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Hypersensitive pupillary light reflex in infants at risk for autism.

Nyström P, Gredebäck G, Bölte S, Falck-Ytter T, EASE te - Mol Autism (2015)

Bottom Line: Moreover, the cholinergic system plays a key role in the early neurodevelopmental processes believed to be derailed early in life in individuals with the disorder.Yet, there is no data from human infants supporting a developmentally important role of this neurotransmitter system.Baseline pupil diameter was equal in the two groups, ruling out tonic autonomic imbalance as an explanation for these differences.

View Article: PubMed Central - PubMed

Affiliation: Uppsala Child & Babylab, Department of Psychology, Uppsala University, Uppsala, Sweden.

ABSTRACT

Background: Post mortem brain tissue data and animal modeling work indicate cholinergic disruptions in autism. Moreover, the cholinergic system plays a key role in the early neurodevelopmental processes believed to be derailed early in life in individuals with the disorder. Yet, there is no data from human infants supporting a developmentally important role of this neurotransmitter system. Because the pupillary light reflex depends largely on cholinergic synaptic transmission, we assessed this reflex in a sample of infants at risk for autism as well as infants at low (average) risk.

Methods: Ten-month-old infants with an older sibling with autism (n = 29, 16 females), and thus a genetic predisposition to developing the disorder themselves, were presented with white flashes on a computer monitor, and pupillary responses were captured using eye tracking. A control group matched on age and developmental level (n = 15, seven females) was also tested.

Results: The siblings of children with autism had a faster and stronger pupillary light reflex compared to control infants. Baseline pupil diameter was equal in the two groups, ruling out tonic autonomic imbalance as an explanation for these differences.

Conclusions: This study establishes that infant siblings of children with autism have hypersensitive pupillary light reflexes, a result which supports the view that altered sensory processing in infancy is associated with elevated autism risk. Moreover, the study indicates that individual differences in autism susceptibility are linked to differences in the cholinergic system during an early developmental period.

No MeSH data available.


Related in: MedlinePlus

Experimental setup and stimuli. (A) Pupillary light reflex measured using noninvasive eye-tracking technology (picture published with consent). (B) Brief flashes of light were shown on monitor, while eye tracker measured induced changes in pupil size.
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Fig1: Experimental setup and stimuli. (A) Pupillary light reflex measured using noninvasive eye-tracking technology (picture published with consent). (B) Brief flashes of light were shown on monitor, while eye tracker measured induced changes in pupil size.

Mentions: Noninvasive eye-tracking technology suitable for infant populations (Figure 1A) was used to measure pupil changes in response to brief flashes of light. Pupil data were collected by a Tobii 1750 eye tracker (Tobii Technology, Danderyd, Sweden) with a sampling rate of 50 Hz in a room with a controlled ambient light level of 0.9 lux. Each stimulus lasted approximately 6 s and consisted of a small central fixation point on a black background (0.9 lux) that flashed white (190 lux) for 75 ms, that is, substantially above visual thresholds [8], with a random onset between 1,600 and 2,400 ms (Figure 1B). The stimulus was presented 16 times to each infant and interleaved with other video clips with a total session duration of approximately 7 min (no breaks). Before each trial, a 15-s video clip with two dynamically moving point light displays (16 points) was presented, one on each side of the screen [20]. This bilateral presentation caused a saccade from the side of the screen to the center of the screen at every trial onset, thereby reducing the risk of different retinal saturation between infants.Figure 1


Hypersensitive pupillary light reflex in infants at risk for autism.

Nyström P, Gredebäck G, Bölte S, Falck-Ytter T, EASE te - Mol Autism (2015)

Experimental setup and stimuli. (A) Pupillary light reflex measured using noninvasive eye-tracking technology (picture published with consent). (B) Brief flashes of light were shown on monitor, while eye tracker measured induced changes in pupil size.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4352563&req=5

Fig1: Experimental setup and stimuli. (A) Pupillary light reflex measured using noninvasive eye-tracking technology (picture published with consent). (B) Brief flashes of light were shown on monitor, while eye tracker measured induced changes in pupil size.
Mentions: Noninvasive eye-tracking technology suitable for infant populations (Figure 1A) was used to measure pupil changes in response to brief flashes of light. Pupil data were collected by a Tobii 1750 eye tracker (Tobii Technology, Danderyd, Sweden) with a sampling rate of 50 Hz in a room with a controlled ambient light level of 0.9 lux. Each stimulus lasted approximately 6 s and consisted of a small central fixation point on a black background (0.9 lux) that flashed white (190 lux) for 75 ms, that is, substantially above visual thresholds [8], with a random onset between 1,600 and 2,400 ms (Figure 1B). The stimulus was presented 16 times to each infant and interleaved with other video clips with a total session duration of approximately 7 min (no breaks). Before each trial, a 15-s video clip with two dynamically moving point light displays (16 points) was presented, one on each side of the screen [20]. This bilateral presentation caused a saccade from the side of the screen to the center of the screen at every trial onset, thereby reducing the risk of different retinal saturation between infants.Figure 1

Bottom Line: Moreover, the cholinergic system plays a key role in the early neurodevelopmental processes believed to be derailed early in life in individuals with the disorder.Yet, there is no data from human infants supporting a developmentally important role of this neurotransmitter system.Baseline pupil diameter was equal in the two groups, ruling out tonic autonomic imbalance as an explanation for these differences.

View Article: PubMed Central - PubMed

Affiliation: Uppsala Child & Babylab, Department of Psychology, Uppsala University, Uppsala, Sweden.

ABSTRACT

Background: Post mortem brain tissue data and animal modeling work indicate cholinergic disruptions in autism. Moreover, the cholinergic system plays a key role in the early neurodevelopmental processes believed to be derailed early in life in individuals with the disorder. Yet, there is no data from human infants supporting a developmentally important role of this neurotransmitter system. Because the pupillary light reflex depends largely on cholinergic synaptic transmission, we assessed this reflex in a sample of infants at risk for autism as well as infants at low (average) risk.

Methods: Ten-month-old infants with an older sibling with autism (n = 29, 16 females), and thus a genetic predisposition to developing the disorder themselves, were presented with white flashes on a computer monitor, and pupillary responses were captured using eye tracking. A control group matched on age and developmental level (n = 15, seven females) was also tested.

Results: The siblings of children with autism had a faster and stronger pupillary light reflex compared to control infants. Baseline pupil diameter was equal in the two groups, ruling out tonic autonomic imbalance as an explanation for these differences.

Conclusions: This study establishes that infant siblings of children with autism have hypersensitive pupillary light reflexes, a result which supports the view that altered sensory processing in infancy is associated with elevated autism risk. Moreover, the study indicates that individual differences in autism susceptibility are linked to differences in the cholinergic system during an early developmental period.

No MeSH data available.


Related in: MedlinePlus