Variations of Brain Functional Connectivity in Alcohol-Preferring and Non-Preferring Rats with Consecutive Alcohol Training or Acute Alcohol Administration

Figures

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  Figure 1. Illustration of the 28 selected brain regions in the structure of the rat brain.

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  Figure 2. Results of the two-bottle free choice of the alcohol drinking training for the alcohol-preferring rats (P-rats) and the alcohol-non-preferring rats (NP-rats).

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  Figure 3. The mean functional connectivity matrices of the P-rats between different periods (alcohol drinking training period: week 0, 2 weeks, and 4 weeks; alcohol stimulation) and the NP-rats. Note, upper row: resting state analysis; lower row: acute alcohol stimulation; (A): P-Pre, week 0; (B): P-Mid, 2 weeks; (C): P-Post, 4 weeks; (D): NP. The horizontal and vertical coordinates are brain region numbers in Figure 1.

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  Figure 4. Examples of the correlation of the resting state functional connectivity in the whole brain for the P- and NP-rats. (A): P-rats RS Post vs. NP-rats RS; (B): P-rats IS Pre vs. P-rats RS Pre; Note: point, functional connectivity of two brain regions; dotted lines, y = x ± 0.15; area between the two dotted lines, the difference of the two examples was smaller than 0.15.

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  Figure 5. Examples of functional connectivity for nine different selected brain ROIs. The red arrows are positive correlations, and the blue ones are negative. The arrow length is proportional to the numerical value. Note: 1—Habenula nucleus; 2—Accumbens nucleus; 4—Olfactory tubercle; 5—Prelimbic cortex; 7—Piriform cortex; 11—Amygdala; 12—Septum; 16—Ventral tegmental area; 22—Visual cortex.

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  Figure 6. Different patterns of change among the analyses of functional connectivity for the whole brain. (A) Tendency of the changes for the acute alcohol stimulation during the Pre- and Post- preference periods, ΔR = IS(r) − RS(r). (B) The functional connectivity increased during the resting state but decreased after acute alcohol stimulation after alcohol preference. (C) The changes of the functional connectivity only happened during the alcohol preference formation period. (D) The functional connectivity only changed during the period of alcohol acute stimulation. The abbreviations of brain areas are the same as in the main text: NAc (nucleus of accumbens), OT (olfactory tubercle), VTA (ventral tegmental area), IC (insular cortex), Hypo (hypothalamus), SNC (compacta of substantia nigra), Au (auditory cortex), DB (diagonal band), Hipp (hippocampus), VLPO (ventrolateral preoptic nucleus); * p < 0.05, ** p < 0.01, *** p < 0.005.

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  Figure 7. Comparison of the functional connectivity between the NP-rats (A) and P-rats (B). The black arrow represents an upward trend, while the red one is a downward trend. The abbreviations of brain areas are the same as in the main text: NAc (nucleus of accumbens), OT (olfactory tubercle), VTA (ventral tegmental area), IC (insular cortex), Hypo (hypothalamus), DB (diagonal band), VLPO (ventrolateral preoptic nucleus); * p < 0.05, *** p < 0.005, **** p < 0.001.