François Y. Doré

Accuracy and Latency of Judgment of Facial Expressions of Emotions

The aim of the experiment was to study the relation between accuracy of judgment of facial expressions of emotions and time for judgment. The results for 34 college students confirmed previous data showing high performance in identification of all emotions, although there were some important differences between emotions. Also, times for judgment were longer for the emotions which were more difficult to identify.

Accuracy of the judgment of facial expression of emotions as a function of sex and level of education

The purpose of this study is to examine the recognition of facial expressions of six emotions as a function of sex and level of education (high school, college, university) of the subjects. Three hundred French-speaking citizens of Quebec had to judge which emotion was expressed in various facial stimuli presented on slides. Results show that overall, the recognition of emotions was very good. However, there were significant and strong differences between emotions and sex and levels of education did not have strong effects on the results.

Judgment of Facial Expressions of Emotion as a Function of Exposure Time

The purpose of this experiment was to study the accuracy of judgment of facial expressions of emotions that were displayed for very brief exposure times. Twenty university students were shown facial stimuli that were presented for durations ranging from 10 to 50 msec. The data showed that accuracy of judgment reached a fairly high level even at very brief exposure times and that human observers are especially competent to process very rapid changes in facial appearance.

Search behavior of dogs (Canis familiaris) in invisible displacement problems.

Gagnon and Doré (1992) showed that domestic dogs are able to solve a Piagetian object permanence task called the invisible displacement problem. A toy is hidden in a container which is moved behind a screen where the toy is removed and left. Dogs make more errors in these problems than they do in visible displacement tests, in which the object is hidden directly behind the target screen. In Experiment 1, we examined components of the standard procedure of invisible displacements that may make encoding or retention of the hiding location more difficult than it is in visible displacements. In Experiment 2, we compared dogs’ performances in visible and invisible displacement problems when delays of 0, 10, and 20 sec were introduced between the object’s final disappearance and the subject’s release. The results revealed that dogs’ poorer performance in invisible displacement tests is related to the complex sequence of events that have to be encoded or remembered as well as to a difficulty in representing the position change that is signaled, but not directly perceived.

Search behavior in cats and dogs: Interspecific differences in working memory and spatial cognition

Cats’ and dogs’ search behavior was compared in different problems where an object was visibly moved behind a screen that was then visibly moved to a new position. In Experiments 1 (cats) and 2 (dogs), one group was tested with identical screens and the other group was tested with dissimilar screens. Results showed that in both species, search behavior was based on processing of spatial information rather than on recognition of the visual features of the target screen. Cats and dogs were unable to find the object by inferring its invisible movement. They reached a high level of success only if there was direct perceptual evidence that the object could not be at its initial position. When the position change was indicated by an indirect cue, cats searched more at the object’s initial than final position, whereas dogs searched equally at both positions. Interspecific similarities and differences are interpreted in terms of the requirements for resetting working memory.

Aspiration lesions of the amygdala disrupt the rhinal corticothalamic projection system in rhesus monkeys

Abstract In macaque monkeys, aspiration but not excitotoxic lesions of the medial temporal lobe limbic structures, the amygdala and hippocampus, produce a severe impairment in visual recognition memory. Furthermore, certain ventromedial cortical regions, namely the rhinal (i.e., entorhinal and perirhinal) cortex, are now known to be critical for visual recognition memory. Because the route taken by temporal cortical efferent fibers, especially perirhinal efferents, passes nearby the amygdala, it is possible that inadvertent damage to these fibers is produced by the aspirative but not the excitotoxic process, thereby accounting at least in part for the different behavioral outcomes of the two types of lesion. To test this idea, we assessed the integrity of the rhinal corticothalamic projection system after aspiration lesions of the amygdala. Three rhesus monkeys with unilateral amygdala removals received bilaterally symmetrical injections of a retrograde fluorescent tracer into the medial portion of the mediodorsal nucleus of the thalamus. Retrogradely labeled cells were identified using conventional fluorescence microscopy techniques. In all three cases, the rhinal cortex of the intact hemispheres contained moderate numbers of retrogradely labeled cells. By contrast, the rhinal cortex of the amygdalectomized hemispheres consistently contained few retrogradely labeled cells, and a direct comparison of the two hemispheres showed this difference to be statistically significant. A similar asymmetric pattern was observed for area TE but not for the cortex lining the dorsal bank of the superior temporal sulcus, nor for the rostral cingulate motor area, which was examined as a control. The results indicate that aspiration lesions of the amygdala not only remove the cell bodies of the amygdala, as intended, but also inadvertently disrupt projection fibers arising from cells in the rhinal cortex and area TE that pass nearby or through the amygdala en route to the thalamus. Behavioral studies examining the effects of aspiration lesions of the amygdala in nonhuman primates need to take these findings into consideration.

