The Role of Locus Coeruleus in the Regulation of Cognitive Performance

Abstract

Noradrenergic locus coeruleus (LC) neurons were recorded in monkeys performing a visual discrimination task, and a computational model was developed addressing the role of the LC brain system in cognitive performance. Changes in spontaneous and stimulus-induced patterns of LC activity correlated closely with fluctuations in behavioral performance. The model explains these fluctuations in terms of changes in electrotonic coupling among LC neurons and predicts improved performance during epochs of high coupling and synchronized LC firing. Cross correlations of simultaneously recorded LC neurons confirmed this prediction, indicating that electrotonic coupling in LC may play an important role in attentional modulation and the regulation of goal-directed versus exploratory behaviors.

The Role of the Locus Coeruleus in Mediating the Attentional Blink: A Neurocomputational Theory.

“…Adapted with permission. Schreiber et al, 1990;Usher et al, 1999). 2 As we show below, in the case of the standard attentional blink paradigm, this translates into more effective target detection.…”

“…These units represent the output, or response, of the model. Note that in the previous modeling work of Usher et al (1999) and Gilzenrat et al (2002), the output units were intended to represent motor responses, whereas in the current model, these units flag the detection of targets in the RSVP stream. If a detection unit crosses a predetermined absolute activity threshold, the 2 LC-induced noradrenergic modulation is nonspecific with respect to stimulus content or location.…”

“…These neuromodulatory effects have been simulated in computational models as transient changes in the gain 1 It is interesting to note that when the animal is disengaged and distractible, the LC phasic response is absent or attenuated, whereas overall tonic firing rate is elevated. The observed correlation between attentional state and LC firing mode has led to a theory of the LC's role in modulating attentional state, which has been described elsewhere (Aston-Jones et al, 1999Cohen et al, 2004;Gilzenrat et al, 2002;Usher et al, 1999). of cortical processing units (Servan-Schreiber, Printz, & Cohen, 1990). It is important to note that when applied in a temporally strategic manner (e.g., when driven by the identification and evaluation of task-relevant stimuli), increases in gain produce an increase in the signal-to-noise ratio of subsequent processing and a concomitant improvement in the efficiency and reliability of behavioral responses, such as signal detection performance (Brown, Gilzenrat, & Cohen, 2004;Gilzenrat et al, 2002;ServanFigure 1.…”

“…This autoinhibition results in a refractory-like period after an LC phasic response, during which subsequent LC phasic discharge is rarely observed Usher et al, 1999). This refractoriness peaks approximately 50 -100 ms following the LC phasic response, typically 200 -250 ms after the eliciting stimulus, and usually lasts 200 ms or until about 400 -450 ms poststimulus (see Figure 1B).…”

Event perception: A mind-brain perspective.

“…Dopamine neurons in the substantia nigra and ventral tegmental area are sensitive to differences between actual and predicted rewards (Schultz, 1998). Norepinephrine neurons in the locus ceruleus appear to track performance in attentiondemanding tasks, and have been proposed to regulate the sensitivity of an organism to external stimuli (Usher, Cohen, Servan-Schreiber, Rajkowski, & Aston-Jones, 1999). The ACC is sensitive to both sorts of error and may play a role in adaptively modulating behavior in response to prediction error (Botvinick, Braver, Barch, Carter, & Cohen, 2001).…”