Dose-Dependent Deficits in Dual Interstimulus Interval Classical Eyeblink Conditioning Tasks Following Neonatal Binge Alcohol Exposure in Rats Kevin L. Brown, Lyngine H. Calizo, and Mark E. Stanton Background: Neonatal alcohol consumption in rats is widely used to model cerebellar injury arising from 3rd-trimester human fetal alcohol exposure. Binge alcohol exposure of 5 g ⁄ kg ⁄ day or more over postnatal days (PD) 4 to 9 in rats damages the cerebellum and consequently impairs classical eyeblink conditioning (EBC). The present study sought to identify deficits in EBC using doses lower than those that have been reported previously following alcohol exposure limited to PD4-9. Complex conditioned response (CR) timing tasks utilizing 2 interstimulus intervals (ISIs) were used to test the hypothesis that 3 g ⁄ kg ⁄ day of alcohol would produce early onset and early peaked CRs, whereas 4 and 5 g ⁄ kg ⁄ day would impair CR acquisition. Methods: Five neonatal treatment groups were used: (1) undisturbed controls, (2) sham intuba- tion controls, (3) 3 g ⁄ kg ⁄ day of alcohol, (4) 4 g ⁄ kg ⁄ day of alcohol, or (5) 5 g ⁄ kg ⁄ day of alcohol. Intubations occurred over PD4-9. In adulthood, rats were trained using ISI discrimination (Experiment 1) or temporal uncertainty (Experiment 2) EBC tasks. In ISI discrimination, 2 dis- tinct conditioned stimuli (CSs; tone and light) are reinforced with a periocular shock uncondi- tioned stimulus (US) at 2 different CS–US intervals. Temporal uncertainty is identical in design with the exception that the same CS is presented at both CS–US intervals. Results: Alcohol-exposed subjects were impaired in CR acquisition in a task- and dose-depen- dent fashion. CR deficits were most salient in the peak amplitude measure and occurred in both tasks following alcohol exposure at 4 and 5 g ⁄ kg ⁄ day. Alcohol at a dosage of 3 g ⁄ kg ⁄ day impaired CR acquisition only in ISI discrimination. All alcohol doses failed to produce short latency CRs in either task. Alcohol-exposed subjects displayed later-onset and later-peaked CRs to the long-ISI CS in ISI discrimination relative to controls. Conclusions: ISI discrimination training may be ideal to identify CR deficits resulting from neonatal exposure to moderate alcohol doses. Applications of this EBC task to humans may enable reliable early identification and diagnosis of individuals with fetal alcohol spectrum disorders. Key Words: Fetal Alcohol Spectrum Disorder, Eyeblink Conditioning, Rat, Cerebellum, Dose–Response. F ETAL ALCOHOL SYNDROME (FAS), officially classified in 1973 (Jones and Smith, 1973; Jones et al., 1973), is characterized by a distinct facial appearance, central nervous system dysfunction, and growth impairments result- ing from prenatal alcohol exposure in humans (Mattson and Riley, 1998; Riley and McGee, 2005; Sampson et al., 1997). More recently, the term fetal alcohol spectrum disorders (FASDs) has been applied to characterize a broad range of deficits present in individuals prenatally exposed to alcohol with or without facial dysmorphology (Hoyme et al., 2005; Manning and Hoyme, 2007; Riley and McGee, 2005). FASD is associated with damage to brain regions including the cerebellum, corpus callosum, basal ganglia, and cerebral cortex (Riley and McGee, 2005; Roebuck et al., 1998) and with a host of cognitive and behavioral impairments, including deficits in attention, memory, execu- tive functioning, reaction time, and motor learning (Jacob- son et al., 1994; Mattson and Riley, 1998; Riley and McGee, 2005). The extent of brain damage and corre- sponding cognitive and behavioral deficits are largely due to the duration, dosage, and developmental timing of alco- hol exposure (Maier et al., 1996) in addition to interac- tions with various maternal and genetic factors (Riley and McGee, 2005). Isolation of specific contributing variables through use of animal models has enhanced our under- standing of the precise neurobiological and neurobehavi- oral consequences of alcohol exposure at critical developmental periods (Cronise et al., 2001; Green, 2004; Department of Psychology, University of Delaware, Newark, Delaware. Received for publication September 6, 2007; accepted November 2, 2007. Reprint requests: Kevin L. Brown, Department of Psychology, University of Delaware, Newark, DE 19716; E-mail: kbrown@psych. udel.edu Research supported by NIH Grant 1-R01-AA11945 and NIAAA Grant 1-F31-AA16250-01. Copyright Ó 2008 by the Research Society on Alcoholism. DOI: 10.1111/j.1530-0277.2007.00579.x Alcoholism: Clinical and Experimental Research Vol. 32, No. 2 February 2008 Alcohol Clin Exp Res, Vol 32, No 2, 2008: pp 277–293 277