Fig. 4

ABCD categories with their respective characteristics for thalamocortical status and clinical signs. The 'A' category, with a dominant frequency of less than 1 Hz, indicates a thalamocortical network that is completely disconnected. Neocortical neurons are significantly hyperpolarized and primarily generate low-frequency oscillations [212]. The likely behavioral diagnosis is VS/UWS [116]. In the 'B' category, where the dominant frequency is ~ 5–9 Hz, the thalamocortical network is severely disconnected (indicated by a thin red dotted line). The intrinsic oscillation of membrane properties in neocortical neurons results in bursts at a rate of about 5–9 Hz due to depressed membrane potentials[213]. The behavioral diagnosis could be VS/UWS or MCS [11]. The 'C' category, characterized by dominant frequencies of approximately 5–9 Hz and 20–35 Hz, corresponds to a moderately disconnected thalamocortical network (indicated by a red dotted line). Partial restoration of neocortical membrane potentials, along with the coincident bursting of deafferented thalamic neurons, leads to the coexistence of theta and beta frequency oscillations in the connected cortex. The behavioral diagnosis would most likely be MCS or CS[11]. The category 'D', with dominant frequencies of approximately 8–13 Hz and 20–35 Hz, signifies a fully intact thalamocortical network. Normal firing patterns of neocortical neurons, coupled with a structurally and functionally interconnected thalamus and cortex (indicated by a red arrow), facilitate the production of alpha and beta frequency oscillations. The behavioral diagnosis could be CS or healthy. VS/UWS: vegetative state/unresponsive wakefulness syndrome; MCS: minimally conscious state; CS: confusional state