Attention and consciousness ch.9 Flashcards
(39 cards)
Subdivision of attention
- vigilance
- arousal
- divided attention
- selective attention
Vigilance
Sustain attention over time
Arousal
Alertness, which improves through the day, reaching a peak in early evening, and then diminishing towards bedtime.
Divided attention
Where there are at least two channels of input and the respondent has to try to “attend” to each one.
Selective (focused) attention
What allows us to focus on one channel at the expense of others.
Orienting response
A spontaneous reaction to a stimulus in which the head and/or body are moved so that the source of the stimulus may be examined.
How to investigate selective attention experimentally?
dichotic listening paradigm; presented with two simultaneous streams of auditory input. The listener should then “shadow” one channel by repeat aloud the stream of words in the “attended” channel in order to assess which information in the unattended channel “gets through”
The “attended” channel have better recall, but in situations where the unattended channel material is “salient”, it is often recalled.
Treisman´s model
although a particular channel might be selected early on in the processing stream, the unattended channel is not being “shut down”, but received less attentional effort than the attended channel.
P300
a positive wave in EPR occurring roughy one-third of a second or later after stimulus presentation. This “late” wave seems to be related to the contextual meaning of the stimulus, and shows that attention can modify the brains response for some time after a stimulus has been presented.
N250
Negative wave in EPR, with a latency of about 250 ms, if the face is meaningful, famous or familiar.
N170
Is strongest to facial images, including animal and cartoon faces.
Brain structures and attention
No single attention “center”,, but several regions forms a distributed neural network that is collectively responsible. the network comprises brainstem, midbrain, and forebrain structures, and impaired attention may result from damage to any of these.
The ascending reticular activating system (ARAS)
A brainstem structure; consist of neurons whose axons send through the midbrain to influence forebrain structures including the cortex.
It consist of several distinct neurotransmitter systems; cholinergic pathway, noardernergic pathway, dopaminergic pathway and serotonergic pathway
Neurotransmitter system ARAS
- cholinergic pathway
- noardernergic pathway
- dopaminergic pathway
- serotonergic pathway.
The axons of many of these neurons divide many times en route to the cortex, and the upshot of this cortical innervation is that a small number of brainstem and midbrain neurons can affect the excitability of virtually every cortical neuron.
Damage to ARAS
This system has been implicated in arousal and the sleep-wake cycle, so damage to ARAS will disrupt circadian rhythms and can result in coma, or chronic vegetative state.
Stimulation of the ARAS, will quickly wake a sleeping animal.
AMPHETAMINE are thought to have particular influence on the neurons in the aRAS and the pathway from it to the cortex.
The superior colliculli
These are two bumps on the dorsal side of the brainstem in the midbrain region
Key role of superior colliculli
Controlling a particular but vital type of eye movement in which object initially in the peripheral field of vision “capture” attention. these are called “express saccades”.
Damage to this part interferes with express saccades but not other slower eye movements.
Supranuclear palsy
Disorder affecting the subcortical regions, including the “superior colliculli” -> patients are unable to direct their gaze in normal way, not looking at someone who is speaking or turning to greet an approaching friend.
The inferior colliculi
Bumps just beneath the superior colliculi play a similar role in orienting the individual towards “salient” auditory stimuli.
The pulvinar region of the thalamus
Appears to play a vital role in filtering material to be attended from the vast amount of sensory input that the brain actually receives.
The thalamus (general role)
The thalamus, as a whole, work as a relay station for almost all sensory inputs en route to the cortex, and is therefor ideally situated to serve as a filter.
The cingulate gyrus
It appears to be involved in several separate attentional processes: cingulate as a whole provides an interface in which sensory inputs are linked to “motional tone”.
The anterior region of this structure are criticaly involved in response section (can I ignore it or do I need to run away?).
The anterior cingulate becomes active in circumstances in which appropriate “correct” response have to be selected in a deliberate manner. e.g. the troop task.
The parietal lobes
Specialized in processing spatial relations and their role in attention.
Parietal damage is associated with hemineglect, an attentional disorder where half of the visual field is ignored. P300 wave is most marked in parietal regions (= might reflect “attentional resource” allocated to a particular task), so the more attention a patient pays to particular stimuli, the larger the resultant P300. Damage to parietal lobe regions > no longer generate P300s.
Brain region WM and EF
Dorsolateral prefrontal cortex (DLPFC) and the anterior cingulate
