Brain Parasite Directly Alters The Brain Chemistry

Research shows infection by the brain parasite Toxoplasma gondii, found in 10-20 per cent of the UK's population, directly affects the production of dopamine, a key chemical messenger in the brain.

Findings from the University of Leeds research group are the first to demonstrate that a parasite found in the brain of mammals can affect dopamine levels.

Whilst the work has been carried out with rodents, lead investigator Dr Glenn McConkey of the University's Faculty of Biological Sciences, believes that the findings could ultimately shed new light on treating human neurological disorders that are dopamine-related such as schizophrenia, attention deficit hyperactivity disorder, and Parkinson's disease.

This research may explain how these parasites, remarkably, manipulate rodents' behaviour for their own advantage. Infected mice and rats lose their innate fear of cats, increasing the chances of being caught and eaten, which enables the parasite to return to its main host to complete its life cycle.

In this study, funded by the Stanley Medical Research Institute and Dunhill Medical Trust, the research team found that the parasite causes production and release of many times the normal amount of dopamine in infected brain cells.

Dopamine is a natural chemical which relays messages in the brain controlling aspects of movement, cognition and behaviour. It helps control the brain's reward and pleasure centres and regulates emotional responses such as fear. The presence of a certain kind of dopamine receptor is also associated with sensation-seeking, whereas dopamine deficiency in humans results in Parkinson's disease.

These findings build on earlier studies in which Dr McConkey's group found that the parasite actually encodes the enzyme for producing dopamine in its genome.

'Based on these analyses, it was clear that T. gondii can orchestrate a significant increase in dopamine production in neural cells,' says Dr McConkey.

'Humans are accidental hosts to T. gondii and the parasite could end up anywhere in the brain, so human symptoms of toxoplasmosis infection may depend on where parasite ends up. This may explain the observed statistical link between incidences of schizophrenia and toxoplasmosis infection.'

Dr McConkey says his next experiments will investigate how the parasite enzyme triggers dopamine production and how this may change behaviour.

Toxoplasmosis, which is transmitted via cat faeces (found on unwashed vegetables) and raw or undercooked infected meat, is relatively common, with 10-20% of the UK population and 22% of the US population estimated to carry the parasite as cysts. Most people with the parasite are healthy, but for those who are immune-suppressed - and particularly for pregnant women - there are significant health risks that can occasionally be fatal.

The parasite infects the brain by forming a cyst within its cells and produces an enzyme called tyrosine hydroxylase, which is needed to make dopamine. Dopamine's role in mood, sociability, attention, motivation and sleep patterns are well documented and schizophrenia has long been associated with dopamine, which is the target of all current schizophrenia drugs on the market.

The enzyme tyrosine hydroxylase is a crucial step in making L-DOPA (prescribed as levodopa for Parkinson's Disease), a chemical that is readily converted to the neurotransmitter dopamine.

The US-based Stanley Medical Research Institute, which focuses on mental health conditions and has a particular emphasis on bipolar illnesses. Dunhill Medical Trust supports research on diseases of aging.

Source of Story:
The above story is reprinted (with editorial adaptations by Science Technologies author) from materials provided by University of Leeds.

Reference of Journal:
Emese Prandovszky, Elizabeth Gaskell, Heather Martin, J. P. Dubey, Joanne P. Webster, Glenn A. McConkey. The Neurotropic Parasite Toxoplasma Gondii Increases Dopamine Metabolism. PLoS ONE, 2011; 6 (9): e23866 DOI: 10.1371/journal.pone.0023866

Read More

It Takes Two: Brains Come Wired For Cooperation - Neuroscientists Asserts

When Nancy Grace and her partner danced a lively rumba to Spandau Ballet's 1980's hit, 'True,' on a recent 'Dancing With the Stars,' more was going on in the legal commentator's brain than worry over a possible wardrobe malfunction.

Deep in Grace's cortex, millions of neurons were hard at work doing what they apparently had been built to do: act and react to partner Tristan MacManus's movements to create a pas de deux that had the dancers functioning together (for the most part) like a well-oiled machine.

That is because the brain was built for cooperative activity, whether it be dancing on a reality television show, constructing a skyscraper or working in an office, according to a study led by Johns Hopkins behavioral neuroscientist Eric Fortune and published in the November 4 issue of the journal Science.

'What we learned is that when it comes to the brain and cooperation, the whole is definitely greater than the sum of its parts,' said Fortune, of the Department of Psychological and Brain Sciences at the Krieger School of Arts and Sciences. 'We found that the brain of each individual participant prefers the combined activity over his or her own part.'

In addition to shedding light on ourselves as social and cooperative beings, the results have important implications for engineers who want to be able to program autonomous robots to work effectively as teams in settings such as bomb squads and combat.

