Survival within this cohort was unaffected by the presence of RAS/BRAFV600E mutations, in contrast to the observed improved progression-free survival associated with the presence of LS mutations.
Through what mechanisms does the cortex facilitate the versatile communication between its various regions? Four mechanisms underpinning temporal coordination in communication are explored: (1) oscillatory synchronization (coherence-based communication), (2) resonance-based communication, (3) non-linear integration of signals, and (4) linear signal transmission (communication-based coherence). Major communication obstacles are investigated by examining layer- and cell-type-specific analyses of spike phase-locking, variations in dynamics across networks and states, and computational models of selective communication. Viable alternatives to computation and selective communication in recurrent networks are posited to include resonance and non-linear integration. Examining communication in the context of cortical hierarchy, we probe the assertion that feedforward signals use rapid (gamma) frequencies, contrasting with slower (alpha/beta) frequencies in feedback pathways. Our alternative view is that feedforward prediction error propagation exploits the non-linear amplification of aperiodic transient signals; meanwhile, gamma and beta rhythms represent stable rhythmic states that permit sustained and effective information encoding and amplification of short-range feedback via resonance.
Anticipation, prioritization, selection, routing, integration, and preparation of signals are essential functions of selective attention, crucial for cognition and adaptive behavior. While most studies have analyzed its consequences, systems, and mechanisms in a fixed manner, focus now centers on the convergence of multiple dynamic influences. As the world advances, our experiences influence our mental faculties, and subsequent signals are disseminated via multiple routes within the dynamic network structures of the brain. click here This review endeavors to amplify understanding and cultivate interest in three significant facets of the influence of timing on our understanding of attention. The intricate dance between the timing of neural and psychological processes and the temporal structure of the surrounding world significantly influences attention. Importantly, monitoring the time course of neural and behavioral modifications using continuous measurements reveals surprising details about the workings and guiding principles of attention.
The tasks of sensory processing, short-term memory, and decision-making are often faced with the need to address multiple items or options at once. By means of rhythmic attentional scanning (RAS), the brain is hypothesized to process multiple items, with each item undergoing a dedicated theta rhythm cycle, including several gamma cycles, forming an internally consistent representation within a gamma-synchronized neuronal group. Every theta cycle involves traveling waves scanning items extended throughout representational space. Cross-scanning may cover a limited set of uncomplicated items interconnected within a cluster.
Gamma oscillations, whose frequency fluctuates between 30 and 150 hertz, are ubiquitous in neural circuit operations. Behaviors, brain structures, and animal species often reveal similar network activity patterns, which are distinguished by spectral peak frequencies. Even with meticulous study, it remains uncertain whether gamma oscillations provide the causal mechanisms for specific brain functions or represent a generalized dynamic mode of neural circuit activity. Considering this viewpoint, we scrutinize recent progress in gamma oscillation studies, aiming for a more comprehensive grasp of their cellular mechanisms, neural pathways, and functional significance. We demonstrate that a particular gamma rhythm, devoid of intrinsic cognitive functionality, is instead a reflection of the cellular mechanisms, communication networks, and computational processes that power information processing in the brain region from which it arises. Hence, we propose redefining gamma oscillations by shifting the analytical approach from frequencies to circuits.
The brain's control over active sensing and the neural mechanisms of attention are subjects of interest for Jackie Gottlieb. Her Neuron interview touches upon formative early experiments, the philosophical questions at the heart of her research, and her optimism for a closer interplay between epistemology and neuroscience.
Neural dynamics, synchrony, and temporal codes have long captivated Wolf Singer's intellectual curiosity. Eighty years old, he shares with Neuron his groundbreaking discoveries, emphasizing the crucial need for public discourse surrounding the philosophical and ethical dimensions of scientific work, and exploring potential trajectories for the future of neuroscience.
Neuronal oscillations serve as a conduit to neuronal operations, encompassing microscopic and macroscopic mechanisms, experimental methods, and explanatory frameworks within a shared context. The field of brain rhythms has emerged as a central discussion point, ranging from the temporal interplay of neurons within and between brain regions to higher-level cognitive functions like language and the implications of brain diseases.
