Researchers stimulated human neurons and tracked gene activity. Activation exposed hidden variants and epigenetic changes linked to schizophrenia and autism, explaining disease risk missed in resting brain studies.
Category: neuroscience
Intraoperative functional brain mapping for glioma surgery: a comprehensive review of the University of California San Francisco mapping protocol
Intraoperative functional brain mapping is an essential and intricate technique in modern-day glioma surgery. This article is not a review of the literature but of the technical protocol at our institution that has evolved over the recent decades to the current time and is intended to highlight details that enable us to perform maximal safe resection of gliomas.
Prior to surgery, anatomical and functional imaging protocols are obtained to determine the tumor to be resected within its anatomical and functional environment. Preoperative assessments are used to determine which mapping procedures and tasks are most appropriate. Cortical and subcortical motor and language mapping using low and high frequency stimulation paradigms are applied when appropriate during resection. Methods to interpret findings and troubleshoot issues are reviewed herein.
All preoperative imaging including magnetic resonance imaging, magnetoencephalography of functional cortex, and diffusion tensor imaging of subcortical tracts are uploaded into the neuronavigation station and used throughout surgery for guidance. The decision to continue with tumor resection is based on constant feedback from the mapping paradigms as functional pathways are approached in real time. Both awake and asleep anesthesia regimens are utilized depending on the type of testing required to assess and preserve functional areas during tumor resection. Postoperatively, deficits are assessed using MRI along with clinical exam to predict whether they will be temporary or permanent.
Molecular basis of human daylight vision
In a new study, the researchers have succeeded for the first time in determining the three-dimensional structure of human cone opsins in their dark state and showing how their molecular architecture enables their rapid activation by light. This provides important new insights into human vision and its evolution and may offer new starting points for the study of eye diseases that currently lack effective treatment. The study published in the journal Science.
Cone opsins are photoreceptor proteins found in the cone cells, which are densely packed in the fovea centralis. This area of the human retina is responsible for sharp vision. We humans have six to seven million cones in each eye. Their receptor proteins are activated by light, triggering a signalling cascade that ultimately produces electrical signals processed by the brain. Because this process is exceptionally fast, cone opsins enable us to track fast-moving objects with our eyes. However, they operate mainly during the day when the light levels are high. In low light, at dusk and at night, their evolutionarily younger relative, the rod opsin in rod cells, takes over this task.
Human colour vision is mediated by three types of cone opsins, each tuned to a different region of the visible spectrum. L cones are most sensitive to red light, M cones to green light, and S cones to blue light. Although there are only three cone types, we see the world in more than just three colours, as our colour perception arises from the interplay of their overlapping spectral sensitivities.
How a brain messenger protein drives progression of Alzheimer’s disease
Alzheimer’s disease is driven by a buildup of a toxic protein called Tau that kills neurons. As toxic Tau spreads to new regions of the brain, symptoms worsen and ultimately become fatal.
Now, researchers have discovered that, in mice, a brain protein called Arc helps spread Tau from sick brain cells to healthy ones.
If therapies could be designed to target the spread, they could be a powerful tool to stop Alzheimer’s disease from getting worse.
Scientists discover how a single cell builds a brain with 170 billion cells
How does a single cell build a brain with billions of precisely organized neurons? Researchers suggest that brain cells use their lineage—their cellular family tree—as a kind of positional map. Cells that come from the same ancestor stay near one another, helping the brain organize itself without relying solely on chemical signals.
Consciousness is not an object we can observe
Physicist Carlo Rovelli recently proclaimed that consciousness is just another physical thing, while materialist philosophers argue that consciousness is simply one brain state observing another. What such views miss, argues Manfred Frank, a leading figure in contemporary German philosophy, is that consciousness comes with a built-in awareness of itself—an awareness that exists prior to any introspection or observation. Consciousness does not observe itself in the way we observe objects; rather, it dissolves the distinction between observer and observed altogether. This is why consciousness cannot be simply another object in the world, but instead exists in an entirely different dimension.
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If we had no consciousness our lives would be devoid of meaning. We have been immersed in this medium since before we were born and remain in it even in our dreams. And we do so without any effort on our part. Apart from when it is interrupted by deep sleep or we are unconscious after fainting or during anaesthesia, we remain in this state or are enveloped in it throughout our entire lives. Nothing is more familiar to us than consciousness; it is so familiar that we rarely notice it or attend to it.
Connectomics and the neural basis of behaviour
Methods to acquire and process synaptic-resolution electron-microscopy datasets have progressed very rapidly, allowing production and annotation of larger, more complete connectomes. More accurate neuronal matching techniques are enriching cell type data with gene expression, neuron activity, behaviour and developmental information, providing ways to test hypotheses of circuit function. In a variety of behaviours such as learned and innate olfaction, navigation and sexual behaviour, connectomics has already revealed interconnected modules with a hierarchical structure, recurrence and integration of sensory streams.
Non-invasive brain stimulation: current and future applications in neurology
Non-invasive brain stimulation (NIBS) shows considerable promise as a therapeutic strategy for neurological and psychiatric disorders. This Review explores the role of NIBS techniques, including repetitive transcranial magnetic stimulation and transcranial electrical stimulation, for treating cognitive impairments, speech and language difficulties, and motor control deficits in people with neurodegenerative or brain lesion disorders.