Prepulse Inhibition in Youth Contact Sports Players

Our main research question will be investigating whether or not there is a significant difference in PPI, as well as startle response probability and magnitude between contact and noncontact youth sports players. The study team will test these questions using a controlled laboratory scenario in which the presentation of startle stimuli can be observed, measured, and quantified in order to compare the results between the two sample populations. During preliminary testing, the study team can predict that there will be no significant differences between contact sports players and noncontact sports players in their startle reactivity and level of exhibited PPI. Based on previous literature, the study team hypothesizes that those in the contact sports group will experience greater startle reactivity and less PPI than those in the noncontact sports group when they are tested at the end of their sports season. Using this information, the present study will allow for additional understanding of the neurological and physiological behaviors associated with subconcussive head impacts.

This study will assess and determine whether prepulse inhibition in youth contact sports players and non-contact sports players, both before and after a sports season, will significantly differ. Measures will include the startle magnitude, startle probability, reaction time, and accuracy of tone detection responses.

The current study is a case-control study, examining the contact sports players as the testing sample and the noncontact sports players as the control sample.

• Participants will arrive and hear an introduction of the study.
• Participants (and their parent/guardian if under the age of 18) will read and sign an informed consent and/or informed assent form.
• Participants will complete a series of questionnaires prior to electrode placement.

• The Health History Questionnaire will be completed first to determine participant eligibility.
• The STAI will be completed next to be used for further analysis in the data compilation.
• Participants will have three electrodes placed on the skin.

• Two electrodes will be placed underneath the left eye as the nasal and temporal electrodes.
• One electrode will be placed on the left temple as the ground electrode.
• These electrodes connect to the Biopac apparatus, the software that measures the participant's EMG activity.
• The procedure of the study will be thoroughly explained to the participants. They will be instructed to wear headphones that will deliver the acoustic startle stimuli and to remain as still and quiet as possible during the startle blocks.

• There will be a total of two startle blocks: baseline and testing.
• The baseline startle block will consist of a combination of prepulses at 70 decibels of 800 and 1000 Hz frequency tones for a duration of 30 milliseconds presented with an onset of 120 milliseconds prior to the presentation of the startle stimulus of 100 decibels of broadband noise for 50 milliseconds on some trials.
• The testing block will also consist of prepulses at 70 decibels of 800 and 1000 Hz frequency tones for a duration of 30 milliseconds presented with an onset of 120 milliseconds prior to the presentation of the startle stimulus of 100 decibels of broadband noise for 50 milliseconds on some trials. For the testing block, participants will be asked to respond on a keypad when they hear the lower prepulse tone of 800 Hz.
• Startle stimuli will be presented via headphones. Startle stimuli will be presented from the Superlab software program which will run from the testing room.
• After the testing block, the electrodes will be removed from the participant's skin.
• Participants will be thoroughly debriefed on the aims of the current study.

This study will take place in the MRI suite of Wake Forest Baptist Health. A single room within the suite will be designated for the PPI testing, in order to control for external noise factors.

After the consent process, subjects will be asked to fill out a brief health history questionnaire. This is for the purpose of determining the subject's eligibility to participate in the study. Subjects will also be asked to complete an STAI form, and this will be used later during data analysis.

This study will last approximately one hour. The introduction and consent process will take about 10 minutes. The questionnaire process is expected to take about 10 minutes. The application of sensors should take about 10 minutes. The testing process, including the explanation of both startle blocks, should last about 20 minutes. The sensor removal and debriefing process will last about 10 minutes.

Inclusion criteria

• Participants are specifically recruited for this study due to their involvement on a sports team that may or may not expose them to head impacts.

Exclusion criteria

• Subjects on psychostimulant, antidepressant, or anxiolytic medications, as well as subjects who have experienced hearing loss, will not be eligible to participate.