Effects of low‐dose isoflurane on saccadic eye movement generation

Abstract

SummaryThe effects of 0.15% quasi-steady-state end-tidal isoflurane on two saccadic eye-movement tests were examined in five volunteers using a newly devised computer-based recording system. The tests were saccadic latency and a countermanding task, the latter being an indicator of the highest levels of conscious performance. A moving light-emitting diode target was displayed on a screen and in the saccadic-latency task the latency of eye movement to the target was measured. In all five subjects the latency increased with anaesthetic by an amount which varied from 8 to 45 ms. This result was significantly different (p < 0.05) from subjects without anaesthetic. In the countermanding task, the subject had to voluntarily inhibit movement to the target. Again anaesthetic increased the latency of response, which varied from 6 to 33 ms. This result was significantly different (p < 0.05) from subjects without anaesthetic. In these studies it appeared that two tasks, one a simple latency test and the other, the countermanding task, requiring higher cortical processing were equally impaired at subanaesthetic concentrations of isoflurane.

Measurement of the extraocular spike potential during saccade countermanding

“…In addition, the saccadic countermanding task has given rise to a strong computational modeling literature leading to breakthroughs in understanding neural saccade production and regulation (Hanes and Schall 1996;Asrress and Carpenter 2001;Lo et al 2009;Wong-Lin et al 2010). Finally, the saccadic stop signal task has had broad clinical significance, providing insights on the action of several popular anesthetic agents (Khan et al 1999;Nouraei et al 2003), as well as the core dysfunctions underlying disorders such as mild traumatic brain injury (DeHaan et al 2007), Parkinson's disease (Joti et al 2007), and attention-deficit hyperactivity disorder (Armstrong and Munoz 2003;Hanisch et al 2006). Given the wide experimental significance of the saccadic stop signal paradigm, the observation of partial muscle activation on canceled saccade trials would have provided important theoretical leverage to the study of behavioral inhibition.…”

Behavioral Inhibition and Addiction

“…Further, countermanding tasks have been used to measure effects of anesthetics on attentional inhibition. Findings show that both isoflurane and sevoflurane increase stop-signal reaction time, indicating impairment of inhibitory mechanisms of attention (Khan et al, 1999;Nouraei, De Pennington, Jones, and Carpenter, 2003).…”

Saccadic latency in hepatic encephalopathy: a pilot study

“…Latencies are highly variable and this randomness has tended to limit their use for staging and diagnosis of neurological diseases (Ali et al 2006; Antoniades et al 2007; Carpenter et al 2002; Khan et al 1999; Michell et al 2006; Nouraei et al 2003; Pearson et al 2007). However despite their randomness, saccadic latencies follow a characteristic skewed distribution that can be transformed to a Gaussian distribution by plotting their cumulative frequency against the reciprocal of latency (Figs.…”