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Is the mind an entity that exists apart from the brain? Is the relationship of brain and mind like that of computer hardware and software? Do animals have minds with which they think? These are some of the questions addressed in \"Mindwaves\" by specialists in brain research.

Key Points Much more is now known about human cortical development than was known in 1970, when the Boulder Committee attempted to standardize the heterogeneous and confusing nomenclature that was used in the field. In light of this, a revised standardization is needed. A transient layer with a diverse population of neurons forms between the neuroepithelium and the pial surface of the dorsal telencephalon before the appearance of the cortical plate (CP). The term preplate, which is already widely used, should be adopted for this layer. The subventricular zone appears as a distinctive proliferative layer before the emergence of the CP, earlier than previously recognized. There is no distinct cell-sparse layer under the pial surface before the CP forms. Thus, the term marginal zone should be used only after the appearance of the CP, to refer to the residual superficial part of the preplate, which becomes the layer 1 of the mature cortex. The term intermediate zone (IZ) has been used in various ways. In future it should be reserved for the heterogeneous compartment that lies between the proliferative layers and the postmigratory cells above. The IZ contains radially and tangentially migrating cells and a thickening layer of extrinsic axons that eventually constitutes the white matter. The subplate (SP) is a distinct and functionally important transient layer, located directly below the cortical plate, which was not recognized by the Boulder Committee. In rodents and carnivores most SP neurons are born before the first CP cells. In humans, preplate cells also contribute to the SP, but its substantial thickening at later stages probably involves the addition of later-born neurons. In 1970 the Boulder Committee met to standardize the nomenclature used to describe the developing human cortex. Bystron and colleagues describe how new insights since that time have led to the need to revise this nomenclature, and provide their recommendations. In 1970 the Boulder Committee described the basic principles of the development of the CNS, derived from observations on the human embryonic cerebrum. Since then, numerous studies have significantly advanced our knowledge of the timing, sequence and complexity of developmental events, and revealed important inter-species differences. We review current data on the development of the human cerebral cortex and update the classical model of how the structure that makes us human is formed.

Drug misuse and abuse are major health problems. Harmful drugs are regulated according to classification systems that purport to relate to the harms and risks of each drug. However, the methodology and processes underlying classification systems are generally neither specified nor transparent, which reduces confidence in their accuracy and undermines health education messages. We developed and explored the feasibility of the use of a nine-category matrix of harm, with an expert delphic procedure, to assess the harms of a range of illicit drugs in an evidence-based fashion. We also included five legal drugs of misuse (alcohol, khat, solvents, alkyl nitrites, and tobacco) and one that has since been classified (ketamine) for reference. The process proved practicable, and yielded roughly similar scores and rankings of drug harm when used by two separate groups of experts. The ranking of drugs produced by our assessment of harm differed from those used by current regulatory systems. Our methodology offers a systematic framework and process that could be used by national and international regulatory bodies to assess the harm of current and future drugs of abuse.

The neural tube defects anencephaly and spina bifida are two of the most common serious congenital malformations. Most cases can be prevented by consuming sufficient folic acid immediately before pregnancy and in early pregnancy. Fortification of flour with folic acid to prevent these defects has been implemented in 81 countries without public objection or indication of harm. An obstacle to the wider adoption of fortification arises from the creation of a “tolerable upper intake level” for folate (which includes natural food folate as well as synthetic folic acid), and which has been set at 1 mg/day, thereby proscribing higher folate intakes. Increasing the intake of folic acid in a population will necessarily increase the number of people with a folate intake greater than 1 mg per day, and this concern is obstructing folic acid fortification. This paper shows that the scientific basis for setting any upper limit, let alone one at 1 mg/day, is flawed. An upper intake level is therefore unnecessary and should be removed, thus allaying unjustified concerns about folic acid fortification. As a result, the full global opportunity to prevent two serious fatal or disabling disorders can and should be realized.

Horace Basil Barlow, Fellow of the Royal Society, winner of the Australia Prize, the Royal Medal of the Royal Society and the Schwartz Prize of the Society for Neuroscience, died on 5 July 2020 at the age of 98, 10 days after suffering a stroke. As news spread among his former students and collaborators, one phrase recurred again and again in the messages of nostalgic reflection: ‘the end of an era’.

