Brain Structure & Function最新文献

The inferior olive (IO) is an important region for motor learning and movement coordination. IO activity carried by the climbing fiber (CF) projection to the Purkinje neurons in the cerebellar cortex drives the complex spike activity, central to theories of cerebellar function. Unlike many other neurons in the olivo-cerebeller system, IO neurons are not spontaneously active but rather spike in response to inputs from various regions of the brain. The superior colliculus (SC), a midbrain structure known for its role in orienting behaviors, is one of the input sources to the IO. Here, we investigate the SC projections to the IO using viral tracers, calcium imaging, and optogenetic stimulation. We reveal that, in addition to the known projections to the medial accessory olive (MAO), the SC axons also project to the ventral principal olive (PO). We show that SC axons terminate on both dendritic shafts and spines of IO neurons, potentially influencing not only spiking probability, but also the network synchronization mediated by gap junction coupling on dendritic spines. As a demonstration of the SC axons' ability to drive IO spiking, we employ in vivo calcium imaging of the IO and show that optogenetic activation of SC inputs can drive spiking and modulate overall synchronization of the IO. This study provides a fundamental basis for studying the behavioral significance of the SC-IO pathway in mice.

An organism's sense of direction depends on vestibular input to thalamic and forebrain structures. The supragenual nucleus (SGN) sits at a prime location in the network to convey vestibular signals forward to update the representation of head direction (HD) with ongoing head movement. The SGN receives anatomical projections from the medial vestibular nuclei and nucleus prepositus hypoglossi and prior reports have suggested that the SGN sends projections to both the dorsal tegmental nucleus (DTN) and lateral mammillary nucleus (LMN), two midbrain nuclei crucial in generating a representation of current HD. It is unknown, however, whether distinct or overlapping populations in SGN project to these structures, which has implications for how the SGN plays a role in generating and updating the HD signal. We performed a dual-color retrograde tracer study to determine whether the DTN and LMN projections from SGN arise from the same or different populations of cells. We report that the SGN→DTN projection is markedly stronger than that to LMN, filling most cells within the SGN, while SGN cells projecting to LMN tended to be smaller and sparser. We also found a small population of SGN cells projecting to both DTN and LMN. Further, our results indicate the presence of a large population of neurons in SGN that project only to the contralateral DTN and that these cells have little overlap with the ipsilateral projection to LMN. These results have implications for how the HD signal is generated within the DTN-LMN network.

The medial prefrontal cortex (mPFC) serves as a critical hub in addiction pathology across binge/intoxication, withdrawal/negative affect, and preoccupation/anticipation/craving stages. This review provides the roles of the mPFC in different stages of addiction, and a focus on the mPFC neurotransmitter systems, neural circuits, molecules and synaptic adaptations on the regulation of addictive behaviors. Neurotransmitter systems of dopaminergic, glutamatergic, and GABAergic imbalances are related to pathological addiction. Circuits of dynamic dysregulation in the mPFC interaction with the striatum, nucleus accumbens (NAc), ventral tegmental area (VTA), dorsal raphe nucleus (DRN), and amygdala drive stage-specific behaviors, such as the prelimbic cortex (PL)→NAc core promoting cocaine-seeking, the infralimbic cortex (IL)→NAc shell suppressing relapse. Alterations in excitation-inhibition of microcircuits pyramidal neurons, GABAergic interneurons impair top-down regulation. Synaptic plasticity induced by drugs is involved in pathological stage-specific addiction, such as persistent craving and compulsive behaviors. Targeting the mPFC circuits offers promising therapeutic strategies for addiction intervention.

Background: Awake surgery with intraoperative language mapping has become increasingly refined, allowing assessment not only of motor but also higher brain functions. Language remains the most critical function to evaluate and preserve. However, reports of multilingual patients undergoing such procedures are still limited, particularly those involving Japanese, a linguistically and structurally unique language.

Case description: We present the case of a 32-year-old right-handed multilingual male (Japanese L1, English L2, French L3), a film director and actor, who underwent awake craniotomy for a recurrent low-grade glioma involving the left temporal lobe. Preoperative functional MRI confirmed left hemispheric language dominance across all three languages, although French and English showed broader activation than Japanese during semantic fluency tasks. During surgery, cortical mapping with object naming and reading tasks was performed in Japanese, English, and French. Naming errors were observed in the posterior superior temporal gyrus across all three languages, whereas semantic paraphasia in the posterior middle temporal gyrus and reading impairment in the posterior inferior temporal gyrus were specific to Japanese. Postoperative MRI revealed subtotal resection with preservation of language function. Histopathology confirmed astrocytoma, IDH-mutant, WHO grade 3.

Conclusion: This case represents the first report of intraoperative language mapping in a Japanese-English-French trilingual patient, demonstrating both overlapping and language-specific cortical regions. The findings underscore the importance of individualized and multimodal language mapping in multilingual patients, particularly when typologically distant languages such as Japanese are involved.

Professor Nieuwenhuys is among the great neuroanatomists and a historical figure of the later 20th and early 21st centuries. His legacy is manifold. There is the tangible legacy of the multiple scientific volumes, at once physical and conceptual entities. There is the generational legacy of handed-on scientific and intellectual traditions, and there is the legacy of specific scientific directions. In this brief Commentary, we highlight just two examples of his scientific contributions.