Noise benefit in prepulse inhibition of the acoustic startle reflex.
BACKGROUND
Under some conditions, external sensory noise enhances cognitive functions, a phenomenon possibly involving stochastic resonance and/or enhanced central dopamine transmission. Prepulse inhibition (PPI) of the startle reflex is a robust measure of sensorimotor gating and can be modulated by activity in the cortex and basal ganglia, including the central dopamine pathways.


OBJECTIVE
Previous empirical studies suggest a differential effect of acoustic noise in normal children and children with attention-deficit hyperactivity disorder (ADHD). This study investigated the effect of acoustic noise on PPI and if dopamine transmission interacts with acoustic noise effects in a rat ADHD model.


METHODS
The effect of background acoustic noise on acoustic startle response and PPI were measured with a constant prepulse to background noise ratio of 9 dB(A). Spontaneously hypertensive (SH) rats were used as the ADHD model and compared with Wistar and Sprague-Dawley rats. Microdialysis, methylphenidate treatment and 6-OHDA lesions were used to investigate interaction with dopamine transmission.


RESULTS
Background noise facilitated PPI differently in SH rats and controls. The prefrontal cortex in SH rats had low basal dopamine concentrations, a high DOPAC/dopamine ratio and blunted dopamine release during PPI testing. Methylphenidate had small, but strain-specific, effects on startle and PPI. Bilateral 6-hydroxydopamine lesions did not alter startle or PPI.


CONCLUSIONS
Prefrontal dopamine transmission is altered in SH rats during the sensorimotor gating task of PPI of the acoustic startle, indicating increased dopamine reuptake in this ADHD rat model. We propose that noise benefit could be explored as a non-pharmacological alternative for treating neuropsychiatric disorders.
Department of Pharmacology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Box 400, 405 30, Gothenburg, Sweden.
Erik
E
Pålsson
Göran
G
Söderlund
Daniel
D
Klamer
Filip
F
Bergquist
D000161:Acoustic Stimulation / Q000379:methods; D000704:Analysis of Variance; D000818:Animals; D001289:Attention Deficit Disorder with Hyperactivity / Q000139:chemically induced / Q000188:drug therapy; D000697:Central Nervous System Stimulants / Q000627:therapeutic use; D004195:Disease Models, Animal; D007266:Inhibition, Psychological; D007276:Injections, Intraventricular; D008297:Male; D008774:Methylphenidate / Q000627:therapeutic use; D017551:Microdialysis; D009622:Noise; D009714:Nucleus Accumbens / Q000187:drug effects / Q000293:injuries / Q000378:metabolism; D016627:Oxidopamine / Q000633:toxicity; D017397:Prefrontal Cortex / Q000187:drug effects / Q000293:injuries / Q000378:metabolism; D011571:Psychoacoustics; D051381:Rats; D011918:Rats, Inbred SHR; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D011930:Reaction Time / Q000187:drug effects; D012022:Reflex, Acoustic / Q000502:physiology*; D055139:Sensory Gating / Q000187:drug effects / Q000502:physiology*; D013045:Species Specificity; D013565:Sympatholytics / Q000633:toxicity
D000697:Central Nervous System Stimulants; D013565:Sympatholytics; D008774:Methylphenidate; D016627:Oxidopamine