Changes in activities of dopamine and serotonin systems in the frontal cortex underlie poor choice accuracy and impulsivity of rats in an attention task

• Published in: Neuroscience Vol. 83; no. 2; pp. 489 - 499
• Main Authors: Puumala, T, Sirviö, J
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.03.1998; Elsevier
• Subjects: 5-HIAA, 5-hydroxyindoleacetic acid; 5-HIAA/5-HT, utilization of serotonin; 5-HT, 5-hydroxytryptamine; ADHD, attention deficit hyperactivity disorder; Animals; Attention - physiology; attention deficit; Attention deficit disorders. Hyperactivity; Biological and medical sciences; Brain Chemistry - physiology; Child clinical studies; DA, dopamine; DOPAC, 3,4-dihydroxyphenylacetic acid; DOPAC/DA, utilization of dopamine; dopamine; Dopamine - metabolism; five-choice serial reaction time task; Functional Laterality - physiology; Homovanillic Acid - metabolism; HVA, homovanillic acid; Hydroxyindoleacetic Acid - metabolism; Impulsive Behavior - metabolism; impulsivity; ITI, intertrial interval; Male; Medical sciences; Norepinephrine - metabolism; Prefrontal Cortex - metabolism; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; rat; Rats; Rats, Wistar; Reaction Time - physiology; serotonin; Serotonin - metabolism; DA, dopamine; DOPAC/DA, utilization of dopamine; ADHD, attention deficit hyperactivity disorder; 5-HIAA/5-HT, utilization of serotonin; rat; ITI, intertrial interval; serotonin; HVA, homovanillic acid; DOPAC, 3,4-dihydroxyphenylacetic acid; impulsivity; 5-HIAA, 5-hydroxyindoleacetic acid; five-choice serial reaction time task; 5-HT, 5-hydroxytryptamine; dopamine; attention deficit; Animal model; Choice; Dopamine; Rat; Serotonin; Hyperactivity; Rodentia; Central nervous system; Frontal cortex; Catecholamine; Vertebrata; Mammalia; Attentional disorder; Neurotransmitter; Reaction time; Brain (vertebrata)
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/S0306-4522(97)00392-8

The purpose of the present study was to investigate whether differences in the function of monoaminergic systems could account for the variability in attention and impulsive behaviour between rats tested in the five-choice serial reaction time task in a model of attention deficit hyperactivity disorder. The ability of a rat to sustain its attention in this task can be assessed by measuring choice accuracy (percent correct responses) to visual stimuli, whereas the percentage of premature responses indicates the level of impulsivity. Following training with the five-choice serial reaction time task, rats were decapitated and brain pieces taken for neurochemical determination. Levels of dopamine, noradrenaline, 5-hydroxytryptamine, the dopamine metabolites, 3,4-dihydroxyphenylacetic acid and homovanillic acid and the 5-hydroxytryptamine metabolite, 5-hydroxyindoleacetic acid were determined in the frontal cortex, nucleus accumbens, dorsal striatum and hippocampus. Multivariate regression analysis with a stepwise method revealed that the indeces of utilization of serotonin (5-hydroxyindoleacetic acid/5-hydroxytryptamine) in the left frontal cortex and dopamine (3,4-dihydroxyphenylacetic acid/dopamine) in the right frontal cortex together accounted for 49% of the variability in attentional performance between subjects. According to the regression analysis, a negative correlation existed between the left frontal cortex 5-hydroxyindoleacetic acid/5-hydroxytryptamine and choice accuracy, and a positive correlation was observed between 3,4-dihydroxyphenylacetic acid/dopamine ratio and choice accuracy on the opposite hemisphere. Additionally, right frontal cortex serotonin utilization was found to correlate positively with the proportion of premature hole responses and this relation accounted for about 24% of the variability in this index of impulsivity between animals. These data indicate that frontal cortex dopamine and serotonin play an important role in the modulation of attention and response control.