Brain Asymmetry Essay

1. INTRODUCTION

1.1 Brain Asymmetry

In general, any biological system shows some degree of asymmetry in their organization. From the highly intelligent system such as human to the lower animals, normal variation and specialization result in formation of asymmetries in both structure as well as function. In some mammalian system including human, the two brain hemisphere differ in their anatomy and function. Gross examination of brain features fails to expose profound left/right differences. However, a detailed and careful examination of the brain structure leads to a variety of asymmetric features. The origin of specialized lateralization, depends on various factors including evolution, development, hereditary, experience and pathology. The

It is shown in several studies that those animals with asymmetry in their nervous system outperformed the ones with symmetrical nervous system in many circumstances (Gunturkun et al 2000; McGrew et al 1999; Rogers et al 2004) indicating that the asymmetry in the nervous system contribute significantly to biological fitness (Frasnelli 2013). Several number of advantages have been suggested as a result of brain asymmetry: avoiding the nervous system to undergo for a duplication of function in the two hemispheres (Levy 1977); ability to process information in parallel (Rogers 2000; Rogers et al 2004) providing one hemisphere a control over the other one and preventing the two hemisphere for incompatible responses initiation (Andrew 1991; Vallortigara 2000). One of the good advantages of brain lateralization is the ability to process information in parallel (Rogers et al 2004). The animals with lateralized brain have the ability to access multiple source of information at the same time while this behaviour is enhanced when they feel that they are in danger (Rogers et al 2004). The animals with lateralized brain showed great deal of problem solving experiments compared to those with non-lateralized ones (Magat & Brown 2009) indicating that cerebral lateralization conveys a significant foraging advantage and supporting the enhanced cognitive function hypothesis (Frasnelli

2). We aim to not only visualize native responses of this neuron, but also monitor the synergistic effect of multimodality inputs. These results will provide abundant ground truth evidence for constructing neuronal computation models. Previous evidence suggested that asymmetry in Drosophila brain can be crucial for learning and memory. But none of the asymmetric circuity has been found nor have their roles in learning and memory been studied. With the single neuron connection prediction and validation, the function of the first, comprehensive asymmetric neuron network can be further tested with different manipulations such as short-term, long-term memory training, or down/over expression of memory proteins in specific neurons.

2.3 Timeline (Yearly goal)

Year 1: Use Flycircuit database to identify asymmetric circuit candidate in the central brain and their neuronal polarity, search for specific driver for labelling asymmetric neurons establish their neuron types (neurotransmitter). Furthermore, record functional responses from asymmetric neurons upon simple stimuli such as odor or light, with GCaMP.

Year 2: Record functional responses with training process in Drosophila such as odor-shock pairing and odor-reward pairing. After that, verify the connectivity in the asymmetric circuit using various