Learning and Memory Flashcards
(43 cards)
1
Q
which psychologists reported on patient HM?
A
Schoville and Milner (1957)
2
Q
what happened to HM?
A
HM suffered from epilepsy and had medial temporary lobe removed to control the seizures including the hippocampus
3
Q
what were the consequences of HM’s treatment for epilepsy? How did his brain change?
A
- Removal of hippocampus caused struggles to acquire new memories of events
- He couldn’t find his way around his new neighbourhood
- he had good memory of events that occurred before his surgery and good short-term memory but could not retain new information.
- He could remember things that happened before his operation
- He could repeat 7 number back to the experimenters as long as he kept repeating the numbers. If he was distracted, he would forget. The next day he would not remember the task or the experimenters
- HM could learn classical conditioning, motor learning and perceptual learning
- HM could not remember declarative memory but could remember nondeclarative memory
4
Q
types of memory deficits
A
anterograde and retrograde amnesia
5
Q
what is anterograde amnesia?
A
cannot remember events that occur after brain damage
6
Q
what is retrograde amnesia?
A
cannot remember events prior to brain damage
7
Q
what are the types of memory?
A
sensory memory
short-term memory
long-term memory
8
Q
what is sensory memory?
A
- A brief period of time that the initial sensation of environmental stimuli is initially remembered
- Length ranges from fractions of a second to a few seconds
- Occurs in each of the senses
9
Q
what is short-term memory?
A
- Contains information from sensory memory only if it is meaningful or salient enough
- Length ranges from seconds to minutes –> Rehearsal can increase the length
- Capacity is limited to a few items –> Chunking can increase the capacity
10
Q
what is long-term memory?
A
- Contains information from short-term memory that is consolidated
- Unlimited capacity and duration
- Strengthened with increased retrieval
11
Q
what are the different types of long-term memory?
A
nondeclarative memory and declarative memory
12
Q
what is nondeclarative memory?
A
Implicit memory
Includes memories that are not necessarily conscious of
Operates automatically and controls motor behaviours e.g. riding a bike
13
Q
what is declarative memory?
A
Explicit memory
Memory of events and facts we can think and talk about - not simply verbal, but like a video
Includes episodic, semantic and spatial memories
14
Q
what are the different types of declarative memory?
A
episodic and semantic and spatial
15
Q
what is episodic memory?
A
context
events and experiences
16
Q
what is semantic memory?
A
facts and concepts
17
Q
what is spatial memory?
A
memories in relation to other things in the environment
18
Q
what are some examples of declarative memory tasks?
A
remembering past experiences
remembering facts
remembering where things are in relation to other places in an environment
19
Q
what are some examples of nondeclarative memory tasks?
A
learning to recognise broken drawings
classical conditioning
operant conditioning
motor learning
20
Q
explain the three store model of memory
A
- Memory consists of 3 stores: sensory, short-term and long-term
- If unattended in sensory store, information is lost
- Information passes from sensory to STM via attention
- If unrehearsed in STM, information is lost
- Information stays in STM via maintenance rehearsal
- Information passes from STM to LTM via encoding
- Information in the LTM may be lost over time
- Information moves from LTM back to STM via retrieval
21
Q
how does the 3 store model of memory explain HM’s case?
A
- In HM’s case, one of the problems was the transfer from short-term to long-term memory
- Anterograde amnesia causes this failure to consolidate information
- HM could hold a limited number of items in the short-term memory store but could not exceed its capacity and if he stopped attending or rehearsing, then information was quickly forgotten
- However, his memory for events consolidated before the surgery was relatively unaffected
22
Q
explain HM’s mirror drawing task
A
- Investigated motor learning
- The outline of a shape is traced using visual cues from a mirror image
- He showed a capacity for learning certain kinds of new information including learning of certain motor skills and Pavlovian conditioning - Although he couldn’t remember doing the task, his performance improved with practise and the improvements were maintained from one day to the next
- This supports the distinction between explicit and implicit memory stores
23
Q
explain HM’s broken drawing task
A
- Investigated perceptual learning
- A set of 5 drawings shows an elephant and an umbrella
- The first 4 sets have discontinuous lines with set 1 being the most discontinuous and the 5th being the complete drawing
- Over time, HM was able to identify the elephant and umbrella from the early sets of drawings even with no memory of doing the task before
- Memories couldn’t stay in LTM but he still learned something
24
Q
explain HM’s eyelid conditioning
A
- Investigated classical conditioning
- UCS = airpuff
- UCR = eyeblink
- NS –> CS = audible tone
- UCS + NS –> CR
- CS –> CR
- CR = eyeblink
- HM was classical conditioned but wasn’t consciously aware of it
- Over time, this conditioning was stored in his LTM
- Shows he has the capacity for learning but not remembering
25
what apparatus was used in the eyelid conditioning experiment?