Object permanence in adult cats (Felis catus)

Human analog tests of object permanence were administered to adult cats in order to assess as accurately as possible their developmental level in this particular cognitive capacity and to analyze their search behavior in situations in which an object has disappeared. Experiment 1 compared two groups, one that received the tests in their usual order of presentation and another that received first the invisible displacement tests and then the visible displacement tests. The results are conflicting with a previous research conducted by Triana and Pasnak (1981): cats are able to solve problems with visible displacements but fail with invisible displacement. Experiment 2 compared two modalities of object disappearance: The object was hidden under a cover through either its front or its rear panel. This experiment confirmed, in a five-choice hiding task, that cats are unable to understand invisible displacements: They searched for the object in the last location they had seen it disappear or under the nearest cover from this location.

Neonatal ventral hippocampus lesions disrupt extra-dimensional shift and alter dendritic spine density in the medial prefrontal cortex of juvenile rats

Recent data showed that neonatal ventral hippocampus (VH) lesions, an approach used to model schizophrenia symptoms in rodents, produce premature deficits of working memory believed to be associated with early medial prefrontal cortex (mPFC) maldevelopment. This experiment expands the investigation of mPFC integrity in juvenile rats with neonatal VH lesions by assessing behavioral flexibility and dendritic spine density. Sixteen Sprague-Dawley male pups received bilateral microinjections of ibotenic acid in the VH or SHAM surgery on postnatal day (PND) 6. On PND 29 and 30, rats were subjected to a spatial shift task in a cross-maze; an attentional set-shifting task was then administered on two consecutive days, between PND 33 and PND 35. Rats were sacrificed at PND 36 and dendritic spine density in the mPFC was assessed using Golgi-Cox staining procedure. Results revealed impaired extra-dimensional shift in VH-lesioned rats and inconsistent reversal discrimination outcomes. Although lesioned animals displayed intact performance in the spatial shift, rates of perseverative responses were higher than normal in this task. Neonatal VH damage resulted in lower dendritic spine density in the mPFC than measured in control brains; however, no significant correlation was found between this outcome and behavioral data. Juvenile morphological and cognitive perturbations are consistent with the early emergence of mPFC anomalies following neonatal VH lesions. Results are discussed in relation with potential common mechanisms linking pre- and post-pubertal onsets of behavioral dysfunction.

Repeated subchronic exposure to phencyclidine elicits excessive atypical grooming in rats

Self-grooming in rodents is stereotypically sequenced and naturally occurs after arousal, novelty, or stress. Grooming expression and syntax resulting from stressful and appetitive conditions were assessed in male Long Evans rats treated daily with 10mg/kg of phencyclidine (PCP) for 15 days. Approximately 20 h after the 1st, the 8th, and/or the 15th injection, grooming was induced with water sprays, a loud sound, or smearing food. Behaviors expressed during the seconds or minutes that followed induction were videotaped and codified. Results showed that subchronic treatment with PCP amplified the grooming response in all stressful and appetitive conditions, but provoked a disorganization of grooming sequences only under the stressful, water condition. Thus, PCP enhanced grooming expression indiscriminately. However, this behavior had to serve both hygienic and stress managing purposes in order for chain sequencing to become disorganized as a consequence of drug treatment. These results suggest that the detailed examination of grooming expression and organization is an appropriate tool to measure stress-induced behavioral sensitization and motor functions in animal models of neuropsychiatric disorders such as schizophrenia.

Computer-automated method to study cardiac conditioning to a chemical cue in young salmon

An apparatus was designed in which young Atlantic salmon (Salmo salar) are rapidly conditioned to reduce heart rate using a chemical-electric shock conditioning procedure. A chemical calibration system permitting efficient stimulus control is described as well as the electronic systems and computer software used to control all events of an experimental session and to quantify cardiac and chemical data. Efficient stimulus control and computer-automated recording techniques minimize inter-trial intervals and the time required for the measurement and analysis of cardiac responses. Data are presented showing that 15-month-old Atlantic salmon can be trained to reduce by 20% their heart rate to the synthetic chemical morpholine within 5 training trials whereas 10-month-old fish did not do so until 15 training trials.