December 5, 2021

I, Science

The science magazine of Imperial College

Margaux Lesaffre on abnormal brain waves that may cause hallucinations in schizophrenia
Screen shot of brain waves of a patient during Slow Wave Sleep (stage 3), when Delta waves begin to appear. The high amplitude EEG, containing the Delta waves, is highlighted in red.

A team of researchers at Brandeis University identified one possible cause of schizophrenic symptoms. The results published in a recent issue of the Journal of Biological Psychiatry shows that symptoms such as hallucinations and delusions may be the result of abnormal waves in schizophrenic brains.

The cause of the illness remained, until now, largely unknown. John Lisman, lead researcher and professor of biology at the university, said that the new study could have “therapeutic value in patients”.

Unusual brain waves, also called neural oscillations, are thought to be linked to schizophrenia. Brain waves originate from electrical pulses emerging from neurons communicating with one another. In healthy brains, one type of waves, called delta waves, are generated during sleep. In people affected by schizophrenia, these oscillations occur during wakefulness.

Schematic diagram of an ion channel. 1 – channel domains (typically four per channel), 2 – outer vestibule, 3 – selectivity filter, 4 – diameter of selectivity filter, 5 – phosphorylation site, 6 – cell membrane.

It is the connection between these oscillations and schizophrenic symptoms that Lisman and his team investigated in this study.
Scientists artificially reproduced these delta waves in the thalamus of rats’ brains, the region most affected by schizophrenia and involved in sensory perception, sleep and working memory. This method involves the injection a light-sensitive protein into the rodents’ brains allowing nerve cells to respond to light. By shining light in the rats’ brains the researchers can stimulate the targeted region of the brain and disrupt the working memory of rats.

“The part of the thalamus that is supposed to carry information about working memory cannot do the task at all with these sleep-like delta waves. We suspect the abnormal delta oscillations seen in patients with schizophrenia are producing a similar jamming of normal signals,” Lisman said.

In schizophrenic patients, delta waves are transmitted via specific ion channels. “If you could block these channels, you could block these bad oscillations,” he adds.

Margaux Lesaffre is studying for an MSc in Science Communication

Images: Delta waves ;  Ion channel (Wikimedia Commons)

Citation: Duan, A.R. et al (2015) Delta Frequency Optogenetic Stimulation of the Thalamic Nucleus Reuniens Is Sufficient to Produce Working Memory Deficits: Relevance to Schizophrenia. J. Biol. Psychia. 77, 1098–1107. DOI: