Schizophrenia fueled by abnormal neural activity

Abnormal neural activity may be fueling disorder thinking, a characteristic symptom of schizophrenia, researchers have found.

Lacking the ability to organize thoughts, often accompanied by delusions or hallucinations is typical to schizophrenia patients. Researchers at the Massachusetts Institute of Technology have found that this is triggered by abnormal neural activity.

The study
For the purpose of the study, researchers tracked neural activity in the brain’s hippocampus in mice genetically engineered to lack the gene coding for calcineurin.

The mice were made to run along a track and the researchers measured their brain activity.

In healthy players, the “place cells” in the hippocampus are launched in a sequence, each signal corresponding to a specific location on the track. These “mental images” are played and replayed every time the mice take a break. These replays occur along very high frequency brain-wave oscillations called ripple events.

On the contrary, in schizophrenia patients the place cells were fired randomly, creating abnormally high ripple events and possibly altering the mental replay of events.

Researchers feel this difference in brain activity may probably explain the reason behind the onset of the symptoms associated with schizophrenia.

“We think that in this mouse model, we may have some kind of indication that there’s a disorganized thinking process going on,” study’s co-author, Junghyup Suh, a research scientist at the Picower Institute said. “During ripple events in normal mice we know there is a sequential replay event. This mutant mouse doesn’t seem to have that kind of replay of a previous experience.”

The study also unveiled the role of calcineurin. Researchers speculate that calcineurin suppressed the connections between neurons, known as synapses, in the brain’s hippocampus.

In mice engineered to lack calcineurin, the long-term potentiation (LTP) becomes more prevalent, making synapses stronger.

“It looks like this abnormally high LTP has an impact on activity of these cells specifically during resting periods, or post exploration periods. That’s a very interesting specificity,” MIT researcher Susumu Tonegawa said. “We don’t know why it’s so specific.”

The findings of the study are reported in the journal Neuron.