Discriminative tasks

Rats exposed to 1,000 ppm TCE for 3 days had disturbed sleep cycles (Arito et al. 1993). Rats exposed to 1,000 ppm for 18 weeks showed increased latency in visual discrimination tasks (Kulig 1987). Sleep apnea has been observed in humans exposed to organic solvents (Edling et al. 1993 Monstad et al. 1987, 1992 Wise et al. 1983). Cardiac arrhythmia has been observed in humans exposed to trichloroethylene vapor (Dhuneretal. 1957 Hewer 1943 Milby 1968 Pembleton 1974 Thiersten et al. 1960). 

Miller, L., Lombardo, T. and Fowler, S. Caffeine and time of day effects on a force discrimination task in humans. Physiology and Behavior 57(6), 1117-1125, 1995. 

The silica microspheres provide some diversity but not enough for many complex discrimination tasks. To introduce more sensor variety, hollow polymeric microspheres have been fabricated8. The preparation of these hollow microspheres involves coating silica microspheres by living radical polymerization, using the surface as the initiation site. Once the polymer layer forms on the silica microbead surface, the silica core is removed by chemical etching. These hollow spheres can be derivatized with the dye of interest. The main advantage of these polymer microspheres is the variety of monomers that can be employed in their fabrication to produce sensors with many different surface functionalities and polymer compositions. 

Berger-Sweeney, J., Libbey, M., Arters, J., Junagadhwalla, M., andHohmann, C.F. (1998) Neonatal monoaminergic depletion in mice (Mus musculus) improves performance of a novel odor discrimination task. Behav. Neurosci. 112, 1318-1326. 

Ginseng extract improves the spatial learning performance of aged rats in an eight-arm radial maze and operant discrimination task (Nitta et al. 1995). It also improves memory performance in active-avoidance (shuttle-box) and passive-avoidance (step-down) tasks, and reinforces staircase-maze learning in both young and aged rats. (Petkov and Mosharrof 1987 Petkov et al. 1990 Petkov et al. 1992). The effects were also very dose dependent, with inverted U-shape dose-response curves. 

Nitta H, Matsumoto K, Shimizu M, Ni XH, Watanabe H. (1995). Panax ginseng extract improves the performance of aged Fischer 344 rats in radial maze task but not in operant brightness discrimination task. Biol Pharm Bull. 18(9) 1286-88. 

Other brain regions are undoubtedly involved in affi-liative behaviors. For example, the ventral temporal area of the cortex appears to be involved in facial discrimination in humans, and abnormalities in the activation of this area during facial discrimination tasks are present in individuals with autism (Schultz et ah, 2000). In rats and other mammals, the olfactory bulb and entorhinal cortex also appear to be involved in affiliative behaviors, including maternal behaviors (Numan, 1994). 

In the dorsal and median raphe nuclei, failed to modify performance in the acquisition of temporal discrimination and memory in a delayed conditional discrimination task in rats (Al-Zahrani et al. 1996) and using a delayed interval bisection task (Al-Zahrani et al. 1997). 

Aged rhesus monkeys were assessed in several cognitive and motor tasks, acquisition of a visual object discrimination, reversal of a visual object discrimination, a delayed response task, a spatial working memory task, and a fine motor task. The S-HTj receptor antagonists ondansetron and SEC-579 at very low oral doses selectively enhanced acquisition of a visual object discrimination task but not the reversal or delayed tasks [Arnsten et al. 1997]. 

The injection of scopolamine into the dorsal hippocampus of the rat impaired choice accuracy in a two-platform spatial discrimination task. The subcutaneous injection of ondansetron antagonized the effect of scopolamine but had no effect when administered alone (Carli et al. 1997). A working memory task with a three-panel runway arrangement showed that the concurrent infusion of the S-ffTj receptor antagonist Y-25130 and scopolamine into the dorsal hippocampus of the rat significantly attenuated the impairment induced by scopolamine. Y-25130 administered alone had no effect and failed to block the impairment induced by the NMDA receptor antagonist ( )-3-(2-carboxypiperazin-4-yl) propyl-l-phosphonic acid (Ohno and Watanabe 1997). 

Al-Zahrani SS, Ho MY, Al-Ruwaitea AS, et al Effect of destruction of the 5-hydroxytryptaminergic pathways on the acquisition of temporal discrimination and memory for duration in a delayed conditional discrimination task. Psychopharmacology 123 103-110, 1996... 

Continuous performance test (CPT) usually discrimination tasks of long duration... 

