On the perturbational complexity index

Introduction

Objective measure

Sensitivity to consciousness

consciousness meter

Discussion

Advantage: quantification on a continuum

quantification of consciousness

Disadvantages: Variability between stimulation sites?

first steps, inspirtions, massemmini

Methods

EEG vs hdEEG

TMS

Algorithmic Compression

Oweb Monti, command following, purposeful behavioutr

Availability

Sensitivity

Cost

integrity of the neuromuscular system

integration

differentiation

differences in what is exactly measured

algorithmic complexity

Further Research

Results

sleep

Psychedelic state?

posterior hotzone

aneasthisia

disorders of consciousness + locked in syndrome

bridging principles

large scale response dynamics

vs alternatives: brain metabolism, cerebral perfusion

set of altered states of consciousness

input-output relationships

uws, minimally conscious state

sensory stimulation: resting vs stim no diff -

adaptation

automatic processing vs conscious perception

risk of a purely stimulation based procedure

attention praradigms stronger, vs just passive stim, better to involve sub in task, boost cognitive

detecting vs communicating

ethical considerations

pain medication in minimally conscious states

neural sign - sign for command following - cognitive task

fully disconnected, input-output disconnection

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low sensitivities for this techniques

low sensitivites

cognitive task:

detached from input output

even verbally recovered: memor y, concentration, attention, motivation

bypassing

requires input - understand process sensory information

consciousness can be generated from within

lack of options, prevent brain death, what does it feel like

artifacts of modern medicine

correlational measure

theoretical foundation (grounded) + practical use

indepndent of sensory processing and motor behaviour

neural correlates and neural substrates

activity as high as in wakefullness

recovery of brain ativity not necessarily needed (also brain metabolsim)

dissociation: decrease in activity during seizures, not based on activity, or metabilic rate

synchrony dissocation - seizures

spectral features, entropy : paradoxes

do not work in all cases

not necisarrily on scalp

contrast with empirical findings

sensitivity and specificity

too many exceptions

IIT

start from phenomenology, then go to the brain

balance btw unity and diversity

modular vs full connection

optimization - functional differnetiation and integration

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so far dimensions have not been combined , phase

difference: coherence - observing vs perturbing

global vs stereotypical - capture

causal interactions vs temporal correlation

intrinsically integrated information

knock on cortex, record the echo

approximates cortico-cortical interactions/potentials

escape the input output chain

source modelling

determinsitic activity

central gravity still there

propofol midazolam ketamine

ketamine - hallucinations - model of full disconnection and conscousness

xenon

stimulate left over cortex islands with neuronavigation

response in VS - sleep like (provided no complete death of neurons)

adavantage: sensitivity to minimally conscious state

therapeutic potential - building up capapcity

determinisitc patterns, binarize

different things at different times

joint presence as an important criterium

circularity: no independent evidence to subjective reports

calibration of measure

benchmark to derive a cutoff

no report, immediate report, delayed report

benchmark population

roc analysis

sensitivity and specificity 100%

detection rates - brain derived fmri active paradigm - 3, p300 erp - 30% - eeg - söow wave alpha delta - 60%, PCI - only 2 out of 38 missed - sensitivity - 94,7 % - perturbing is mroe than observing

retained capacity that has been missed by focusing on overt
input-output behaviour

aphalic syndrome

appalic syndrome

assume there is a physical substrate that is cabable of consciousness until proven otherwise

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resore functional external communication or restore complexity

cut-off values, benchmark poulation validation

Mechanims

why does complexity collapse

nobody is cutting the snapses - physiological state no one is cutting the synapses

functional change in how neurons are working

neuronal bistability

anatomical structure is the same

stochstical continuation of activity

causal trace

corroborated by intracranial data

complexitiy recovery, local physiological mechnaisms, low complexity state - pharmacological interventions


cortical deafferentiation

different perturbations = different reposnes

coarse measurement, only a flavour of phi

relative changes not absolute

across subjects as well as within subjects

calibration - exhaustive measure, rel measure

content vs complexity

system property

confounding factors in ROC curves - forgot to have been cosncious - ground truth that you trust - best: own experience, subjective reports

make up and confabulate

step wise distillation

local global - bekenschtein - distraction