Case 1 - Analgesia Flashcards
what is the cortical processing of pain thought of as/conceptualised as?
Cortical processing of pain thought of as consisting of a medial and lateral pain system originating from medial & lateral thalamic nuclei
what does the medial pain system consist of?
Medial pain system – originates form medial thalamic nuclei
Consists of medial thalamic nuclei, anterior cingulate cortex (ACC) & insula
Mediates affective-cognitive-evaluative aspects of pain (the A&C aspects on the nature of pain)
what does the lateral pain system consist of?
Lateral pain system – originates from lateral thalamic nuclei
Consists of lateral thalamic nuclei, primary (SI) and secondary (SII) somatosensory cortices
Mediates sensory/discriminative aspect of pain
what is the role of the periaqueductal grey (PAG)?
PAG is the primary control centre for the
descending pain modulatory system, it consits of:
* Integration of ascending pain stimuli and
descending influences from higher cortical
regions
* Receives information from ascending pain fibres and temperature fibres of the spinothalamic tract
Role of the periaqueductal grey (process)?
Stimulation of the PAG activates enkephalin-releasing neurons that project to the raphe nucleus in the medulla of the brainstem
When enkephalin-releasing neurons project to the raphe nucleus in the brainstem, this leads to the release of serotonin.
Serotonin descends from the brain stem to the dorsal horn of the spinal cord, where it binds to interneurons in the substantia gelatinosa (substantia gelatinosa is located in the dorsal horn of the spinal cord)
Activation of enkephalin-releasing neurons causes interneurons to release endogenous opioid neurotransmitters
These endogenous opioid neurotransmitters bind to μ (mew) opioid receptors on the axons of incoming Aδ (A-delta) and C fibres
μ-opioid receptors inhibit the release of substance P so inhibits the experience of pain
Activation of cortical regions and circuits inhibits or facilitates pain processing
pain perception involves what psychological processes?
Pain perception involves several psychological processes:
* Attentional orienting to painful sensation and its source
* Cognitive appraisal of the meaning of the sensation
* Subsequent emotional, psychophysiological (e.g., stress) & behavioural reactions
All of which in turn feedback to influence the experience of pain
how can acute fight or flight stress responses affect pain perception?
Acute fight or flight stress response can (temporarily) reduce pain perception via the release of noradrenaline & activation of PAG and endogenous opioids
