Additional functional effects of nAChRs include alterations in pain, anxiety, appetite, depression, epilepsy, and motoric abilities. Although a comprehensive discussion of these effects is beyond the scope of the present review, their potential influence (direct or indirect) on learning and memory deserves mention. We will use as an example the locomotor effects of centrally located nAChRs. Most of the nonhuman animal research investigating attention, reward, or working memory include controls to assess whether the motoric effects of the nAChR ligand of interest could account for group differences. Such controls are important in that nAChR agonists can alter general locomotor activity.8,42,61,68,92 Whether the change is locomotor suppression or stimulation depends on such factors as selectivity of ligand, dose, pretreatment or preexposure history, rodent strain, and environmental familiarity. Accordingly, if one is investigating the memory enhancing effects of, say, chronic nicotine, then an index of locomotor stimulation will be important. Arguably, these locomotor stimulant effects could enhance acquisition and performance in certain learning tasks perhaps by producing small decreases in the time between stimulus-outcome or behavior-outcome relations (i.e., improved temporal contiguity) inherent in learning situations.72,93,97 Along these lines, it is interesting to note that the a4p2* nAChRs42 and increased dopamine release in the nucleus accumbens5appear to be important for the locomotor stimulant effects of nicotine (see section on Reward/Incentive Effects). Likely, future research will begin to more specifically identify the links between the effects we have listed as "Other" and memory. Perhaps the anxiolytic effects of ABT 4 1 830 or nicotine19 allow an animal to use neural processing resources released from this decrease in anxiety toward the learning/memory task prescribed by the experimenter.
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