Learning task

II. General Problem Statement and Scope of the Learning Task.381... 

First-order horn clause logic is the representation that has been adopted by workers in the field of explanation-based learning (Minton et al., 1990). Hence, using this representation allows us take advantage of the results and algorithms developed in that field to carry out the machine learning task. 

The purpose of this section is to try and link these abstract components to the learning task which we have defined. 

Ferguson and Bowman 1990 Gilbert and Rice 1987 Hopper et al. 1986 Krasovskii et al. 1979 Levin et al. 1988 Massaro and Massaro 1987 Overmann 1977 Rice 1985a). It appears that animals are affected at roughly the same blood lead levels as humans. Measured neurotoxic effects in animals include significantly delayed motor function and reflexes, decreased performance on learning tasks, and impaired spatial discrimination. Additional animal studies are needed to investigate the neurotoxic effects of subchronic inhalation exposures to establish external dose-effect relationships. 

Table 6.1. Memory and learning tasks where drug-free recreational Ecstasy users have displayed significant performance deficits.

Cohen MJ and Rickies WH Jr (1974). Performance on a verbal learning task by subjects of heavy past marijuana usage. Psychopharmacologia, 37, 323-330. 

Both the M2 and M4 receptors are, as indicated above, coupled to Gj pathways and appear to mediate similar responses. The M2 receptor is widely expressed in the CNS but also present in heart and smooth muscle, while M4 is preferentially expressed in the CNS, especially in forebrain. Ablation of the M2 receptor leads to complete loss of muscarinic-agonist-stimulated bradycardia [55]. In the CNS, deletion of the M2 receptor abolishes oxotremorine induced akinesia and tremors [56]. Memory and learning tasks including passive avoidance and working memory are impaired in M2-receptor knockout mice, and there is decreased LTP in hippocampal slices [12],... 

Kanit L, Taskiran D, Furedy JJ, Kulali B, McDonald R, Pogun S. (1998). Nicotine interacts with sex in affecting rat choice between "look-out" and "navigational" cognitive styles in the Morris water maze place learning task. Brain Res Bull. 46(5) 441-45. 

Rapin JR, Lamproglou I, Drieu K, DeFeudis FV. (1994). Demonstration of the "anti-stress" activity of an extract of Ginkgo biloba (EGb 761) using a discrimination learning task. Gen Pharmacol. 25(5) 1009-16. 

Yamamuro Y, Hori K, Tanaka J, Iwano H, Nomura M. 1995. Septo-hippocampal cholinergic system under the discrimination learning task in the rat a microdialysis study with the dual-probe approach. Brain Res 684(1) 1-7. 

The influence of BDNF regulation of synaptic function on behaviour has still to be fully determined. Rats treated with antibodies to BDNF (icv) were signihcantly impaired in a spatial learning task (Mu et ah, 1999). Levels of BDNF expression in CAl were rapidly and selectively increased following contextual fear conditioning, a form of learning also dependent on the hippocampus (Hall et ah, 2000). 

With the exception of degraded picture identification (Bondi Kaszniak, 1991), PD patients perform normally on implicit tests of perception, and are only slightly deficient in motor learning tasks (Harrington et al., 1990). Their habit learning skills seem to be more severely compromised (Knowlton et al., 1996). 

Similarly, intrahippocampal injections of 8-OH-DPAT induced no change in performance levels of the rat trained to run in a radial maze (Buhot et al. 1995). However, the intrahippocampal injection of the 5-HTjg receptor agonist CP-93,129 [3-(l,2,5,6-tetrahydropyrid-4-yl] pyrrolo [3,2-6] pyrid-5-one] induced a higher frequency of reference memory errors than of working memory. It was concluded that stimulation of 5-HT,g receptors in the CAl field of the dorsal hippocampus impairs performance of rats in a spatial learning task. 

Rouillon F, Serrurier D, Miller H, et al Prophylactic efficacy of maprotiline on unipolar depression relapse. J Chn Psychiatry 52 423-431, 1991 Rowan MJ, Cullen WK, Moulton B Buspirone impairment of performance of passive avoidance and spatial learning tasks in the rat. Psychopharmacology 100 393-398,... 

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