If memories of your long lost love keep cropping up while you are trying to focus on your current assignment, your brain may literally be stuck between two frequencies, reports Laura Colgin, a postdoctoral researcher at the Norwegian University of Science and Technology. This can be frustrating. It's like trying to catch an update on NPR while a Michael Jackson song pops in and out, she says. In her research, Colgin is looking at how the brain's ability to switch between different frequencies of gamma brainwaves helps us stay focused.
Radio Brain
Researchers have known for some time that gamma waves correlate with conscious experience. But they could not explain why frequencies alternated widely. To get to the bottom of this mystery, Dr. Colgin and her colleagues looked at gamma brainwaves in the rat hippocampus, a central area for memory. They found that lower frequencies of gamma waves carry information about the past, whereas higher frequencies uncover the present. Neurons normally stay on the relevant frequency. But neurological disorders can impair the brain's switching mechanism.
Filing Cabinet
Cells in the hippocampus not only act as gamma switches, they are also highly specialized in terms of which kinds of information they store, report Wake Forest researchers in the March 2, 2004 issue of Proceedings of the National Academy of Sciences. Other brain cells compute shape, color or brightness. The hippocampus' category cells are different; they sort information based on common features. "For example, [we found that] the same cell responded to both tulips and daisies because they are both flowers," says team member Terry Stanford. The findings indicate that memory may fail when category cells become less efficient, something that often happens with old age.
Aging
Bad concentration and memory in elderly individuals have different neural correlates, report researchers from Baycrest's Rotman Research Institute. Difficulties forming new memories correlates with decreased activity in the hippocampus, whereas difficulties focusing correlates with increased activity in the sensory systems and the frontal lobe. The team stumbled on these findings when they looked at how the loud noise from brain scanners affects brain activity in elderly study participants. Only elderly individuals' brains were significantly affected by the scanner's banging noise, explains junior researcher Dale Stevens.
Chronic Pain
Chronic pain may impair working memory, reveals a Canadian research team in the May, 2007 issue of Anesthesia and Analgesia. Working memory is what allows you to keep information in your head. The capacity of working memory is low, but "chunking" can improve its retentiveness. For example, by using labels such as "Christmas," "birth year" and "terrorism," someone born in 1982 may be able to retain the 12-digit sequence "122519820911." Pain can disrupt this ability and hinder long-term storage, report the researchers.
Chemobrain
Cancer patients frequently experience neurological side effects of chemotherapy, such as difficulties concentrating and retaining new information. Specialists used to attribute the symptoms to depression. But they now recognize "chemobrain" as a real neurological disorder. Chemotherapy can damage the brain's white matter, the myelinated nerve fibers that carry impulses between neurons, report researchers from the University of Rochester Medical Center and Harvard Medical School in the April 22, 2008 issue of Journal of Biology. The researchers found that chemotherapy can damage stem cells that develop into white matter. This can impair processing of sensory information.
References
- Science Daily: How the Brain Filters out Distracting Thoughts to Focus on a Single Bit of Information
- Science Daily: New Findings On Memory Could Enhance Learning
- Science Daily: More Evidence The Aging Brain Is Easily Distracted
- "Anesthesia and Analgesia"; Disruption of Attention and Working Memory; Dick & Rashiq; May 2007
- Science Daily: Chemotherapy's Damage To The Brain Detailed
