Visual emotion: From input to behavioral output

Patients with brain damage may encounter several social and (neuro)psychological problems in daily life, including difficulties in interacting with others or having a poor memory. Some neuropsychological problems might not directly be noticed by the outside world, such as deficits in visual functions or deficits in the ability to perceive facial emotional expressions. Despite their apparent subtilty, these more private deficits can have severe repercussions for daily-life functioning.
In this thesis, several visual cognitive functions, their interrelationships and their neural underpinnings were studied in different clinical populations, ranging from a large cohort of stroke patients, patients with isolated lesions in the cerebellum, to patients with neurodegenerative diseases.
The results in this thesis show that deficits in so-called ‘mid-range’ visual functions (e.g. shape or motion perception) and deficits in ‘higher-order’ visual cognitive functions (including visual emotion perception) occur frequently in neurological patients. However, they proved to be relatively independent. This means that supposedly lower-level visual impairments do not necessarily affect higher-order visual functions, arguing for parallel processing in the brain. Still, the presence of mid-range visual deficits was in some circumstances thought to explain a perceptual distortion: an intriguing deficit known as ‘metamorphopsia’. The lesion studies in this thesis suggest that the architecture of the brain for facial emotion perception involves a general network in the fronto-temporal region with separate nodes related to specific emotions, including the cerebellar areas. Lastly, deficits in processing emotional signals were found to underlie risky decision-making, which highlights the importance of a proper assessment to improve detection and treatment of these impairments.