TY - BOOK
T1 - Central Control of Visually Guided Walking
AU - Jensen, Peter
N1 - CURIS 2018 NEXS 272
PY - 2018
Y1 - 2018
N2 - The importance of investigating visually guided walking comes from everyday life where navigating in
traffic, avoiding a puddle etc. makes the efficiency of visually guided walking crucial. Most knowledge
about cortical contributions to muscle activity during visually guided walking comes from studies in
the cat. In humans, the central control of visually guided walking has not been investigated as
thoroughly and the theories developed on the basis of research in the cat should be confirmed in
human studies to ensure their validity and relevance.
The overall aim of the thesis was to investigate the central control of walking with a special focus on
visually guided gait. A custom virtual locomotor stepping task was made that enabled us to perform
different visually guided walking tasks while collecting EEG and EMG measurements. In paper I it was
investigated whether subjects were able to integrate a novel virtual visually guided locomotor
sequence task with normal walking on a motorized treadmill. A sequence specific learning effect was
found in both children and adult subjects indicating that visually guided walking may be modulated by
activity in the corticospinal tract. The subsequent papers investigated the relations between
corticospinal coherence and normal and visually guided walking.
In paper II the corticospinal drive to the plantar flexors was investigated during normal walking using
EEG-EMG coherence over the motor cortex and EMG from soleus (SOL) and medial gastroc (MG)
muscles, respectively. The plantar flexors are important when modifying step length and plantar
flexor force are highly dependent on an intact corticospinal pathway. However, almost no prior
knowledge about central common drive to the plantar flexors exists. Results from this study showed
EEG-EMG coherence in the gamma frequency band indicating that the plantar flexors receive direct
cortical input during normal walking. The overall correlation was highest towards push off indicating
that the motor cortex contributes to plantar flexor activity and push off during normal walking.
In paper III the corticospinal drive during visually guided walking was estimated using EEG-EMG
coherence between EEG over 1) the motor cortex and EMG from tibialis anterior (TA) and 2) the
motor cortex and EMG from MG & SOL, respectively. The central common drive was estimated as
EMG-EMG coherence between proximal & distal TA and MG & SOL, respectively. Results showed
increased beta and gamma band EMG-EMG coherence for both TA-TA and MG-SOL indicating that,
like in the cat, human motor cortex directly modulates visually guided gait.
Finally in paper IV the central common drive was investigated during the same visually guided
locomotor sequence learning task, as presented in paper I. Here an additional increase in gamma
coherence was seen when comparing visual guided walking to a random or sequence specific walking
task. In addition beta band coherence was higher in the random stepping task compared to sequence
specific task. It was speculated that the difference was due to a need for increased attention during
the unpredictable random stepping task.
To conclude, the main results of the thesis showed increased central common drive during visually
guided walking indicating increased corticospinal contributions during visually guided walking. In
addition a novel locomotor sequence task can be integrated with normal walking. This is relevant in
sporting settings where complex movement patterns has to be integrated with running and walking
and the automatic control of certain movement pattern may free cognitive resources crucial to
success. It may also have perspectives for rehabilitation as the increased cortical activation could
benefit rehabilitation outcomes. Further research should address the potential for visually guided
walking in rehabilitation and sporting movements.
AB - The importance of investigating visually guided walking comes from everyday life where navigating in
traffic, avoiding a puddle etc. makes the efficiency of visually guided walking crucial. Most knowledge
about cortical contributions to muscle activity during visually guided walking comes from studies in
the cat. In humans, the central control of visually guided walking has not been investigated as
thoroughly and the theories developed on the basis of research in the cat should be confirmed in
human studies to ensure their validity and relevance.
The overall aim of the thesis was to investigate the central control of walking with a special focus on
visually guided gait. A custom virtual locomotor stepping task was made that enabled us to perform
different visually guided walking tasks while collecting EEG and EMG measurements. In paper I it was
investigated whether subjects were able to integrate a novel virtual visually guided locomotor
sequence task with normal walking on a motorized treadmill. A sequence specific learning effect was
found in both children and adult subjects indicating that visually guided walking may be modulated by
activity in the corticospinal tract. The subsequent papers investigated the relations between
corticospinal coherence and normal and visually guided walking.
In paper II the corticospinal drive to the plantar flexors was investigated during normal walking using
EEG-EMG coherence over the motor cortex and EMG from soleus (SOL) and medial gastroc (MG)
muscles, respectively. The plantar flexors are important when modifying step length and plantar
flexor force are highly dependent on an intact corticospinal pathway. However, almost no prior
knowledge about central common drive to the plantar flexors exists. Results from this study showed
EEG-EMG coherence in the gamma frequency band indicating that the plantar flexors receive direct
cortical input during normal walking. The overall correlation was highest towards push off indicating
that the motor cortex contributes to plantar flexor activity and push off during normal walking.
In paper III the corticospinal drive during visually guided walking was estimated using EEG-EMG
coherence between EEG over 1) the motor cortex and EMG from tibialis anterior (TA) and 2) the
motor cortex and EMG from MG & SOL, respectively. The central common drive was estimated as
EMG-EMG coherence between proximal & distal TA and MG & SOL, respectively. Results showed
increased beta and gamma band EMG-EMG coherence for both TA-TA and MG-SOL indicating that,
like in the cat, human motor cortex directly modulates visually guided gait.
Finally in paper IV the central common drive was investigated during the same visually guided
locomotor sequence learning task, as presented in paper I. Here an additional increase in gamma
coherence was seen when comparing visual guided walking to a random or sequence specific walking
task. In addition beta band coherence was higher in the random stepping task compared to sequence
specific task. It was speculated that the difference was due to a need for increased attention during
the unpredictable random stepping task.
To conclude, the main results of the thesis showed increased central common drive during visually
guided walking indicating increased corticospinal contributions during visually guided walking. In
addition a novel locomotor sequence task can be integrated with normal walking. This is relevant in
sporting settings where complex movement patterns has to be integrated with running and walking
and the automatic control of certain movement pattern may free cognitive resources crucial to
success. It may also have perspectives for rehabilitation as the increased cortical activation could
benefit rehabilitation outcomes. Further research should address the potential for visually guided
walking in rehabilitation and sporting movements.
UR - https://rex.kb.dk/primo-explore/fulldisplay?docid=KGL01011893330&context=L&vid=NUI&search_scope=KGL&tab=default_tab&lang=da_DK
M3 - Ph.D. thesis
BT - Central Control of Visually Guided Walking
PB - Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen
CY - Copenhagen
ER -