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Tag: Sinapsių genėjimas

  • New study maps adolescent synapse hotspots, raising fresh questions about brain pruning and schizophrenia risk

    New study maps adolescent synapse hotspots, raising fresh questions about brain pruning and schizophrenia risk

    Researchers have identified previously overlooked synapse hotspots that form during adolescence, suggesting the teenage brain may actively build dense new connections alongside the well-known process of synaptic pruning. The findings, reported by Kyushu University scientists in Science Advances, add nuance to how neural circuits mature during a critical developmental window.

    Synapses are the communication points between neurons, and for decades a common model held that synapse numbers rise in childhood and then drop in adolescence as weaker links are removed. That pruning-focused framework has influenced theories of neuropsychiatric disorders, including the idea that excessive synapse loss could contribute to schizophrenia.

    The new work points to a more complex picture: localized bursts of synapse formation in specific parts of neurons. Using a tissue-clearing technique and super-resolution imaging, the team mapped dendritic spines across entire Layer 5 cortical neurons, which play a major role in integrating signals and producing cortical output.

    In young mice before weaning, dendritic spines were distributed more evenly along neurons. Between about three and eight weeks of age, the researchers observed a sharp rise in spine density in a single section of the apical dendrite, culminating in a tightly packed hotspot that was not present earlier.

    The authors argue this pattern means adolescent development is not defined solely by pruning, but also by targeted construction of new synaptic clusters. They also report that in mice carrying mutations in genes linked to schizophrenia risk, the hotspot did not develop normally because synapse formation during adolescence was reduced.

    While the results rely on mouse models and do not confirm the same mechanism in humans, they sharpen questions about which circuits are built during adolescence and how disruptions might alter brain function. The researchers say the next step is to identify the brain regions and inputs driving these newly formed connections during the adolescent period.

  • Study of the hippocampus suggests newborn brains start densely wired, then prune connections for sharper memory

    Study of the hippocampus suggests newborn brains start densely wired, then prune connections for sharper memory

    The hippocampus, a brain region essential for forming memories and mapping space, may develop in a way that challenges the long-held idea of the mind as a blank slate. New research from the Institute of Science and Technology Austria suggests key memory circuits begin life with unusually dense wiring that is later trimmed and refined.

    In a study published in Nature Communications, scientists examined how a major hippocampal network changes after birth in mice. The team focused on CA3 pyramidal neurons, cells widely seen as central to storing and retrieving memories.

    How the CA3 circuit develops

    Using patch-clamp recordings and high-resolution imaging, researchers compared the CA3 network across early postnatal stages, adolescence, and adulthood. The methods allowed them to measure tiny electrical signals and map how strongly neurons were connected at different ages.

    The results pointed to an early-life circuit that is highly connected and seemingly random, followed by a gradual shift toward fewer but more organized links. Rather than adding connections over time, the network became more efficient by losing many of its initial ones.

    Pruning may boost memory efficiency

    Lead researcher Peter Jonas said the pattern fits a pruning model in which the system starts full and then becomes streamlined. The researchers argue that an initially exuberant network could help the hippocampus quickly integrate different kinds of sensory information into usable memories.

    If the brain started with far fewer built-in links, the team notes, neurons would first need more time to find and connect to each other, potentially slowing early information processing. The study adds to broader evidence that brain development often involves overproduction of connections followed by activity-dependent pruning.

    While the work was conducted in mice, the hippocampus is highly conserved across mammals, making the findings relevant to ongoing debates about how genetics and experience shape learning. The authors say future research will need to clarify what signals drive which connections are kept or removed, and how this process relates to memory performance.