Yang et al.1, in this Neuron issue, illuminate a previously unrecognized impact of cocaine on VTA circuitry. Chronic cocaine use's effect on GABAergic neuron tonic inhibition was observed, specifically mediated by Swell1 channel-dependent GABA release from astrocytes. This disinhibited dopamine neurons, leading to hyperactivity and addictive behaviors.
Neural activity's rhythmic fluctuations pervade sensory processes. Mind-body medicine Perceptual processes in the visual system are theorized to be orchestrated by broadband gamma oscillations (30-80 Hz), which act as a form of communication. Still, the oscillations' fluctuating frequencies and phases create hurdles in coordinating spike timing throughout different brain areas. To demonstrate the propagation and synchronization of narrowband gamma oscillations (50-70 Hz) throughout the awake mouse visual system, we examined Allen Brain Observatory data and performed causal experiments. Regarding NBG phase, the firing of lateral geniculate nucleus (LGN) neurons was precisely timed in primary visual cortex (V1) and various higher visual areas (HVAs). NBG neurons demonstrated enhanced functional connectivity and robust visual responses across different brain areas; intriguingly, NBG neurons within the LGN, which responded more strongly to bright (ON) stimuli compared to dark (OFF) stimuli, showed distinct firing patterns during specific NBG phases across the cortical hierarchy. NBG oscillations may therefore act as a mechanism for coordinating the timing of spikes between different brain regions, thereby aiding in the transmission of varied visual characteristics during the process of perception.
Long-term memory consolidation, though aided by sleep, presents a puzzling contrast to the mechanisms at play during wakeful hours. Our review's focus on recent advancements in the field indicates that the repeated replay of neuronal firing patterns is a fundamental mechanism that initiates consolidation, whether during sleep or wakefulness. Memory replay, a process occurring during slow-wave sleep (SWS) within hippocampal assemblies, is interwoven with ripples, thalamic spindles, neocortical slow oscillations, and noradrenergic activity during sleep. It is expected that hippocampal replay potentially influences the development of schema-like neocortical memories from hippocampus-dependent episodic memories. Sleep-dependent global synaptic renormalization can be coordinated with local synaptic readjustment concurrent with memory transformation, a process facilitated by REM sleep occurring after SWS. Despite the immaturity of the hippocampus, sleep-dependent memory transformation demonstrates increased intensity during early development. Unlike wake consolidation, which is hampered by hippocampal processes, sleep consolidation appears to be facilitated by spontaneous hippocampal replay, a likely key to memory development in the neocortex.
The close association between spatial navigation and memory is often evident in both cognitive and neural investigations. We consider models that posit the hippocampus and other elements of the medial temporal lobes as essential to both navigational abilities, with a particular emphasis on allocentric strategies, and aspects of memory, particularly episodic memory. While these models provide explanations in areas where they intersect, their ability to elucidate functional and neuroanatomical disparities is constrained. Considering human cognitive functions, we scrutinize navigation, a dynamically acquired skill, and memory, an internally driven process, to potentially account for the divergence between them. We also consider network models of navigation and memory, which lean toward the significance of connections over the isolated activity of specific brain zones. The models' ability to clarify the contrast between navigation and memory, and the unique influence of brain lesions and age, may be greater.
The prefrontal cortex (PFC) provides the capacity for a vast spectrum of intricate behaviors, encompassing the creation of strategies, the resolution of difficulties, and the accommodation to novel environments based on both external information and internal conditions. The tradeoff between neural representation stability and flexibility is a key aspect of higher-order abilities, collectively termed adaptive cognitive behavior, and necessitates the coordinated action of cellular ensembles. MRI-directed biopsy Uncertainties still exist regarding the operation of cellular ensembles, but recent experimental and theoretical investigations indicate that dynamic temporal control facilitates the formation of functional ensembles from prefrontal neurons. A hitherto largely distinct line of inquiry has focused on the prefrontal cortex's efferent and afferent connections.