Time-Delay Latency of Resting-State Blood Oxygen Level-Dependent Signal Related to the Level of Consciousness in Patients with Severe Consciousness Impairment

Abstract

Recent evidence on resting-state functional magnetic resonance imaging (rs-fMRI) suggests that healthy human brains have a temporal organization represented in a widely complex time-delay structure. This structure seems to underlie brain communication flow, integration/propagation of brain activity, as well as information processing. Therefore, it is probably linked to the emergence of highly coordinated complex brain phenomena, such as consciousness. Nevertheless, possible changes in this structure during an altered state of consciousness remain poorly investigated. In this work, we hypothesized that due to a disruption in high-order functions and alterations of the brain communication flow, patients with disorders of consciousness (DOC) might exhibit changes in their time-delay structure of spontaneous brain activity. We explored this hypothesis by comparing the time-delay projections from fMRI resting-state data acquired in resting state from 48 patients with DOC and 27 healthy controls (HC) subjects. Results suggest that time-delay structure modifies for patients with DOC conditions when compared with HC. Specifically, the average value and the directionality of latency inside the midcingulate cortex (mCC) shift with the level of consciousness. In particular, positive values of latency inside the mCC relate to preserved states of consciousness, whereas negative values change proportionally with the level of consciousness in patients with DOC. These results suggest that the mCC may play a critical role as an integrator of brain activity in HC subjects, but this role vanishes in an altered state of consciousness.

Latency structure of BOLD signals within white matter in resting-state fMRI

“…A detailed investigation of the influences of factors including correlation magnitude, data length, and temporal resolution, on time delay estimation can be found in [34], though using either surrogate time series or multiple-session individual real data [34][72]. In spite of the sampling error in estimated lags, latency analysis based on current method [5] could give rise to differences between groups [73][74][75] using typical scanning parameters (e.g. TR = 2000ms, acquisition length = 8min or 10min).…”

Time-delay structure predicts clinical scores for patients with disorders of consciousness using resting-state fMRI

“… ( Xu et al, 2020 ) 4 Altered propagation structure of iBA in DOC patients DOC: 48 HC: 27 TR = 2 s 3 T ±0.2 s Significant altered TD P was found in critical regions (e.g., middle cingulate cortex, precuneus, inferior frontal gyrus) are found in DOC patients. ( Rudas et al, 2020 ) 5 Specific propagation structure of iBA at the individual level HC: 11 TR = 1.16/2.2 s 3 T ±0.5 s Propagation structure of iBA was stable at individual level and similar to that of the group level. ( Raut et al, 2019a ) 6 Possible sources of propagation structure of iBA in visual cortex in HC HC: 1,250 TR = 0.72/0.65 s 1.5 T ± 0.3 s The iBA in early visual cortex propagated from the central to peripheral visual fields in HC.…”

Engine Of Consciousness In Brain - A Review

“…It is used for coma retrieval during intensive procedures (Redinbaugh et al, 2020). It is different from the midcingulate cortex, which has a critical role in the integrator of brain activity which vanishes in an altered state of consciousness (Rudas, 2020).…”

“…Disorders of consciousness is a set of clinical conditions where consciousness is affected by brain damage to the cerebral cortex (Rudas, 2020). The brain activation consists of some awareness in the cognition of vegetative or minimally conscious state (Monti, 2010).…”