<p> The possible contribution of neural plasticity to ON, OFF and steady state
responses elicited by brief, repetitive trains of stimulation was investigated in the intact
human subject with the use of the electroencephalogram (EEG). Experiment One
implemented trains of stimulation at three different repetition rates, 1.5Hz, 4Hz and
13Hz. The goal was to investigate the nature of the ON, OFF and steady state responses
evoked at these repetition rates. The experiment was carried out in three modalities:
visual (n=13), auditory (n=lO) and somatosensory (n=12). The main result was that the
ON and OFF responses were enhanced at 13Hz compared to the lower repetition rates.
Experiment Two sought to answer the question of whether enhancement depended on the
repetition rate or the increased experience provided by the higher frequencies. The
number of stimuli in the 13Hz trains was reduced to equal the 1.5Hz condition from
Experiment One. Graded exposure was then provided to the 13Hz stimulation. This
procedure was implemented in two groups of subjects: Replication One (n=12) used
13Hz stimulation and Replication Two (n=24) used 14Hz stimulation. A subset (n=IO)
of the Replication Two subjects returned for a second session (Day 2) 24 hours after the
first. An assessment of effects was made after minutes and hours. There were four main
results. The OFF response was observed after nine 13Hz pulses and did not change over
the course of the experiment. The ON response increased with exposure to the 13Hz
trains. Steady state responses diminished and showed a phase shift over the experimental
session. Results for Day 1 and Day 2 were not different. Within session changes, as a
result of exposure to the stimulus, were seen. These effects were not long lasting. </p> / Thesis / Master of Science (MSc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/22671 |
| Date | 08 1900 |
| Creators | Branscombe, Amy |
| Contributors | Roberts, L. E., Psychology |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
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