Late phase synaptic plasticity tagged by increase in puncta sites

Our models of synaptic action are still very incomplete and will benefit from more empirical research. In this direction, Antonova et al (here) cultured relatively young ( 2 – 3 week old) hippocampal neurons from one day old rats. They placed the neurons in either glutamate in Mg2+-free bath solution or control solution. They then [...]

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Question #17: Biological and physical basis of fMRI

Functional magnetic resonance imaging is pretty technical stuff. As the Neuroskeptic aptly puts it, “when you do an fMRI scan you’re using a superconducting magnet to image human neural activity by measuring the quantum spin properties of protons. It doesn’t get much more technical.” The technique for measuring neural activity has become a household name [...]

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Nuclear morphology of medium spiny neurons in the striatum

The major input of the basal ganglia, the striatum, contains ~ 6 cell types, primarily: 1) medium spiny neurons ( ~ 96%), 2) Deiter’s neurons (2%), 3) cholinergic interneurons (1%; tonically active but usually stop firing in response to reward). Medium spiny neurons are particularly interesting little buggers. All medium spiny neurons in the striatum [...]

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Synaptic activity dependent survival via neurotrophins and training in newborn hippocampal neurons

Granulocyte-colony stimulating factor (GCSF) is a recently discovered neurotrophic factor that counteracts apoptosis, boosts synaptic plasticity, and, perhaps through the same mechanism, increases neurogenesis. Diederich et al (here) have an interesting study showing that the beneficial cognitive effects of training on a radial maze for 11 days and receiving daily 20 µg/kg injections of G-CSF [...]

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Gene expression in astrocytes, neurons, and oligodendrocytes

In order to gather data on the gene expression characteristics of the brain, Cahoy et al purified cell suspensions of astrocytes, neurons, and oligodendrocyte lineage cells. They then used dChip software (here) to determine the gene expression of each cell type at various days postnatal.  Here’s a dendogram showing the hierarchical clustering of cell types [...]

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RNA interference to reduce expression of neuropilin-2 receptors

Using RNAi to knock down the expression of particular receptors and signaling molecules is an intriguing pathway for neural engineering. For example, reducing the expression of neuropilin-2, a molecule that acts as a axon guiding cue, may improve axon outgrowth following injury. In order to study one method, Ehlert et al injected short hairpin RNAs [...]

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Question #16: Three applications of the local field potential

The local field potential (LFP) is extracted by placing a extracellular microelectrode in the middle of a group of neurons without being too close to any particular cell. When ion channels open and close, charged molecules diffuse around. This changes the electrical potential of the medium surrounding the cells, which the electrode detects and transduces. [...]

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Question #15: The neurogenetics of interspecies brain size variance

Neural tissue is nearly an order of magnitude more energetically taxing than other tissue types, so evolutionarily, larger brains would only evolve if they endowed a selective advantage large enough to compensate for the high energy cost. On the molecular level, increases in brain size could be accounted for by various gene duplications and divergences. [...]

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Question #14: Three lesion studies on orbitalfrontal cortex function

The frontal lobe is predictably divided from the temporal lobe by the central sulcus. However, the morphology of the central sulcus varies between subjects, due in part to handedness and aging. The frontal lobes have traditionally been associated with executive functions. The prefrontal cortex is a part of the frontal lobe. Specifically, it contains the [...]

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Imaging the postsynaptic density microdomain postmortem

Variance at the postsynaptic density (PSD) has the potential to account for various differences in human mental characteristics. Hahn et al (here) examined the prefrontal cortex (BA 9) of 12 human brains after death with mean postmortem intervals of 9.6 hours and mean freezing times at – 80°C of 10.2 +/- 1.9 years. They then [...]

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