In either case, information about the content of the image would need to be conveyed to the oculomotor structures responsible for saccadic adaptation. Recent studies (Blurton, Raabe, & Greenlee,
2012; Gerardin, Miquée, Urquizar, & Pélisson,
2012) have shown activity during saccadic adaptation in cortical areas, in addition to the cerebellum, and provided evidence of cortical contribution to adaptation via transcranial magnetic stimulation (Panouillères et al.,
2014). The influence of the content of the image, and perhaps its motivational or rewarding character, may be conveyed by this route or, alternatively, by direct influences on cerebellar plasticity. A further possibility is the involvement of basal ganglia circuits that contribute to eye movement control and to reward-based learning (Hikosaka, Kim, Yasuda, & Yamamoto,
2014). The basal ganglia maintain long-term associations between stimuli and rewards and modify eye movement vigor to rewarding stimuli. The caudate nucleus can encode stable as well as flexible stimulus–reward associations at different sites. The coupling of stimuli and reward manifests in a capture of attention and gaze of the rewarded stimuli as well as quick and fast saccades going to high-value targets (Anderson & Yantis,
2013; Kim & Hikosaka,
2013; Takikawa et al.,
2002; Yasuda, Yamamoto, & Hikosaka,
2012). Dopaminergic input to the caudate nucleus could account for reward specific plasticity (Kim, Ghazizadeh, & Hikosaka,
2014). Dopamine neurons become active when an outcome is better than expected, and their plasticity in the long run could maximize reward for future trials (Schultz,
1998). However, the role of basal ganglia in saccadic adaptation is poorly understood. A study with patients suffering from Parkinson's disease suggested that dopaminergic mechanisms in the basal ganglia contribute to adaptive lengthening of memory-guided saccades but not reactive saccade (MacAskill et al.,
2002). The scanning saccades used in our study share some properties with memory-guided saccades (Hopp & Fuchs,
2004; Pélisson et al.,
2010) such that a contribution of the basal ganglia might be conceivable. In either case, the influence of image content on saccadic adaptation shows that the typical procedure to study eye movements, namely by using simplified point targets to concentrate on spatial and temporal aspects of the stimulation, does not cover all aspects of oculomotor control. Even supposedly simple mechanisms can be different for richer stimuli. However, other aspects of the oculomotor behavior in our experiment indeed confirmed the automaticity of the process. For example, the stereotypical performance of corrective saccades occurred in all conditions, irrespective of whether they afforded successful target viewing or not.