Intrafemale agonistic interactions in the domestic rabbit (oryctolagus cuniculus L.)

Agonistic interactions between adult domestic rabbit females were observed. Females were housed in groups of four in outdoor enclosures measuring 4 × 4 m. Agonistic patterns included aggression (AG), flight (FL), and submission (SB). Observations focused on 1) initial interactions between unfamiliar females, concomitant with the formation and establishment of a social structure (Phase 1); and 2) interactions between familiar females organized in a stable social structure (Phase 2). AG was frequent between unfamiliar females and appeared related to the acquisition of social dominance. When social organization was settled, there was a dramatic reduction in the number and frequency of aggressive behaviors. Similarly, FL was more frequent when females were unfamiliar, but it did not appear to be merely a response to AG. The decreased frequency of both AG and FL in Phase 2 was paralleled by an increased frequency of SB with respect to FL. Under stable social conditions, subordinate females frequently signalled submission to dominant counterparts. In contrast, the latter did not signal their social status with any consistent behavioral pattern. It follows that SB was not necessarily induced as the appropriate response to aggression given by dominant females. Thus, SB appeared relevant in social communication especially in structured groups, where it conveyed information on the actor's subordination and possibly inhibited the receiver's aggression. A further possibility is that it has an autonomous rather than secondary role in the maintenance of stable dominance/subordination relationships.     

Effects of neonatal treatment with 1-(2,5-dimethoxy-4-lodophenyl)-2 aminopropane HCI (DOI) and ritanserin on agonistic behavior in adult male and female rats

The role played by the neonatal 5-hydroxytryptamine (5HT) system in the organization and sexual differentiation of adult agonistic behavior was investigated in rats. Focus was on the 5HT2 receptor subtype, which has been demonstrated to be involved in agonism control in the adult. 5HT2 activity was experimentally manipulated by administration of a specific agonist [1-(2, 5-dimethoxy-4-iodophenyl)-2-aminopropane HCl (DOI)] or antagonist (ritanserin) during the second week of life, when serotonin is known to concur to anatomical and behavioral sexual differentiation. Interactions between early 5HT2 activity, genetic sex, and neonatal circulating testosterone (T) were studied by administering the ligands to males, females, and androgenized females. At adulthood, the animals were tested for both aspects of agonism, i. e., aggression and defense, in a 20-min confrontation with an unfamiliar conspecific of the same sex, age, body weight, and social experience. Neonatal administration of the 5HT2 antagonist ritanserin increased aggression independently of sex; it also increased defense, but this effect was confined to males. The agonist DOI had no effect on aggression, but enhanced defense in males and androgenized females, with an effect which depended therefore more on neonatal T than genetic sex. Females appeared in general less sensitive to neonatal 5HT2 manipulation than both androgenized females and males; this suggests that neonatal T is crucial for experimental modifications of neonatal 5HT2 activity to have any consistent effect on adult agonistic behavior. On the other hand, effects observed in males and androgenized females were dependent on the behavior considered and the drug administered. This was especially evident for defense, enhanced by ritanserin in males only, and in both males and androgenized females by DOI. Neonatal 5HT2 activity seems therefore to play a role in the modulation of adult agonistic behaviors, which depends on the behavior considered and is under multiple control of genetic sex and hormonal neonatal substrate. © 1994 Wiley-Liss, Inc.     

The structure of language abilities at 4 years: a twin study

Normal language development was studied in 310 pairs of 4-year-old twins born in the United Kingdom in 1994. Twins were assessed individually in their homes on a diverse battery of language and nonverbal measures. Rotated factor analyses indicated the presence of a general Language factor (L) as well as a general Nonverbal (NV) factor. Moderate genetic influence was found for both L and NV abilities. Bivariate genetic analysis estimated a genetic correlation of .63 between L and NV abilities, implying that over half of the genetic influence on L overlaps with genetic influence on NV. These results suggest that at age 4, genetic influences on individual differences in language overlap substantially with genetic influences on individual differences in other cognitive abilities, although perhaps less so than later in development.     

Newborns' preference for faces: what is crucial?

