Memories From A Window High Quality
Real-world memories are formed in a particular context and are often not acquired or recalled in isolation1-5. Time is a key variable in the organization of memories, as events that are experienced close in time are more likely to be meaningfully associated, whereas those that are experienced with a longer interval are not1-4. How the brain segregates events that are temporally distinct is unclear. Here we show that a delayed (12-24 h) increase in the expression of C-C chemokine receptor type 5 (CCR5)-an immune receptor that is well known as a co-receptor for HIV infection6,7-after the formation of a contextual memory determines the duration of the temporal window for associating or linking that memory with subsequent memories. This delayed expression of CCR5 in mouse dorsal CA1 neurons results in a decrease in neuronal excitability, which in turn negatively regulates neuronal memory allocation, thus reducing the overlap between dorsal CA1 memory ensembles. Lowering this overlap affects the ability of one memory to trigger the recall of the other, and therefore closes the temporal window for memory linking. Our findings also show that an age-related increase in the neuronal expression of CCR5 and its ligand CCL5 leads to impairments in memory linking in aged mice, which could be reversed with a Ccr5 knockout and a drug approved by the US Food and Drug Administration (FDA) that inhibits this receptor, a result with clinical implications. Altogether, the findings reported here provide insights into the molecular and cellular mechanisms that shape the temporal window for memory linking.
Memories From a Window
In mice, two fear-associated memories that are created close in time are represented in the brain's amygdala by the activation of overlapping ensembles of neurons. As a result, eliminating the fear of one memory also extinguishes fear of the other.
Debugger windows like Watch, Autos, Locals, and the QuickWatch dialog show you variables, which are stored at specific locations in memory. The Memory window shows you the overall picture. The memory view is convenient for examining large pieces of data (buffers or large strings, for example) that don't display well in the other windows.
To enable the Memory windows, Enable address-level debugging must be selected in Tools > Options (or Debug > Options) > Debugging > General.
Under Debug > Windows > Memory, select Memory 1, Memory 2, Memory 3, or Memory 4. (Some editions of Visual Studio offer only one Memory window.)
You can instantly go to a specified address in the Memory window by using drag-and-drop, or by entering the address in the Address field. The Address field accepts alphanumeric addresses, and expressions that evaluate to addresses, such as e.User.NonroamableId.
By default, the Memory window treats Address expressions as live expressions, which are re-evaluated as the app runs. Live expressions can be useful, for example, to view the memory that is touched by a pointer variable.
Drag and drop the address or pointer in the Memory window. That address then appears in the Address field, and the Memory window adjusts to display that address at the top.
By default, memory contents appear as 1-byte integers in hexadecimal format, and the window width determines the number of columns shown. You can customize the way the Memory window shows memory contents.
When you use a debug command such as Step, the memory address displayed in the Address field and at the top of the Memory window automatically changes as the pointer changes.
Imagine we close the browser window created by showNotes() above. There's no event handler listening to detect that the window has been closed, so nothing is informing our code that it should clean up any references to the document. The nextSlide() function is still "live" because it is bound as a click handler in our main page, and the fact that nextSlide contains a reference to notesWindow means the window is still referenced and can't be garbage collected. Illustration of how references to a window prevent it from being garbage collected once closed.See Solution: communicate over postMessage to learn how to fix this particular memory leak.There are a number of other scenarios where references are accidentally retained that prevent detached windows from being eligible for garbage collection:Event handlers can be registered on an iframe's initial document prior to the frame navigating to its intended URL, resulting in accidental references to the document and the iframe persisting after other references have been cleaned up.
A memory-heavy document loaded in a window or iframe can be accidentally kept in-memory long after navigating to a new URL. This is often caused by the parent page retaining references to the document in order to allow for listener removal.