A sense to assess and another to react


Lateralisation in humans and other vertebrates involves the input of sensory information more strongly to the brain hemisphere responsible for a required task.  Examples include eye preference, and asymmetric inputs of sound  and smell , which improve cognitive tasks when individuals process stimuli. Interestingly, the degree and direction of lateralisation can also vary between individuals depending on personality phenotype, which affects their behavioural responses towards stimuli. However, it is not known how sensory information is lateralised when processing stimuli and simultaneously organising a behavioural response towards them. In a recent study we show that this can be accomplished by separate senses being lateralised differently. We demonstrate for the first time that electrosensing is lateralised in weakly-electric fish, Gnathonemus petersii, and find that the direction of laterality towards an unfamiliar object varies with personality; bold fish lateralise towards the right and timid fish the left hemisphere. By contrast, visual inputs do not vary between individuals, but are lateralised across the population towards the left hemisphere, responsible in fish for the analysis of unfamiliar objects. This species has a stronger representation of electrical than visual signals in its brain , which could drive the differences between senses in functional laterality. This novel observation reveals that different senses can be selected for lateralisation in different ways, depending on their dominance, which has implications for the evolution and development of brain structure.