Three experiments investigated whether the presence of more elements in the upper part of a configuration (i.e., up-down asymmetry) plays a role in determining newborns' preference for facelike patterns. Newborns preferred a nonfacelike stimulus with more elements in the upper part over a nonfacelike stimulus with more elements in the lower part (Experiment 1), did not show a preference for a facelike stimulus over a nonfacelike configuration equated for the number of elements in the upper part of the configuration (Experiment 2), and preferred a nonfacelike configuration located in the upper portion of the stimulus over a facelike configuration in the lower portion of the pattern (Experiment 3). Results demonstrated that up-down asymmetry is crucial in determining newborns' face preference.     

Selective impairment of lexical stress assignment in an Italian-speaking aphasic patient

Psycholinguistic speech production models assume that lexical stress is stored and accessed separately during phonological encoding. We address the questions of the storage and computation of lexical stress in a case study of an Italian-speaking patient with an impairment of lexical stress assignment in naming, reading, and repeating single words. The patient's stress error pattern and his performance on tasks examining lexical stress in perception suggest an impairment in the retrieval of the stress pattern of irregular words. In contrast, his assignment of stress to nonstored phonological forms suggests that the computation of stress is unimpaired.     

An fMRI study on conceptual, grammatical, and morpho-phonological processing

The aim of the present study was to determine whether processing of syntactic word information (lemma) is subserved by the same neural substrate as processing of conceptual or word form information (lexeme). We measured BOLD responses in 14 native speakers of German in three different decision tasks, each focussing specifically on one level of lexical processing (conceptual, syntactic, and morpho-phonological). The test parameters were natural gender, grammatical gender, and word form derivation, respectively. Discrimination between words played backwards and complex sounds served as control task. Complex contrasts revealed a functional fractionation of the left inferior frontal gyrus for each level of lexical processing.     

Acquired ‘theory of mind'' impairments following stroke

The ability to attribute thoughts and feelings to self and others (‘theory of mind') has been hypothesised to have an innate neural basis and a dedicated cognitive mechanism. Evidence in favour of this proposal has come from autism; a brain-based developmental disorder which appears to be characterised by impaired theory of mind, despite sometimes good general reasoning skills/IQ. To date no case of specific acquired theory of mind impairment has been reported. The present study examined theory of mind in adults who had suffered right hemisphere stroke, a group known to show pragmatic and social difficulties. In one study using story materials and two using cartoons, patients' understanding of materials requiring attribution of mental states (e.g. ignorance, false belief) was significantly worse than their understanding of non-mental control materials. Data from healthy elderly subjects, and a small group of left hemisphere patients (who received the tasks in modified form), suggest that this impairment on mental state tasks is not a function of task difficulty. The findings support the notion of a dedicated cognitive system for theory of mind, and suggest a role for the healthy right hemisphere in the attribution of mental states.     

Effects of the Novel Acetylcholinesterase InhibitorN-Octyl-1,2,3,4-tetrahydro-9-aminoacridine on Locomotor Activity and Avoidance Learning in Mice

The acetylcholinesterase reversible inhibitorN-octyl-1,2,3,4-tetrahydro-9-aminoacridine (THA-C8) is a new synthesized derivative of tacrine (THA) characterized by an alkyl chain in the molecular structure which ameliorates the penetrability of the compound into the central nervous system. THA-C8 (0.1–5 mg/kg) significantly reduced spontaneous locomotor activity in CD1 mice at a dose of 3 mg/kg. Moreover, THA-C8 (0.2–2 mg/kg) significantly improved shuttle-box avoidance acquisition at doses (0.25, 0.3, 1 mg/kg) not affecting locomotion and that are much lower than the doses reported to be effective for THA in animal models. From the data reported it seems that the new compound could be interesting for therapeutic purposes.     

The gap effect in newborns

In four experiments we investigated the gap effect in infants within the first 3 days of life. Reaction times (RTs) to make a saccade to a peripheral target were measured on gap trials, in which the central fixation stimulus went off 500 ms before target presentation, and on overlap trials, in which the central fixation stimulus remained on. In every experiment the fixation stimulus was a flashing light. The target stimulus was a schematic face in Experiment 1, a flashing light shown at 20° eccentricity in Experiment 2, a flashing light shown at 30° eccentricity in Experiment 3, and an upside-down schematic face in Experiment 4. In Experiments 1–3 a gap effect was found. That is, RT was faster on gap than on overlap trials. In contrast, the gap effect was absent in Experiment 4. These findings are consistent with the view that the superior colliculus plays a major role in producing the gap effect at birth.