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Neuroscientist analyzes human ability to look forward

"The development of civilization as it stands is only because of an awareness of the existence of a future," said Endel Tulving, the Tanenbaum chair in cognitive neuroscience at the Rotman Research Institute of Baycrest Centre at the University of Toronto, during his lecture in a mostly-filled Love Auditorium yesterday.

Using his thesis, Tulving discussed with his audience of professors and students that this awareness is a unique form of memory that does not exist in other species and is primarily located within a specific brain structure.

Tulving defined the awareness of our personal past and future as autonoetic consciousness, also known as episodic memory.

"Autonoetic memory is unique in that no other kind of memory requires you to travel back into your own past," he said, contrasting autonoetic with semantic memory, which comprises activities like recalling a phone number, for example.

Other memories involve the past, but not the personal past.

To illustrate the importance of episodic memory, Tulving discussed a patient whom he calls K.C. The patient is a 50 year-old man who suffered from a traumatic brain injury as a result of a motorcycle accident 20 years ago.

He remembers the rules of chess, though he cannot play a very good game, and can elaborate on the details of the latest Star Wars movie.

K.C. cannot, however, remember anything he's experienced on his own.

"He also cannot tell you anything about his own future," Tulving said.

In short, unlike other humans, K.C. cannot travel into his own past or future, so he cannot, for example, describe what he will do for the remainder of his day.

Although Tulving's theory proposes that animals do not have this kind of memory, he conceded that there is no real evidence to prove or disprove this aspect of his theory. He further explained that it is difficult to think of a reason as to why animals would need episodic memory to survive and adapt.

During his lecture, Tulving asked why episodic memory evolved in humans and what purpose it serves. "The adaptive value lies not in being able to remember facts but in... an awareness of subjective time," Tulving said. "The most important human capacity... is our ability to be consciously aware of an existence of the future and take account of it [in our actions]."

Like other forms of memory, episodic memory has been localized to a specific brain region. Tulving said that likely candidates had included any "place in the brain that's recently evolved... and whose functions are unknown."

Using PET imaging, Tulving and his colleagues determined that the portion of the brain closest to the forehead, known as the prefrontal cortex, is active when people are involved in a task using episodic memory.

Even more accurately, episodic memory is localized to the right hemisphere of this part of the brain. Tulving warned his audience, however, that "the past is not in the right prefrontal cortex." That part of the brain is simply prominently used when a test subject is involved in a task that requires episodic memory.

So, having determined the primary location of episodic memory, Tulving asked his audience to consider the location of autonoetic awareness of the future. "Where is the awareness of the future? I cannot tell you because the research has not been done yet," Tulving quipped, encouraging younger members of the audience to go into the labs and find out.

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