Crucial to our daily interactions is temporal attention, yet the intricate neural processes that underpin it, and whether its exogenous and endogenous varieties share overlapping brain areas, are still subject to investigation. This research highlights the correlation between musical rhythm training and improved exogenous temporal attention, which is further supported by more consistent timing within sensory and motor processing regions of the brain. These advantages, however, were not observed for endogenous temporal attention, implying that different brain regions are engaged in the processing of temporal attention, predicated on the source of the timing information.
Abstraction is aided by sleep, though the precise mechanisms behind this phenomenon remain elusive. Our objective was to explore the potential of sleep reactivation to expedite this process. To facilitate memory reactivation in 27 human participants, 19 of whom were female, we associated abstraction problems with sounds, then played back these sound cues during either slow-wave sleep (SWS) or rapid eye movement (REM) sleep. Abstract problem-solving performance was better in REM than in SWS, as revealed by the study. Surprisingly, the improvement connected to the cue wasn't substantial until a subsequent retest one week after the manipulation, implying that REM might trigger a sequence of plasticity changes demanding a prolonged time frame for their completion. Additionally, auditory stimuli associated with memory produced distinct neurological responses during REM, but not during non-REM slow-wave sleep stages. From our study, we infer that memory reactivation in REM sleep could plausibly facilitate the extraction of visual rules, yet this effect takes time to fully manifest. Despite the recognized connection between sleep and the facilitation of rule abstraction, the question of active intervention in this process and the specific stage of sleep most essential to this remain unresolved. During sleep, the targeted memory reactivation (TMR) technique uses sensory triggers connected to learned material to increase memory consolidation. The application of TMR during REM sleep is demonstrated to support the complex recombination of information essential for the formation of rules. Furthermore, our results reveal that this qualitative REM-related advantage emerges within a week of learning, indicating that the integration of memories could require a more gradual form of plasticity.
In complex cognitive-emotional processes, the amygdala, hippocampus, and subgenual cortex area 25 (A25) are central players. The pathways linking the hippocampus and A25 to their postsynaptic counterparts in the amygdala are mostly obscure. In rhesus monkeys, irrespective of sex, we utilized neural tracers to meticulously examine the manner in which pathways from A25 and the hippocampus link to excitatory and inhibitory microcircuits within the amygdala, at multiple scales. The hippocampus and A25 were found to innervate the basolateral (BL) amygdalar nucleus, with some of the sites being distinct and others overlapping. The intrinsic paralaminar basolateral nucleus, associated with plasticity, is heavily innervated by unique hippocampal pathways. Orbital A25, in contrast, preferentially targets the intercalated masses, an inhibitory network that controls amygdala-driven autonomic reactions and dampens fear-related actions. Ultimately, high-resolution confocal and electron microscopic (EM) analyses revealed that, within the basolateral amygdala (BL), both hippocampal and A25 pathways predominantly formed synapses with calretinin (CR) neurons. These CR neurons, renowned for their disinhibitory properties, are likely to amplify excitatory signals within the amygdala. Parvalbumin (PV) neurons, receiving input from A25 pathways, alongside other inhibitory postsynaptic sites, may flexibly modulate the gain of neuronal assemblies within the basal ganglia (BL), impacting the internal state. In contrast to other neural pathways, hippocampal pathways innervate calbindin (CB) inhibitory neurons, thus impacting specific excitatory inputs for understanding context and the learning of accurate associations. Specific innervation patterns of the amygdala, driven by the hippocampus and A25, could clarify why certain cognitive and emotional functions are particularly vulnerable in psychiatric illnesses. We observed that A25 is prepared to impact diverse amygdala operations, ranging from emotional displays to the acquisition of fear responses, by innervating the basal complex and the intrinsic intercalated masses. Learning adaptability is reflected in hippocampal pathways' distinct connection to an intrinsic amygdalar nucleus, associated with plasticity, highlighting a flexible signal processing approach within learning contexts. HSP inhibitor Within the basolateral amygdala, a key area for fear learning, hippocampal and A25 neurons demonstrate a preferential connection to disinhibitory neurons, resulting in a heightened excitation. Other inhibitory neuron classes were innervated differently by the two pathways, suggesting circuit-specific features which may be affected in psychiatric disorders.
