How our perception of the world is formed remains a topic of debate. Generally there are two different views – either perception is primarily driven by external sensory inputs or it is primarily driven by the internal circuitry of the brain. Scientists have recently discovered that the brain is never quiet but rather is always active regardless of what an individual is doing. It is likely then, that perception is formed through the interaction between ongoing cortical activity and sensory input. Dr. MacLean and his lab will examine how ongoing spontaneous activity in the cortex interacts with thalamic inputs – the thalamus is the relay station between the outside world and the brain.
They will perform these experiments in the visual and auditory cortex. They have previously examined this interaction in the somatosensory cortex and have found that ongoing activity acts to suppress the influence of sensory inputs in the brain suggesting that perception is at least in part determined by the internal circuitry of the brain. However it is unclear whether this type of interaction is specific to the somatosensory cortex or whether it is a general property of the sensory cortices. Dr. MacLean will replicate these experiments in the auditory and visual cortex in order to evaluate the interaction between the thalamus and ongoing cortical activity in these two other primary sensory cortices. He will then be able to compare and contrast the role of ongoing activity in sensory information processing across the three sensory modalities. In tum he will be able to look for common strategies in coding, anatomy and processing in the primary sensory cortices. This study will lead to new insights into how ongoing spontaneous activity that occurs in the brain affects how we perceive our world.