St. Michael's Hospital in Toronto is reporting only the second known case of a brain injury causing the development of synesthesia, a condition where sensory information — such as a particular shade of blue or the smell of tiger lilies — involuntarily becomes linked to an emotional response like anger or elation.

Most people with synesthesia, including famous artists and musicians Franz Liszt, Vasily Kandinsky, Duke Ellington, and Billy Joel, are born with it, but incidents involving the misprocessing of emotions are extremely rare.

In this case, a 45-year-old male, who wishes to remain anonymous, developed synesthesia nine months after suffering a hemorrhagic stroke in his brain's thalamus. Whenever the man heard high-pitched brass instruments — specifically the theme song from James Bond movies — he became overwhelmingly elated.

At the same time his perception of the color blue shifted. Eating raspberries made him automatically think of a shade of blue, but conversely seeing the color made his mouth taste like raspberries.

MRI brain scans of the stroke patient in question revealed that his thalamus now responded differently to these sounds and colors when compared to six men with a similar age and education level.

"The areas of the brain that lit up when he heard the James Bond Theme are completely different from the areas we would expect to see light up when people listen to music," said Dr. Tom Schweizer, director of the neuroscience research program at St. Michael's Li Ka Shing Knowledge Institute. Schweizer published the details of this clinical case in Neurology.

"Huge areas on both sides of the brain were activated that were not activated when he listened to other music or other auditory stimuli and were not activated in the control group," Schweizer writes.

The thalamus is a region of the brain that serves as the mind's crossroads, especially when it comes to the primary senses: sight, hearing, taste, smell, and touch. When sensory information — like colors or sounds — are fed into the brain, they pass through and encoded by the thalamus before being sent to the parts of the mind that decide how to react. The other known case of acquired synesthesia was also the result of a thalamic injury.

This patient could also turn his synesthesia on and off, which was another unusual, but cool, feature of his newly acquired brain function.

Dr. Luis Fornazzari, a behavioural neurologist at St. Michael's Hospital who first identified the patient's synesthesia, describes the symptoms of synesthesia.

Source: Schweizer TA, Li Z, Fischer CE, Alexander MP, Smith SD, Graham SJ, Fornazarri L. From the thalamus with love: A rare window into the locus of emotional synesthesia. Neurology. 2013.