Modification of body temperature and sleep state using behavioral conditioning

Area of Science:

• Neuroscience
• Immunology
• Behavioral Science

Background:

• The acute-phase response, involving physiological changes like fever and sleep alterations, is crucial for fighting infection.
• Previous studies indicate that components of the acute-phase response can be conditioned.
• The conditionability of fever and sleep changes together during the dark phase in rats remains unexplored.

Purpose of the Study:

• To investigate if fever and sleep alterations, as part of the acute-phase response, can be conditioned in rats.
• To determine if a novel taste (saccharin) paired with an immune stimulus (lipopolysaccharide) can elicit conditioned fever and sleep changes.

Main Methods:

• Rats were given saccharin solution (conditioned stimulus, CS) followed by lipopolysaccharide (unconditioned stimulus, UCS).
• Body temperature and sleep patterns (slow wave sleep - SWS, rapid eye movement sleep - REM) were monitored.
• Conditioned responses were assessed upon re-exposure to saccharin alone after 7 days.

Main Results:

• Rats showed a significantly higher body temperature upon saccharin re-exposure, indicating conditioned fever.
• A conditioned increase in the frequency of slow wave sleep (SWS) episodes was observed.
• The reduction in rapid eye movement (REM) sleep induced by lipopolysaccharide was not re-elicited.

Conclusions:

• Fever and specific sleep alterations (increased SWS frequency) are conditionable components of the acute-phase response.
• These findings suggest that multiple sickness behaviors can be learned and occur together.
• Simultaneous conditioning of these responses may optimize the body's environment for pathogen elimination.