The lecture will take place Nov. 9 at 2pm in the Robert McEwen Auditorium, W141 Seymour Schulich Building, Keele campus. AĚýreception will follow the talk.

Brains need to make quick sense of massive amounts of ambiguous information with minimal energy costs and have evolved an intriguing mixture of analog and digital mechanisms to allow this efficiency. Analog electrical and biochemical signals inside neurons are used for integrating synaptic inputs from other neurons. The digital part is the all-or-none action potential, or spike, that lasts for a millisecond or less and is used to send messages over a long distance.

Terry Sejnowski

"Spike coincidences occur when neurons fire together at nearly the same time," says Sejnowski. "In this lecture I will show how rare spike coincidences can be used efficiently to represent important visual events and how this architecture can be implemented with analog Very Large Scale Integration (VLSI) technology to simplify the early stages of visual processing."

Sejnowski is professor and laboratory head of the Computational Neurobiology laboratory.ĚýHe is considered to beĚýa pioneer in computational neuroscience and his goal is to understand the principles that link brain to behavior. His laboratory uses both experimental and modeling techniques to study the biophysical properties of synapses and neurons and the population dynamics of large networks of neurons.

Among other things, Sejnowski is interested in the hippocampus, believed to play a major role in learning and memory; and the cerebral cortex, which holds our knowledge of the world and how to interact with it. In his lab, Sejnowski's team uses sophisticated electrical and chemical monitoring techniques to measure changes that occur in the connections among nerve cells in the hippocampus during a simple form of learning. They use the results of these studies to instruct large-scale computers to mimic how these nerve cells work. By studying how the resulting computer simulations can perform operations that resemble the activities of the hippocampus, Sejnowski hopes to gain new knowledge of how the human brain is capable of learning and storing memories. This knowledge ultimately may provide medical specialists with critical clues to combating Alzheimer's disease and other disorders that rob people of the critical ability to remember faces, names, places and events.

Sejnowski has published more than 300 scientific papers and 12 books, including The Computational Brain (1992), with Patricia Churchland.ĚýHeĚýreceived his PhD in physics from Princeton University and was a postdoctoral fellow at Harvard Medical School. He was on the faculty at the Johns Hopkins University and now holds the Francis Crick Chair at The Salk Institute for Biological Studies. HeĚýis a professor of biology at the University of California, San Diego, where he is co-director of the Institute for Neural Computation and co-director of the National Science Foundation (NSF)Ěý.ĚýSejnowski is the president of the Neural Information Processing Systems (NIPS) Foundation, which organizes an annual conference attended by over 1000 researchers in machine learning and neural computation and is the founding editor-in-chief of Neural Computation published by the MIT Press.

An investigator with the , he is also a Fellow of the American Association for the Advancement of Science and a Fellow of the Institute of Electrical and Electronics Engineers. He has received many honors, including the NSF Young Investigators Award, the Wright Prize for interdisciplinary research from the Harvey Mudd College, the Neural Network Pioneer Award from the Institute of Electricaland Electronics Engineers and the Hebb Prize from the International Neural Network Society.

Sejnowski wasĚýelected to the Institute of Medicine in 2008, to the National Academy of Sciences in 2010 and to the National Academy of Engineering in 2011. He is one of only 10 living persons to be a member of allĚýthree national academies.

The Ian P. Howard Lecture Series in Vision ScienceĚýprovides a venue for world-renowned vision researchers to deliver lectures on their findings.

The series was established in 2006 to celebrate Howard’s enormous contributions to the international reputation ofĚý91ŃÇÉ«'s Centre for Vision Research. Howard’s own research investigates the fundamental mechanisms that enable humans to orient themselves and perceive the three-dimensional layout of their surroundings.

For further information, contact Teresa Manini, administrative assistant, Centre for Vision Research, at manini@cvr.yorku.ca.

Republished courtesy of YFile– 91ŃÇɫ’s daily e-bulletin to research stories on the research website.

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His talk, Circadian rhythms: Molecules, Neurons and Circuits, will take place Wednesday, Oct. 24, from 1:30 to 2:30pm, in the Senate chamber, Ross N920, Keele campus, as part of Gairdner’s National Program lecture series.

