The earliest known example of human brain imaging was a recording obtained in 1927 by the German psychiatrist Dr. Hans Berger. He found that it was possible to capture faint electric currents generated in the brain without opening the skull, and to depict them graphically onto a strip of paper. Berger named this new form of recording as the electroencephalogram (EEG).
Since these early days, new technologies have been developed which allow scientists to “see” inside the living brain. For many decades these techniques were used almost exclusively by clinicians to diagnose and treat of illnesses such as epilepsy and traumatic brain injury.
Starting in the 1980s, additional non-invasive methods of brain imaging emerged. Collectively, these became priceless tools for researchers in the growing domain of cognitive neuroscience.
At Baycrest’s Rotman Research Institute, scientists design research studies and use one or more of these brain imaging technologies to study everything from memory, emotion and learning to how brain function is affected by normal aging and in the presence of cognitive illnesses such as Alzheimer’s Disease.
There are many ways to study the internal workings of the brain, says Dr. Jennifer Ryan, a senior scientist at Baycrest’s Rotman Research Institute who holds the Canada Research Chair in the Cognitive Neuroscience of Memory at the University of Toronto.
“Whether a person is meditating or performing a particular experimental task, we can pick up brain activity as changes in electromagnetic signals, in cerebral blood flow, and in neurotransmitter uptake,” she explains. “Combining various neuro-imaging techniques allows us to see where in the brain these changes are occurring, when those changes arise, and how those changes are ultimately related to behavior, all within the same testing session.”.
But it takes more than just combining two or more brain imaging techniques to fully enter into the domain of “convergent technology.” Researchers must demonstrate that such testing yields information that is new and valuable, and they must develop protocols that optimize the information gleaned from each methodology. Finally, they must be equipped to analyze the resulting data and explain their findings to others.
“In many ways Baycrest is ideal for this converging technologies approach to happen and to be rewarding,” says Dr. Randy McIntosh, Director of the Rotman Research Institute, and vice-president of research at Baycrest. “We have access to the necessary hardware—the MRI, EEG, PET, MEG and eye-tracking equipment—and to the software. In fact, we have actually developed many of the analytical techniques in-house, and make them available open source to the scientific community.”
Here six Baycrest scientists, including Dr. Ryan, describe the role of different brain imaging in their own research:
“Auditory perception and how the perception of sound changes as we get older. For example, we know that many older people find it hard to communicate when they’re in a crowded and noisy room. But how do you manage to segregate the conversation that you are interested in? What are the relevant cues, what parts of our brains help us sort this out this auditory scene? And how does this change with age?
To gain more information, we are using different brain imaging techniques. Basic EEG recording allows us to measure how long it takes the subject’s brain to process different kinds of information. Using functional MRI adds another angle, helping us see what part of the person’s brain might be involved as he or she tries to understand speech in a noisy situation.
Our goal is to see how these different measurements of brain activity can inform each other. As we learn more, we could develop concrete solutions–for example, modified hearing aids – and advice for older people to help them overcome the changes in auditory processing which occur with aging.”
“My research is focused on what causes that crucial shift from Stage 2 of a specific type of dementia called frontotemporal dementia (i.e., a definitely abnormal behavioural and personality change that intensifies and almost always requires pharmacotherapy) to Stage 3 (i.e., the person’s symptoms subside and he or she becomes withdrawn, unmotivated, and intermittently agitated).
In the past, the only way to study the progression of frontotemporal dementia was to wait and do post-mortem (after death) analysis of brain tissue. But we may be able to derive valuable information while the person is still alive. My own efforts have utilized positron emission tomography (PET) imaging and functional MRI methods. The long-range goal is to identify a clear target to inform the development and use of cognition-enhancing drug therapies.”
“While many of the cognitive deficits that occur after traumatic injury, neurological illness or stroke are obvious, others are quite subtle and hard to measure and aren’t readily apparent in neuropsychological or neurological examinations. We are hoping to close that gap.
We’re developing and using novel assessment and rehabilita¬tion techniques, coupled with new brain imaging tools such as structural and functional mag¬netic resonance imaging (fMRI), electroencephalography (EEG), and magnetoencephalography (MEG), a non-invasive technology that measures the magnetic fields generated by brain activity.”
“We have been studying how memory works – and fails to work – in people affected by Alzheimer’s Disease, brain tumors and infections, by traumatic brain injury, and by psychiatric disturbances such as Post-traumatic Stress Disorder (PTSD) and delusions.
My own research involves using a variety of brain imaging methods including functional magnetic resonance imaging (fMRI) and positron emission tomography (PET).”
“My research interest in cognitive neuroscience focuses on brain plasticity and its implications for neurotraining and neurorehabilitation. I am especially interested in how training and rehabilitation can affect higher order processes such as language, memory and intelligence. My research program incorporates multiple platforms including behavioural testing, electroencephalography (ERP), magnetoencephalography (MEG), functional magnetic resonance imaging (fMRI) and neuropsychological studies.”
“I take a converging methodologies approach to address questions regarding the type of information maintained in representations formed by working- and long-term memory systems and the role of conscious awareness in the use of such representations in performance.
Our lab provided what we believe to be the first demonstration of simultaneous eye movement and magnetoencephalograpy recordings. This combination of techniques is being used to outline the memory systems that support the access of stored information and the comparison of such information with the external environment. The goal is to understand the neural changes that accompany conscious awareness for stored information and environmental changes. Ultimately this research will be extended to investigate the underlying changes that culminate in age-related cognitive impairments”.
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