Lateralization of visuospatial processing in the bottlenose dolphin (Tursiops truncatus)

Area of Science:

• Neuroscience
• Animal Behavior
• Comparative Psychology

Background:

• Cerebral asymmetries, or brain lateralization, influence cognitive functions across species.
• The visuospatial domain is often lateralized, with a common right-hemisphere advantage in mammals and birds.
• Bottlenose dolphins (Tursiops truncatus) are intelligent marine mammals with complex cognitive abilities.

Purpose of the Study:

• To investigate cerebral asymmetries in bottlenose dolphins concerning visuospatial processing.
• To determine if dolphins show a lateralized advantage for visuospatial tasks.
• To compare dolphin lateralization patterns with those observed in other species.

Main Methods:

• Two adult female bottlenose dolphins were trained on a three-choice spatial discrimination task.
• The task required navigating through three hoops in sequence without omission or repetition.
• Monocular trials, alternating between left and right eye vision, were conducted after binocular criterion was met.

Main Results:

• Both dolphins demonstrated superior performance when using their right eye compared to their left eye.
• Performance with the right eye was comparable to binocular (both eyes) performance.
• The left eye performance was significantly lower than both right eye and binocular performance.

Conclusions:

• The observed right-eye superiority suggests a left-hemispheric dominance for visuospatial information processing in these dolphins.
• This finding represents a significant deviation from the commonly observed right-hemisphere advantage in other mammalian and avian species.
• The study highlights potential unique patterns of brain lateralization in cetaceans.