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Jacinta Anne Walz, Revathy Mani, Lisa J Asper, Valarmathi Arunachalam, Sieu Khuu; The impact of traumatic brain injury on pupillary responses in a delayed anti-saccade task.. Invest. Ophthalmol. Vis. Sci. 2020;61(7):5069.
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© ARVO (1962-2015); The Authors (2016-present)
Traumatic brain injury (TBI) can cause cognitive, attentional and sensorimotor disturbances, and such deficits can impact on daily functioning. In the present study we investigated whether and how the time required to attend a stimulus is affected by TBI using an anti-saccade task. In this task, pupillary response latencies (i.e., time required for pupils to dilate in response to the allocation of attention) were measured after the presentation of visual cue at which time an anti-saccade was performed. Different pre-cue delays were introduced to investigate the time course at which attention is engaged after cueing.
Ten subjects ((mean age= 23.3yr±6.7), two females) with TBI and ten controls ((mean age=22.3yr±7.9), six females) participated. In a trial, subjects fixated a central target and made an anti-saccade in response to a peripheral target after a time delay which was signalled by a central visual cue. The cue appeared after delay periods of 0, 0.0625, 0.125, 0.250, 0.500 and 1s. Pupillary responses against time was measured using a 150Hz GazepointGP3 eye tracker. Pupil size change was plotted as a function of time and logistic functions were fitted to data, and the pupillary response latency (i.e., 50% point on the curve) was derived for different delays.
A two-way between groups ANOVA (delay (6) x group (2)) showed main effects of group (F(1,108)=100.10, p<0.0001) with longer latencies observed in the TBI group (average: 15-30ms), and delay (F(5,108)=8.60, p<0.0001) such that latency times increased with delay. A significant interaction effect was also evident (F(5,108)=2.92, p=0.02) which suggests change in pupil latency times with delay was different between the two groups. As shown in Figure 1, latency times for controls markedly increased with delay, but latency times were longer overall for TBI participants and they did not change with delay.
The present study demonstrated that pupil latency times are affected by TBI and were longer than controls. Additionally, the allocation of attention in TBI is not influenced by the immediacy of the cue particularly at very short delays. This implicates impaired attention processing, and in particular, there is no priming benefit from the cueing as was the case for controls.
This is a 2020 ARVO Annual Meeting abstract.
Figure 1. Pupillary latency times plotted as a function of the pre cue delay. Error bars signify 1 standard error of the mean
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