Impact of Afferent Inputs on Purkinje Cell Spiking Patterns and Motor Coordination

The brain is what makes us human. Feelings, memories, complex social interactions, language and movement – all of it originates in the brain. On average, the human brain contains approximately 50–100 billion neurons that communicate with each other through the vast network of 100 – 500 trillion connections called synapses. More than half of the total number of neurons make a structure called the cerebellum. In vertebrates, the cerebellum (Latin for little brain) controls movement and monitors its efficiency by collecting sensory information such as visual cues, limb positions and balance. This information is necessary to adequately respond to the environment by controlling and correcting the movements. Historically, since the 18th century when Arne – Charles Lorry showed that the damage to this structure results in loss of motor coordination1, the cerebellum has been known to be involved in motor coordination. In the 19th century neurophysiologists such as Luigi Rolando and Jean Pierre Flourens revealed that animals with cerebellar damage can still move, but with a loss of coordination and that recovery after the lesion can be nearly complete unless the lesion is very extensive2. The milestone for understanding the cerebellum was placed by the research of Camillo Golgi and Satiago Ramon y Cajal in the late 1800s. The work of these anatomists enabled visualization of individual neurons revealing for the first time the structural organization of the brain, including the cerebellum. More than a century later researchers still battle with two main questions. Firstly, how does the cerebellar function contribute and/or results in such a sophisticated level of motor coordination that enables us to do things like playing the violin or ballroom dancing? Secondly, how do we acquire those new motor skills? The cerebellar network seems to be holding the key to answering both of those questions. It has the capacity to process the sensory information and translate it into a motor command. In this thesis, we describe the effects of alteration in the cerebellar system unraveling the possible role of its afferent inputs.