Memory Systems in the Brain Erik Avila Michelle Yarbrough Donnell Upchurch Greg Kalkanoff

Introduction In order to determine whether or not two memory systems do exist we conducted an experiment to prove our hypothesis. Hypothesis: We believe that electrical activity in the brain will generate different brainwave patterns depending on the responses elicited, ultimately proving that there are indeed two memory systems.

Method and Procedure One subject was used to conduct this EEG experiment There were 200 high- familiarity words and 200 low-familiarity words chosen to be presented as the stimuli The subject was also exposed to 200 distracter words The subject studied the 400 high and low familiarity words and then asked to provide a “remember,” “know”or “new” response. “Remember” indicates recalling the word being present in the group of word he had studied earlier “Know” response indicated a vague feeling of familiarity “New response indicated an unfamiliar word

In all of the trials in which the test subject gave a correct response of “remember,” activity in the frontal region of the brain is observed throughout the entire 1000 ms. This suggests the presence of a separate explicit memory system in this area.

In the trials in which the test subject gave the correct answer of “know,” although there was activity observed in the frontal area at 200 ms, all of the following activity is measured in the rear or occipital region of the brain. This suggests a separate implicit memory system that functions only in the occipital area of the brain.

In all trials where the test subject correctly answered “remember” where the words were of low familiarity, high activity was observed in the occipital region of the brain, but also observed in the frontal portion of the brain from 200 ms and continuing throughout the measuring period, also confirming the existence of an separate explicit memory system in this area.

In the trials in which the words were of low-familiarity and the test subject answered with the correct response of “know,” oddly, both the frontal and occipital regions of the brain were active throughout the measuring time. This, although not disproving the idea of two distinct memory systems, does suggest that perhaps in cases of low-familiarity words, both the implicit and explicit systems are used in conjunction to recall the desired info.

In the overall trials the only area of the brain in which the activity was higher for a remember response was in the frontal region, confirming the existence of the explicit memory system in the frontal lobe. Although in the frontal area of the brain, the familiar response also generated high activity, but this could be explained by the presence of low-familiarity words, causing both systems to activate.

FINDINGS CONCLUSIONS “Remember” and “know” responses produced different amounts of electrical activity in different regions of the brain, suggesting the existence of two separate memory systems. Low-familiarity words tended to generate activity in both implicit and explicit systems, whereas high familiarity words activated the explicit system on most occasions. Electrical activity in the frontal region measured when the test subject gave a “remember” response suggests a separate explicit system in this area. Electrical activity in the occipital region measured when the test subject gave a “know” response suggests a separate implicit memory system in this area. In an optimal laboratory setting, multiple subjects would be required to substantiate the data by offering more trials to reduce the amount of possible error. To explore this further more information on the brain activity and history of the test subject would also have been helpful. Different conditions applied to the same subjects would help to demonstrate the existence of the two memory systems and the instances in which they would be active.