action judgments on low sound–low action words. For the first time, we directly related computational simulations of the TMS-induced electrical field to behavioral performance, which revealed that stronger stimulation of left pIPL is associated with worse performance for action but not sound judgments. These results indicate that left pIPL causally supports conceptual processing when action knowledge is task-relevant and cannot be compensated by sound knowledge. Our findings suggest that left pIPL is specialized for the retrieval of action knowledge, challenging the view of left pIPL as a multimodal conceptual hub

Molecular cloning and complete primary sequence of human erythrocyte porphobilinogen deaminase.

We have cloned and sequenced a cDNA clone coding for human erythrocyte porphobilinogen deaminase. It encompasses the translated region, part of the 5' and the 3' untranslated regions. The deduced 344 amino acid sequence is consistent with the molecular weight and the partial amino-acid sequence of the NH2 terminal of the purified erythrocyte enzyme. Southern analysis of human genomic DNA shows that its gene is present as a single copy in the human genome and Northern analysis demonstrates the presence of a single size species of mRNA in erythroid and non-erythroid tissues and in several cultured cell lines. Quantitative determinations indicate that the amount of PBG-D mRNA is modulated both by the erythroid nature of the tissue and by cell proliferation, probably at the transcriptional level

Structure of the gene for human uroporphyrinogen decarboxylase.

Uroporphyrinogen decarboxylase, the fifth enzyme of the heme biosynthetic pathway, is an housekeeping enzyme whose activity is enhanced during erythropoietic differentiation. We have previously shown that this increased activity was in part accounted for by an enhanced transcription of the gene in erythropoietic tissues. To elucidate further the tissue specific regulation of an housekeeping gene we have isolated the human URO-D gene and determined its organization. The cloned gene comprises 10 exons spread over 3 Kb. Two transcriptional start sites were determined and analysis of 900 bp of the 5' flanking region suggests a very simple structural organization for the URO-D gene promoter. We also show that this gene is functional when transfected into mouse fibroblasts, and that its promoter is sensitive to a viral enhancer