Lecture 8 - Arousal and Consciousness

consciousness

could refer to the state of being awake and aware of one’s surroundings, wakefulness and awareness vary throughout the day so consciousness varies too between being awake, in deep sleep or dreaming, in addition to the default state of consciousness, there might be many altered states, wakefulness, awareness and connectedness are differentiated states that define consciousness but there could be different states were in

Anil Seth

believes that progress depends on specifying closer explanatory mappings between first person subjective (phenomenological descriptions) and third person descriptions of embodied and embedded (neuronal mechanisms), new layer of complexity in our study of consciousness, explains why we have states of sleep, there are a lot of ways to study consciousness

states of consciousness (objective measures)

defined by neural correlates like brain activity on fMRI and EEG scans and metrics based on it like PCI, behavioral and physiological correlates like response to stimuli such as pain, heat, sound, objects for example via the glasglow coma scale, heart rate and respiration,

states of consciousness (subjective measures)

self reported phenomenological correlated like the altered state of consciousness scale (SD-ASC) and the gray near death experience scale (Gray NDE)

is meditation an altered state?

it is associated with many effects on arousal like breathing, heart rate and brain activity, we can compare the physiological characteristics of meditation to that of other states like sleep and relaxation, if the physiological characteristics of meditation are different. we can argue that meditation is a unique state

why is physiology affected in meditation?

involved in assuming specific breathing patterns and body posture very early in the set of instructions, these are associated with physiological changes within the session, form of exercise that will change your body long term, meditation also differs from sleep and relaxation because it involves focus

mindfulness

factors specific to this style is nonjudgmental acceptance, key ingredient of mindfulness based treatment programs for mood disorders and pain, includes both fixed attention and open monitoring

transcendental

key factors include enlightenment and inner calm

loving kindness

key factors include changing personal relationships, focus on attention is key in many styles of meditation, relaxation and sleep do not generally involve an emphasis on these processes

fixed attention meditation

focusing on something for prolonged periods like body, sound, an idea, etc, this is more emphasized than open monitoring meditation

open monitoring/awareness meditation

no explicit focus, maintain a repetitive state, monitor whatever incoming thoughts arise

breathing and heart rate

we need oxygen to live and inhale it from the air, breathing is about oxygenating the blood and this is given to red blood cells in the lungs (respiration), oxygenated blood is pumped through our body by the heart which created a heart beat

why does meditation work?

it affects the autonomic nervous system and its target organs including lungs and heart, activity affects sensory motor and internal organ connections that make up the peripheral nervous system

autonomic nervous system

made up of the sympathetic and peripheral nervous system

sympathetic nervous system

fight or flight, allows you to survive a threat by utilizing energy effectively, when it dominates this increases breathing, heart rate, decreases HRV, increases blood pressure and decreases galvanic skin resistance and increases cathecolamines

parasympathetic nervous system

rest and digest, brings about better healing of tissues, changes energy utilization so other things are possible, relaxation meditation corresponds to PNS dominance, causes lower respiration, lower HR, increased HRV, lower BP’ higher galvanic skin resistance and less catecholamines

neurovisceral system

the higher level structures in this model are all targeted by meditation, includes PFC, cingulate cortex, amygdala and insula, meditation might affect HR for the same reason it might affect stress reactivity

breathing (respiration)

meditation styles comes with guidelines for breathing rate, respiration oxygenates the body, respiration rate is an extremely important vital sign, though respiration is not frequently measured, it can predict negative outcomes, ex; deterioration, long term meditation is associated with lower respiration rates, if you compare ppl who perform meditation to a no meditation group, respiration rate is slower for meditators, even for someone who isn’t currently meditation, just having experience is enough, the issue is the study is not experimental, they could be healthy for other reasons, evidence is only correlational

heart rate

typical heart rate is 60 to 100 beats per minute, this can be measured non invasively by taking pulse, using a heart monitor or an electrocardiogram, it is important because high heart rate is a risk factor for multiple health issues like myocardial infarction, arrhythmias and sudden death including cognitive impairment with aging, keeping heart rate in a healthy range and having a healthy cardiovascular system is a great way to improve overall well being, mediation might be useful in managing cardiovascular health and in treating cardiovascular disease

meditation and heart rate

during most styles of meditation, HR drops, long term meditation may persistently reduce HR even when someone is not meditating, several forms of meditation have this effect (transcendental, mindfulness, yogi practices, etc), some styles are associated with faster HR

heart rate variability (HRV)

heart rate is not constant and adapts to different circumstances, changes in heart beat intervals overtime provides info about how the heart adapts, changes in the time interval between consecutive heart beats is termed HRV

importance of HRV

provides a survival advantage, it allows the cardio vascular system to adapt to different challenges, correlated with emotional arousal, psychological well being and physiological health, initial research suggested HRV may predict pathology particularly for mood disorders and cardiac disorders, later work is more critical

