Does Aβ act to trigger a disease that becomes Aβ independent, is some threshold level of brain Aβ elevation required, or does Aβ drive pathological processes in a continuous fashion at all stages of the disease?
One becomes demented only if a cognitive reserve capacity falls below a specific threshold of functioning brain tissue.
Taken together, our results suggest that CR cells are involved in a novel excitatory loop of the postnatal hippocampal formation, which potentially contributes to shaping the flow of information between the hippocampus, parahippocampal regions and entorhinal cortex, and to the low seizure threshold of these brain areas.
DeCarli and colleagues [ 81] demonstrated similar findings using PET, showing that a threshold of >0.5% of brain parenchymal fraction was significantly associated with poorer performance on executive function and mental flexibility tasks (phonemic fluency, Trails B).
31 For THs, a threshold of 60% mean brain intensity defined the brain-cerebrospinal fluid (CSF) boundary, with manual editing where required.
Instead of changing the level of the threshold, the brain changes the level of the starting point of the accumulation and adds a time-dependent signal to the accumulated evidence.
To correct for multiple comparisons, resulting brain images were thresholded at p <.05 FWE cluster-level extent using an initial threshold of p <.001 uncorrected Brain regions were identified that correlated with rejection rates for unfair proposals for the contrast (unfair > fair).
Analyses were performed at the whole brain level and the initial threshold for significance was a cluster-level statistic of P<.05FWEcorrected at the whole brain threshold of P<.001uncorrected.
Although significantly stronger activations were present bilaterally in the frontal lobe in Microstate 4 (compared to Microstate 3), these activations did not pass our cluster threshold of >10 contiguous activated brain solution points (right frontal activations: t = 3.26 with 6 activated solution points; left frontal activations: t = 2.67 with 3 activated solution points).
He suggested a theory of a critical threshold of asphyxia beyond which brain damage occurs.
