Preferences for visual stimuli following amygdala damage

Bilateral damage to the human amygdala impairs retrieval of emotional and social information from faces. An important unanswered question concerns the specificity of the impairment for faces. To address this question, we examined preferences for a broad class of visual stimuli in two subjects with complete bilateral amygdala damage, both of whom were impaired in judgments of faces. Relative to controls, the subjects showed a positive bias for simple nonsense figures, color patterns, three-dimensional-looking objects and landscapes. The impairment was most pronounced in regard to those stimuli that are normally liked the least. The human amygdala thus appears to play a general role in guiding preferences for visual stimuli that are normally judged to be aversive.     

Neurons in the human amygdala selective for perceived emotion

The human amygdala plays a key role in recognizing facial emotions and neurons in the monkey and human amygdala respond to the emotional expression of faces. However, it remains unknown whether these responses are driven primarily by properties of the stimulus or by the perceptual judgments of the perceiver. We investigated these questions by recording from over 200 single neurons in the amygdalae of 7 neurosurgical patients with implanted depth electrodes. We presented degraded fear and happy faces and asked subjects to discriminate their emotion by button press. During trials where subjects responded correctly, we found neurons that distinguished fear vs. happy emotions as expressed by the displayed faces. During incorrect trials, these neurons indicated the patients’ subjective judgment. Additional analysis revealed that, on average, all neuronal responses were modulated most by increases or decreases in response to happy faces, and driven predominantly by judgments about the eye region of the face stimuli. Following the same analyses, we showed that hippocampal neurons, unlike amygdala neurons, only encoded emotions but not subjective judgment. Our results suggest that the amygdala specifically encodes the subjective judgment of emotional faces, but that it plays less of a role in simply encoding aspects of the image array. The conscious percept of the emotion shown in a face may thus arise from interactions between the amygdala and its connections within a distributed cortical network, a scheme also consistent with the long response latencies observed in human amygdala recordings.The human amygdala plays a crucial role in processing socially and emotionally salient stimuli (1, 2). A large literature, primarily from studies in animals, shows that the amygdala is critical for conditioned fear responses (3). However, a number of other studies show that it is involved also in broader aspects of social perception, notably aspects of face processing (4). These two themes converge in several human studies: there is an impairment in recognizing fear faces in subjects that lack a functional amygdala (5) in addition to the impairment of fear conditioning (6, 7). Neuroimaging studies have also reported significant activation of the amygdala to fear faces (8).In humans, it has been reported that amygdala neurons are selective for a variety of visual stimuli (9, 10). One category of stimuli that the amygdala plays a key role in analyzing is faces and facial emotions. Subjects with amygdala damage fail to recognize fear faces (5), although there is now a consensus that the amygdala is involved in processing many emotions from faces, not just fear (11). Electrophysiological recordings in monkeys have found single neurons that respond not only to faces as such (12, 13), but also to face identities, facial expressions, and gaze directions (14, 15). Single neurons in the human amygdala discriminate faces from inanimate objects (10). Furthermore, single neurons in the human amygdala were found to encode whole faces selectively (16) and show abnormal facial feature selectivity in autism (17). Thus, there is substantial evidence from neurophysiological, lesion, and functional MRI studies for the involvement of the primate amygdala in face processing.More detailed investigations suggest that impaired fear recognition after amygdala damage can be attributed to a failure to fixate on the eyes (18), suggesting that the amygdala might act as a detector of perceptual saliency and biological relevance (19, 20). This was complemented by a neuroimaging study showing that amygdala activity was specifically enhanced for fear faces when saccading from the mouth to the eye region (21). Patients with schizophrenia (22), social phobia (23), and autism (24) also show abnormal facial scanning patterns, which have been hypothesized to result from amygdala dysfunction (25). The functional role of the amygdala is supported by its connection with visual cortices specialized for face processing (26–28) as well as reciprocal connections with multiple visually responsive areas in the temporal (29–31) and frontal lobes (32). All of these findings, while supporting a clear role for the amygdala in face processing, also suggest that this role may be relatively specific for certain properties or features of faces, raising the question of what function distinguishes the amygdala’s role in face processing from the better-known role of temporal cortex in face processing (Discussion). We focused on one particular question in the present study.Neurons in the monkey and human amygdala respond to the emotional expression of faces, but it remains unknown whether these responses are driven primarily by image properties of the stimuli, by the perceptual judgments of the perceiver, or by behavioral categorization in terms of motor output. To investigate this question, we recorded 210 neurons from 7 neurosurgical patients with implanted depth electrodes on an established “bubbles” task (18, 33), in which patients discriminated emotions from sparsely sampled fear or happy faces. We first characterize neurons that distinguished fear vs. happy emotions expressed by the displayed faces, on those trials where subjects responded correctly. Next we show that these neurons tracked the patients’ subjective judgment regardless of whether it was correct or incorrect. Population permutation analysis confirmed the robustness of this result, on average, across the entire population of neurons. Our data suggest that neuronal responses within the human amygdala are selective for perceived emotion shown in faces and track subjective judgment expressed by behavior rather than visual properties of the stimuli.     

