In patients with Huntington' s disease, it' s the part of the brain called the basal gangl
Within explicit, or declarative memory, on the other hand, there are specific subsystems that handle shapes, textures such as faces, names--even distinct systems to remember nouns vs. verbs. All of these different types of memory are ultimately stored in the brain' s cortex, within its deeply furrowed outer layer--a component of the brain dauntingly more complex than comparable parts in other species. Experts in brain imaging are only beginning to understand what goes where, and how the parts are reassembled into a coherent whole that seems to be a single memory is actually a complex construction. Think of a hammer, and your brain hurriedly retrieves the tool's name, its appearance, its function, its heft and the sound of its clang, each extracted from a different region of the brain. Fail to connect person ' s name with his or her face, and you experience the breakdown of that assembly process that many of us begin to experience in our 20s and that becomes downright worrisome when we reach our 5Os.
It was this weakening of memory and the parallel loss of ability to learn new things easily that led biologist Joe Tsien to the experiments reported last week. "This age-dependent loss of function." he says, "appears in many animals, and it begins with the onset of sexual maturity."
What' s happening when the brain forms memories--and what fails with aging, injury and disease--involves a phenomenon know as "plasticity". It's obvious that something in the brain changes as we learn and remember new things, but it' s equally obvious that the organ doesn ' t change its overall structure or grow new nerve cells wholesale. Instead, it' s the connections between new cells and particularly the strength of these connections that are altered by experience. Hear a word over and over, and the repeated firing of certain cells in a certain order makes it easier to repeat the firing pattern later on. It is the pattern that represents each specific memory.
Which of the following symptoms can be observed in a person who suffers from the Hunting ton' s disease?
A.He cannot remember what he has done but can remember trying to learn.
B.He cannot do something new but he can remember doing it.
C.He suffers from a bad memory and lack of motor skills.
D.He suffers from a poor basal ganglia and has intact explicit memory