Enhanced retention in the passive-avoidance task by 5-HT(1A) receptor blockade is not associated with increased activity of the central nucleus of the amygdala

The effect of blockade of 5-HT1A receptors was investigated on (1). retention in a mildly aversive passive-avoidance task, and (2). spontaneous single-unit activity of central nucleus of the amygdala (CeA) neurons, a brain site implicated in modulation of retention. Systemic administration of the selective 5-HT1A antagonist NAN-190 immediately after training markedly-and dose-dependently-facilitated retention in the passive-avoidance task; enhanced retention was time-dependent and was not attributable to variations in wattages of shock received by animals. Systemic administration of NAN-190 had mixed effects on spontaneous single-unit activity of CeA neurons recorded extracellularly in vivo; microiontophoretic application of 5-HT, in contrast, consistently and potently suppressed CeA activity. The present findings-that 5-HT1A receptor blockade by NAN-190 (1). enhances retention in the passive-avoidance task, and (2). does not consistently increase spontaneous neuronal activity of the CeA-provide evidence that a serotonergic system tonically inhibits modulation of retention in the passive-avoidance task through activation of the 5-HT1A receptor subtype at brain sites located outside the CeA.     

The Jewish Cultural Complex

Although 70 years have passed since the Nazi Holocaust, the aftereffects resulting from it and centuries of Jewish oppression persist in Jewish tribal identity and in the mechanisms for its survival. In much the same way that PTSD affects individuals who have suffered life-threatening situations, a history of collective trauma has produced within Jewish psyches symptoms such as hypervigilance, reactivity, and a sense of profound danger in the world. The author proposes that such sedimented responses form a Jewish cultural complex with a hypermuscular defense system armed against further psychic attacks. Healing involves a restoration of the feeling function and a return to the rich body of Jewish ethical principles that balance personal security with compassion for self and other.     

Seeing structure: Shape skeletons modulate perceived similarity

An intrinsic part of seeing objects is seeing how similar or different they are relative to one another. This experience requires that objects be mentally represented in a common format over which such comparisons can be carried out. What is that representational format? Objects could be compared in terms of their superficial features (e.g., degree of pixel-by-pixel overlap), but a more intriguing possibility is that they are compared on the basis of a deeper structure. One especially promising candidate that has enjoyed success in the computer vision literature is the shape skeleton—a geometric transformation that represents objects according to their inferred underlying organization. Despite several hints that shape skeletons are computed in human vision, it remains unclear how much they actually matter for subsequent performance. Here, we explore the possibility that shape skeletons help mediate the ability to extract visual similarity. Observers completed a same/different task in which two shapes could vary either in their skeletal structure (without changing superficial features such as size, orientation, and internal angular separation) or in large surface-level ways (without changing overall skeletal organization). Discrimination was better for skeletally dissimilar shapes: observers had difficulty appreciating even surprisingly large differences when those differences did not reorganize the underlying skeletons. This pattern also generalized beyond line drawings to 3-D volumes whose skeletons were less readily inferable from the shapes’ visible contours. These results show how shape skeletons may influence the perception of similarity—and more generally, how they have important consequences for downstream visual processing.

     

INCREASING SPONTANEOUS PLAY BY SUPPRESSING SELF-STIMULATION IN AUTISTIC CHILDREN1

Appropriate play with toys was studied in two autistic children with high occurrences of self-stimulatory behavior. Each child participated in the experimental sessions in an A-B-A design, where “A” refers to baseline sessions and “B” refers to self-stimulation suppression sessions. It was found that: (a) during the baseline sessions, the children exhibited low levels of play and high levels of self-stimulatory behavior; (b) the per cent of unreinforced, spontaneous, appropriate play increased when self-stimulatory behavior was suppressed; and (c) when the suppression of self-stimulation was discontinued, the per cent of self-stimulation and that of appropriate play approached their presuppression levels. These results seem particularly significant because they identify a set of conditions under which spontaneous appropriate behavior, uncommon in autistic children, occurs at an increased level.     

The development of generalized imitation within topographically determined boundaries

A multiple baseline technique was employed to examine the experimental development of an imitative repertoire within preselected topographical boundaries. Four severely retarded children, initially nonimitative, were individually trained to imitate a number of motor and vocal responses by shaping and fading procedures. Other untrained responses (probes) were demonstrated to the subjects systematically throughout the ongoing training. Training responses were divided into three topographical types: small motor, large motor, and short vocal responses. Probe responses were divided into four topographical types: small motor, large motor, short vocal, and long vocal responses. Following a multiple baseline format, sequential training of the first three types was begun at different temporal periods of the study; unreinforced imitative generalization was continually measured by the probes. Generalized imitation was observed in each subject (untrained responses were imitated even though unreinforced); but this generalization was restricted to the topographical type of imitation currently receiving training or having previously received training.