We describe a distinctive, widespread population of neurons situated beneath the pial surface of the human embryonic forebrain even before complete closure of the neural tube. These 'predecessor' cells include the first neurons seen in the primordium of the cerebral cortex, before the onset of local neurogenesis. Morphological analysis, combined with the study of centrosome location, regional transcription factors and patterns of mitosis and neurogenesis, indicates that predecessor cells invade the cortical primordium by tangential migration from the subpallium. These neurons, described here for the first time, precede all other known cell types of the developing cortex.

How bilingual brains accomplish the processing of more than one language has been widely investigated by neuroimaging studies. The assimilation-accommodation hypothesis holds that both the same brain neural networks supporting the native language and additional new neural networks are utilized to implement second language processing. However, whether and how this hypothesis applies at the finer-grained levels of both brain anatomical organization and linguistic functions remains unknown. To address this issue, we scanned Chinese-English bilinguals during an implicit reading task involving Chinese words, English words and Chinese pinyin. We observed broad brain cortical regions wherein interdigitated distributed neural populations supported the same cognitive components of different languages. Although spatially separate, regions including the opercular and triangular parts of the inferior frontal gyrus, temporal pole, superior and middle temporal gyrus, precentral gyrus and supplementary motor areas were found to perform the same linguistic functions across languages, indicating regional-level functional assimilation supported by voxel-wise anatomical accommodation. Taken together, the findings not only verify the functional independence of neural representations of different languages, but show co-representation organization of both languages in most language regions, revealing linguistic-feature specific accommodation and assimilation between first and second languages. Functional MRI data from Chinese-English bilingual participants during a reading task reveals linguistic feature-specific accommodation and assimilation between first and second languages.

We localized regions in the fusiform gyrus and superior temporal sulcus that were more active when subjects viewed photographs of real faces than when they viewed complex inanimate objects and other areas in the parahippocampal gyrus and the lateral occipital lobe that showed more activity during the presentation of nonface objects. Event-related functional magnetic resonance imaging was then used to monitor activity in these extrastriate visual areas while subjects viewed Rubin's vase–face stimulus and indicated switches in perception. Since the spontaneous shifts in interpretation were too rapid for direct correlation with hemodynamic responses, each reported percept (faces or vase) was prolonged by suddenly adding subtle local contrast gradients (embossing) to one side or the other of the figure–ground boundary, stabilizing the percept. Under these conditions, only face-selective areas in the fusiform gyrus responded more strongly during the perception of faces. To control for effects of the physical change to Rubin's stimulus (i.e., addition of embossing), we compared activity when the face contours were embossed after the subject had just reported the onset of perception of either faces or vase. Activity in the fusiform face area responded more strongly under the first condition, despite the fact that the physical stimulus sequences were identical. Moreover, on a trial-to-trial basis, the activity was statistically predictive of the subjects' responses, suggesting that the conscious perception of faces could be made explicit in this extrastriate visual area.

During development of the cerebral cortex, the invasion of thalamic axons and subsequent differentiation of cortical neurons are tightly coordinated. Here we provide evidence that glutamate neurotransmission triggers a critical signaling mechanism involving the activation of phospholipase C-β1 (PLC-β1) by metabotropic glutamate receptors (mGluRs). Homozygous null mutation of either PLC-β1 or mGluR5 dramatically disrupts the cytoarchitectural differentiation of 'barrels' in the mouse somatosensory cortex, despite segregation in the pattern of thalamic innervation. Furthermore, group 1 mGluR-stimulated phosphoinositide hydrolysis is dramatically reduced in PLC-β1 −/− mice during barrel development. Our data indicate that PLC-β1 activation via mGluR5 is critical for the coordinated development of the neocortex, and that presynaptic and postsynaptic components of cortical differentiation can be genetically dissociated.

In a recent editorial, we argued that the UK's Medical Research Council (MRC) was neglecting the field of bacteriology. Here, Colin Blakemore FRS, Chief Executive of the MRC, responds to these criticisms.