A novel micro-ECoG recording method for recording multisensory neural activity from the parietal to temporal cortices in mice.

Characterization of inter-regional interactions in brain is essential for understanding the mechanism relevant to normal brain function and neurological disease. The recently developed flexible micro (μ)-electrocorticography (μECoG) device is one prominent method used to examine large-scale cortical activity across multiple regions. The sheet-shaped μECoG electrodes arrays can be placed on a relatively wide area of cortical surface beneath the skull by inserting the device into the space between skull and brain.

Synaptotagmins 1 and 7 Play Complementary Roles in Somatodendritic Dopamine Release.

The molecular mechanisms underlying somatodendritic dopamine (DA) release remain unresolved, despite the passing of decades since its discovery. Our previous work showed robust release of somatodendritic DA in submillimolar extracellular Ca concentration ([Ca]). Here we tested the hypothesis that the high-affinity Ca sensor synaptotagmin 7 (Syt7), is a key determinant of somatodendritic DA release and its Ca dependence.

Activity-dependent somatodendritic dopamine release in the substantia nigra autoinhibits the releasing neuron.

Somatodendritic dopamine (DA) release from midbrain DA neurons activates D2 autoreceptors on these cells to regulate their activity. However, the source of autoregulatory DA remains controversial. Here, we test the hypothesis that D2 autoreceptors on a given DA neuron in the substantia nigra pars compacta (SNc) are activated primarily by DA released from that same cell, rather than from its neighbors.

Lithium increases synaptic GluA2 in hippocampal neurons by elevating the δ-catenin protein.

Lithium (Li) is a drug widely employed for treating bipolar disorder, however the mechanism of action is not known. Here we study the effects of Li in cultured hippocampal neurons on a synaptic complex consisting of δ-catenin, a protein associated with cadherins whose mutation is linked to autism, and GRIP, an AMPA receptor (AMPAR) scaffolding protein, and the AMPAR subunit, GluA2. We show that Li elevates the level of δ-catenin in cultured neurons.

Presynaptic D1 heteroreceptors and mGlu autoreceptors act at individual cortical release sites to modify glutamate release.

The aim of this work was to study release of glutamic acid (GLU) from one-axon terminal or bouton at-a-time using cortical neurons grown in vitro to study the effect of presynaptic auto- and heteroreceptor stimulation. Neurons were infected with release reporters SypHx2 or iGluSnFR at 7 or 3 days-in-vitro (DIV) respectively. At 13-15 DIV single synaptic boutons were identified from images obtained from a confocal scanning microscope before and after field electrical stimulation.

beta-Phorbol ester-induced enhancement of exocytosis in large mossy fiber boutons of mouse hippocampus.

beta-Phorbol esters (BPE), synthetic analogues of diacylglycerol (DAG), induce the potentiation of transmission in many kinds of synapses through activating the C(1) domain-containing receptors. However, their effects on synaptic vesicle exocytosis have not yet been investigated. Here, we evaluated the vesicular exocytosis directly from individual large mossy fiber boutons (LMFBs) in hippocampal slices from transgenic mice that selectively express synaptopHluorin (SpH).

Photocurrent attenuation by a single polar-to-nonpolar point mutation of channelrhodopsin-2.

Channelrhodopsin-2 (ChR2), one of the algal light-gated cation channel rhodopsins, contains five peculiar glutamic acid residues in the N-terminal region corresponding to the second to third transmembrane helices. Here we made systematic mutations of these polar amino acid residues of ChR2 into nonpolar alanine, and evaluated their photocurrent properties. Amongst them, the photocurrent generated by the E97A mutation, ChR2(E97A), was much smaller than expected from its expression.

Molecular determinants differentiating photocurrent properties of two channelrhodopsins from chlamydomonas.

A light signal is converted into an electrical one in a single molecule named channelrhodopsin, one of the archaea-type rhodopsins in unicellular green algae. Although highly homologous, two molecules of this family, channelrhodopsin-1 (ChR1) and -2 (ChR2), are distinct in photocurrent properties such as the wavelength sensitivity, desensitization, and turning-on and -off kinetics. However, the structures regulating these properties have not been completely identified.

Synaptic vesicle dynamics in the mossy fiber-CA3 presynaptic terminals of mouse hippocampus.

The mossy fiber (MF)-CA3 synapse in the hippocampus is unique in the CNS because of its wide dynamic range of transmitter release during short- and long-term plasticity. The presynaptic mechanisms underlying the fidelity of transmission were investigated for the MF-CA3 synapses. The relative size of readily releasable pool (RRP) of vesicles was estimated by counting the number of docked vesicles at an active zone (AZ) on the transmission electron microscopy (TEM) image.

Transgenic mouse lines expressing synaptopHluorin in hippocampus and cerebellar cortex.

We generated six transgenic mouse lines in which synaptopHluorin (SpH), one of green fluorescent protein-based sensors of vesicular exocytosis, was expressed under the control of neuron-specific Thy-1.2 promoter. In situ hybridization study revealed that SpH mRNA was expressed in a broad spectrum of brain regions in four of them, whereas in others it was expressed in the specific regions of the hippocampus.