Cursed complexity. Computational properties of subcortical neuronal microcircuitry in sensorimotor control
Författare
Summary, in English
The initial part of the thesis investigates the properties of the spinocerebellar circuitry of the nervous system, and its role in motor control. Especially the cerebellum has been shown to play an important role in the coordination of fast movements, such as reaching and pointing. Paper I uses theoretical reasoning based on previously found experimental studies to show that the cerebellar circuitry should not be studied in isolation if the aim is to explore cerebellar function. The inputs provided by the pre-cerebellar circuits in the spinal cord and brain stem can significantly reduce the complexity of the problem that the cerebellar circuitry needs to solve.
Papers II, IV and V investigate the properties of the mossy fiber pathways. Both the spinal border cell neurons that ascend the ventral spinocerebellar tract with sensorimotor information related to locomotion and the neurons of the cuneate nucleus that process tactile information are studied using behavioral stimulation, either in vivo (Paper V) or through modeling (Paper IV). The results indicate both that the overall activity of the circuitry provides the cerebellum with an easy to interpret encoding, but the individual neurons can at the same time segregate underlying features and details of the stimulus. This result can be seen as a parallel to the found statistics of spike generation in Paper III. Even though the neurons have complex electrodynamic properties, their average activity, described by their firing statistics is surprisingly similar between neurons with vastly different morphology.
Paper VI reviews the theoretical grounds for sparse coding, and compares them to recent experimental findings, both in the cerebellum and the neocortex. While there are beneficial properties of certain sparse codes, the experimental results rather indicate that the circuitry both in the cerebellum and the neocortex do not actively maintain a sparse population code.
Avdelning/ar
Publiceringsår
2015
Språk
Engelska
Publikation/Tidskrift/Serie
Lund University Faculty of Medicine Doctoral Dissertation Series
Volym
2015:89
Fulltext
- Available as PDF - 10 MB
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Dokumenttyp
Doktorsavhandling
Förlag
Neural basis for sensorimotor control
Ämne
- Neurosciences
Nyckelord
- spike firing statistics
- spontaneous activity
- sensorimotor control
- tactile processing
- cuneate nucleus
- sparse coding
- spinal border cells
- cerebellum
Status
Published
Forskningsgrupp
- Neural Basis of Sensorimotor Control
ISBN/ISSN/Övrigt
- ISSN: 1652-8220
- ISBN: 978-91-7619-168-2
Försvarsdatum
7 september 2015
Försvarstid
09:00
Försvarsplats
Segerfalksalen, BMC A10, Sölvegatan 17, Lund
Opponent
- Gerald E. Loeb (Prof.)