Scientists at Arizona State University have developed a new method of non-surgical brain stimulation using pulsed ultrasound that enhances cognitive function in mice, and may one day be used to non-invasively treat patients with mental retardation, Alzheimer’s disease and other CNS dysfunctions. In intact motor cortex in mice, ultrasound was found to stimulate action potentials and elicit motor responses comparable to those only previously achieved with implanted electrodes and related techniques. It also activates meaningful brain wave patterns and the production of brain-derived neurotrophic factor (BDNF) in the hippocampus – one of the most potent regulators of brain plasticity.
From the article in Neuron:

Deeper in subcortical circuits, we used targeted transcranial ultrasound to stimulate neuronal activity and synchronous oscillations in the intact hippocampus. We found that ultrasound triggers TTX-sensitive neuronal activity in the absence of a rise in brain temperature (<0.01°C). Here, we also report that transcranial pulsed ultrasound for intact brain circuit stimulation has a lateral spatial resolution of approximately 2 mm and does not require exogenous factors or surgical invasion.
Highlights:

Transcranial pulsed ultrasound stimulates intact mouse brain circuits

Ultrasound can stimulate intact cortex and hippocampus without exogenous factors

Ultrasound consistently stimulates temporally precise TTX-sensitive brain activity

Transcranial pulsed ultrasound confers an ~2 mm lateral functional resolution

Article in Neuron: Transcranial Pulsed Ultrasound Stimulates Intact Brain Circuits…
Press release: New method offers platform for brain treatment…

Green fluorescent protein has done wonders in biology labs to track all kinds of things in vivo. Being a pretty bulky protein itself, though, makes it difficult to use GFP to label other proteins. Now MIT researchers have developed a method called PRIME (PRobe Incorporation Mediated by Enzymes) that uses a much smaller blue fluorescent probe (7-hydroxycoumarin) that doesn’t seem to interfere with natural function of proteins it’s been attached to.

Unlike GFP, the new probe is not joined to the target protein as it’s produced inside the cell. Instead, the probe is attached later on by a new enzyme that the researchers also designed.
For this to work, the researchers must add the gene for the new enzyme, known as a fluorophore ligase, to each cell at the same time that they add the gene for the protein of interest. They also add a short tag (13 amino acids) to the target protein, and this tag allows the enzyme to recognize the protein. When the blue fluorescent probe (7-hydroxycoumarin) is added to the cell, the enzyme attaches it to the short tag on the target protein.
With this method, proteins such as actin can move freely throughout the cell and cross into the nucleus even when tagged with the fluorescent probe.
The researchers also demonstrated that they can label proteins in specific parts of the cell, such as the nucleus, cell membrane [see image] or cytosol (the interior of the cell), by tagging the enzyme with genetic sequences that direct it to specific locations. That way, the enzyme attaches the fluorescent probe only to proteins in those locations.

MIT press release: Giving proteins a new glow…
Abstract in PNAS: A fluorophore ligase for site-specific protein labeling inside living cells

The Economist has recently featured an interesting article on the behavioral effects that parasitic protozoa Toxoplasma gondii has on its mammalian hosts. Many of these effects have been recognized for years, and some of us here at Medgadget been privy to Toxoplasma news, thanks to a friend at Stanford who works with Dr. Robert Sapolsky, a leading researcher in the field. First of all, there is strong evidence that urine from cats is sexually attractive to rats infected with Toxoplasma. Then there seems to be a connection between Toxoplasma gondii and schizophrenia, lack of interest in the novelties of life, and a noted correlation with people getting into more car accidents. It seems that the nature of this parasite’s life cycle has created a strange symbiotic, psychological relationship between it and its typical feline and rodent hosts. The Economist provides a handy overview of the latest knowledge around this topic.

If an alien bug invaded the brains of half the population, hijacked their neurochemistry, altered the way they acted and drove some of them crazy, then you might expect a few excitable headlines to appear in the press. Yet something disturbingly like this may actually be happening without the world noticing….
One reason to suspect [that some people have their behaviour permanently changed] is that a country’s level of Toxoplasma infection seems to be related to the level of neuroticism displayed by its population. Another is that those infected seem to have poor reaction times and are more likely to be involved in road accidents. A third is that they have short attention spans and little interest in seeking out novelty. A fourth, possibly the most worrying, is that those who suffer from schizophrenia are more likely than those who do not to have been exposed to Toxoplasma.
Nor is any of this truly surprising. For, besides humans, Toxoplasma has two normal hosts: rodents and cats. And what it does to rodents is very odd indeed.

Here’s a must watch video interview of Sapolsky with Edge.org:

Somehow, this damn parasite knows how to make cat urine smell sexually arousing to male rodents…

Read on at The Economist: A game of cat and mouse
Edge: TOXO – A Conversation With Robert Sapolsky…
Image: Rev. Xanatos Satanicos Bombasticos