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Stimuli Alone (stimulus + alone)
Selected AbstractsMale Mate Choice in the Guppy (Poecilia reticulata): Do Males Prefer Larger Females as Mates?ETHOLOGY, Issue 2 2004Emily J. E. Herdman Although females are the choosier sex in most species, male mate choice is expected to occur under certain conditions. Theoretically, males should prefer larger females as mates in species where female fecundity increases with body size. However, any fecundity-related benefits accruing to a male that has mated with a large female may be offset by an associated fitness cost of shared paternity if large females are more likely to be multiply mated than smaller females in nature. We tested the above hypothesis and assumption using the Trinidadian guppy (Poecilia reticulata) by behaviourally testing for male mate choice in the laboratory and by ascertaining (with the use of microsatellite DNA genotyping) patterns of male paternity in wild-caught females. We observed significant positive relationships between female body length and fecundity (brood size) and between body length and level of multiple paternity in the broods of females collected in the Quaré River, Trinidad. In laboratory tests, a preference for the larger of two simultaneously-presented virgin females was clearly expressed only when males were exposed to the full range of natural stimuli from the females, but not when they were limited to visual stimuli alone. However, as suggested by our multiple paternity data, males that choose to mate with large females may incur a larger potential cost of sperm competition and shared paternity compared with males that mate with smaller females on average. Our results thus suggest that male guppies originating from the Quaré River possess mating preferences for relatively large females, but that such preferences are expressed only when males can accurately assess the mating status of encountered females that differ in body size. [source] Alterations in behaviour and glutamate transmission following presentation of stimuli previously associated with cocaine exposureEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2001Gregory Hotsenpiller Abstract To study the role of glutamate in cocaine-conditioned responses, we developed a rat model in which conditioned locomotion is produced by repeated pairing of cocaine with discrete stimuli (flashing light and metronome). ,Paired' subjects received cocaine (15 mg/kg) prior to six exposures to stimuli for 30 min in the test environment. ,Unpaired' subjects received equivalent presentations of the stimuli yet received cocaine in home cages. Tests with the stimuli alone demonstrated that the conditioned locomotion displayed by Paired subjects was evident at 3 or 10 days post-training and resistant to two sessions of testing. The degree of conditioned locomotion was not correlated with the subjects' response to novelty or cocaine. Administration of the noncompetitive AMPA receptor antagonist GYKI 52466 (2.5 mg/kg, a dose without effect on spontaneous activity) attenuated the expression of conditioned activity. In vivo microdialysis revealed that Paired subjects had significantly lower basal glutamate levels in the nucleus accumbens (NAc) than did Unpaired subjects when no stimuli were presented. Presentation of the conditioned stimuli resulted in significant increases in glutamate levels in the NAc in the Paired group whilst glutamate levels in the Unpaired group remained unchanged. The associative control of glutamate levels in the NAc by stimuli formerly paired with a drug of abuse is an unprecedented finding. It is likely to reflect the convergence of excitatory inputs that the NAc receives from limbic structures. [source] Crossmodal influences in somatosensory cortex: Interaction of vision and touchHUMAN BRAIN MAPPING, Issue 1 2010Jennifer K. Dionne Abstract Previous research has shown that information from one sensory modality has the potential to influence activity in a different modality, and these crossmodal interactions can occur early in the cortical sensory processing stream within sensory-specific cortex. In addition, it has been shown that when sensory information is relevant to the performance of a task, there is an upregulation of sensory cortex. This study sought to investigate the effects of simultaneous bimodal (visual and vibrotactile) stimulation on the modulation of primary somatosensory cortex (SI), in the context of a delayed sensory-to-motor task when both stimuli are task-relevant. It was hypothesized that the requirement to combine visual and vibrotactile stimuli would be associated with an increase in SI activity compared to vibrotactile stimuli alone. Functional magnetic resonance imaging (fMRI) was performed on healthy subjects using a 3T scanner. During the scanning session, subjects performed a sensory-guided motor task while receiving visual, vibrotactile, or both types of stimuli. An event-related design was used to examine cortical activity related to the stimulus onset and the motor response. A region of interest (ROI) analysis was performed on right SI and revealed an increase in percent blood oxygenation level dependent signal change in the bimodal (visual + tactile) task compared to the unimodal tasks. Results of the whole-brain analysis revealed a common fronto-parietal network that was active across both the bimodal and unimodal task conditions, suggesting that these regions are sensitive to the attentional and motor-planning aspects of the task rather than the unimodal or bimodal nature of the stimuli. Hum Brain Mapp, 2010. © 2009 Wiley-Liss, Inc. [source] Squirrel monkey chuck call: vocal response to playback chucks based on acoustic structure and affiliative relationship with the callerAMERICAN JOURNAL OF PRIMATOLOGY, Issue 3 2002Joseph Soltis Abstract Adult female squirrel monkeys (genus Saimiri) that are socially familiar often exchange the chuck vocalization, which differs acoustically across individuals. We used behavioral observations, vocalization playback experiments, and analysis of the acoustic properties of vocalizations to investigate the effect of caller identity and acoustic structure on vocal response to playback chucks in two all-female social groups (n=10 females). Females were most likely to respond with a chuck to the playback chucks of their closely affiliated partners compared to those of nonaffiliated group members. This shows for the first time that the chuck stimulus alone is sufficient to elicit a chuck response from a female's affiliated partner. Additionally, females responded with a chuck mostly to familiar playback chucks from their own group and least to playbacks of silent controls. Unfamiliar playback chucks from the same species and a different squirrel monkey species elicited chuck responses intermediate between familiar chucks and silent controls. Post-hoc discriminant function analyses provide preliminary evidence that females are most likely to respond to unfamiliar chucks when those chucks are close in acoustic structure to familiar chucks from their own social group. These results provide a provisional explanation for error in the squirrel monkey signal processing system, in which unfamiliar chucks never heard before nevertheless elicit a chuck response if they are similar in acoustic structure to familiar group chucks. © 2002 Wiley-Liss, Inc. [source] | ||||||||||