Basal ganglia network by constrained spherical deconvolution: A possible cortico‐pallidal pathway?

Abstract

In the recent past, basal ganglia circuitry was simplified as represented by the direct and indirect pathways and by hyperdirect pathways. Based on data from animal studies, we hypothesized a fourth pathway, the cortico-pallidal, pathway, that complements the hyperdirect pathway to the subthalamus. Ten normal brains were analyzed by using the high angular resolution diffusion imaging-constrained spherical deconvolution (CSD)-based technique. The study was performed with a 3T magnetic resonance imaging (MRI) scanner (Achieva, Philips Healthcare, Best, Netherlands); by using a 32-channel SENSE head coil. We showed that CSD is a powerful technique that allows a fine evaluation of both the long and small tracts between cortex and basal ganglia, including direct, indirect, and hyperdirect pathways. In addition, a pathway directly connecting the cortex to the globus pallidus was seen. Our results confirm that the CSD tractography is a valuable technique allowing a reliable reconstruction of small- and long-fiber pathways in brain regions with multiple fiber orientations, such as basal ganglia. This could open a future scenario in which CSD could be used to focally target with deep brain stimulation (DBS) the small bundles within the basal ganglia loops.

The Olfactory System Revealed: Non-Invasive Mapping by using Constrained Spherical Deconvolution Tractography in Healthy Humans

“…These data extend previous works showing that CSD is a robust technique for the in vivo reconstruction of the intricate and complex brain networks (Lambert et al, 2012; Arrigo et al, 2014; Milardi et al, 2015a,b, 2016a,b; Mormina et al, 2015; Cacciola et al, 2016, 2017). …”

“…A technical intrinsic weakness of tractography is the incapability to detect the presence of synapsis and gap junctions as well as the directionality (afferent-efferent) of the signal transmission (Chung et al, 2011; Parker et al, 2013; Milardi et al, 2015b). …”

“…Using this approach, we have recently shown that a consistent reconstruction of the basal ganglia, red nucleus, claustrum and limbic connectome is feasible (Arrigo et al, 2014; Milardi et al, 2015a,b, 2016a,b; Mormina et al, 2015; Cacciola et al, 2016, 2017). …”

Arkypallidal Cells Send a Stop Signal to Striatum

“…We showed here that Arkys have a more specific Stop response than the most rapidly activated STN neurons, but more slowly activated STN neurons are potential contributors to Arky activity, as are neurons in the parafascicular nucleus (Kimura et al, 2004; Yasukawa et al, 2004). Finally, there are also direct cortical inputs to GPe (Naito and Kita, 1994; Milardi et al, 2015) to which no function has yet been ascribed, and this pathway might help tie together the cortex-focused literature on human stopping with our basal ganglia results.…”

Prelemniscal Lesion for Selective Improvement of Parkinson Disease Tremor

“…These fibers have been described in anatomical studies as well; arriving at the thalamus in the thalamic fasciculus [7], the fibers connect the Vop with the supplementary motor area and the dorsolateral frontal cortex. Since the supplementary motor area has been related to motor control for posture and movement preparation [8, 9] and Gp-DBS or lesioning has been reported to be more effective for rigidity, gait, and L-DOPA-induced dyskinesia than for tremor control [10, 11], this Gp fiber component is more likely related to the physiopathology of rigidity and gait disturbances in PD.…”