How Astroglia Respond to Hippocampal Plasticity
Andrea J. Nam, Masaaki Kuwajima, Patrick H. Parker, Jared B. Bowden, Wickliffe C. Abraham, and Kristen M. Harris
(see article e0943252025)
Astrocytes support neurotransmission and can influence the strength of neural synapses. Nam and colleagues found that the hippocampal dentate gyrus, which is important for learning and memory, has astroglia at over 85% of excitatory synapses. Thus, the authors predicted that astroglia may play an important role in regulating these synapses as they undergo changes in strength—or plasticity—during learning. To explore the relationship between astroglia and plasticity in this hippocampal region, Nam and colleagues used delta-burst stimulation (DBS) on a neural pathway that targets dentate granule cells in awake male rats. DBS strengthened synapses (also known as long-term potentiation) in the middle molecular layer and diminished the presence of astroglial processes, thus reducing their access to hippocampal dendritic spines. The same DBS weakened synapses (also known as long-term depression) in the outer molecular layer of dentate granule cells, which conversely increased the astroglia presence. Thus, astroglia access to these synapses may be shaped by the structural dynamics of the synapses during plasticity.
Electron microscopy image showing an astroglia (light blue) 10 nm away from the axon (dark blue)–spine (yellow) interface (top and inset orange diamond) and another astroglia 140 nm away on the opposite edge (bottom orange diamond). In red is the postsynaptic density. See Nam et al. for more information.
Exploring Attention Control in People
Sreenivasan Meyyappan, Mingzhou Ding, and George R. Mangun
(see article e2073242025)
Before viewing an object, people can proactively bias their attention to different features of the stimulus, like color or motion direction. Feature-based attention involves frontoparietal brain control networks that bias processing in the visual cortex, promoting focus on the intended information and avoiding distraction. Meyyappan et al. explored whether this anticipatory attention control biases the general category of a feature (e.g., color or motion) before biasing specific feature attributes (e.g., blue or green). The authors used electroencephalography to record brain activity as people attended to specific colors or motion directions. They discovered that general category-level biasing (color versus motion) emerged before more fine-grained biasing of feature attributes (blue vs green or up vs down). The authors propose a temporal hierarchy in feature-based attention, where selection of category-level information precedes the selection of specific feature attributes.
Footnotes
This Week in The Journal was written by Paige McKeon