We sought to determine the unique importance of the transferrin (Tf) cycle in oligodendrocyte development and function by disrupting the transferrin receptor (Tfr) gene expression in oligodendrocyte progenitor cells (OPCs) of mice of either sex, employing the Cre/lox system. Iron incorporation through the Tf cycle is abolished by this ablation, yet other Tf functions remain. Mice lacking Tfr, specifically within NG2 or Sox10-positive oligodendrocyte precursor cells, displayed a characteristic hypomyelination phenotype. Tfr deletion caused a disruption of OPC iron absorption, alongside detrimental effects on OPC differentiation and myelination. The brains of Tfr cKO animals demonstrated a decrease in the quantity of myelinated axons, as well as a lower number of mature oligodendrocytes. Though other factors might be involved, the ablation of Tfr in adult mice demonstrated no effect on mature oligodendrocytes or myelin formation. HSP inhibitor RNA-seq experiments on Tfr conditional knockout oligodendrocyte progenitor cells (OPCs) indicated aberrant expression of genes influencing OPC maturation, myelination processes, and mitochondrial dynamics. Epigenetic mechanisms, critical for gene transcription and the expression of structural mitochondrial genes, were also impacted by TFR deletion in cortical OPCs, alongside the disruption of the mTORC1 signaling pathway. RNA-seq analyses were extended to OPCs with disrupted iron storage, achieved through the deletion of the ferritin heavy chain. The genes involved in iron transport, antioxidant defense, and mitochondrial activity display altered regulation in these OPCs. Our research demonstrates the crucial role of the transferrin cycle (Tf cycle) in iron homeostasis within oligodendrocyte progenitor cells (OPCs) during postnatal CNS development. Further, we show the essentiality of iron uptake via transferrin receptor (Tfr) and ferritin-mediated storage for energy production, mitochondrial function, and the maturation of these postnatal OPCs. RNA sequencing analysis further suggested that Tfr iron uptake and ferritin iron storage are indispensable for the appropriate mitochondrial activity, energy output, and maturation of oligodendrocyte precursor cells.
The perceptual experience of bistable perception comprises the back-and-forth shift between two alternative interpretations of a constant input. Neural recordings in bistable perception studies are often divided into stimulus-related epochs, and subsequently, neuronal differences between these epochs are assessed, relying on the perceptual reports of the subjects. Computational studies successfully mimic the statistical properties of percept durations, utilizing modeling principles like competitive attractors and Bayesian inference. In contrast, integrating neuro-behavioral findings into theoretical models requires the meticulous analysis of dynamic single-trial data. To extract non-stationary time-series features from single trial electrocorticography (ECoG) data, we devise an algorithm. The proposed algorithm was used to analyze 5-minute recordings of ECoG activity from the human primary auditory cortex of six participants (four male, two female) during an auditory triplet streaming task involving perceptual alternations. We find two emergent neuronal feature sets present in every trial block. An ensemble comprised of periodic functions describes the predictable response to the stimulus. Distinctly, the other part possesses more transient characteristics and encodes the time-sensitive dynamics of bistable perception across multiple timeframes, specifically minutes (internal trial changes), seconds (duration of each perception), and milliseconds (transitions between perceptions). A slowly shifting rhythmic pattern in the second ensemble was found to coincide with perceptual states and various oscillators exhibiting phase shifts near perceptual transitions. Across diverse stimulus types and subject groups, projecting single-trial ECoG data onto these features consistently unveils low-dimensional, attractor-like geometric structures. HSP inhibitor The neural underpinnings of oscillatory attractor-based computational models are underscored by these findings. Regardless of the sensory modality employed, the extraction methods of features, as presented, are applicable to cases where low-dimensional dynamics are presumed to characterize the underlying neurophysiological system. We advocate for an algorithm extracting neuronal features from large-scale single-trial auditory perception data, remaining independent of the subject's perceptual feedback. The algorithm's methodology captures the evolving dynamics of perception across minutes (within-trial variations), seconds (durations of percepts), and milliseconds (timing of changes), and successfully separates neural representations dedicated to the stimulus from those representing the perceptual state. Through our final analysis, a set of latent variables is identified that display alternating dynamic patterns along a low-dimensional manifold, reminiscent of the trajectories in attractor-based models for perceptual bistability.