Rosbash of the Howard Hughes Medical Institute, Department of Biology, Brandeis University, is the 2012 Canada Gairdner Award winner. He’ll delve into the mysteries of how the human body’s biological clock works. Despite the fact that it’s been known for centuries that the human body is controlled by a biological clock, it has remained a mystery. Rosbash will look at how this internal clock guides the body through the day.

Michael Rosbash

Circadian clocks are active throughout the body’s cells, where they use a common genetic mechanism to control the rhythmic activities of various tissues. This is important as circadian clocks affect patterns of sleep and wakefulness, metabolism and the body’s response to disease. Understanding how the biological clock works has already allowed scientists to pinpoint irregularities in important sleep disorders.

“The opportunity to learn from the world’s greatest medical minds is one we hope will inspire students across the country to be imaginers, innovators, and ultimately, cultivators of the future of medicine in Canada and around the world,” said Dr. John Dirks, president and scientific director of Gairdner. “Gairdner’s National Program is our way of helping to ensure that Canada continues to grow as a global leader in medical science.”

The Gairdner awards are among the world’s most important biomedical research honours and a major indicator of leading scientific discovery. The Gairdner National Program is a month-long lecture series given by Canada Gairdner Award winners to over 6,000 students at 21 universities from St John's to Vancouver.

The National Program reaches students across the country, making the superstars of science accessible and inspiring the next generation of researchers. Along with the Canada Gairdner Awards, the National Program is part of Gairdner's efforts to promote a stronger culture of research and innovation across the country.

Republished courtesy of YFile– 91ŃÇɫ’s daily e-bulletin to research stories on the research website.

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“Your ability to recognize objects and your ability to recognize scenes are independent,” says Steeves.Ěý

Their study is published in the December issue of the Journal of Cognitive Neuroscience – “TMS to the Lateral Occipital Cortex Disrupts Object Processing but Facilitates Scene Processing”.

Left: Psychology Professor Jennifer Steeves applies rTMS stimulation toĚýPhD candidate Caitlin Mullin. Images of Mullin's brain can be seen on the adjacent screenĚý

The finding discounts an earlier theory that scene perception relies on the recognition of individual objects and instead finds that the gist of a scene can be ascertained by its spatial layout alone.

Steeves and Mullin conducted two experiments. Both showed that when the ability to see objects is impaired, the brain can still determine what it’s looking at by taking in the scene. But what surprised the researchers is that when object recognition was temporarily knocked out, the ability to categorize scenes, such as distinguishing a forest from a cityscape, increased.

“It’s like you can see the forest better when you can’t see the trees,” says Steeves, who heads up the Perceptual Neuroscience LabĚýin 91ŃÇÉ«'s . “We didn’t expect this at all. The stimulationĚýmust be releasing some inhibitory process in people's brains.”

The experiments involved nine individuals with healthy brains. Repetitive transcranial magnetic stimulation (rTMS) was applied to the left lateral occipital cortex (LO), the object processing area of the brain just behind each ear, to disrupt object processing. This was done while showing the subjects pictures of scenes and objects.

Right: Jennifer Steeves

The idea was to see how the LO contributed to the perception of scenes. The rTMS momentarily scrambled the neurons in the LO, preventing the subject from recognizing the objects, but they were able to categorize the scenes more quickly and accurately than before. The first experiment involved using a longer disruption time for object processing than that used in the second experiment.

“There was a split second interruption to the brain in the second experiment,” says Steeves. Still, the second experiment confirmed the findings of the first. “It’s a really robust effect. The TMS showed us that even though the two functions are independent, they still work together.”

Steeves and Mullin are now doing research find out what other parts of the brain are affected when rTMS is applied to specific areas. “We’re finding so far that stimulating one region can have an effect on other areas,” says Mullin.

The research is part of the nuts and bolts of mapping the brain, which could have implications down the road in helping people with brain injuries or informing computer modelling. “What’s nice is we’re learning about networks in the brain,” says Steeves. And that is where it all starts.

The experiments were funded through grants from the Canada Foundation for Innovation, the Ontario Research Fund and the Natural Sciences & Engineering Research Council of Canada.

By Sandra McLean, YFile writer

Republished courtesy of YFile– 91ŃÇɫ’s daily e-bulletin.

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