dents, a principal, classrooms with desks and chairs, etc. Connectionismtheory states that
memory is stored throughout the brain in connections between neurons,many of which
work together to process a single memory. Changes in the strength of synaptic connections
are the basis of memory. Cognitive psychologists and computer scientists interested in artifi-
cial intelligence(AI) have designed the neural networkorparallel processing modelthat
emphasizes the simultaneous processing of information, which occurs automatically and
without our awareness. Neural network computer models are based on neuronlike systems,
which are biological rather than artificially contrived computer codes; they can learn, adapt to
new situations, and deal with imprecise and incomplete information.
Biology of Long-Term Memory
According to neuroscientists, learning involves strengthening of neural connections at
the synapses, called long-term potentiation(or LTP). LTP involves an increase in the
efficiencywith which signals are sent across the synapses within neural networks of long-term
memories.This requires fewer neurotransmitter molecules to make neurons fire and an
increase in receptor sites. Where were you when you heard about the 9/11 disaster? Like a
camera with a flashbulb that captures a picture of an event, you may have captured that
event in your memory. A flashbulb memory,a vivid memory of an emotionally arousing
event, is associated with an increase of adrenal hormones triggering release of energy for
neural processes and activation of the amygdala and hippocampus involved in emotional
memories. Although memory is distributed throughout the brain, specific regions are
more actively involved in both short-term and long-term memories. The role of the
thalamusin memory seems to involve the encoding of sensory memory into short-term
memory. STM seems to be located primarily in the prefrontal cortex and temporal lobes.
Thehippocampus, frontal and temporal lobes of the cerebral cortex, and other regions
of the limbic system are involved in explicitlong-term memory. Destruction of the
hippocampus results in anterograde amnesia,the inability to put new information into
explicit memory; no new semantic memories are formed. Another type of amnesia, retro-
grade amnesia,involves memory loss for a segment of the past, usually around the time
of an accident, such as a blow to the head. This may result from disruption of the process
of long-term potentiation. Studies using fMRI indicate that the hippocampus and left
frontal lobe are especially active in encoding new information into memory, and the right
frontal lobe is more active when we retrieve information. A person with damage to the
hippocampus can develop skills and learn new procedures. The cerebellumis involved in
implicitmemory of skills.
Retrieving Memories
Retrievalis the process of getting information out of memory storage. Whenever we take
tests, we retrieve information from memory in answering multiple-choice, fill-in, and essay
questions. Multiple-choice questions require recognition,identification of learned items
when they are presented. Fill-in and essay questions require recall,retrieval of previously
learned information. Often the information we try to remember has missing pieces, which
results in reconstruction,retrieval of memories that can be distorted by adding, dropping,
or changing details to fit a schema.
Hermann Ebbinghaus experimentally investigated the properties of human memory
using lists of meaningless syllables. He practiced lists by repeating the syllables and keeping
records of his attempts at mastering them. He drew a learning curve. Keeping careful rec-
ords, he then tested to see how long it took to forget a list. He drew a forgetting curvethat
declined rapidly before slowing. He found that recognition was sometimes easier than recall
to measure forgetting. A method he used to measure retention of information was the sav-
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