Isolation-dependent enhancement of 2-[14C]deoxyglucose uptake in the forebrain of zebra finch males

In a previous study (H. J. Bischof & K. Herrmann (1986), Behavioral Brain Research, 21, 215-221) we demonstrated that four forebrain areas of the zebra finch male are activated in situations which arouse the animal, for example when the birds are chased around the cage or when they are exposed to a female. These areas, the hyperstriatum accessorium-dorsale (HAD), a part of the medial neo-hyperstriatum (MNH), the lateral neo-hyperstriatum (LNH), and a portion of the caudal archi-neostriatum (ANC), show enhanced 2-[14C]deoxyglucose (2-DG) uptake according to the experimental situation. On the basis of these experiments, we examined whether the activation of the areas is correlated with motor activity and is influenced by different isolation times prior to a 2-DG experiment, where courtship of the male birds is elicited by exposing them to a female zebra finch. For this purpose, we isolated male zebra finches for 1 day, 1 week, or 8 weeks, respectively, before we injected the 2-DG and exposed the birds to a female. During the experiment, besides other activities, the number of song motifs performed by the bird and the frequency of changing perches was recorded. Our experiments demonstrate that there is a weak negative correlation between motor activity and 2-DG uptake, and a positive correlation between isolation time and 2-DG uptake. We suggest that long isolation blocks courtship behavior by some unknown mechanisms, and that the "internal drive" of the animal, which possibly corresponds with the activity of the four forebrain areas, is enhanced by isolation and by the fact that the birds do not perform the consummatory behavior. Our results also demonstrate that the 2-DG method can show up small differences in the internal state of an animal, which cannot easily be detected by behavioral measurements.     

Cerebral hemispheric mechanisms in the retrieval of ambiguous word meanings

Targets related to ambiguous primes were projected to the left and right visual fields in a lexical priming experiment with stimulus onset asynchronies (SOA) of 35 and 750 msec. Right visual field results were similar to our earlier results with central projection (G. B. Simpson & C. Burgess, 1985, Journal of Experimental Psychology: Human Perception and Performance, 11, 28-39). Facilitation was found for the more frequent meaning at both SOAs and a decrease in facilitation for the less frequent meaning at the longer SOA. In contrast, left visual field results indicated a decay of facilitation for the more frequent meaning at the longer SOA, while activation for the subordinate meaning increased. Results suggest that, while automatic processing occurs in both hemispheres, only the left hemisphere engages in controlled processing of ambiguous word meanings. In addition, the present results support the idea that the right hemisphere has a special role in ambiguity resolution and that the right hemisphere lexicon possesses a richer endowment than earlier thought.     

Nonverbal communication as a compensative strategy for severely nonfluent aphasics? A quantitative approach

Seven severely nonfluent aphasics and one relative or close friend were investigated in an interview situation. The conversation was videotaped and analyzed for the use of nonverbal communication between aphasic and partner. The results indicate that the group of aphasics used significantly more frequently and for a significantly longer period of time nonverbal channels of communication than their healthy partners. The aphasic patients also used significantly fewer speech-focused movements and significantly more codified gestures. Nonverbal elements were more frequently used as speech substitutes by the group of aphasics.     

Chronic sweet intake lowers pain thresholds without changing brain mu- or delta-opiate receptors

Sprague-Dawley rats drank sweetened (3% dextrose + 0.144% saccharin, w/v) or unflavored water for 18 days and subsequent pain reactivity was assessed using a hot plate. Compared to the rats that consumed unflavored water, the rats that consumed sweet water responded more quickly on the hot plate indicating that their threshold for pain was lowered. Another group of rats given identical exposure to the fluids had their brains prepared for measuring opiate receptor binding using the delta-receptor ligand [3H]D-Ala-D-Leu-enkephalin ([3H]DADLE) and the mu-receptor selective ligand [3H]Tyr-D-Ala-Gly-MePhe-Gly-ol ([ 3H]DAGO). Binding of these opiates to mu- and delta-receptors in the cerebral cortex, striatum, hippocampus, hypothalamus, brain stem, and remaining brain regions was the same for the rats that drank sweet fluids and those that drank unflavored water. These findings suggest that drinking sweet fluids lowers pain thresholds but does not alter mu- and delta-receptors.     

Role of the area postrema in three putative measures of motion sickness in the rat

After thermal cauterization of the area postrema in rats the absence of conditioned taste aversion to sucrose paired with lithium chloride (0.15 M, 3.3 ml/kg) was used as a pharmacologic/behavioral index of area postrema damage. In a subsequent experiment the effects of area postrema lesions on three measures proposed as species-relevant measures of motion sickness were studied, using off-vertical rotation at 150 degrees/s for either 30 or 90 min. Lesions of area postrema did not alter postrotational suppression of drinking or amount of defecation during motion. The initial acquisition of conditioned taste aversion to a novel cider vinegar solution paired with motion was not affected by lesioning of the area postrema, but these taste aversions extinguished more slowly in lesioned rats than in sham-operates or intact controls. Results are discussed in terms of proposed humoral factors which may induce motion sickness and in light of recent data on the role of the area postrema in similar measures in species possessing the complete emetic reflex.     

Naltrexone-reversible pain suppression in the isolated attacking mouse

Fighting pairs of isolated DBA/2 mice showed a significant increase in tail-flick response latencies independent of whether opponents were losing or winning the combat. The effect lasted less than 10 min in both animals. Elevated pain thresholds were also found in isolates that attacked a nonaggressive conspecific, and were prevented by naltrexone (0.2 mg/kg), while a larger dose (1.0 mg/kg) inhibited the attack behavior. A small increase in pain threshold was observed after exposure of isolates to the test box alone, while isolation per se had no effect on baseline tail-flick latencies. The data demonstrate that endogenous pain suppressing systems are activated during attack and suggest that this opioid-mediated antinociception is a correlate of the isolation syndrome, reflecting enhanced arousal of the attacking animal.     

Understanding the central processing limit in consistent-mapping visual search tasks

Effects of load (i.e., the number of stimuli in the display) have been observed in multiple-frame studies using a consistent mapping of stimuli to responses (e.g., Fisher, 1982, 1984). In a series of four experiments, it is shown that these effects are not the consequence of differences across the high- and low-load conditions in either decision noise or peripheral masking. Additionally, it is shown that of two modes of limited capacity (a limited-channel and divided-capacity model) considered as possible explanations of load effects in tasks where subjects are required to locate a target, only one--the limited-channel model--is consistent with the results from all three location tasks. Finally, it is argued that the limited-channel model predicts not only the behavior observed in the four consistent-mapping experiments reported in this article but also the behavior observed in several related consistent-mapping tasks (Kleiss & Lane, 1986; Shiffrin & Gardner, 1972).     

Affective state mediates causal attributions for success and failure

The influence of affect on causal attributions for success and failure was examined in this experiment. A positive, neurtral, or negative mood was induced in subjects who then learned they had either succeeded or failed an aptitude test taken previously. Relative to neutral mood control conditions, subjects in both positive and negative mood conditions showed a pronounced self-serving bias, particularly following success. The finding is interpreted as self-regulation of affective state. Specifically, causal attribution of success to internal factors can sustain or enhance positive affect; attribution of failure to external factors can diminish negative affect. Ancillary analyses corroborated this interpretation.     

Race and Moral Judgment Development Scores

Black and White college students were studied to determine reactions to moral dilemmas when the race of the central character in the dilemma was changed.