For example, prefrontal injury has been shown to lead to abrupt decreases in blood flow to the contralateral cerebellum, and vice versa. dia: across, schisis: break) is an existing neurological term indicating a sharp inhibition in activity at a site that is distant from a site of injury, but is anatomically connected with it through fiber tracts. To summarize the concept of developmental influence between brain regions, we use the term developmental diaschisis. We end by describing how new methods for imaging, mapping, and perturbing neural circuits can be used to explore the complex role of the cerebellum in guiding nonmotor function.Īs part of this framework, we propose that cerebellar dysfunction may disrupt the maturation of distant neocortical circuits. We propose that the cerebellum takes an early role in processing external sensory and internally generated information to influence neocortical circuit refinement during developmental sensitive periods. A variety of observations can be explained by the following unified hypothesis: in addition to its role in the mature brain, the cerebellum acts in early life to shape the function of other brain regions, especially those relating to cognition and affect. In this review, we outline a development-based framework for understanding the nonmotor roles of cerebellum.

This has led to the proposal that the cerebellum performs a common algorithm upon a variety of inputs, whether sensory, motor, cognitive, or affective. The cerebellar cortex and nuclei have a distinctive circuit structure that is repeated in a modular fashion throughout the cerebellum, and is highly conserved among vertebrates ( Apps and Hawkes, 2009). Recently, the extension of this parcellated mapping to nonmotor brain structures has become clearer using modern methods ( Buckner et al., 2011 Strick et al., 2009). While some cerebellar regions project predominantly to sensorimotor cortex, homologous connections project to cognitive and affective regions, and comprise a large fraction of cerebellar connectivity ( Strick et al., 2009). Second, cerebellar connectivity is highly differentiated, and focal injury typically leads to focal deficits ( Romaniella, 2012). The consequences of cerebellar deficit are highly dependent on when the outcome is assessed. Monitoring the short-term results of injury does not capture long-term consequences that can accumulate over time. First, the most prominent deficits in acute cerebellar injury in adults are of a motor nature.

Two facts have stood in the way of wider recognition of the nonmotor aspects of cerebellar function.

Evidence for cerebellar lesions leading to nonmotor deficits has come from adult cases showing subtle cognitive and affective changes ( Stoodley et al., 2012), and congenital cerebellar defects, where deficits are much more pronounced ( Basson and Wingate, 2013 Steinlin, 2013). This idea is not new: cognitive roles for cerebellum have been discussed since the mid-19th century (reviewed in Steinlin, 2013), with a resurgence of interest in recent years ( D'Angelo and Casali, 2012 Koziol et al., 2014 Mariën et al., 2014). Receiving much less emphasis has been the role of the cerebellum in higher function. Emerging from this program is the view that the cerebellum acts as a processor that uses a variety of inputs to guide movement. This framework has been explored in the greatest detail in cases where input pathways convey sensory information to the cerebellum, and outputs influence motor effectors. In recent decades, much neuroscience research has focused narrowly on the cerebellum’s role in balance, posture, and motor control.

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