Social visual attentional engagement and memory in Phelan-McDermid syndrome and autism spectrum disorder: a pilot eye tracking study

Background The current study used eye tracking to investigate attention and recognition memory in Phelan-McDermid syndrome (PMS), a rare genetic disorder characterized by intellectual disability, motor delays, and a high likelihood of comorbid autism spectrum disorder (ASD). Social deficits represent a core feature of ASD, including decreased propensity to orient to or show preference for social stimuli. Methods We used a visual paired-comparison task with both social and non-social images, assessing looking behavior to a novel image versus a previously viewed familiar image to characterize social attention and recognition memory in PMS (n = 22), idiopathic ASD (iASD, n = 38), and typically developing (TD) controls (n = 26). The idiopathic ASD cohort was divided into subgroups with intellectual disabilities (ID; developmental quotient 70) and the PMS group into those with and without a co-morbid ASD diagnosis. Results On measures of attention, the PMS group with a comorbid ASD diagnosis spent less time viewing the social images compared to non-social images; the rate of looking back and forth between images was lowest in the iASD with ID group. Furthermore, while all groups demonstrated intact recognition memory when novel non-social stimuli were initially presented (pre-switch), participants with PMS showed no preference during the post-switch memory presentation. In iASD, the group without ID, but not the group with ID, showed a novelty preference for social stimuli. Across indices, individuals with PMS and ASD performed more similarly to PMS without ASD and less similarly to the iASD group. Conclusion These findings demonstrate further evidence of differences in attention and memory for social stimuli in ASD and provide contrasts between iASD and PMS

Attentional Influences on Visual Working Memory in Development

Visual Working Memory (VWM) in humans is a limited-capacity system for the online maintenance and manipulation of visual information. There are considerable improvements in VWM abilities in the first few years of life. To understand the developmental trajectory of these changes it is important to consider the processes that support VWM. In this thesis, I investigated the role of attention and its interaction with VWM, characterizing how this relationship changes from infancy to adulthood. First, a change detection study examined two processes related to memory encoding in 12-month-old infants and adults. Infants demonstrated both an ability to accumulate information from increased exposure duration to objects in a scene (where successful change detection was related to increased time attending to the to-be-changed object during encoding), and a persistence of memory (a familiarity across repeat exposures and interruptions). Next, changes in the flexibility in allocating attentional resources were examined both externally (with pre-cues) and internally (with retro-cues), in VWM with 4-7-year-old children and adults. Task-irrelevant information systematically biased children\u27s memory representations and younger, 4-5-year-old children were the most susceptible to its influence. Furthermore, 4-5-year-olds were less able to shift their attentional focus using retro-cues. Lastly, pupillometry was used as a real-time measure of cognitive effort and attention in a working memory paradigm in adults. Task-evoked pupil responses increased as a function of set-size and baseline pupil measurements were more variable when participants could predict the difficulty of upcoming trials, adjusting their overall effort level. Together these studies provide insights into the relationships between different facets of visual attention and VWM over development

Visual evoked potential abnormalities in Phelan-McDermid syndrome.

The current study utilized visual evoked potentials (VEPs) to examine excitatory and inhibitory postsynaptic activity in children with Phelan-McDermid syndrome (PMS) and the association with genetic factors. PMS is caused by haploinsufficiency of SHANK3 on chromosome 22 and represents a common single-gene cause of autism spectrum disorder (ASD) and intellectual disability. Transient VEPs were obtained from 175 children, including 31 with PMS, 79 with idiopathic ASD, 45 typically developing controls, and 20 unaffected siblings of children with PMS. Stimuli included standard and short-duration contrast-reversing checkerboard conditions and the reliability between these two conditions was assessed. Test-retest reliability and correlations with deletion size were explored in the group with PMS. Children with PMS and, to a lesser extent, those with idiopathic ASD, displayed significantly smaller amplitudes and decreased beta and gamma band activity relative to TD controls and PMS siblings. Across groups, high intraclass correlation coefficients were obtained between standard and short-duration conditions. In children with PMS, test-retest reliability was strong. Deletion size was significantly correlated with P -N amplitude for both conditions. Children with PMS displayed distinct transient VEP waveform abnormalities in both time and frequency domains that might reflect underlying glutamatergic deficits which were associated with deletion size. A similar response pattern was observed in a subset of children with idiopathic ASD. VEPs offer a noninvasive measure of excitatory and inhibitory neurotransmission that holds promise for stratification and surrogate endpoints in ongoing clinical trials in PMS and ASD