Lack of short-latency-potentials in the VEP reflects immature extra geniculate visual function in delayed visual maturation (DVM)

Barriers and facilitators to cervical cancer screening uptake among women in Nepal - a qualitative study

The global incidence of cervical cancer is approximately 570,000 cases and 311,000 deaths annually. Almost 90% of cervical cancer deaths occur in low and middle income countries. Screening is the most effective tool in prevention, early diagnosis, and treatment of cervical cancer. Nepal has no national cervical cancer screening programme, and data from 2003 showed that only 2.8% of Nepalese women had ever been screened. We conducted a qualitative study to obtain better insight into barriers and facilitators to cervical cancer screening among women in Nepal to generate data to inform interventions. In February 2019, four focus group discussions with previously screened and non-screened women, and Female Community Health Volunteers and four in-depth interviews with health workers were conducted in Pokhara Metropolitan City. Semi-structured interview guides were used, interviews were audio-recorded, transcribed verbatim, and analyzed using grounded theory approach with open coding. This resulted in five main themes: 1) lack of husband's support for screening, 2) prevalent stigma and discrimination, 3) lack of awareness about screening options, 4) getting screened, and 5) health care providers. We encourage policymakers and stakeholders apply these findings to improve awareness, access to information, and better screening services in Nepal.

Developmental deficits in social perception in autism: the role of the amygdala and fusiform face area

Autism is a severe developmental disorder marked by a triad of deficits, including impairments in reciprocal social interaction, delays in early language and communication, and the presence of restrictive, repetitive and stereotyped behaviors. In this review, it is argued that the search for the neurobiological bases of the autism spectrum disorders should focus on the social deficits, as they alone are specific to autism and they are likely to be most informative with respect to modeling the pathophysiology of the disorder. Many recent studies have documented the difficulties persons with an autism spectrum disorder have accurately perceiving facial identity and facial expressions. This behavioral literature on face perception abnormalities in autism is reviewed and integrated with the functional magnetic resonance imaging (fMRI) literature in this area, and a heuristic model of the pathophysiology of autism is presented. This model posits an early developmental failure in autism involving the amygdala, with a cascading influence on the development of cortical areas that mediate social perception in the visual domain, specifically the fusiform "face area" of the ventral temporal lobe. Moreover, there are now some provocative data to suggest that visual perceptual areas of the ventral temporal pathway are also involved in important ways in representations of the semantic attributes of people, social knowledge and social cognition. Social perception and social cognition are postulated as normally linked during development such that growth in social perceptual skills during childhood provides important scaffolding for social skill development. It is argued that the development of face perception and social cognitive skills are supported by the amygdala-fusiform system, and that deficits in this network are instrumental in causing autism.

Normal vernier acuity in infants with delayed visual maturation

PURPOSE

Measures of vernier acuity may correlate accurately with measures of Snellen acuity. We used the sweep visual evoked potential to determine whether vernier acuity is normal in children with delayed visual maturation (DVM).

DESIGN

Case series of two infants.

METHODS

Thresholds for grating and vernier acuity were measured electrophysiologically in two infants with DVM using the sweep visual evoked potential. Acuity thresholds were calculated for each of these visual functions.

RESULTS

Two infants with DVM had normal thresholds for grating and vernier acuity, even though their visual behavior as determined clinically was abnormal.

CONCLUSIONS

Some children with DVM have normal acuity thresholds, even though the behaviors associated with vision are delayed or absent.

Subcortical Discrimination of Unperceived Objects during Binocular Rivalry

Rapid identification of behaviorally relevant objects is important for survival. In humans, the neural computations for visually discriminating complex objects involve inferior temporal cortex (IT). However, less detailed but faster form processing may also occur in a phylogenetically older subcortical visual system that terminates in the amygdala. We used binocular rivalry to present stimuli without conscious awareness, thereby eliminating the IT object representation and isolating subcortical visual input to the amygdala. Functional magnetic resonance imaging revealed significant brain activation in the left amygdala but not in object-selective IT in response to unperceived fearful faces compared to unperceived nonface objects. These findings indicate that, for certain behaviorally relevant stimuli, a high-level cortical representation in IT is not required for object discrimination in the amygdala.

Innate visual object recognition in vertebrates: some proposed pathways and mechanisms

Almost all vertebrates are capable of recognizing biologically relevant stimuli at or shortly after birth, and in some phylogenetically ancient species visual object recognition is exclusively innate. Extensive and detailed studies of the anuran visual system have resulted in the determination of the neural structures and pathways involved in innate prey and predator recognition in these species [Behav. Brain Sci. 10 (1987) 337; Comp. Biochem. Physiol. A 128 (2001) 417]. The structures involved include the optic tectum, pretectal nuclei and an area within the mesencephalic tegmentum. Here we investigate the structures and pathways involved in innate stimulus recognition in avian, rodent and primate species. We discuss innate stimulus preferences in maternal imprinting in chicks and argue that these preferences are due to innate visual recognition of conspecifics, entirely mediated by subtelencephalic structures. In rodent species, brainstem structures largely homologous to the components of the anuran subcortical visual system mediate innate visual object recognition. The primary components of the mammalian subcortical visual system are the superior colliculus, nucleus of the optic tract, anterior and posterior pretectal nuclei, nucleus of the posterior commissure, and an area within the mesopontine reticular formation that includes parts of the cuneiform, subcuneiform and pedunculopontine nuclei. We argue that in rodent species the innate sensory recognition systems function throughout ontogeny, acting in parallel with cortical sensory and recognition systems. In primates the structures involved in innate stimulus recognition are essentially the same as those in rodents, but overt innate recognition is only present in very early ontogeny, and after a transition period gives way to learned object recognition mediated by cortical structures. After the transition period, primate subcortical sensory systems still function to provide implicit innate stimulus recognition, and this recognition can still generate orienting, neuroendocrine and emotional responses to biologically relevant stimuli.

The neonatal development of the light flash visual evoked potential

AIMS

To follow visual development longitudinally in the normal neonate using the flash visual evoked potential (VEP) and to find indications for a relationship between potential development and visual development.

METHODS

Twenty healthy infants, born at term, were included in the study. Flash and patterned flash VEPs were used. The first VEP was recorded the day of birth or just postnatally, and succeeding recordings were performed the following weeks and months.

RESULTS

The data revealed different types of VEP in the neonatal period suggesting great variability in visual function on the day of birth. In the early development a potential of long latency and duration preceded the development of a more compound potential of shorter latency. The two types of responses seemed to coalesce during early development; the first late response was attenuated and was eventually integrated in the more mature VEP. At approximately five weeks of age changes in the VEP were simultaneous with the development of responsive smiling and another visual behaviour of the infants.

CONCLUSIONS

The results showed many similarities between the VEP development in infants and in immature animals. In developing animals geniculo-cortical and extra-geniculate visual afferent pathways evoke two types of VEPs similar to those recorded in the present study. The early responses were also similar to previous recordings from children with lesions in the geniculo-striatal pathway or primary cortex. Our interpretation of the results was that the human VEP also consists of responses evoked by afferents running both in geniculo-cortical and extra-geniculate pathways and that the two types of responses could be separated in the VEP in the neonatal period. These findings are important for our understanding of conditions with a delay in visual maturation, for example intracranial haemorrhages, hydrocephalus, pre/dys-maturity and 'idiopathic' delayed visual maturation.