Miller JP, McAuley JD, Pang KC (2006) Effects of selective cholinergic NBM lesions on short-interval timing. Neuroscience 2006 Abstracts 572.24. Society for Neuroscience, Atlanta, GA.
Summary: The nucleus basalis magnocellularis (NBM) and its connection to the frontal cortex are important for timing short durations and divided attention. Although the NBM provides the major cholinergic input to the frontal cortex, GABAergic and other neurons are also located in the NBM and project to neocortex. To examine the role of the NBM in timing and attention, previous investigators used non-selective lesions of the NBM using ibotenic acid (IBO). In the present study, we examined the importance of cholinergic NBM neurons in timing using the selective immunotoxin 192-IgG saporin (SAP). Fisher 344 rats were trained on a peak-interval (PI) procedure using fixed-intervals of 12 s and 24 s. Once trained, stereotaxic surgeries where conducted on the rats and either SAP or nothing (SHAM) was administered into the NBM to create selective cholinergic or control lesions respectively. Preliminary results show that SAP did not alter peak times (SHAM: 11.82 s & 22.59 s versus SAP: 11.98 s & 22.88 s) or coefficient of variability (CV, SHAM: 0.41 & 0.45 versus SAP: 0.44 & 0.47). However, upon inspection of the brains, SAP lesions did not reduce the number of cholinergic neurons in the NBM. In a separate study using the PI procedure with a single fixed-interval of 18 s, IBO altered timing accuracy as measured by the absolute difference in peak times (pre-op versus post-op: SHAM = 0.60 s; IBO = 1.94 s) and altered variability as measured by the change in CV (pre-op versus post-op: SHAM = 0.02; IBO = 0.20). Preliminary results with IBO showing a non-directional reduction in accuracy are different from previous studies that have reported systematic overestimation of duration, although in our study the damage caused by IBO was restricted to the anterior NBM. Current studies are further evaluating the role of NBM neurons in timing with more selective and complete cholinergic lesions using SAP and more complete non-selective lesions using IBO.
Related Products: 192-IgG-SAP (Cat. #IT-01)