Unusual Stimuli Research Articles

Robust multisensory deviance detection in the mouse parietal associative area

Context modulates how information is processed in the mammalian brain. For example, brain responses are amplified to contextually unusual stimuli. This phenomenon, known as "deviance detection,"1,2 is well documented in early, primary sensory cortex, where large responses are generated to simple stimuli that deviate from their context in low-order properties, such as line orientation, size, or pitch.2,3,4,5 However, the extent to which neural deviance detection manifests (1) in broader cortical networks and (2) to simple versus complex stimuli, which deviate only in their higher-order, multisensory properties, is not known. Consistent with a predictive processing framework,6,7 we hypothesized that deviance detection manifests in a hierarchical manner across cortical networks,8,9 emerging later and further downstream when stimulus deviance is complex. To test this, we examined brain responses of awake mice to simple unisensory deviants (e.g., visual line gratings, deviating from context in their orientation alone) versus complex multisensory deviants (i.e., audiovisual pairs, deviating from context only in their audiovisual pairing but not visual or auditory content alone). We find that mouse parietal associative area-a higher cortical region-displays robust multisensory deviance detection. In contrast, primary visual cortex exhibits strong unisensory visual deviance detection but weaker multisensory deviance detection. These results suggest that deviance detection signals in the cortex may be conceptualized as "prediction errors," which are primarily fed forward-or downstream-in cortical networks.6,7.

A Review of Neural Data and Modelling to Explain How a Semicircular Canal Dehiscence (SCD) Causes Enhanced VEMPs, Skull Vibration Induced Nystagmus (SVIN), and the Tullio Phenomenon

Angular acceleration stimulation of a semicircular canal causes an increased firing rate in primary canal afferent neurons that result in nystagmus in healthy adult animals. However, increased firing rate in canal afferent neurons can also be caused by sound or vibration in patients after a semicircular canal dehiscence, and so these unusual stimuli will also cause nystagmus. The recent data and model by Iversen and Rabbitt show that sound or vibration may increase firing rate either by neural activation locked to the individual cycles of the stimulus or by slow changes in firing rate due to fluid pumping (“acoustic streaming”), which causes cupula deflection. Both mechanisms will act to increase the primary afferent firing rate and so trigger nystagmus. The primary afferent data in guinea pigs indicate that in some situations, these two mechanisms may oppose each other. This review has shown how these three clinical phenomena—skull vibration-induced nystagmus, enhanced vestibular evoked myogenic potentials, and the Tullio phenomenon—have a common tie: they are caused by the new response of semicircular canal afferent neurons to sound and vibration after a semicircular canal dehiscence.

Amygdala on the Lookout.

results present an explanatory challenge: why would the amygdala be hypoactive in paranoid individuals who exhibit heightened threat perception and elevated physiological arousal? To explain this paradoxical finding, some investigators hypothesized that reduced frontal control over the amygdala due to dysconnectivity of frontolimbic circuitry could lead to hypervigilanceand misattribution of fear to incoming signals (3). AnotherpossibilityisthatmethodologicallimitationsofBOLD fMRI have obstructed a more accurate quantification of amygdala activity. In this issue of the Journal, a new study conducted by Pinkham and colleagues (5) offers a methodological explanation for discrepant findings concerning aberrant amygdala activity in paranoid schizophrenia. The authors definitively demonstrate higher baseline amygdala activity in paranoid compared with nonparanoid patients with schizophrenia, by employing arterial spin labeling perfusion MRI. Arterial spin labeling allows for a noninvasive and quantitative measurement of regional cerebral blood flow (CBF) by using magneticallylabeledarterialbloodwaterasanendogenoustracer (asopposedtoexogenousradioactivetracersusedinpositron emission tomography) (6). There are both important methodological and conceptual advances here worthy of note. In addition to arterial spin labeling, the authors acquired BOLD fMRI data while participants rated photographs of faces for trustworthiness. By measuring resting state regional CBF and task-related BOLD activity in the same participants, the authors were able to examine group differences in baseline amygdala activity alongside differences in task-related fluctuations of amygdalaactivity.Suchcomparisonsareparticularlyrelevant to schizophrenia, as prior evidence of amygdala hypoactivation relied on BOLD contrasts blind to potential group differences in baseline activity. Indeed, Pinkham and colleagues found that acutely paranoid patients exhibited higher resting CBF in the bilateral amygdala compared with nonparanoid patients and healthy comparison subjects, who did not differ from each other. On the other hand, the BOLD fMRI task analysis revealed a general trend of amygdala hypoactivation in paranoid compared with nonparanoid participants. Thus, observed taskrelated amygdala hypoactivity likely reflects higher baseline amygdala activity that mitigates the stimulus-driven signal change detected by the BOLD contrast. Additional wholebrain group comparisons found greater CBF in the internal capsule, the corpus callosum, and portions of the inferior temporal and fusiform gyri in paranoid compared with nonparanoid patients. Overall, these results suggest that paranoia

A case study on prison conditions for young children of imprisoned mothers in a selected prison of Uttar Pradesh, India

Prison environment is not conducive for optimal development of the child so when mothers are imprisoned the children require a special attention. To examine this case study was done in a selected prison of Uttar Pradesh. The results reflect that the children are vulnerable in a situation where they are in other than home environment and are subjected to lots of unusual stimuli that the children who live in their normal homes do not face.

