Non-Photic Phase Shifting: Acetylcholine and Arousal

Non-photic stimuli are capable of producing large phase advances of the suprachiasmatic nuclei (SCN) during the midday in a manner that is different than light. Two prominent non-photic stimuli include confinement to a novel running wheel, and sleep deprivation by gentle handling. It was hypothesized that these stimuli both provide a sustained level of behavioral arousal to the animals in order to bring about phase shifts. If this was the case, then neurotransmitters involved in behavioral arousal should also participate in non-photic phase shifting. Neurotransmission of acetylcholine (ACh) is involved in bringing about arousal and also has been shown to play a role in the circadian system. The purpose of these experiments was to determine if ACh plays a role in non-photic phase shifting and to what extent arousal is involved. First, it was shown that Fos expression is increased in general areas containing ACh, orexin and histamine in Syrian hamsters undergoing sleep deprivation. Next, it was found that Fos expression specifically in cholinergic cells of the forebrain is increased in animals undergoing novel wheel confinement, but not sleep deprivation. It was then found that in vivo electrical stimulation of the basal forebrain region containing cholinergic neurons phase advanced circadian rhythms of wheel running activity at midday. The phase shifts to these stimulations was found to be dependent on a direct cholinergic input into the SCN. Finally, it was shown that blocking cholinergic neurotransmission in the SCN attenuates phase advances to novel wheel confinement. Taken together, these results show that ACh participates in non-photic phase shifting of the SCN through direct projections from forebrain cells. This also provides evidence for a role of behavioral arousal in novel wheel confinement induced phase shifts and a system that can feedback information on behavioral state onto the SCN.

Name thesis:degree_name

Doctor of Philosophy (PhD)

Discipline thesis:degree_discipline

Psychology

Grantor dc:publisher.institution

Graduate Studies

Year dc:date.issued

2014

Author dc:creator

• Yamakawa, Glenn

Advisor dc:contributor.advisor

• Antle, Michael

• Neuroscience
• Psychology--Behavioral
• Psychology--Experimental

Statement dc:rights

• University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.

Language dc:language.iso

eng

DOI

http://dx.doi.org/10.11575/PRISM/27124

OAI identifier oai:identifier

oai:ucalgary.scholaris.ca:11023/1462