1960 apparatus - headgear holds a device to measure eyelid closure and a means to deliver an airpuff to the eye and used a piece of wire to measure closure
Modern apparatus is similar but computer controlled and eyelid closure can be measured non-invasively with an infrared monitor
26
explain how Hebb's law supports the idea of classical conditioning
- Hypothesis proposed by Donald Hebb that cellular basis of learning involves strengthening of synapse that is repeatedly active when postsynaptic neuron fires
- When puff of air is presented, a neuron in the somatosensory system fires a strong synapse which travels to a motor neurone which elicits a blink
- When the tone is presented, a neuron in the auditory system fires a weak synapse which doesn't cause a blink as it is too weak
- However, when the 1000Hz tone is presented just before the puff of air to the eye, the previously weak synapse is strengthened - it takes less to stimulate an action potential in the motor neuron which causes a blink
27
structure of the hippocampus
little seahorse (Lewis, 1923)
28
evidence supporting function of hippocampus - human studies
- Maguire, Frackowiak and Frith (1997) had taxi drivers talk about their routes and monitored hippocampal activity
- Maguire et al. (1998) showed activity in the right hippocampus in participants navigating around a virtual town
- Feigenbaum and Morris (2004) showed damage limited to the right hippocampus causes spatial impairment
- Luzzi et al. (2000) reported patient with damage to the right parahippocampal gyrus could only find his room by counting the doors from the end of the hall
29
further evidence supporting function of hippocampus - animal studies
Allocentric navigational task
- Barkas et al. (2012) reported both rats and epilepsy patients with scarring caused by seizures in the right hippocampus could not use spatial cues to locate objects
- Morris et al. (1982) used Water Mazes for humans and rats to support this
30
evidence that not all spatial ability is controlled by hippocampus
Egocentric navigational tasks
- McDonald & White (1995) found that entorhinal cortex controls egocentric guidance
- Barkas et al. (2010) found that epilepsy patients with lesions to the right hippocampus were impaired in allocentric but not egocentric navigational task
31
what is the difference between allocentric and egocentric navigational tasks?
allocentric tasks - released from different starting point on each trial
egocentric tasks - released from same starting point on each trial
rats with hippocampal damage had memory deficits on allocentric tasks not egocentric tasks during Morris' water maze experiment
32
what is the role of the hippocampus in the consolidation of declarative memories?
- Hippocampus receives information about what is going on from the sensory and motor association cortex and processes this information
- Through its efferent connections with these regions, it modified the memories that are being consolidated, linking them together so we can remember the relationships among the elements of the memories
- The hippocampus places episodic memories in the right order so they make sense
33
what is the role of the hippocampus in terms of spatial information?
The right side of the hippocampus tells you where you are in relation to the things around you
34
what is the role of the entorhinal cortex in terms of spatial information?
The entorhinal cortex tells you which direction to go
35
evidence of long term potentiation
- The sensitisation of the synapse so that it triggers to a small amount of action potential
- An electrical stimulating electrode delivers stimulation to neurons running from the entorhinal cortex which synapse on the dentate gyrus cells in the hippocampus
- If a low intensity probe stimulus is applied then a small response is recorded from the dentate gyrus cells
- However, if the probe stimulus, is preceded by a high frequency potentiating stimulus then the subsequent responses to the probe stimulus are potentiated
- This potentiation lasts a long time.
36
what is an action potential?
the brief electrical impulse that provides the basis for conduction of information along an axon
messages travel along a neuron via the action potential
37
what is the threshold of excitation?
the value of the membrane potential that must be reached to produce an action potential
must reach -60mv to be fired
38
procedure of long-term potentation
stimulate the axon going into the dentate gyrus repeatedly
this increases the sensitivity of the neurone to any action potentials that come in
meaning that the action potential is triggered more easily than before
39
what causes the neurone to become more sensitive?
glutamate
NMDA receptors
40
what is the role of glutamate in long-term potentiation?
- Long-term potentiation (LTP) is a series of synaptic changes
- LTP among glutamate synapses in the hippocampus help establish conditioned responses
- Synaptic changes in the glutamate system increase the excitatory post synaptic potential (EPSP) to the postsynaptic cell
- Makes the postsynaptic membrane more sensitive to the neurotransmitters coming in
41
what happens at the NDMA and AMPA receptors during long-term potentiation?
- Glutamate bonds with two types of receptors NDMA and AMPA receptors in the post-synaptic membrane
- When post synaptic membrane is at resting potential (-70mv) the NMDA receptors are blocked by magnesium
- Glutamate opens AMPA receptors which lets in sodium molecules
- The positive sodium molecules will depolarise the neuron which unblocks the NDMA receptors allowing calcium ions into the neuron as well
- The calcium ions activate enzymes in the spine which cause AMPA receptors to move into the spine
- An increased number of AMPA receptors in the postsynaptic membrane strengthens the synapse and makes it more sensitive
42
what is the NMDA receptor?
- A neurotransmitter-dependent and voltage-dependent ion channel
- Shaped like a wide cylinder
43
process of long-term potentiation
1. Along the dendritic spine are 2 NMDA receptors and 2 AMPA receptors
2. Molecules of glutamate bind tothe receptors.
3. When the conditions for long-term potentiation (LTP) are met, calcium ions enter the channel, and activate enzymes in the spine, and initiate LTP.
3. The activated enzymes cause AMPA receptors along the extension of the neck of the dendrite spine to move into the spine
4. An increased number of AMPA receptors in the postsynaptic membrane strengthens the synapse.