HRV from ECG data

beat to beat variation in heart rate is the R-R interval is computed from ECG data, amount of time between heart beats

gathering HRV data

if we track HR for a long time, we get many more RR intervals, if you take someone in a relaxed state, you exceed on particular power of RR intervals overtime, particular pattern here of resting state contrasts with TILT there are small RR intervals so faster HR

complex waves

this would be like an HRV wave, they can be thought as a combination of many simpler waves, they may reflect distinct biological processes, there are low and high frequency waves

rest condition

there are way more high frequency waves and less low frequency, this is what you would see during relaxation meditation, this ranges from 0.15 to 0.40 Hz and is correlated with PNS activation, this measure is favored over HR in meditaion studies

tilt condition

see more low frequency HRV waves and less high frequency, this ranges from 0.04 to 0.15 Hz and is more ambiguous, doesn’t really tell you anything about meditation

meditation and HRV

looking at different papers, notice many meditative styles are associated with more high frequency HRV, ppl have become more critical of HRV analysis overtime, relaxing meditation styles tend to increase HF-HRV balance, effects of meditaion on HRV may differ in patient interventions are inconclusive, interpret with caution as there are a number of small number high quality studies that has made meta analysis difficult, methodological concerns

vajrayana meditation

tends to decrease HF-HRV balance

HRV predicts meditation benefits

change in HRV is correlated with reduction in pain unpleasantness in meditators but not sham meditators

blood pressure

refers to the pressure of blood against arterial blood vessels in systemic circulation, systolic and diastolic components, expresses as a ratio of SBP/DBP, healthy range varies, 120/80 in adults, it is an important predictor of health more useful than HR or HRV, BP is lower d uring meditation, long term meditation may persistently reduce BP

hypertension

excessively high BP

hypotension

excessively low blood pressure

MBIs and BP

MBIs have effects on systolic BP but not diastolic BP in patients with cardiovascular disorders, meditation is not always relaxing

meditation and arousal

when comparing HR in baseline to relaxation heart rate is slower with relaxation meditation, and when you compare HR and respiration in baseline to breath fire and segmented breathing meditation, breath fire is much more arousing increasing HR more than segmented breathing but both cause increased HR compared to baseline

what makes a style of meditation arousing?

many possibilities like differences in breathing, posture and fixed attention practices, one study looked specifically at how attention during meditation was related to HRV, it compared the effects of random thinking, fixed thinking, meditative focusing and defocused meditation on HRV

meditative focusing (Dharana)

participants were asked to open their eyes and gaze at sanskrit syllable OM as it is written in sanskrit, during this time guided instructions required them to direct thoughts to physical attributes of the syllable, that is the shape, size and color then to close their eyes and continue to visualize the syllable mentally, main emphasis during meditative focusing was that thoughts are consciously brought back if they wander to the single thought of OM

defocused meditation (dhyana)

during this session participants had to keep their eyes closed and dwell on thoughts of OM without any effort, particularly on the subtle rather than physical attributes and connotations of the syllable, this would gradually allow participants to experience brief periods of silence which they reported after the session

findings of the meditative vs defocused meditation study

meditative focusing was associated with lower HF-HRV and higher HR’ defocused meditation was associated with lower HR, meditative focusing elicits a physiologically distinct effect from defocused meditation, in short focus matters

electroencephalogram (EEG)

measures electrical activity in specific brain regions, regions measured determined by electrodes used, very useful in studies of arousal

what is an EEG measuring?

each electrode is positioned above a small amount of those neurons, produces moment to moment readout so temporal resolution is very good, group of measurements of neurons, picks up an electrical signal overtime, measures potential difference overtime, voltage varies in a wave like manner (something that has a variation overtime that repeats with peaks and valleys, this variation in voltage over time gives us the frequency

EEG frequency ranges

frequency corresponds to the number of cycles per unit time, measured in HZ, different frequency ranges are evident in the EEG, different states of consciousness have different (characteristic) frequency patterns

beta

13 to 30 Hz, awake

alpha

7 to 13 Hz, drowsy, relaxed states

theta

4 to 7 Hz, stage N1 sleep

delta

1 to 4 Hz, stage N3 sleep/deep sleep

why use an EEG to measure brain activity and not an fMRI?

EEG has high temporal resolution measuring electrical activity in specific brain regions, it is less disruptive to the ongoing mental state, more accessible, you can do it comfortably while in fMRI you are confined and mental state affects results like movement, its also more cost effective

meditation vs sleep

meditation is visually and physiologically similar to hypometabolic states like sleep, argument that transcendental meditation wasn’t just similar to sleep, it was sleep (micro naps observed) but now if we compare to sleep on the EEG closely, we notice several differences

EEG and sleep stages

in meditation maintain a brain activity level that is around light sleep or relaxation, alpha power goes up in most areas

phenomenological analysis

self report by the subject on the characteristics of their mental state in a particular situation (ex; meditation), assessed by many tests like Greyson NDE scale and altered states of consciousness test as well as by less structured interviews, scales applied in meditation research and other fields, notably psychedelic research

differentiating SoCs

overlap between ppl interested in psychedelics and those who are interested in meditation

meditation and psychedelics

recently there has been great interest in both meditation and psychedelics as potential treatments for depression, anxiety and addiction, many ppl have commented on a connection between meditation and psychedelics, there are some reports that meditation in combination with psychedelics can improve well being, progress has been slow because psychedelics are very tightly regulated and not as well funded