Mineralization and mechanical properties of the canine mandible distraction wound following acute molding

To investigate the influence of an acute single step callus manipulation immediately after distraction on mechanical properties and mineralization of the regenerate, custom made distraction devices were bilaterally placed in the mandibular angle of 15 beagle dogs, allowing to simultaneously compress and stretch the regenerate after completed linear distraction. The animals were divided in three groups (n=5): Group 1 and 2 underwent manipulation of the regenerate, group 3 remained in a linear position. After 42 (group1) and 90 (group 2 and 3) days of consolidation the animals were sacrificed. The mechanical properties were assessed in an Instron testframe and bone density quantified by quantitative computed tomography and three- dimensionally assessed (Scion Image processing and analysis software). After 6 weeks of consolidation 25% of the specimens reached a stiffness which was >/=90% of the mean values of the unoperated reference hemi-mandibles. After a 13 week consolidation period, 62.5% were as stiff as the referenced specimens. Manipulated regenerates, allowed to heal under stable conditions for 13 weeks, had the same mechanical properties as specimens that underwent pure linear distraction. A temporary but not significant delay of osseous healing had to be postulated for the stretched zone after 6 weeks, indicating this area to be more critical than the compressed area.     

Reward processing in autism: a thematic series

This thematic series presents theoretical and empirical papers focused on understanding autism from the perspective of reward processing deficits. Although the core symptoms of autism have not traditionally been conceptualized with respect to altered reward-based processes, it is clear that brain reward circuitry plays a critical role in guiding social and nonsocial learning and behavior throughout development. Additionally, brain reward circuitry may respond to social sources of information in ways that are similar to responses to primary rewards, and recent clinical data consistently suggest abnormal behavioral and neurobiologic responses to rewards in autism. This thematic series presents empirical data and review papers that highlight the utility of considering autism from the perspective of reward processing deficits. Our hope is that this novel framework may further elucidate autism pathophysiology, with the ultimate goal of yielding novel insights with potential therapeutic implications.     

Preferential attention to animals and people is independent of the amygdala

The amygdala is thought to play a critical role in detecting salient stimuli. Several studies have taken ecological approaches to investigating such saliency, and argue for domain-specific effects for processing certain natural stimulus categories, in particular faces and animals. Linking this to the amygdala, neurons in the human amygdala have been found to respond strongly to faces and also to animals. However, the amygdala’s necessary role for such category-specific effects at the behavioral level remains untested. Here we tested four rare patients with bilateral amygdala lesions on an established change-detection protocol. Consistent with prior published studies, healthy controls showed reliably faster and more accurate detection of people and animals, as compared with artifacts and plants. So did all four amygdala patients: there were no differences in phenomenal change blindness, in behavioral reaction time to detect changes or in eye-tracking measures. The findings provide decisive evidence against a critical participation of the amygdala in rapid initial processing of attention to animate stimuli, suggesting that the necessary neural substrates for this phenomenon arise either in other subcortical structures (such as the pulvinar) or within the cortex itself.     

