The frontal lobes rely on processing of internal information, including memories, in order to guide behavior, while the parietal lobes specialize in processing of externally-based sensory information, in order to guide behavior. Both sources of information are needed to self-regulate one's own behaviors but internal mnemonic sources are crucial to resist enslavement to external and salient events (p. 72)."
While McNamara has explained the technical functions taking place in the hippocampus, he ends his explanation above by helping us understand, in short, the hippocampus is our "self-regulation" of our behavior, or our personality (p. 72). It is how we, or others, might describe us.
Injury or disease can interrupt or alter the processes taking place between the frontal systems and the posterior parietal systems, and since the frontal lobes rely on processing information, including memories, damage can result in how that information is processed and can impact, of course, the personality since the hippocampus is the regulator of personality (p. 72).
The frontal lobes were only supposed to assist other neuroanatomical structures (e.g., the hippocampus) in doing the real work of memory. The role of the frontal lobes was restricted to helping develop strategies to facilitate encoding, storage, or retrieval. Patients with frontal lobe dysfunction, for example, do not spontaneously use categorization or chunking strategies to memorize large amounts of material. They do not efficiently encode contextual information, such as time and place, surrounding an event (or an experimental trial). They do not easily recall where or how they acquired or learned a new piece of information (source amnesia), nor can they say which piece of information, among an array of similar items, they learned most recently. Finally, patients with frontal lesions are not as proficient as controls at making judgments and predictions about their own memory abilities. All of these deficits seem to involve memory operations, rather than memory content per se, so it is not surprising that before the advent of PET scanning, the role of the frontal lobes in memory was assumed to be important but indirect and peripheral to the main action (p. 74)."
As our understanding of memory and how it stored, retrieved begins to take shape, we readily see that there is much more to memory, memory storage, and memory retrieval than probably most people might have thought there was to it. But the understanding the hippocampus, our personality, where it comes from and how it works with our memory in the way we respond to stimuli is just a small part of the overall process.
Learning and Memory
Old theories and beliefs about memory and the brain have been revised over the past two decades of research. Technology has contributed to this revised understanding, and what has been learned thanks to the technological advances in medicine and science are intriguing and fascinating insights into how memory works. Judy Willis (2007) discusses these new insights, saying:
It was a long-held misconception that brain growth stops with birth and is followed by a lifetime of brain cell death. Now we know that although most of the neurons where information is stored are present at birth, there is lifelong growth of the supporting and connecting cells that en rich the communication between neurons. These "dendrites" sprout from the neuron's arms (axons) or cell body (p. 310)."
While this new information is still being studied and analyzed, certain tests have, as reported by Willis, shown that certain learning activities, such as learning to juggle or learning a second language, produce certain changes in the brain (p. 310). Willis says that engaging in learning actually increases one's capacity to learn (p. 310). However, when learning ceases, for instance, when the juggler stops juggling, the result is that the chemical (in the case of juggling) the gray matter that was created by the brain and directly associated with juggling, ceased being created by the brain. The juggling was the stimuli that created the chemical creation and release of the gray matter in the brain that was observed in the occipital lobes, or the visual memory areas (p. 310). In other words, in the instance of juggling, the juggler would have had a greater degree of visual memory ability as a result of the activity of juggling; when the activity ceased, so did the increased ability that existed in the visual memory relationship (p. 310).
This would be a good scientific explanation to a judge as to why a group of individuals witnessing the same event might describe it differently from one person to the next. Unless the person describing the event is engaged in an activity or event on a regular basis that stimulates the brain to create the visual memory relationship, as in the case of the juggler; then an individual's visual memory might not be as keen from one person to the next.
It is also why policemen are deemed memory credible, because the activity of observation and paying close attention to the details of what is taking place around them is a continual activity.
Connectionist or neural network models are based on the principle that the brain stores engrams by increasing the strength of connections between different neurons that participate in encoding an experience. When we encode an experience, connections between active neurons become stronger, and this specific pattern of brain activity constitutes the engram. Later, as we try to remember the experience, a retrieval cue will induce another pattern of activity in the brain. If this pattern is similar enough to a previously encoded pattern, remembering will occur. The "memory" in a neural network model is not simply an activated engram, however. It is a unique pattern that emerges from the pooled contributions of the cue and the engram. A neural network combines information in the present environment with patterns that have been stored in the past, and the resulting mixture of the two is what the network remembers. The same conclusion applies to people. When we remember, we complete a pattern with the best match available in memory; we do not shine a spotlight on a stored picture (1996, p. 71)."
McNamara discusses the selectionist theory of memory model, saying:
any selectionist theory of memory must be composed of at least three processing components: a generation (or proliferation) phase, a selection phase, and a cumulative retention or amplification phase (p. 38)."
Both Schacter and McNamara are talking about the levels of processing theory introduced in 1972 by Craik and Lockhart, whose theory held that there were levels of memory processing: depth of processing, maintenance and elaborative rehearsal, implicit and explicit memory, and update (Craik, Fergus and Lockhart, R.S., 1972, p. 301)."
It is possible to test Willis' and McNamara's theories and models using our example of the policeman. The hypothesis is: A policeman's memory will fit the description of the models (both of which are based on the Craik and Lockhart levels of processing theory). The policeman's memory will, by virtue of his continuous use of his memory and attention to detail, much like the juggler, will have a higher level of gray matter (the visual to memory relationship) in the brain than will a witness selected from a category of employment whose work does not involve the continuous attention to detail - like a rock musician.
We might test the memory of the musician and against that of the policeman for an accuracy of visual details with specific test that employs a series of actions using a series of items. We might, for instance, take a crime scene from the hit movie Heat (1995), directed by Michael Mann. There is a bank robbery scene towards the end of the film, and there are a series of events that are detailed and numerous and require the viewer to pay attention closely to be able to follow the remainder of the film. We will show the selected three-minute segment of the film to a group of police officers, and to a group of musicians, whose daily lives involve the sensory memory as opposed to the visual memory.
After the viewing of the film, we will administer a questionnaire designed to take the participants through the levels of processing, and analyze the results for the greater level of demonstrated accuracy.
The hypothesis is that the policemen will, by virtue of the fact that the viewed segment is criminal elements vs. law enforcement, demonstrate a more precise level of recall concerning the details and events.
Memory Loss and Disease
This brief study has shown that the discussion of memory is a fascinating one, and that it is impossible to consider all of the information and processing of this fascinating aspect of human ability and functioning in a brief study. However, one area that must be given attention is memory loss, defect, and disease.
As has been mentioned already, when the brain suffers an injury or experiences deficiencies in chemical production, the result is disease and memory…