Most of my research is based on the use of a model system of learning and memory: classical conditioning of the rabbit's nictitating membrane (NM) response. In collaboration with the late John A. Harvey of this department, research with this preparation over the last 10 years has been concerned with two different projects: 1) characterizing the influence of the serotonergic system on associative learning and 2) delineating the long-term behavioral and cognitive consequences of prenatal exposure to cocaine.
The serotonergic system is known to influence many human behaviors, including cognitive processing. For example, the prototypical hallucinogen LSD is thought to exert its sensory and associative effects by stimulating serotonin (5-HT) receptors in various parts of the brain. We have shown that one family of 5-HT receptor subtypes, the 5-HT2 family, influences the rate of associative learning in the rabbit NM preparation. Specifically, drugs which act as agonists at 5-HT2 receptor sites tend to accelerate the rate of NM conditioning whereas 5-HT2 antagonists tend to retard the rate of conditioning. We recently showed that the 5-HT2A subtype receptor appears to mediate these effects on associative learning and that upregulation of that receptor in cortex is associated with an accelerated rate of learning.
Human infants exposed to cocaine prenatally have been reported to exhibit a variety of behavioral and physiological anomalies. Several years ago, my colleagues and I began characterizing the neuroanatomical, neurochemical, neurophysiological, behavioral and cognitive consequences of prenatal exposure to cocaine in a rabbit model. We recently reported that attentional processing is one of the cognitive processes altered in rabbits prenatally exposed to cocaine. This altered attentional processing sometimes leads to an accelerated rate of learning and at other times to a retarded rate of learning, depending on the complexity of the learning task.
"Selective remodeling of rabbit frontal cortex: relationship between 5-HT2A receptor density and associative learning"
Harvey, J. A., Quinn, J. L., Liu, R., Aloyo, V. J., & Romano, A. G.
Psychopharmacology, 172: 435-442, 2004.
"Dissociable effects of the 5-HT2 antagonist mianserin on associative learning and performance in the rabbit"
Romano, A. G., Hood, H., & Harvey, J. A.
Pharmacology Biochemistry and Behavior, 67:103-110, 2000.
"Variations in CS associability and multiple unit hippocampal activity in the rabbit"
Romano, A. G.
Behavioural Brain Research, 103: 163-173, 1999.
"Effect of 5-HT2 receptor antagonists on a cranial nerve reflex in the rabbit: Evidence for inverse agonism"
Harvey, J. A., Welsh, S. E., Hood, H., & Romano, A. G.
Psychopharmacology, 141:162-168, 1999.
"Prenatal cocaine exposure: Long-term deficits in learning and motor performance"
Romano, A. G., & Harvey, J. A.
Annals of the New York Academy of Sciences, 846:89-108, 1998.
"Effects of serotonin 5-HT2A/2C antagonists on associative learning in the rabbit"
Welsh, S. E., Romano, A. G., & Harvey, J. A.
Psychopharmacology, 137:157-163, 1998.
"Elicitation and modification of the rabbit's nictitating membrane reflex following prenatal exposure to cocaine"
Romano, A. G., & Harvey, J. A.
Pharmacology Biochemistry and Behavior, 53:857-862, 1996.
"Prenatal exposure to cocaine disrupts discrimination learning in adult rabbits"
Romano, A.G., & Harvey, J.A.
Pharmacology Biochemistry and Behavior, 53:617-621, 1996.