MSGID: 1:317/3 62720184   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Finding your car in a parking lot relies on this newly discovered brain   
   circuit    
    'CEO of the brain' focuses attention on the most relevant stimuli in the   
   environment    
      
     Date:   
         May 3, 2022   
     Source:   
         University of California - San Francisco   
     Summary:   
         When exploring a new environment, mice make use of a unique   
         long-distance connection in the brain that prompts them to   
         pay attention to the most salient features of the environment,   
         according to new research. The link, originating in the prefrontal   
         cortex and stretching to the hippocampus, provides evidence of how   
         the brain's higher cognitive regions refine operations occurring   
         in distant brain areas.   
      
      
      
   FULL STORY   
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   When exploring a new environment, mice make use of a unique long-distance   
   connection in the brain that prompts them to pay attention to the most   
   salient features of the environment, according to new research from UC   
   San Francisco.   
      
   The link, originating in the prefrontal cortex and stretching to the   
   hippocampus, provides evidence of how the brain's higher cognitive   
   regions refine operations occurring in distant brain areas.   
      
      
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   "This circuit is a gateway to understanding how the brain allows the   
   prefrontal cortex to exert top-down regulation of other parts of the   
   brain," said Vikaas Sohal, MD, PhD, senior author on the study, published   
   April 28, 2022, in Cell.   
      
   "It's a type of long-range, inhibitory pathway connecting two brain   
   regions that hasn't been seen before."  The prefrontal cortex (PFC),   
   sometimes thought of as the "CEO of the brain," controls executive   
   functions like attention, planning and decision making. The hippocampus   
   stores memory and processes spatial information, helping us to navigate   
   the environment.   
      
   The newly discovered circuit facilitates the ability to focus attention   
   on what's important in the environment and ignore other sensory stimuli,   
   said the study's lead author, Ruchi Malik, PhD.   
      
   "It's as if the PFC is taking in all of this sensory information and   
   saying 'Hey, hippocampus, we're here in this particular context, so pay   
   attention to this particular information right now,'" Malik said.   
      
   She gives the example of a parking lot as a context in which the PFC   
   exerts that kind of top-down control over the hippocampus. "To remember   
   where you parked, the PFC would tell the hippocampus to selectively pay   
   attention to landmarks, and then recall and seek out those landmarks   
   when you return," said Malik.   
      
      
      
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   Fine-Tuning Attention by Inhibiting Neurons Most unique about this circuit   
   is the complex way that it accomplishes the task of focusing attention:   
   it heightens and focuses activity in specific microcircuits of the   
   hippocampus by turning off signals that would otherwise tamp down those   
   microcircuits. The result is a very clear signal from the PFC telling   
   the hippocampus what to attend to, and an extremely deft means of fine-   
   tuning that message as surroundings change.   
      
   The team showed this by putting mice into a small arena for 10 minutes,   
   where there were a few small objects. While exploring the arena, the   
   mice would inspect the objects for a minute or two, and then move on. By   
   looking at activity in the brains of the mice, the researchers saw that   
   the signals between the two brain regions synchronized.   
      
   When a mouse passed that object again, the researchers could see that   
   the signals within the hippocampus were refined and enhanced.   
      
   "There was this dialogue happening; the hippocampus was mapping the   
   locations of objects in space and the PFC was instructing the hippocampus   
   on the relevance of each location," said Malik.   
      
      
      
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   The team also found that data indicated which neurons were firing at a   
   given time and identify where the mouse was at that moment, confirming   
   that brain activity changes as the mouse approaches or investigates an   
   object that the PFC has deemed important.   
      
   This suggests that as the hippocampus is mapping the environment, it is   
   also becoming fine-tuned to produce certain patterns of neural activity   
   when the prefrontal cortex detects that the mouse is approaching an   
   important target such as a new object.   
      
   Dysfunction of Brain Circuit May Be Linked to Dementia, ADHD The team   
   would like to get a better sense of the role this circuit might play in   
   executive function, and what the consequences are when it's not able to   
   do its job effectively. Malik believes that dysfunction in this pathway   
   may underlie cognitive issues related to attention or memory, such as   
   dementia, ADHD or psychiatric disorders.   
      
   Their next move toward that goal is to get a sense of how this circuit   
   impacts behavior by looking at how it functions during more complex   
   activities, like using information stored in working memory to decide   
   which path to follow to find a reward.   
      
   Malik thinks it's likely that this connection from the higher-order,   
   cognitive part of the brain to the more ancient and universal wayfinding   
   center may exert broad influence.   
      
   "To operate in a complex environment, to go look for food or rewards   
   and then come back, you need to be able to pay attention to specific   
   stimuli and arrange them in space in a precise way," she said. "The   
   filtering job of this circuit is absolutely essential."  This research   
   was supported by NIMH grants R01MH106507 and R01MH117961.   
      
      
   ==========================================================================   
   Story Source: Materials provided by   
   University_of_California_-_San_Francisco. Original written by Robin   
   Marks. Note: Content may be edited for style and length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. Ruchi Malik, Yi Li, Selin Schamiloglu, Vikaas S. Sohal. Top-down   
      control   
         of hippocampal signal-to-noise by prefrontal   
         long-range inhibition. Cell, 2022; 185 (9): 1602 DOI:   
         10.1016/j.cell.2022.04.001   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2022/05/220503141313.htm   
      
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