Distinct neural responses used to gain insight into hallucinatory perception in patients with schizophrenia

ObjectiveMost patients with schizophrenia suffer from various types of hallucinations, which commonly produce distress, functional disability or behavioral dyscontrol. The neural process of adapting to hallucinations in patients with schizophrenia remains unknown. MethodsFunctional magnetic resonance imaging (MRI) responses to an unusual threatening visual stimulus designed to simulate a hallucinatory experience were compared between 16 patients with schizophrenia and 17 healthy controls. Linear and quadratic repetition-variant as well as repetition-invariant responses to the stimulus were compared between the two groups. ResultsRepetition-invariant responses were similar between patients with schizophrenia and healthy controls. Patients with schizophrenia exhibited a linear activation pattern in the anterior cingulate, whereas healthy controls exhibited a parabolic activation pattern in the anterior prefrontal cortex, occipito-temporal junction and amygdala. ConclusionsThese results provide us with a better understanding of the neural processes involved in gaining insight into unreality. Patients with schizophrenia may use a salience-related region instead of reality monitoring-related regions to react to the unusual stimuli, and this peculiarity of the neural processes may be related to vulnerability to psychosis.

A unique role for the human amygdala in novelty detection

Previous research indicates that the amygdala and hippocampus are sensitive to novelty; however, two types of novelty can be distinguished – stimuli that are ordinary, but novel in the current context, and stimuli that are unusual. Using functional magnetic resonance imaging, we examined blood oxygen dependent level (BOLD) response of the human amygdala and hippocampus to novel, commonly seen objects versus novel unusual objects. When presented with the novel common stimuli, the BOLD signal increased significantly in both the amygdala and hippocampus. However, for the novel unusual stimuli, only the amygdala showed an increased response compared to the novel common stimuli. These findings suggest that the amygdala is distinctly responsive to novel unusual stimuli, making a unique contribution to the novelty detection circuit.

Prefrontal and parietal regions are involved in naming of objects seen from unusual viewpoints.

Object naming is commonly used for demonstrating semantic memory abilities, known to be affected in normal aging. Yet, neuropsychological assessments of older people do not reflect irregularities. The authors used a test with 2 levels of naming complexity by 2 kinds of stimuli: common objects pictured from a conventional viewpoint (usual condition) or from an unconventional viewpoint (unusual condition). The authors studied naming performance with 129 healthy participants, aged 20-85 years. For the usual stimuli, the success rate was high (90.9%), with no reduction in performance until 65 years of age. However, for the unusual stimuli, there was a marked reduction in performance with age. Brain activity was studied on 11 healthy young participants (20-30 years of age) using functional magnetic resonance imaging. The usual condition activated brain regions associated with visual perception, language, and memory. Additional brain regions associated with semantic searching and decision making were obtained in the unusual condition in the prefrontal cortex (Brodmann's area [BA] 9 and BA 47) and anterior cingulate (BA 32). The results suggest that the poor naming performance for unusual-viewed objects in older people might be related to the shrinkage of frontal gray matter with age.

PEAK SHIFT DISCRIMINATION LEARNING AS A MECHANISM OF SIGNAL EVOLUTION

"Peak shift" is a behavioral response bias arising from discrimination learning in which animals display a directional, but limited, preference for or avoidance of unusual stimuli. Its hypothesized evolutionary relevance has been primarily in the realm of aposematic coloration and limited sexual dimorphism. Here, we develop a novel functional approach to peak shift, based on signal detection theory, which characterizes the response bias as arising from uncertainty about stimulus appearance, frequency, and quality. This approach allows the influence of peak shift to be generalized to the evolution of signals in a variety of domains and sensory modalities. The approach is illustrated with a bumblebee (Bombus impatiens) discrimination learning experiment. Bees exhibited peak shift while foraging in an artificial Batesian mimicry system. Changes in flower abundance, color distribution, and visitation reward induced bees to preferentially visit novel flower colors that reduced the risk of flower-type misidentification. Under conditions of signal uncertainty, peak shift results in visitation to rarer, but more easily distinguished, morphological variants of rewarding species in preference to their average morphology. Peak shift is a common and taxonomically widespread phenomenon. This example of the possible role of peak shift in signal evolution can be generalized to other systems in which a signal receiver learns to make choices in situations in which signal variation is linked to the sender's reproductive success.

Rationality, Meaning, and the Analysis of Delusion

On what I will call a rationalist approach to delusion, delusion is a matter of top-down disturbance in some fundamental beliefs of the subject, which may consequently affect experiences and actions. On an empiricist approach, in contrast, delusion is a rational response to highly unusual experiences that the subject has, perhaps as a result of organic damage. Ellis and Young (1990) recently provided an empiricist analysis of the Capgras and Cotard delusions. I want to begin with some remarks on just why it is important to the empiricist approach that it should acknowledge the rationality of the subject's delusional responses to unusual stimuli. We will see that when the rationale for the rationality constraint is fully set out, it is questionable whether Ellis and Young's approach actually succeeds in giving its place to the rationality constraint. In conclusion, I will look briefly at the prospects for a rationalist approach and at what other approaches might be possible.

