Working Memory

Question 1

What is working memory?

Answer 1

the ability to keep something active in one’s mind for a short period of time

Question 2

Give examples of working memory

Answer 2

• being able to remember a phone number long enough to dial it
• holding the steps of a maths problem in mind as you solve it
• liistening and comprehending a long sentence

Question 3

What is the difference between working and long-term memory?

Answer 3

• working is used for immediate processing and manipulation of information
• long term is used for storing information over an extended period

Question 4

Describe the experiment used to distinguish working memory from long-term memory

Answer 4

• subjects are asked to briefly remember a string of digits
• normal controls learn to remember long strings, because they can use working and long-term memory
• patients with MTL lesions never learn to remember long strings, because they only have working memory, which has a limited capacity

Question 5

What tasks use working memory?

Answer 5

those that require several intermediate steps and are interrupted by distractions

Question 6

How does the PFC contribute to working memory?

Answer 6

• maintains information in an active state even in the absence of external stimuli
• integrates information from different sources to allow for decision making and problem solving

Question 7

How does the PFC contribute to goal-directed behaviour?

Answer 7

• involved in planning and decision making to help formulate strategies to achieve desired outcomes
• behavioural flexibility when circumstances change
• top down control

Question 8

What is top-down control?

Answer 8

PFC exerts control over other brain regions to align actions with goals which ensures that behaviour is guided by internal goals rather than immediate external stimuli

Question 9

How can visual input enable the PFC keep a visual scene in working memory?

Answer 9

via the dorsal and ventral visual streams

Question 10

What can communication with the MTL allow the PFC to do?

Answer 10

control which short-term memories get backed up in long-term storage

Question 11

Give an example of a working memory task

Answer 11

• decide if an initial sound is the same as a test sound with either a silent delay between or pure tone distractors
• patients with a prefrontal lesion were unable to complete the task with distractors

Question 12

What is the neural basis of working memory?

Answer 12

neurons in the PFC continue to fire and maintain information about a stimulus during a delay period

Question 13

What is the IPSC reversal potential and decay time of GABA A receptors?

Answer 13

• reversal potential = -70mV
• decays in ~50ms

Question 14

What is the IPSC reversal potential and decay time of GABA B receptors?

Answer 14

• reversal potential = -90mV
• decays in ~300ms

Question 15

When does AMPA receptor conductance increase?

Answer 15

when presynaptic excitatory neurons release glutamate

Question 16

When does GABA A receptor conductance increase?

Answer 16

when presynaptic inhibitory neurons release GABA

Question 17

What happens as AMPA receptor conductance increases?

Answer 17

the neuron membrane potential is pulled towards the AMPA reversal potential

Question 18

What happens as GABA A receptor conductance increases?

Answer 18

the neuron membrane potential is pulled towards the GABA reversal potential