Caudate Computations in Support of Spatial Navigation

• Applicant: Professor Dr. Thomas Wolbers
• Subject Area: Human Cognitive and Systems Neuroscience
• Term: from 2018 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 391520072

The dorsal striatum, including the caudate, is a key brain structure to support spatial navigation, through its computation of stimulus-response associations. The resulting rigid representations are thought to be very different, though, from the flexible, map-like knowledge acquired by the hippocampus. However, recent theories have argued for a much broader role of the caudate in supporting goal-directed spatial behavior, calling for a reexamination of the computational processes subserved by the caudate. To address this important problem, the proposed project will combine neurophysiological approaches in macaque monkeys with ultra high-field (7T) magnetic resonance imaging (MRI) in humans to precisely characterize navigational computations carried out in the caudate and its major input and output structures. First, by combining psychophysics, invasive electrophysiology and computational techniques in behaving monkeys, we will investigate the caudate contribution to basic spatial coding. Specifically, we focus on mechanisms of self-motion perception, a critical component for successful path integration, including (i) the computation of heading and distance signals, (ii) the interaction between the caudate and frontal-parietal structures in self-motion perception, and (iii) the causal contributions of the caudate to heading/distance estimation. Our studies will thus shed light on the caudate contributions to processing self-motion signals.Second, using 7T MRI in humans, we will identify caudate computations and its functional interactions with cortical structures in support of higher-level navigational functions. These will include landmark-goal vector coding and the acquisition of cognitive map representations. Our studies thus aim to unveil, for the first time, the precise computations in the caudate for complex metric spatial coding. Third, bringing together the above two approaches, we will characterize how self-motion and landmark cues are integrated in the caudate and its extended network for computing positional information. At present, the neural mechanisms underlying cue integration during positional coding, a critical process for accurate navigation, are not well understood. Hence, we will first determine, in macaques, the neural mechanisms by which striatal neurons integrate self-motion and landmark cues for location estimation. Based on this work, we will then test specific hypotheses about cue integration mechanisms in the human caudate.Finally, we will characterize whether age-related changes in the cortico-caudate circuit contribute to navigational deficits in old age. To achieve this, we will determine how cognitive aging affects the integration of navigational cues and whether a decline in caudate structural integrity can help explain such deficits. This line of studies will provide a more detailed understanding of age-related navigational impairments, which is an important prerequisite for developing novel interventions.

• DFG Programme: Research Grants
• International Connection: China
• Partner Organisation: National Natural Science Foundation of China
• Cooperation Partner: Professor Dr. Yong Gu