Neural Activation Patterns Arising From Gesture Recognition
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The human brain is composed of a complex network of neurons that create a representation of the world through sensation and perception. This representation facilitates interacting with the environment and is thus vital to the human experience. One aspect that is crucial to normal functioning is the ability to identify and classify the different types of gestures we see every day. Broadly, gestures are classified into three categories: transitive, intransitive and neutral. Transitive gestures involve specific hand-object actions such as tool-use; while, intransitive gestures are communicative in nature. In this experiment, we propose that the main aspect of a gesture is the context in which the gesture is performed. For example, the gesture of waving goodbye to someone, an intransitive gesture, and the gesture of wiping a window, a transitive gesture, both involve the same biomechanics and motor control; however, they differ greatly based on the context in which they were performed. To understand and differentiate such kinematically similar gestures, the cerebral cortex or deep brain structures might exhibit unique patterns of activations specific to differentiating context. Therefore, the objective in this experiment is to map patterns of neural activation that specifically encode and differentiate context when viewing kinematically similar transitive and intransitive gestures. The participants recruited were 19 young adults between the ages 20 to 30. To map the pattern of neural activation, this experiment employed the use of a neuroimaging technique called functional magnetic resonance imaging or fMRI. fMRI indirectly measures the hemodynamic response that represents the flow of blood to specific regions of the brain that are active in response to the viewing a picture such as a particular type of gesture. Each participant was placed in an MRI machine and exposed to 75 images containing gestures in either a transitive, intransitive, or neutral context. For the purposes of this experiment, we defined the neutral context as a gesture devoid of any context. Once the data was collected, a Linux based software called FSL was used to analyze the data. Analysis thus far has displayed neural activation patterns for the three types of gestures primarily in the visual cortex, along the dorsal and ventral streams and along the primary motor cortex. When contrasting transitive and intransitive gestures, there is no difference in neural activation. Data from this experiment gives insight into the basic neuroscience of how the brain effortlessly recognizes daily gestures and has clinical implications towards ideomotor apraxia, a neurological disorder that is characterized by an inability to recognize and perform transitive gestures.