Consciousness Flashcards
What is the difference between awareness and wakefulness?
Wakefulness (also vigilance) - physiological aspect, degree of responsiveness or interaction with environment.
Awareness - the subjective feeling of consciousness
What are some purposes of sleep?
replenishment of storages (e.g. glycogen), elimination of metabolic waste products, memory consolidation, growth processes in children (e.g. release of hormone somatotropin)
What are some (electro-)physiological/behavioural markers of sleep?
For example, low energy consumption, decreased body temperature, suspension of consciousness, specific EEG patterns
What happens to EEG response in sleep stages I-IV?
Descent into stage I non-REM sleep is characterized by decreasing EEG frequency (4 to 8 Hz) and increasing amplitude (50 to 100 μV), called theta waves. Descent into stage II non-REM sleep is characterized by 10 to 12 Hz oscillations (50 to 150 μV) called sleep spindles, which occur periodically and last for a few seconds. Stages III and IV of non-REM sleep are characterized by slower waves (also called delta waves) at 0.5 to 4 Hz (100 to 150 μV).
REM sleep is characterized by low-voltage, high-frequency EEG activity. Yes/No
Yes, this is similar to patterns shown by awake individuals.
Name some structures involved in sleep
sleep entails interaction between brainstem, hypothalamus, thalamus, and cortex
Where do you find the ascending reticular activating system (ARAS)? What is its significance?
Stimulating a group of neurons near the junction of the pons and midbrain causes a state of wakefulness and arousal. This region of the brainstem was given the name reticular activating system. [The] work implied that wakefulness requires specialized activating circuitry—that is, wakefulness is not just the result of adequate sensory experience. (Purves, p. 655)
A pontine structure which releases NE to various cerebral structures and has been found to promote wakefulness
locus coerulus (LC)
Histamine-containing neurons are located in this hypothalamic structure, which also acts as the “main switch” in wakefulness and sleep.
tuberomammillary nucleus (TMN)
Activation of cholinergic and monoaminergic networks together produces the awake state. The locus coeruleus and raphe nuclei are modulated by the TMN neurons located near the tuberal region. The TMN is activated by neurons in the lateral hypothalamus that secrete the peptide orexin (also called hypocretin), which promotes waking. Conversely, antihistamines inhibit the histamine-containing TMN network, which is why they tend to make people drowsy. (Purves, p. 656)
Suprachiasmatic nucleus (SCN) serves as “master clock” for autonomous circadian rhythm. where is this structure located?
the hypothalamus.
Synchronization of thalamic and cortical neurons is a hallmark of wakefulness. Yes/No
No: When thalamocortical neurons are in the bursting state, the neurons in the thalamus become synchronized with those in the cortex, essentially “disconnecting” the cortex from the outside world. The disconnection is maximal during slow-wave sleep, when EEG recordings show the lowest frequency and the highest amplitude.
These neurons receive ascending information from the brainstem and descending projections from cortical neurons, and they contact the thalamocortical neurons. When the ____ neurons undergo a burst of activity, they cause thalamocortical neurons to generate short bursts of action potentials, which in turn generate spindle activity in cortical EEG recordings (indicating a lighter sleep state).
GABAergic thalamic nuclei neurons (specifically, thalamic reticular nucleus)
There are two parallel pathways for pain perception. What are they?
The spinothalamic tract conveys signals that mediate the sensory discrimination of first pain (sensory-discriminative pathway). The affective and motivational aspects of second pain are mediated by complex pathways that reach integrative centers in the limbic forebrain. The affective-motivational system taps into several brainstem regions responsible for emotional assessment (amygdala, cingulum, insula) and response (hypothalamus), as well as arousal (reticular formation, parabrachial nucleus), giving it strong drive on vigilance and attention.
see Purves, p.219 or Nov 19, tutorial slide 9
Local anesthetics (lidocaine, procaine etc.) work by which mechanism?
They are Na+ channel blockers, and inhibit action potential propagation along nociceptive and somatosensory nerve fibers.
The neural pathway that conveys pain and temperature information to higher centers is often referred to as the ____ system.
The anterolateral system - it supplies information to different structures in the brainstem and forebrain that contribute to different aspects of the experience of pain
