Involvement of the basolateral amygdala in muscarinic cholinergic modulation of extinction memory consolidation

Previous studies have reported that drugs affecting neuromodulatory systems within the basolateral amygdala (BLA), including drugs affecting muscarinic cholinergic receptors, modulate the consolidation of many kinds of training, including contextual fear conditioning (CFC). The present experiments investigated the involvement of muscarinic cholinergic influences within the BLA in modulating the consolidation of CFC extinction memory. Male Sprague Dawley rats implanted with unilateral cannula aimed at the BLA were trained on a CFC task, using footshock stimulation, and 24 and 48 h later were given extinction training by replacing them in the apparatus without footshock. Following each extinction session they received intra-BLA infusions of the cholinergic agonist oxotremorine (10 ng). Immediate post-extinction BLA infusions significantly enhanced extinction but infusions administered 180 min after extinction training did not influence extinction. Thus the oxotremorine effects were time-dependent and not attributable to non-specific effects on retention performance. These findings provide evidence that, as previously found with original CFC learning, cholinergic activation within the BLA modulates the consolidation of CFC extinction.     

A high density ERP comparison of mental rotation and mental size transformation

To compare mental rotation and mental size transformation, 128-channel EEG was recorded while subjects performed both tasks using random two-dimensional shapes as stimuli. Behavioural results showed significant linear effects of both size transformation and mental rotation on reaction times. Rotation ERPs showed experimental effects at two latencies: a bilateral component distributed over posterior parietal electrodes at a latency of approximately 232-300ms and a second component at approximately 424-492ms distributed over right anterior parietal electrodes. The latency and spatial distribution of this second effect is consistent with previous research indicating a functional connection between this component and mental rotation. ERPs for the size-transformation task showed an effect at 180-228ms distributed bilaterally over occipital-temporal electrodes. These results are consistent with previous hemodynamic imaging studies that show involvement of parietal cortex in mental rotation and also the involvement of BA 19 in size-transformation tasks. However, the superior temporal resolution of the present data indicates that BA 19 activation may occur at a latency that is more likely related to apparent motion than to the size-transformation operation per se.     

Hearing what the eyes see: auditory encoding of visual temporal sequences

When the senses deliver conflicting information, vision dominates spatial processing, and audition dominates temporal processing. We asked whether this sensory specialization results in cross-modal encoding of unisensory input into the task-appropriate modality. Specifically, we investigated whether visually portrayed temporal structure receives automatic, obligatory encoding in the auditory domain. In three experiments, observers judged whether the changes in two successive visual sequences followed the same or different rhythms. We assessed temporal representations by measuring the extent to which both task-irrelevant auditory information and task-irrelevant visual information interfered with rhythm discrimination. Incongruent auditory information significantly disrupted task performance, particularly when presented during encoding; by contrast, varying the nature of the rhythm-depicting visual changes had minimal impact on performance. Evidently, the perceptual system automatically and obligatorily abstracts temporal structure from its visual form and represents this structure using an auditory code, resulting in the experience of "hearing visual rhythms."     

Determining sociability, social space, and social presence in (a)synchronous collaborative groups.

The effectiveness of group learning in asynchronous distributed learning groups depends on the social interaction that takes place. This social interaction affects both cognitive and socioemotional processes that take place during learning, group forming, establishment of group structures, and group dynamics. Though now known to be important, this aspect is often ignored, denied or forgotten by educators and researchers who tend to concentrate on cognitive processes and on-task contexts. This "one-sided" educational focus largely determines the set of requirements in the design of computer-supported collaborative learning (CSCL) environments resulting in functional CSCL environments. In contrast, our research is aimed at the design and implementation of sociable CSCL environments which may increase the likelihood that a sound social space will emerge. We use a theoretical framework that is based upon an ecological approach to social interaction, centering on the concept of social affordances, the concept of the sociability of CSCL environments, and social presence theory. The hypothesis is that the higher the sociability, the more likely that social interaction will take place or will increase, and the more likely that this will result in an emerging sound social space. In the present research, the variables of interest are sociability, social space, and social presence. This study deals with the construction and validation of three instruments to determine sociability, social space, and social presence in (a)synchronous collaborating groups. The findings suggest that the instruments have potential to be useful as measures for the respective variables. However, it must be realized that these measures are "first steps."     

