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Title: Imaging haemodynamic activity in the mouse visual cortex
Author: Pisauro, M. A.
ISNI:       0000 0004 5359 0307
Awarding Body: University College London (University of London)
Current Institution: University College London (University of London)
Date of Award: 2014
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Neurovascular coupling, the relationship between neural and haemodynamic activity, is not a fixed property of the brain. Physiological, behavioural and cognitive factors can strongly modulate the degree to which haemodynamic responses to perceptual stimuli reflect co-localized neural responses. Moreover, a significant part of the haemodynamic activity is not directly coupled with the spiking activity. Here we show how anaesthesia can influence the relationship between haemodynamic and neural activity and how the former can be expressed as the sum of two components: one which is well coupled with neuronal responses and the other which seem to be independent of them and which correlates with alertness. We used wide-field optical imaging of intrinsic signals in mouse primary visual cortex (V1). Haemodynamic responses could be used to obtain clear maps of retinotopy in both anaesthetized and awake mice. However, when the mice were awake, responses were four times larger and twice as fast compared to when they were anaesthetized. By measuring neural responses we could establish that the effects of anaesthesia on haemodynamic responses were due to changes in neurovascular coupling. By activating V1 via optogenetics, we replicated the effects of anaesthesia in terms of delay of the response but not of amplitude. We then asked whether haemodynamic activity can all be explained in terms of local neural activity. By imposing a precise spatiotemporal pattern of neural responses in visual cortex we were able to distinguish two component of the haemodynamic activity: one reflects responses to visual stimuli, and is local to the retinotopic region activated by the stimuli. The second correlates strongly with pupil diameter, which reflects a measure of arousal, and is shared simultaneously by large regions of cortex.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available