Necrotizing soft tissue infection of the scalp after fronto-facial advancement by internal distraction in a 7-year old girl with Gorlin–Chaudhry–Moss syndrome – A case report

In 1960, Gorlin, Chaudhry and Moss described a syndrome consisting of craniofacial dysostosis in association with hypertrichosis, cardiac, genital, dental and ocular anomalies. Diagnosis is based on typical clinical findings and cannot be performed by molecular genetic analysis until now. There is little in the clinical literature concerning this rare craniofacial syndrome.For functional and psychosocial reasons, surgical correction of the complex craniofacial malformation in a 7-year old Hungarian girl with Gorlin–Chaudhry–Moss syndrome was performed by fronto-facial advancement using internal distraction devices. Postoperatively necrotizing soft tissue infection of the scalp developed leading to termination of the distraction process ahead of schedule and requiring aggressive surgical management. Typical physiological and clinical characteristics were observed both during the initial craniofacial correction as well as during the management of the infectious complication suggesting that the linking of different conditions (surgical trauma plus the selection of toxic microorganisms) has caused tissue destruction rather than the syndromal disorder or the surgical technique of distraction osteogenesis. Although skeletal improvement was achieved residual damage from the infectious complication must be considered as severe.     

Normal recognition of emotional similarity between facial expressions following bilateral amygdala damage.

Bilateral damage to the amygdala in humans has been previously linked to two deficits in recognizing emotion in facial expressions: recognition of individual basic emotions, especially fear, and recognition of similarity among emotional expressions. Although several studies have examined recognition of individual emotions following amygdala damage, only one subject has been examined on recognition of similarity. To assess the extent to which deficits in recognizing similarity among facial expressions might be a general consequence of amygdala damage, we examined this ability in two subjects with complete bilateral amygdala damage. Both subjects had previously demonstrated entirely normal recognition of individual facial emotions. Here we report that these two patients also are intact in their ability to recognize similarity between emotional expressions. These results indicate that, like the recognition of individual basic emotions in facial expressions, the recognition of similarity among emotional expressions does not have an absolute dependence on the amygdala.     

Towards the neural basis for hypersociability in a genetic syndrome.

Williams syndrome (WMS), a rare disorder with a distinctive profile of medical, psychological, neurophysiological and neuroanatomical characteristics, results from hemizygous deletion of about 20 genes. The phenotype exhibits specific dissociations in higher cognitive functions: general cognitive deficits but spared linguistic abilities; extreme spatial cognitive deficits, but intact face processing. Of special interest is an unusual social phenotype in WMS: an overly friendly, engaging personality and excessive sociability with strangers. In this first experimental study of social behavior in WMS, we report that WMS subjects show an abnormal positive bias in their social judgments of unfamiliar individuals, consistent with their behavior in real life. Our findings contribute to an understanding of the neural and genetic bases of human social behavior.     

The influence of autonomic arousal and semantic relatedness on memory for emotional words.

Increased memory for emotional stimuli is a well-documented phenomenon. Emotional arousal during the encoding of a stimulus is one mediator of this memory enhancement. Other variables such as semantic relatedness also play a role in the enhanced memory for emotional stimuli, especially for verbal stimuli. Research has not addressed the contributions of emotional arousal, indexed by self-report and autonomic measures, and semantic relatedness on memory performance. Twenty young adults (10 women) were presented neutral-unrelated words, school-related words, moderately arousing emotional words, and highly arousing taboo words while heart rate and skin conductance were measured. Memory was tested with free recall and recognition tests. Results showed that taboo words, which were both semantically related and high arousal were remembered best. School-related words, which were high on semantic relatedness but low on arousal, were remembered better than the moderately arousing emotional words and semantically unrelated neutral words. Psychophysiological responses showed that within the moderately arousing emotional and neutral word groups, those words eliciting greater autonomic activity were better remembered than words that did not elicit such activity. These results demonstrate additive effects of semantic relatedness and emotional arousal on memory. Relatedness confers an advantage to memory (as in the school-words), but the combination of relatedness and arousal (as in the taboo words) results in the best memory performance.     

Effect of intralesional and systemic BCG-application or a combined cyclophosphamide/BCG treatment on experimental bladder cancer

Summary Infiltrating transitional cell carcinomas of the urinary bladder were induced by ingestion of 0.188% N-[4-(5-nitro-2-furyl)-2-thiazolyl] formamide (FANFT) in 145 female Wistar rats. After 8 months of carcinogen exposure, the animals were divided into different treatment groups. They received cyclophosphamide intraperitoneally as a single injection or BCG either once intralesionally or weekly subcutaneously or a combination of cyclophosphamide followed by subcutaneous BCG. The treatment effect was determined by body weight measurements and bladder tumour weight after 12 months. Compared with a control group statistically significant differences of bladder tumour weights were found after treatment with BCG alone or in combination with cyclophosphamide. Intralesional BCG resulted in an insignificant increase of tumour weights.