Motor activity changes were also observed in rats administered doses of FireMaster FF-1 as low as 1 mg/kg/day for 4 weeks (Geller et al. 1979). In this experiment, neither learning nor performance of a simple discrimination task was affected by 1, 3, or 6 mg/kg/day dosage levels, but increased motor activity was observed at 1 mg/kg/day. No changes were apparent at 3 mg/kg/day and decreased motor activity was apparent at 6 mg/kg/day, compared with controls. Weakness of the hind limb was noted in rats treated with 10 mg/kg/day FireMaster FF-1 for 6 months compared with control rats (Cabe and Tilson 1978). Histological examination of brain and/or spinal nerve tissue found no FireMaster FF-l-related alterations in rats or mice administered up to 10 mg/kg/day for 25 weeks (NTP 1983) or 3.9 mg/kg/day for up to 105 weeks (NTP 1992). 

Stickgold R, Whidbee D, Schirmer B, Patel V, Hobson JA. Visual discrimination task improvement a multi-step process occurring during sleep. J Cognit Neurosci 2000 12(2) 246-254. 

If odor-evoked slow temporal patterns actually provide higher brain centers with information about the odor quality, identification and discrimination cannot be instantaneous as many of the temporal features in the response profiles appear late or even after offset of odor exposure. Honeybees need 500 ms for a response to (non-sexual pheromone) odors but at least 1 second of stimulation is required for a correct discrimination (J. Klein, unpublished, cited in Galizia el al., 2000a). Thus, it appears that time is an important factor in discrimination tasks involving non-pheromonal odors and the slow temporal patterns could theoretically contribute to an olfactory code. In contrast, these temporal patterns would be too slow to encode information about sexual pheromones. Male moths, for example, must be able to respond to rapid changes in stimulus intermittency when moving upwind in pheromone plumes in search of a calling female. 

Iwanami A, Shinba T, Sumi M, Ozawa N, Yamamoto K. 1994. Event-related potentials during an auditory discrimination task in rats. Neurosci Res 21 103-106. 

Polich J. 1987. Comparison of P300 from a passive tone sequence paradigm and an active discrimination task. Psychophysiology 24 41-46. 

Robbins TW, Giardini V, Jones GH, Reading PE, Sahakian BJ (1990) Effects of DA depletion from the caudate-putamen and nucleus accumbens septi on the acquisition and performance of a conditional discrimination task. 

Geller, I., Hartmarm, R.J., Moran, E., Leal, B.Z., Haines, R.J., Cause, E.M. (1985). Acute soman effects in the juvenile baboon effects on a match-to-sample discrimination task and on total blood acetylcholinesterase. Pharmacol. Biochem. Behav. 22 961-6. 

FIGURE 63.7. Mean (SEM) perfomiances (trials to criterion) of acquisition (14-15 days post-soman) in the brightness discrimination task. Drugs are as in Figure 63.6. Significantly different from all other groups (p < 0.05). 

Myhrer, T. (2000). Effects of selective perirhinal and postrhinal lesions on acquisition and retention of a visual discrimination task in rats. Neurobiol. Learn. Mem. 73 68-78. 

Single photon emission tomography (SPECT) demonstrates reduced blood flow in the area of the caudate andputamen (Harper, 1996). Positron emission tomography (PET) shows reduced glucose metabolism in the striatum (Eolstein, 1989 Harper, 1996 Fahn, 2005). Functional MRI (flMRI) shows reduced subcortical (region of caudate and thalamus) participation in a time-discrimination task in prechnical HD subjects (Paulson et al., 2004). 

Another advantage of operant chamber-based procedures is the enormous flexibility they provide for behavioral assessment and the ease with which they can be carried out in these devices. For example, conditional discrimination problems, which are more difficult discrimination tasks, can be easily implemented in operant chambers. Matching to sample is one such method. In this task, the subject first makes a designated response to indicate that it is attending to... 

Other methods for measurement of memory function rely on explicit discrimination tasks. The matching to sample task described earlier is one example. In this paradigm, a sample stimulus is presented briefly to the subject. The subject must then pick the sample stimulus when subsequently presented with multiple stimulus options (i.e., the subject must match the sample). When delay intervals are imposed between the presentation of the sample stimulus and the subsequent presentation of multiple stimuli, the task becomes a memory task. In this case, the subject must remember the sample stimulus in order to perform correctly. As in the delayed alternation procedure. 

Discrimination tasks have proved useful in detecting effects of toxicants on learning and memory. The procedure most often employed is termed a forced choice because the animal is presented with two or... 

Discrimination tasks have proved to be sensitive to impairment resulting from exposure to lead. The difficulty of the task may have an important impact on the effects of a toxicant on performance. 

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