Kandel, and Compare and Contrast

¶ … Kandel, and compare and contrast the declarative (explicit) and non-declarative (implicit) memory and learningsy stems. Include the biological (e.g., neural substrate, neurophysiological) and cognitive/psychological processes (e.g., can be established in a single trial or experience) that uniquely implement these two forms of learning and memory.

Biologists and practitioners of neuroscience have long since recognized that people have two forms of memory systems: the declarative (explicit) and non-declarative (implicit) memory and learning system. Each originates from different sources, does different tasks, and inhabits different regions of the brain. Evidence for separate memory systems of explicit and implicit learning was documented by the neurophysiologist in the famous case of HM where it was discovered that HM could learn new motor skills at a normal rate whilst learning gaps in his explicit abilities, unable for instance to remember details about his wife or where he had been the previous moment. HM, for instance could draw the outlines of a tar whilst looking at that same star within a mirror. Further work on HM by Larry Squire and others showed that these memory skills also extended to others such as priming or perceptual tasks as well as operant conditioning. The commonality was that the tasks tended to be reflexive rather than reflective and did not require conscious awareness. All of this fell under the hubris of explicit memory. Experimentation on HM more clearly demonstrated that implicit and explicit memory was two different capacities.

The neurobiological study of memory comes up with certain generalizations: memory proceeds in stages; long-term memory is represented in various neural regions throughout the nervous systems; and explicit and implicit memories employ different neuronal circuits. Both explicit and implicit memory inhabits different regions and consequently does different tasks. Explicit memory (or declarative memory) is harder to retrieve. It involves the memorizations of facts, experiences and stimuli and retrieving of this data. Entrenched data that is vivid and consciously reiterated in the brain can be easily retrieved, but other data needs conscious effort and takes far slower than implicit memorization.

Explicit memory may also be classified and reducible to "episodic" (memory of events and personal experiences) and "semantic" (memory for facts).

The implicit memory on the other hand (or procedural or non-declarative) is innate. It takes a while to master the craft (such s driving) in the first place, but once mastered the memory of the steps is instinctive and prodded effortlessly.

Long-term storage of explicit memory requires the temporal lobe system. Storage of implicit memory however relies on cerebellum, amygdala and specific sensory and motor systems that are necessary and involved with that specific learned task.

On the other hand, similarities with both implicit and explicit memories that learning data are lodged in various regions of the brain simultaneously so that when one is corrupted all share impediments although unless impediment is widely spread the larger characteristic remains present. This explains why a lesion does not erase a memory or why a single impediment in speech may (for instance cause a stammer) but does not erase the ability of speech.

With explicit memory, on the other hand, any lesion effecting any major neural region can have a tremendous impact on the explicit memory system as a whole as in the case of Alzheimer where since the lesion exists in a major neural cortex it effects that whole memory system. Researchers, in fact, have discovered that whilst victims of Alzheimer are unable to remember fundamental explicit details such as their name or names of those closest to them, they do remember how to (for instance) brush their teeth. The explicit memory is destroyed; the implicit memory remains.

Lesions also with explicit memory affect the explicit data in a different way than lesions connected with implicit data does. Researchers, for instance, found that certain lesions interfere with the memory of living objects but not with the memory of inanimate objects.

Discussing similarities, however, both types of memory share similarities in that both are stored in association cortices meaning that when any one part of the memory is prodded, it stimulates a chain of similar memories (associates) in response. Trying to remember someone's name for instance stirs s up other details such as visual details of face and other associative details of person. In a similar way, details connected with a procedure (of implicit memory) flow into the brain in a holistic undifferentiated picture due to both types of memory being stored in association cortices.