Perceiving object motion using vision and touch

In a previous experiment, we showed that bistable visual object motion was partially disambiguated by tactile input. Here, we investigated this effect further by employing a more potent visuotactile stimulus. Monocular viewing of a tangible wire-frame sphere (TS) rotating about its vertical axis produced bistable alternations of direction. Touching the TS biased simultaneous and subsequent visual perception of motion. Both of these biases were in the direction of the tactile stimulation and, therefore, constituted facilitation or priming, as opposed to interference or adaptation. Although touching the TS biased visual perception, tactile stimulation was not able to override the ambiguous visual percept. This led to periods of sensory conflict, during which visual and tactile motion percepts were incongruent. Visual and tactile inputs can sometimes be fused to form a coherent percept of object motion but, when they are in extreme conflict, can also remain independent.     

Depth capture by kinetic depth and by stereopsis

The perceived depth of regions within a stereogram lacking explicit disparity information can be captured by the surface structure of regions where disparity is explicit: stereo capture. In two experiments, observers estimated surface curvature/depth of an untextured object (a 'ribbon') superimposed on a cylinder textured with dots, the cylinder curvature being defined by disparity (stereo depth) or by motion parallax (kinetic depth: KD). With the stereo-defined cylinder, depth capture was obtained under conditions where the disparity of the ribbon was ambiguous; with the KD, cylinder depth capture was obtained under conditions where the motion flow of the cylinder was in a direction parallel to that of the ribbon. These results demonstrate yet another similarity between KD and stereopsis.     

Acetaminophen effects on behavioral thermoregulation in albino rats

Acetaminophen (N-Acetyl-p-aminophenol) was administered intraperitoneally to 15 Sprague-Dawley rats partitioned into 3 studies (5 rats per study) using a within subjects, repeated-measures reversal design. Behavioral thermoregulation was assessed in a cold Skinner Box using 5-sec. exposures of microwave radiation [Specific Absorption Rate = 0.34 Watts/kg/(mW/cm2)] as reinforcing stimuli under a fixed-interval 2-min. schedule of positive reinforcement. Doses of 10, 20, 30, 40, and 50 mg/kg (in solutions of 1%, 2%, 3%, 4%, and 5%) acetaminophen showed stable rates of operant responding for heat compared with significant changes in rates for comparable doses of aspirin in a 1993 study by Vitulli, et al. Weight reductions and temperature increases varied significantly with before-session and after-session measures, respectively. 1994-95 biochemical data of Murphy, et al. from humans following aspirin or acetaminophen ingestion which affect thermoregulation and sleep patterns are discussed in conjunction with behavioral data from rats.     

The suppression of exciting thoughts

We examined how the suppression of an exciting thought influences sympathetic arousal as indexed by skin conductance level (SCL). Subjects were asked to think aloud as they followed instructions to think about or not to think about various topics. Experiment 1 showed that trying not to think about sex, like thinking about sex, elevates SCL in comparison to thinking about or not thinking about less exciting topics (e.g., dancing). Experiment 2 revealed that the suppression of the thought of sex yielded SCL elevation whether or not subjects believed their think-aloud reports would be private or public, and it also revealed that the effect dissipated over the course of a few minutes. Experiment 3 found such dissipation again but showed that subsequent intrusions of the suppressed exciting thought are associated with further elevations in SCL over 30 min. Because such an association was not found when subjects were trying to think about the exciting thought, it was suggested that the suppression of exciting thoughts might be involved in the production of chronic emotional responses such as phobias and obsessive preoccupations.     

Preattentive vision and perceptual groups

Recent evidence suggests that preattentive processing may not be limited to the analysis of simple stimulus features as previously suggested. To explore this idea a visual search task was used to test whether the shapes of several perceptual groups can be processed in parallel. Textured displays that give rise to strong perceptual grouping were used to create figures on a background. Search times for a target figure distinguished by a unique shape were found to be independent of the number of distractor figures in the display. This result indicates that perceptual groups may be processed in parallel and suggests an expanded role for preattentive processing in vision.