Frontal Lobes and Memory
I’ve been developing an interest in the role that the frontal lobes play in memory. We traditionally think of memory as heavily based in the medial temporal lobes. At least, the medial temporal lobes are larely responsible for the creation of new memories. Without the hippocampus and the surrounding area people have anterograde amnesia, which is the inability to form new memories. The classic and most well known example of this is the patient H.M. Researchers recognize the role that other areas of the brain have in memory but most memory research has focused on the medial temporal lobes – at least until recently (with recently being the last 20 years or so). New ideas take a while to develop and gain acceptance so some of these ideas about the role of other brain areas in memory creation are still developing.
For example, we now know that when information needs to be organized, such as in something like the Rey-Osterrieth Complex Figure (read here for a short description of the test) or with a list learning task with words from specific semantic categories, the frontal lobes are involved.
If the frontal lobes are heavily involved in the organization of information it follows that memory tests that require more organization of material should be affected by dysfunctioning of the frontal lobes. Some researchers are now trying to place certain functions with greater specificity within the frontal lobes. This isn’t really phrenology because the methods of phrenology were entirely suspect. Phrenologists extrapolated personality and cognitive characteristics of people based of measurements of their skulls. Many researchers who are interested in localizing brain functions do so by testing people with specific brain
lesions (injuries). If enough patients have damage to X part of the brain and subsequently have Y deficits, then we can assume that X is necessary for Y to occur (but is not necessarily sufficient for Y to occur). Phrenologists never looked at the brain or the head in this manner. Paul Broca was one of the first, with his patient Tan, to systematically look at the relationship between brain injury and behavior.
For a long time many people believed (and many still do) that certain areas of the frontal lobes, specifically the most anterior areas of the frontal lobes, are essentially superfluous. They base this idea on cases where
people have had damage to this area of the brain but apparently suffered no ill effects. Research has consistently not supported that view. We don’t have any non-necessary brain. What we do have are tests and measures that are not sufficiently sensitive nor specific. The brain is also very complex and most functions rely on networks of brain structures. We are also learning that the white matter in the brain is very involved in behavior and cognition (this is my own area of research). The more we learn, the more we realize our ignorance about the brain. There are layers upon layers to be unwrapped and understood about the brain.
Image by Debbi in California.