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Fixational saccade‐related activity of pedunculopontine tegmental nucleus neurons in behaving monkeys
Author(s) -
Okada Kenichi,
Kobayashi Yasushi
Publication year - 2014
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/ejn.12632
Subject(s) - saccade , neuroscience , pedunculopontine tegmental nucleus , psychology , tonic (physiology) , fixation (population genetics) , eye movement , microsaccade , population , stimulus (psychology) , premovement neuronal activity , context (archaeology) , brainstem , cognitive psychology , saccadic masking , biology , medicine , paleontology , environmental health
Fixational saccades are small, involuntary eye movements that occur during attempted visual fixation. Recent studies suggested that several cognitive processes affect the occurrence probability of fixational saccades. Thus, there might be an interaction between fixational saccade‐related motor signals and cognitive signals. The pedunculopontine tegmental nucleus ( PPTN ) in the brainstem has anatomical connections with numerous saccade‐related and limbic areas. Previously, we reported that a group of PPTN neurons showed transient phasic bursts or a pause in activity during large visually guided and spontaneous saccades, and also showed sustained tonic changes in activity with task context. We hypothesised that single PPTN neurons would relay both fixational saccade‐related and task context‐related signals, and might function as an interface between the motor and limbic systems. We recorded the activity of PPTN neurons in behaving monkeys during a reward‐biased task, and analysed neuronal activity for small fixational saccades during visual fixation, and compared it with the activity for large visually guided targeting saccades and large spontaneous saccades during intertrial intervals. A population of PPTN neurons exhibited a fixational saccade‐related phasic increase in activity, and the majority of them also showed activity modulation with large targeting saccades. In addition, a group of these neurons showed a task‐related tonic increase in activity during the fixation period, and half of them relayed the saccade signal only when the neuron exhibited higher tonic activity during the task execution period. Thus, fixational saccade‐related signals of PPTN neurons overlap with tonic task‐related signals, and might contribute to the cognitive modulation of fixational saccades.