Table 1. Paradoxical effect of DBS on alcohol relapse-like drinking (ADE) measured by the drinkometer device.

Treatment	Fourrier coefficients	Water	5% EtOH	10% EtOH	20% EtOH
Baseline
	Amplitude Frequency	0.500 0.046	0.004 0.044	0.005 0.044	0.005 0.046
ADE, day 1
Sham	Amplitude Frequency	0.080 0.044	0.016a 0.046	0.016a 0.616a	0.003 0.466a
DBS	Amplitude Frequency	0.400b 0.052	0.026a 0.220a,b	0.030a 0.562a	0.012a,b 0.080b
ADE, days 2–4
Sham	Amplitude Frequency	0.170 0.044	0.020a 0.042	0.009 0.230a	0.003 0.184a
DBS	Amplitude Frequency	0.210 0.031	0.020a 0.044	0.017a,b 0.044b	0.004 0.087a,b

Abbreviations: ADE, alcohol-deprivation effect; DBS, deep-brain stimulation; NAcs, nucleus accumbens shell.

Data are given for alcohol-dependent rats in the sham-stimulated control group (n=8) and in the bilateral NAcs DBS group (n=5). Chronic-continuous bilateral NAcs stimulation started 3 days before the end of the abstinence phase and continued for four post-abstinence days. The table shows the differential effects of chronic-continuous DBS on the drinking patterns. The model parameters derived from the Fourier coefficients describe the maximal peak of water/ethanol intake during 5-min intervals (amplitude: in ml kg⁻¹ of body weight for water, and in grams of pure alcohol per kilogram of body weight for each ethanol solution) and the number of maximal intake-peak occurrences in 1 h (frequency). The Fourier coefficients calculated for the last days of baseline drinking (Baseline), the first post-abstinence day (ADE, day 1) and the average of the successive three post-abstinence days (ADE, days 2–4) in both control sham-stimulated and DBS rats are displayed. Data are presented as means ±s.e.m., P<0.05.

^aIndicates significant differences from the baseline condition.

^bIndicates significant difference from the control sham group.