Assessing contributions of nucleus accumbens shell subregions to reward-seeking behavior.

Background: The nucleus accumbens (NAc) plays a key role in brain reward processes including drug seeking and reinstatement. Several anatomical, behavioral, and neurochemical studies discriminate between the limbic-associated shell and the motor-associated core regions. Less studied is the fact that the shell can be further subdivided into a dorsomedial shell (NAcDMS) and an intermediate zone (NAcINT) based on differential expression of transient c-Fos and long-acting immediate-early gene ΔFosB upon cocaine sensitization.

Behavioral effects of acclimatization to restraint protocol used for awake animal imaging.

Functional MRI in awake rats involves acclimatization to restraint to minimize motion. We designed a study to examine the effects of an acclimatization protocol (5 days of restraint, 60 min per day) on the emission of 22-kHz ultrasonic vocalizations and performance in a forced swim test (FST). Our results showed that USV calls are reduced significantly by days 3, 4 and 5 of acclimatization.

Increased BOLD activation to predator stressor in subiculum and midbrain of amphetamine-sensitized maternal rats.

Amphetamine, which is known to cause sensitization, potentiates the hormonal and neurobiological signatures of stress and may also increase sensitivity to stress-inducing stimuli in limbic areas. Trimethylthiazoline (5μL TMT) is a chemical constituent of fox feces that evokes innate fear and activates the neuronal and hormonal signatures of stress in rats. We used blood oxygen level dependent (BOLD) MRI to test whether amphetamine sensitization (1mg/kg, i.