News / Science News

    Seizures disrupt memory network

    NIH | MAY 7, 2016

    Memory depends on a process called consolidation, in which different brain regions coordinate their activities during sleep. This process involves “ripples” of electrical activity in the hippocampus that are sometimes followed by bursts of activity in the prefrontal cortex called “spindles.” Abnormal electrical activity may disrupt normal brain activity patterns.



    In people with epilepsy, abnormal bursts of electrical activity in the brain can interfere with memory.


    People with temporal lobe epilepsy often experience memory impairments.

    A group led by Dr. György Buzsáki at New York University took a closer look at how temporal lobe epilepsy affects the brain’s memory network.

    In people with temporal lobe epilepsy, spontaneous bursts of abnormal brain activity can sometimes occur even between seizures. These are called interictal epileptiform discharges (IEDs).

    Buzsáki’s group first looked at whether seizure- and IED-like activity that starts in the hippocampus impairs memory in a rat model of epilepsy. They trained the rats to find 3 hidden rewards in a maze and assessed their ability to remember the locations the following day. The rats showed memory deficits that were largely associated with the more frequently occurring IEDs rather than with the rare seizures.

    The researchers found that hippocampal IEDs were followed by spindles in the prefrontal cortex. Normally, such spindles only follow hippocampal ripples during non-rapid-eye-movement (non-REM) stages of sleep.

    In rats that experienced seizures, hippocampal IEDs also elicited cortical spindles during REM and an awake state. These findings suggest that seizures may alter how the prefrontal cortex responds to hippocampal activity and thus interfere with normal memory consolidation.

    The group next studied brain activity in 4 patients with epilepsy. IEDs were followed by cortical spindles at time intervals similar to that seen in the rats. The results suggest that these mistimed IEDs disrupt a brain network that’s essential for memory and reveal a time window for potential intervention in the altered communication between brain regions.

    Since spindles can be detected noninvasively with EEG, a test that measures brain waves, the authors suggest that these findings may also be useful for diagnosing temporal lobe epilepsy. Spindles that occur outside normal non-REM sleep (while awake or during REM) could suggest IED activity in the temporal lobe.




    YOU MAY ALSO LIKE

    A new study analyzing samples from patients with and without acute flaccid myelitis (AFM) provides additional evidence for an association between the rare but often serious condition that causes muscle weakness and paralysis, and infection with non-polio enteroviruses.
    Astronomers have uncovered a near-record breaking supermassive black hole, weighing 17 billion suns, in an unlikely place: in the center of a galaxy in a sparsely populated area of the universe.
    Paleontologists working in Tanzania have identified a new species of hyaenodont, a type of extinct meat-eating mammal.
    Researchers used computer modeling to show how the spleen maintains the quality of red blood cells in the bloodstream.
    Graphene could provide alternative to chemicals in insect repellant and protective clothing.
    Women who experience pregnancy loss and do not go on to have children are at greater risk of cardiovascular disease, such as heart disease and stroke, compared with women who have only one or two children.

    © 1991-2023 The Titi Tudorancea Bulletin | Titi Tudorancea® is a Registered Trademark | Terms of use and privacy policy
    Contact