Butt AE, Amodeo D, Flesher M, Marsa K, Holt R, Lladones R, Olney R, Haynes J, Kinney-Hurd BL, Dach N (2007) 192 IgG-saporin lesions of the cholinergic basal forebrain disrupt selective attention and trace conditioning but spare delay and long-delay conditioning. Neuroscience 2007 Abstracts 424.9/HHH8. Society for Neuroscience, San Diego, CA.
Summary: Recent research suggests that Pavlovian trace conditioning, but not delay conditioning, is a form of declarative memory that requires attention, where both of these processes depend on specific brain systems. For example, past research has shown that although amnesiac humans with damage to the hippocampus (HPC) acquire a normal conditioned response (CR) in delay conditioning paradigms, where the conditioned stimulus (CS) and unconditioned stimulus (US) partly overlap, they fail to acquire the CR in trace conditioning paradigms, where the CS and US are separated in time. Others have shown that the anterior cingulate cortex (ACC) in rats and the medial prefrontal cortex (mPFC) in rabbits are similarly necessary for trace but not delay conditioning. The basal forebrain cholinergic system (BFCS) has projections to the mPFC, ACC, and HPC. Given that each of these regions is critical for trace but not delay conditioning, we hypothesized that lesions of the BFCS using 192 IgG-saporin (SAP) would selectively impair trace but not delay or long-delay appetitive conditioning in rats. Additionally, given evidence suggesting BFCS involvement in attention, it was hypothesized that the addition of varying levels of distraction during the trace conditioning task would cause progressively greater degrees of impairment in the BFCS lesion groups compared to controls. In contrast, neither the control groups nor the BFCS lesion groups were expected be negatively affected by the addition of a distracting stimulus in the delay and long-delay conditioning tasks. Rats received bilateral SAP lesions or sham lesions of the BFCS prior to conditioning with a white noise CS and sucrose pellet US in either a delay, long-delay, or 10 s trace conditioning paradigm. Separate groups of BFCS lesion and control rats were subjected to varying levels of visual distraction (flashing house light) in each paradigm; no distraction, low distraction (continuously blinking light), and high distraction (intermittent, unpredictable flashing light). Results supported our hypotheses, with the BFCS lesion groups showing normal delay and long-delay conditioning regardless of level of distraction. In contrast, trace conditioning was impaired in the BFCS lesion groups, with progressively greater degrees of impairment occurring with greater levels of distraction, and complete disruption of learning in the high distraction condition. Together, these experiments suggest that the BFCS is necessary for normal trace conditioning, and that the BFCS is critically involved in selective attention tasks where animals must discriminate relevant stimuli from distracting background stimuli.
Related Products: 192-IgG-SAP (Cat. #IT-01)