View
231
Download
2
Category
Tags:
Preview:
Citation preview
Sensory Memory and Working Memory
Sensory Memory
• Brief• Iconic/echoic• High capacity• Pre-attentive• Is there a Neural Correlate of Sensory
Memory?
Is there a Neural Correlate of Sensory Memory?
• Stimuli that deviate from a regular sequence cause a change in the ERP/MEG called the mismatch negativity/mismatch field
• MMN/MMF only occurs when stimuli are close together in time
• Thought to reflect an automatic response to detection of difference between current and previous stimuli
Short-Term Memory
• Duration of seconds• Limited capacity• Not pre-attentive
Neuropsychology of STM
Removal of tumor in L. Angular Gyrus
• Patient E.E.• Reduced digit-span• Normal speech,
comprehension• Normal long-term memory• Why is this finding puzzling?
Working Memory
• STM has been replaced by Working Memory model
Working Memory
• STM has been replaced by Working Memory model
• “Transient representations of task relevant information”
• Limited capacity store AND mechanism for working with that information
• Are there brain structures associated with these functions?
Working Memory
• Left Supramarginal Gyrus and left premotor lesions associated with difficulty holding strings of words in mind
• Right parieto-occipital damage associated with visuospatial memory deficits
• Thus these are doubly dissociated
Working Memory and Frontal Cortex
• An important aspect of working memory is maintaining a representation of previous information while it remains relevant to a current goal
• This information may come via sensory systems, or it may be reactivated from a long-term store
Working Memory and Frontal Cortex
• Animal lesion studies reveal that the Lateral Prefrontal cortex is critical for maintaining these “working” representations
Working Memory and Frontal Cortex
• Goldman-Rakic et al. • Spatial working memory is dissociable from
long-term associative memory
Working Memory and Frontal Cortex
• Working Memory Task– Well is baited with food– Target well changes from
trial to trial– Monkey’s view is blocked
for a delay interval– Monkey must indicate the
baited well to get rewarded
– Requires maintained representation of current target location
Working Memory and Frontal Cortex
• Associative Memory Task– Each well is indicated by a
picture– Target is always associated
with the same picture(s)– Monkey’s view is blocked
for a delay interval– Monkey must indicate the
baited well to get reward– Requires recall of cue from
LTM
Working Memory and Frontal Cortex
• Goldman-Rakic et al. • Spatial working memory is dissociated from
long-term memory• Lesions cause deficit in working memory task
but not association task
Working Memory and Frontal Cortex
• Goldman-Rakic et al. • Spatial working memory is dissociable from
recognition memory
Working Memory and Frontal Cortex
• Working Memory Task– 1 of 3 objects is indicated
to the monkey– View is blocked for a delay– 2 of the 3 objects are
presented– Monkey must select the
non-match object– Requires working memory
because no other cues differentiate the two objects
• Recognition Memory Task– Same as Working memory
task except…– After delay, indicated
object is paired with a novel object
– Monkey must select novel object
– Requires recognition memory to differentiate unfamiliar from familiar objects
Working Memory and Human Frontal Cortex?
Working Memory and Human Frontal Cortex
BOLD signal in lateral prefrontal cortex (area 46) is greater for memory task than for colorDiscrimination task
Recommended