Journal Club – In Vivo Inhibition Dynamics

18 02 2010

Inhibition has a powerful role shaping the network dynamics of the cortex, but most studies of inhibitory circuitry are done in brain slice or anesthetized animals. In Membrane potential dynamics of GABAergic neurons in barrel cortex of behaving mice, Gentet et al use two-photon imaging to guide dual, whole-cell patch clamp of inhibitory and excitatory neurons in the mouse barrel cortex.  These mice are head fixed, but awake and naturally whisking.  The authors can then see how the membrane dynamics of both subthreshold and suprathreshold voltages are correlated across pairs of cells.  Differences between the correlations for excitatory and inhibitory neurons shed light on how cortical circuitry processes sensory information in natural brain states.

For Journal Club #5, Mac Hooks, a post-doc here at Janelia working with Gordon Shepard and Karel Svoboda, walks us through these results.  Also, there is a video introduction of the work by the lab head of the paper, Carl Petersen, provided by Cell Press.

Gentet, L., Avermann, M., Matyas, F., Staiger, J., & Petersen, C. (2010). Membrane Potential Dynamics of GABAergic Neurons in the Barrel Cortex of Behaving Mice Neuron, 65 (3), 422-435 DOI: 10.1016/j.neuron.2010.01.006


Blog Roundup

27 02 2008

Here’s a quick overview of some posts that got my attention in the last month…

Neurodudes has a brief writeup of video-rate superresolution imaging from Stefan Hell’s group. I don’t have access to Science Express PDF’s through our institutional subscription (how much must they be charging for that?), making a full writeup impossible. But you can at least check out the abstract and supporting info here. Video-Rate Far-Field Optical Nanoscopy Dissects Synaptic Vesicle Movement (Westphal et al.). The optical resolution isn’t quite as good as PALM or STORM, but the speed of acquisition is fantastic, permitting its use on dynamic living processes.

Eric Thomson from Neurochannels has posted a detailed Journal Club style review at Nature Network of the paper Spatiotemporal Dynamics of Cortical Sensorimotor Integration in Behaving Mice (Ferezou et al.) from Carl Petersen’s group. Using voltage-sensitive dyes they show the timing and spreading of activity from the sensory to motor cortex, following whisker stimulation in awake mice.

Biosingularity reports on results from Susumu Tonegawa’s group published in Science Express as Transgenic Inhibition of Synaptic Transmission Reveals Role of CA3 Output in Hippocampal Learning (Nakashiba et al.). They use a novel method, doxycycline-inhibited circuit exocytosis-knockdown (DICE-K), to transiently and selectively shut down the tri-synaptic pathway of the hippocampus (ER->DG->CA3->CA1->ER), while leaving the monosynaptic pathway (ER->CA1->ER) intact. These mice can still learn incrementally, but one-trial contextual learning and pattern completion recall is wiped out.