Action and perception are temporally coupled by a common mechanism that leads to a timing misperception

Evidence From Parkinson's Disease That the Superior Colliculus Couples Action and Perception

BACKGROUND

Action and perception should be coordinated for good visual-motor performance. The mechanism coupling action and perception may be a prominence map in the intermediate layer of the superior colliculus that modulates motor and attentional/perceptual processes. This coordination comes with a cost: the misperception that briefly overlapping stimuli are separated in time. Our model predicts that abnormal intermediate layer of the superior colliculus inhibition, such as that arising from increased basal ganglia output, would affect the action and perception coupling, and it would worsen the misperception.

OBJECTIVE

To test the prominence map model by measuring reaction times and perceptions in human intermediate layer of the superior colliculus dysfunction.

METHODS

We measured the saccadic and perceptual reaction time changes and the percept for different temporal asynchronies between fixation point offset and peripheral target onset in Parkinson's disease (PD).

RESULTS

We found that increased basal ganglia inhibitory output to the intermediate layer of the superior colliculus prominence map disrupted the normal coupling of action and perception. With increasing temporal asynchronies, the PD perceptual reaction times increased approximately 3 times more than the increase of the saccadic reaction times. Also, PD subjects misperceive small overlaps as gaps for temporal asynchronies up to 3 times longer than controls. The results can be reproduced by an intermediate layer of the superior colliculus rostral-caudal gradient of inhibition.

CONCLUSION

These findings support the hypothesis that a prominence map in the intermediate layer of the superior colliculus couples action and perception through modulation of attention. A dysfunction of this network quantifies abnormal basal ganglia output and could underlie visual deficits, including common, yet poorly understood, misperceptions and visual-motor deficits of PD. © 2019 International Parkinson and Movement Disorder Society.

Autism Pathogenesis: The Superior Colliculus

After been exposed to the visual input, in the first year of life, the brain experiences subtle but massive changes apparently crucial for communicative/emotional and social human development. Its lack could be the explanation of the very high prevalence of autism in children with total congenital blindness. The present theory postulates that the superior colliculus is the key structure for such changes for several reasons: it dominates visual behavior during the first months of life; it is ready at birth for complex visual tasks; it has a significant influence on several hemispheric regions; it is the main brain hub that permanently integrates visual and non-visual, external and internal information (bottom-up and top-down respectively); and it owns the enigmatic ability to take non-conscious decisions about where to focus attention. It is also a sentinel that triggers the subcortical mechanisms which drive social motivation to follow faces from birth and to react automatically to emotional stimuli. Through indirect connections it also activates simultaneously several cortical structures necessary to develop social cognition and to accomplish the multiattentional task required for conscious social interaction in real life settings. Genetic or non-genetic prenatal or early postnatal factors could disrupt the SC functions resulting in autism. The timing of postnatal biological disruption matches the timing of clinical autism manifestations. Astonishing coincidences between etiologies, clinical manifestations, cognitive and pathogenic autism theories on one side and SC functions on the other are disclosed in this review. Although the visual system dependent of the SC is usually considered as accessory of the LGN canonical pathway, its imprinting gives the brain a qualitatively specific functions not supplied by any other brain structure.