Volume 6, Spring 2008 - Saddleback College

35
Saddleback Journal of Biology
Spring 2008
Fall 2007 Biology 3A Abstracts
Mean Recall
6
5
4
3
2
types of variables were difficult to control for and may
have led to the undesirable results.
With a better designed cognitive ability test
and perhaps more subjects a different result could
possibly have been obtained. However, in the case of
this study, the original thought that lactate levels have a
significant effect on memory capabilities is rejected,
and the findings suggest there is not a significant
effect.
1
0
Memory Test 1 Memory Test 2
Figure 1. Mean for memory test one, performed at baseline
lactate levels, was 5.2 ± 0.47(s.e.m.). Mean for memory test
two, performed at elevated lactate levels, was 4.7 ±
0.45(s.e.m.). One-tailed t-Test assuming unequal variances P
= 0.22. Error bars indicate standard error of the mean.
Discussion
According to this study lactate level has no
significant effect on cognitive abilities. There was a
slight difference between the memory recall for lower
lactate level and higher lactate levels, however, the
results were not consistent. Five subjects score higher
on the first cognitive test when their lactate levels were
rather low. Four subjects scored the same regardless of
their lactate level. Finally, one subject scored better on
the cognitive test when their lactate levels were
elevated. The latter result was interesting because this
subject looked visually to be the most fatigued. This is
in direct contrast with the findings by Fleury and Bard.
However, this result seems to be in concordance with a
finding by Urrila et al., which found that higher lactate
levels were associated with cognitive functioning.
As there was no difference in the cognitive
abilities one may assume the levels of lactate crossing
the blood brain barrier were not sufficient during short
term bouts of activity above the anaerobic threshold to
impair cognitive ability.
A possible source of error in this study was
the design of the memory test. Roediger found that in
the case of pictures verses words on a memory tests,
subjects were able to use priming, to help them
remember, when pictures were used in the memory
test. So if a subject sees two items that are related to
each other in some way the subject may remember both
easier because they associate one with the other.
Another reason for insignificant results could
have included the small number of subjects. It was
also difficult to control the subjects’ environment and
activity prior to testing. One subject became physically
ill after testing, and the researchers later learned the
subject had not eaten for a long period of time. These
References
Bakker, F. C., Klijn, C. J.M., van der Grond, J.,
Kappelle, L. J. and Jennekens-Schinkel, A. (2004).
Cognition and quality of life in patients with carotid
artery occlusion (A follow-up study). Neurology,
2004;62:2230-2235.
De Bruin, L. A., Schasfoort, E. M., Steffens, A. B., &
Korf, J. (1990). Effects of Stress and Exercise on Rat
Hippocampus and Striatum Extracellular Lactate.
American Journal Physiology – Regulatory
Integrative Comparative Physiology, 259: 773-779.
Farina, D., Macaluso, A., Ferguson, R., and De Vito,
G. (2004) Effect of power, pedal rate, and force on
average muscle fiber conduction velocity during
cycling, Journal of Applied Physiology.
Fleury, M. & Bard, C. (1987). Effects of Different
Types of Physical Activity on the Performance of
Perceptual Tasks in Peripheral and Central Vision
and Coincident Timing. Ergonomics, 30 (6), 945-
958.
Gibbs, M. E., Lloyd, H. G. E., Santa, T. and Hertz, L.
(2007). Glycogen Is a Preferred Glutamate Precursor
During Learning in
1-Day-Old Chick: Biochemical and Behavioral
Evidence, Journal of Neuroscience Research
85:3326–3333.
Kaufmann, P., Shungu, D.C., Sano, M.C., Jhung, S.,
Engelstad, K., Mitsis, E., Mao, X., Shanske, S.,
Hirano, M., DiMauro, S. and De Vivo, D.C. (2004).
Cerebral lactic acidosis correlates with neurological
impairment in MELAS, Neurology 2004;62:1297-
1302.
Nemoto, E. M. &Severinghaus, J. W. (1974).
Stereospecific Permeability of Rat Blood-Brain
Barrier to Lactic Acid. Stroke, 5 (January-February),
81-85.
Roediger, H. L. (1990). Implicit Memory, Retention
Without Remembering. American Psychologist, 45
(9), 1043-1056.