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noradrenaline and acetylcholine - Coggle Diagram
noradrenaline and acetylcholine
physiology of noradrenaline
projects from locus ccoeruleus
projections to midbrain, brainstem and spinal cord - sympathetic nervous system
no evidence of a direct role in memory or movement, but degeneration of NA is common in neurodegenerative disorders
co-release with other neurotransmitters
physiology of acetylcholine
projects from 3 nuclei in the basal forebrain
only 5% of cells are cholinergic
projections to midbrain, brainstem and spinal cord - parasympathetic nervous system
no evidence of a direct role in memory or movement, but degeneration of NA is common in neurodegenerative disorders
co-release with other neurotransmitters
potential roles of noradrenaline
effort and motivation
at the time of performing an action, activity in LC neurons was correlated with physical effort required from the task (Varazanni et al, 2015)
higher effort was associated with greater firing rate
may be involved in activation of autonomic nervous system to allow for muscle activation for an effortful task
reacting to information about the current task and modulating activity to reflect the difficult
contrasts role of DA - encodes effort as a cost and considered as part of decision on whether to act - is it worth putting in high effort for a poor reward?
does this also translate to different types of effort e.g. when tasks require a high level of cognitive effort
impairment on watermaze task was explained by a lack of motivation caused by NA knockout (Thomas and Palamiter, 1997)
disengaging from task/switching behaviours
noradrenaline signalling increased on trials where reward was no longer contingent on action (Dalley et al, 2001)
importance of NA in detecting changes in predictive relationship between action and reinforcement
important for learning new strategies
rapid plasticity in LC neurons when reward contingencies were changed during an odour-reward association task (Bouret and Sara, 2004)
setting optimum level of arousal
strong relationship between LC activity and arousal level
mismatch/prediction errors
activity in LC axons was correlated with visuomotor prediction errors when visual and motor information did not match up (Jordan and Keller, 2023)
facilitates sensorimotor plasticity to allow for behavioural changes to be made - enhances behavioural flexibility
potential roles of acetylcholine
sustained attention
high levels of ACh were associated with better performance on trials where reward was contingent on action (Dalley et al, 2001)
good performance on this task was reliant on sustained attention
changes in behaviour/attention after an error
ACh-mediated pMFC activity predicted adjustments in brain areas processing task-relevant stimuli features after an error - when ACh antagonists were used, this relationship was disrupted (Danielmeier et al, 2015)
mediating behavioural and neural control after an error is made
ACh transients were only seen on signal-hit trials and only when trial was preceded by an incongruent trial (Howe et al, 2013)
ACh transients mediated the shift in attention to cue-evoked activation of response rules
signal detection
higher levels of ACh in distracted condition, where it is harder to detect cues
activating ACh neurons made you more likely to report a cue (including false positives) and supressing ACh made you less likely to detect cues (Gritton et al, 2015)
enhancing or supressing hit rate relied on modulation cholinergic activity
sensory surprise
evaluation of the literature
limitations
implications
neurodegenerative diseases
strengths
future research