Disruption of attention to novel events after frontal lobe injury in humans

OBJECTIVETo investigate whether frontal lobe damage in humans disrupts the natural tendency to preferentially attend to novel visual events in the environment.METHODSNine patients with chronic infarctions in the dorsolateral prefrontal...

Relationship of Optimum Stimulation Level to Fashion Behavior

According to optimum stimulation level theory, each individual seeks optimum stimulation. Environmental stimulation may include novelty, excitement, or new experiences. Optimum stimulation level may operate to guide consumer behavior, and particularly, regarding fashion. One way to increase stimulation might be to shop for and adopt new clothing fashions. This study investigated gender differences in (a) fashion behavior, (b) optimum stimulation level (OSL), and (c) the relationship of subjects' OSL to fashion behavior. Subjects were 335 students who filled out a questionnaire containing OSL measures and fashion behavior measures. Females scored higher on fashion leadership and arousal from unusual stimuli while males scored higher on arousal from sensuality and new environments. Fashion behavior was primarily related to three OSL factors: arousals from change (males and females), risk, and unusual stimuli (males).

Consumer Responses to Fashion Advertisements Using Models in Wheelchairs: Is There a Relationship to Consumers' Optimum Stimulation Level?

This study examines consumer responses tofashion advertisements using 2 advertising stimuli (model in wheelchair/lawn chair). Further, because models in wheelchairs are unusual stimuli, the effect of consumers' Optimum Stimulation Level (OSL) on responses to the advertising stimuli is explored. In an experiment using stimulus sampling, 101 working women viewed a fashion advertisement featuring 1 of 3 models in a wheelchair or a lawn chair and rated the likelihood that they would inquire about, would consider purchasing, and would actually purchase advertised items. There were no significant effects for OSL, social desirability, or individual models on consumer responses. Consumers were more likely to inquire about, more likely to consider purchasing, and more likely to actually purchase the clothing items presented by a model in a wheelchair. Results have implicationsfor OSL theoryfashion marketers targeting working women, models in wheelchairs, and society as a whole.

Liturgical Practices with Persons with Severe and Profound Mental Retardation

ABSTRACT This paper explores the presence of liturgical practices which enhance sensory participation of persons with mental retardation in the worship setting. Questions that are explored include: Does the addition of sensory stimuli to a worship service for persons with mental retardation add to subjects' ability to participate? Addition of different and unusual stimuli (auditory, visual and olfactory) at specific times in such a service indicated that both music and incense had a positive effect.

Neuropsychological Consequences of the Exposure of a Group of Telephonists to Unusual Auditory Stimuli

A group of 144 right-handed telephone operators reported a number of psychosomatic complaints after long-lasting unusual presentation of auditory stimuli to their left ears during working hours. The main finding of the study of their hemisphere organisation for verbal stimuli, as measured by dichotic listening to pairs of digits, is that the group displayed a clear shift of the right-ear preference to the left and differed significantly from the control group of 40 persons. The finding was verified by a follow-up study conducted eight years later.

Aspects of branchial irrigation in the lobster Homarus americanus. I. Functional analysis of scaphognathite beat, water pressures and currents.

ABSTRACT The movements of the scaphognathites of the lobster, Homaros americanos, and the resulting thrust, were resolved in two dimensions accompanied by attack angle changes. Correlation of these scaphognathite and related body movements with branchial hydrostatic pressures during forward and reversed pumping were effected by simultaneously recording on video tape. Forward pumping maintains a negative pressure within the branchial chambers of 2·5–10 mm H2O superimposed on a maintained negative pressure relative to the outside of 0·5 mm H2O. The scaphognathite, by assuming a negative attack angle to the water during the upstroke of the beat, produces the positive pressure of reversals. Contraction of the epimeral attractor muscle appears to contribute to the re-establishment of branchial negativity following each reversal. This muscle inserts on the epimera and by contraction enlarges the branchial chamber. The role of reversals is discussed and it is concluded that their primary function is to clean foreign material from the border of hairs which filter incurrent water. Reversed beating may be a general response to all unusual stimuli to the respiratory system. The pattern of water flow into and through the gill chambers was determined. The relative volume of water entering each incurrent aperture between the legs was calculated and indicated that approximately equal volumes of water entered each aperture. It is concluded that forward pumping adequately irrigates all gill surfaces.

A personal post from Rio.

A WELL known writer once told me that he could do his best writing in the top room of his house in a dense London fog, since this eliminated nearly all external stimuli. I am writing this in Rio de Janeiro on the way back from Buenos Aires, where the Seventh International Diabetic Federation meeting was held, and although it is one of the noisiest cities I have ever visited, and I have been subjected to many unusual external stimuli in the last few weeks, I am far enough from home to be able to reflect in a more detached . . .