MaxWell Monthly Must Reads Blog May Hippocampus

Time goes by fast, and it is already time for the May edition of MaxWell Monthly Must-Reads. This month’s blog series will focus on a well-studied region of the brain, the Hippocampus. We picked this topic for this month as the hippocampus is an interesting model system for studying mechanisms involved in memory storage. MaxOne provides a high-resolution recording and stimulation platform for investigating single cells and networks in hippocampal slices and cell cultures.

This month’s MMM includes a methods article utilizing our technology to study organotypic hippocampal slices, studies focused on the effects of modulating cell activity in the hippocampus, and articles related to brain dysfunctions involving the hippocampus.

  1. Multiple single-unit long-term tracking on organotypic hippocampal slices using high-density microelectrode arrays
    by Wei Gong, Jure Sencar, Douglas J. Bakkum, David Jackel, Marie Engelene Obien, Milos Radivojevic and Andreas R. Hierlemann. Frontiers in Neuroscience. November 2016. 
    This article combines our technology with the roller-tube method for studying organotypic hippocampal slice cultures. One of the key results of this article is label-free tracking of the activity of single neurons across multiple days in brain slices.
    Read the paper here.

  2. Short-term depression of axonal spikes at the mouse hippocampal mossy fibers and sodium channel-dependent modulation
    by Shunsuke Ohura and Haruyuki Kamiya. eNeuro. February 2018.
    Using loose-patch to record action potentials from mossy fiber boutons in the CA3 region of hippocampal brain slices, the authors were able to reveal that repetitive stimulation caused succeeding spikes to have smaller amplitudes, i.e., depression of axonal spikes. This effect was significantly accelerated upon application of veratridine, an inhibitor of inactivation of sodium channels. This work suggested that sodium channels contribute to the use-dependent depression of axonal spikes at the hippocampal mossy fibers.
    Read the paper here. 

  3. Analog closed-loop modulation of hippocampal pyramidal cells dissociates gamma frequency and amplitude
    by Elizabeth Nicholson, Dmitry Kuzmin, Marco Leite, Thomas E. Akam and Dimitri M. Kullmann. Preprint in bioRxiv. May 2018.
    This work proposes a closed-loop optogenetic modulation of principal neurons to study hippocampal gamma oscillations. The closed-loop modulation altered the synchrony of action potentials in principal cells, but not the mean firing rate. The authors found out that the modulation of phasic excitatory currents was enough to manipulate oscillations.
    Read the paper here.

  4. Nav1.1 – Overexpressing interneuron transplants restore brain rhythms and cognition in a mouse model of Alzheimer’s disease 
    by Magdalena Martinez-Losa, Tara E. Tracy, Keran Ma, Laure Verret, Alexandra Clemente-Perez, Abdullah S. Khan, Imma Cobos, Kaitlyn Ho, Li Gan, Lennart Mucke, Maluel Alvarez-Dolado and Jorge J. Palop. Neuron. April 2018.
    In Alzheimer’s disease (AD), the oscillatory rhythms in the brain are disrupted. In this work, the researchers transplanted interneurons overexpressing Nav1.1, a voltage-gated sodium channel, to restore gamma oscillatory activity, reduce network hypersynchrony, and improve cognition in a mouse model of AD. On the other hand, transplanting Nav1.1-definient interneurons caused behavioral abnormalities in wild-type mice. In conclusion, the level of Nav1.1 in transplanted interneurons contribute to the efficacy of the therapy applied to a mouse model of AD.
    Read the paper here. More information can be found here.

  5. Effects of anti-epileptic drugs on spreading depolarization-induced epileptiform activity in mouse hippocampal slices
    by Ching-Huei Lin, Shih-Pin Hsu, Ting-Chun Cheng, Chin-Wei Huang, Yao-Chang Chian, I-Han Hsiao, Ming-Hsueh Lee, Mei-Lin Shen, Dong Chuan Wu and Ning Zhou. Scientific Reports. September 2017.
    Mouse hippocampal slices has been frequently used as an in vitro model for epilepsy. In this work, the authors investigated the effects of 11 anti-epileptic drugs to spreading depolarization (SD) evoked epileptiform activities.
    Read the paper here.