The Basal Ganglia and the Cerebellum in Human Emotion

Jordan E. Pierce; Julie Péron

Disclosures

Soc Cogn Affect Neurosci. 2020;15(5):599-613. 

In This Article

Direct Connectivity Between the BG and Cerebellum

It was initially assumed that the BG and cerebellum separately impacted cortical activity through distinct thalamic pathways (Mink, 1996; Middleton and Strick, 2000), yet the existence of direct subcortical connections between these two structures is now recognized and, thus, their ability to jointly influence motor, cognitive and limbic functions (Figure 2; Caligiore et al., 2017; Bostan and Strick, 2018). The first study to identify a structural link between the BG and cerebellum in non-human primates used transneuronal viral tracing to label neurons in the dentate nucleus that project to the intralaminar nuclei of the thalamus and then to the striatum and the external globus pallidus (Hoshi et al., 2005). Later work expanded this finding by showing a connection in the opposite direction, with the STN projecting to the pontine nuclei and then to the contralateral cerebellar hemisphere (Bostan et al., 2010). In both cases, these projections innervated the motor and non-motor functional domains, meaning the BG and cerebellum can modulate a wide range of habitual and goal-directed behaviors (Xiao et al., 2018). Furthermore, it has been shown that these connections exhibit short latency responses which would allow for rapid communication to impact early stages of processing (Chen et al., 2014).

Figure 2.

Connections and select functions of the BG, cerebellum and cortex. This diagram shows the structural organization and functions of relevant pathways in the BG, cerebellum and cortex. During processing of an emotional stimulus, these regions (as well as, e.g. amygdala, hippocampus) cooperatively analyze the incoming information and generate an appropriate response, which includes action tendencies, physiological changes and subjective feelings. Green arrows indicate excitatory pathways, red arrows indicate inhibitory pathways, and the blue arrow indicates the dopaminergic pathway from the SN. SN, substantia nigra; GPi/GPe, internal/external globus pallidus; STN, subthalamic nucleus; PN, pontine nuclei; DCN, deep cerebellar nuclei; IO, inferior olive.

Importantly, the existence of these connections in humans has been supported by diffusion-weighted imaging studies, which can measure the strength of white matter tracts non-invasively. Pelzer et al. identified tracts between the dentate and striatum and the STN and cerebellum via the thalamus and pontine nuclei (Pelzer et al., 2013; Pelzer et al., 2017), mirroring the results from the earlier animal studies. Another study in humans extended these findings by reporting structural connections between the dentate and globus pallidus and substantia nigra (Milardi et al., 2016). Functional connectivity studies also have confirmed the co-activation of BG nuclei and the cerebellum and associated these subcortical structures with multiple resting-state networks that encompass large portions of the neocortex, including limbic regions such as the orbitofrontal cortex and the amygdala (Habas et al., 2009; Brunenberg et al., 2012).

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