John Martindale

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A recent nonlinear system by Friston et al. (2000. NeuroImage 12: 466-477) links the changes in BOLD response to changes in neural activity. The system consists of five subsystems, linking: (1) neural activity to flow changes; (2) flow changes to oxygen delivery to tissue; (3) flow changes to changes in blood volume and venous outflow; (4) changes in flow,(More)
The spatial resolution of hemodynamic-based neuroimaging techniques, including functional magnetic resonance imaging, is limited by the degree to which neurons regulate their blood supply on a fine scale. Here we investigated the spatial detail of neurovascular events with a combination of high spatiotemporal resolution two-dimensional spectroscopic optical(More)
An understanding of the relationship between changes in neural activity and the accompanying hemodynamic response is crucial for accurate interpretation of functional brain imaging data and in particular the blood oxygen level-dependent (BOLD) fMRI signal. Much physiological research investigating this topic uses anesthetized animal preparations, and yet,(More)
Optical imaging slit spectroscopy is a powerful method for estimating quantitative changes in cerebral haemodynamics, such as deoxyhaemoglobin, oxyhaemoglobin and blood volume (Hbr, HbO2 and Hbt, respectively). Its disadvantage is that there is a large loss of spatial data as one image dimension is used to encode spectral wavelength information. Single(More)
Unexpected, biologically salient stimuli elicit a short-latency, phasic response in midbrain dopaminergic (DA) neurons. Although this signal is important for reinforcement learning, the information it conveys to forebrain target structures remains uncertain. One way to decode the phasic DA signal would be to determine the perceptual properties of sensory(More)
An essential prerequisite for the accurate interpretation of noninvasive functional brain imaging techniques, such as blood oxygen level dependent (BOLD) fMRI, is a thorough understanding of the coupling relationship between neural activity and the haemodynamic response. The current study investigates this relationship using rat barrel cortex as a model.(More)
Optical imaging spectroscopy (OIS) and laser Doppler flowmetry (LDF) data sequences from anesthetized rats were used to determine the relationship between changes in oxy-and deoxygenated hemoglobin concentration and changes in blood volume and flow in the presence and absence of stimulation. The data from Jones et al. (accompanying paper) were used to(More)
The temporal relationship between changes in cerebral blood flow (CBF) and cerebral blood volume (CBV) is important in the biophysical modeling and interpretation of the hemodynamic response to activation, particularly in the context of magnetic resonance imaging and the blood oxygen level-dependent signal. measured the steady state relationship between(More)
The relationship between neural activity and accompanying changes in cerebral blood flow (CBF) and oxygenation must be fully understood before data from brain imaging techniques can be correctly interpreted. Whether signals in fMRI reflect the neural input or output of an activated region is still unclear. Similarly, quantitative relationships between(More)
This article investigates the relation between stimulus-evoked neural activity and cerebral hemodynamics. Specifically, the hypothesis is tested that hemodynamic responses can be modeled as a linear convolution of experimentally obtained measures of neural activity with a suitable hemodynamic impulse response function. To obtain a range of neural and(More)