But Fortune's work didn't involve androids or take place on a battlefield. Instead, he and his team took to the cloud forests of Ecuador, on the slopes of the active Antisana Volcano. Why? It's one of the only places in the world where you can find plain-tailed wrens. These chubby-breasted rust-and-gray birds, who don't fly so much as hop and flit through the area's bamboo thickets, are famous for their unusual duets. Their songs - sung by one male and one female - take an ABCD form, with the male singing the A and C phrases and the female (who seems to be the song leader) singing B and D.

'What's happening is that the male and female are alternating syllables, though it often sounds like one bird singing alone, very sharply, shrilly and loudly,' explained Fortune, who spent hours hacking through the thick bamboo with a machete, trying to catch the songbirds in nets. 'The wrens made an ideal subject to study cooperation because we were easily able to tape-record their singing and then make detailed measurements of the timing and sequences of syllables, and of errors and variability in singing performances.'

The team then captured some of the wrens and monitored activity in the area of their brains that control singing. They expected to find that the brain responded most to the animal's own singing voice. But that's not what happened.

'In both males and females, we found that neurons reacted more strongly to the duet song - with both the male and female birds singing - over singing their own parts alone. In fact, the brain's responses to duet songs were stronger than were responses to any other sound,' he said. 'It looked like the brains of wrens are wired to cooperate.'

So it's clear that nature has equipped the brains of plain-tailed wrens in the Andes of Ecuador to work cooperatively, and to prefer 'team' activities to solo ones. But what does that have to do with people?

'Brains among vertebrate animals - frogs, cats, fish, bears and even humans - are more similar than most people realize,' Fortune said. 'The neurotransmitter systems that control brain activity at the molecular level are nearly identical among all vertebrates and the layout of the brain structures is the same. Thus, the kinds of phenomena that we have described in these wrens is very relevant to the brains of most, if not all, vertebrate species, including us humans.'

Co-authors on the study are Gregory F. Ball of the Department of Psychological and Brain Sciences at the Johns Hopkins University; Carlos Rodriguez of Pontificia Universidad Catolica del Ecuador; and Melissa Coleman, of Claremont McKenna College. David Li, an undergraduate student majoring in neuroscience at Johns Hopkins, also is a co-author.

This research was supported by the National Science Foundation.

Source of Story:
The above story is reprinted (with editorial adaptations by Science Technologies author) from materials provided by Johns Hopkins University.

Reference of Journal:
E. S. Fortune, C. Rodriguez, D. Li, G. F. Ball, M. J. Coleman. Neural Mechanisms for the Coordination of Duet Singing in Wrens. Science, 2011; 334 (6056): 666 DOI: 10.1126/science.1209867

Read More

Interactive Play With The Blocks Found To Facilitate Development Of Spatial Vocabulary

Parents and researchers have long speculated that playing with construction toys might offer a rich environment that would support later learning in the science, technology, engineering and mathematics (STEM) disciplines.

In a recent study published in Mind, Brain and Education, researchers at Temple's Infant Lab found there are some very real benefits to playing with that old toy classic - blocks.

The researchers found that when playing with blocks under interactive conditions, children hear the kind of language that helps them think about space, such as 'over,' 'around' and 'through.'

'When parents use spatial language, they draw attention to spatial concepts,' said Nora Newcombe, co-director of Temple's Infant Lab. 'The development of a spatial vocabulary is critical for developing spatial ability and awareness.'

Spatial skills are important for success in the STEM disciplines, but they are also involved in many everyday tasks, such as packing the trunk of a car or assembling a crib.

They are a central component of intellect and, as those who struggle finding their way around a new city can attest, they show marked individual differences.

'There is evidence that variations in the spatial language young children hear, which directs their attention to important aspects of the spatial environment, may be one of the mechanisms that contribute to differences in spatial ability,' says Newcombe, who is also the principal investigator of the Spatial Intelligence and Learning Center (SILC), headquartered at Temple.

To investigate how play affects variations in language, investigators observed children and parents in one of three situations: in 'free' play, where the subjects are encouraged to play with the blocks as they would at home; in 'preassembled' play, where the subject are given blocks that have been glued together in a preformed, fixed structure; and in 'guided' play, where the subjects are given the blocks along with graphic instructions for creating a particular structure.

Parents in the guided play condition produced significantly higher proportions of spatial talk than parents in the other two conditions, and children in the guided play condition produced significantly more spatial talk than those in the free play condition.

'This study gives parents news they can use. It shows that, rather than leaving kids alone with a preassembled activity, interactive play that draws out conversation is best at facilitating spatial development,' Newcombe said.

Source of Story:
The above story is reprinted (with editorial adaptations by Science Technologies author) from materials provided by Temple University. The original article was written by Kim Fischer.

Read More