Chapter 14: Learning and Memory

Question 1

How do we learn and remember?

Answer 1

connecting learning and memory

dissociating memory circuits

neural systems underlying explicit and implicit memories

structural basis of brain plasticity

recovery from brain injury

Question 2

What are types of experiences that change the brain?

Answer 2

development, culture, preferences, coping

learning is common to these experiences

Question 3

What is neuroplasticity?

Answer 3

the nervous system’s potential for physical or chemical change, which enhances its adaptability

Question 4

What is learning?

Answer 4

a relatively permanent change in an organism’s behavior as a result of experience

Question 5

What is memory?

Answer 5

the ability to recall or recognize previous experience

a mental representation of a previous experience

corresponds to a physical trace (engram) in the brain, most likely involving synapses

Question 6

What is Pavlovian conditioning?

Answer 6

learning achieved when a neutral stimulus (such as a tone) comes to elicit a response after its repeated pairing with some event (such as delivery of food)

also called classical conditioning or respondent conditioning

Question 7

What is an conditioned stimulus (CS)?

Answer 7

in Pavlovian conditioning, an originally neutral stimulus that triggers a conditioned response (CR) after association with an unconditioned stimulus

Question 8

What is an unconditioned stimulus (UCS)?

Answer 8

a stimulus that naturally and automatically (unconditionally) triggers an unconditioned response (UCR)

Question 9

What is an unconditioned response (UCR)?

Answer 9

unlearned, naturally occurring response to an unconditioned stimulus (UCS), such as salivation when food is in the mouth

Question 10

What is a conditioned response (CR)?

Answer 10

in Pavlovian conditioning, the learned response to a formerly neutral conditioned stimulus

Question 11

What is the eyeblink conditioning experiment?

Answer 11

a tone (CS) is associated with a painless puff of air (UCS) to a participant’s eye

blinking is a normal reaction (UCR) to a puff of air

learning has occurred when blinking is a response to the CS alone (CR)

Question 12

What is operant conditioning?

Answer 12

learning procedure in which the consequences (such as obtaining a reward) of a particular behavior (such as pressing a bar) increase or decrease the probability of the behavior occurring again

also called instrumental conditioning

Question 13

What was Thorndike’s puzzle box?

Answer 13

a cat gradually learned that its actions had consequences

on the initial trial, the cat touched the releasing mechanism only by chance as it restlessly paced inside the box

the cat learned that something it had done opened the door, and it tended to repeat its behaviors from just before the door opened

Question 14

What is implicit memory?

Answer 14

unconscious memory

subjects demonstrate knowledge, such as a skill, conditioned response, or recalling events on prompting, but cannot explicitly retrieve the information

Question 15

What is explicit memory?

Answer 15

conscious memory

subjects can retrieve an item and indicate that they know the retrieved item is the correct one

Question 16

What is the pursuit-rotor task?

Answer 16

people with amnesia, a partial or total loss of memory, perform at normal on tests on implicit memory

presented with the same task a week later, both controls and amnesiacs take less time to perform it

amnesiacs fail to recall having performed the task before

Question 17

What is declarative memory?

Answer 17

ability to recount what one knows, to detail the time, place, and circumstances of events; often lost in amnesia

same thing as explicit memory

Question 18

What is procedural memory?

Answer 18

ability to recall a movement sequence or how to perform some act or behavior

same thing as implicit memory

Question 19

How is implicit information processed?

Answer 19

implicit information is processed in a bottom-up, or data-driven, manner

information is encoded in the same way it was perceived

Question 20

How is explicit information processed?

Answer 20

explicit information is processed in a top-down, or conceptually driven, manner

the subject recognizes the information before it is encoded

Question 21

How are implicit and explicit tasks encoded in memory?

Answer 21

in implicit tasks, the person has a passive role, whereas in explicit tasks, the person has an active role

Question 22

What is priming?

Answer 22

using a stimulus to sensitize the nervous system to a later presentation of the same or a similar stimulus, often used to measure implicit memory

Question 23

What is short term memory?

Answer 23

few minutes

information is held in memory only briefly, then discarded; involves the frontal lobes

Question 24

What is long term memory?

Answer 24

indefinite duration

information is held in memory indefinitely, perhaps for a lifetime; involves the temporal lobe

Question 25

How is memory stored?

Answer 25

information from different sensory modalities (e.g. vision, audition) is processed and stored in different neural areas

Question 26

What is episodic memory?

Answer 26

autobiographical memory for events pegged to specific place and time contexts

Question 27

What is episodic amnesia?

Answer 27

inability to recall any personal experience associated with frontal lobe injury or reduced blood flow to the frontal lobes frontal loves may allow us to mentally travel through our past

Question 28

What is highly superior autobiographical memory (HSAM)?

Answer 28

people display virtually complete recall for events in their lives, usually beginning around age 10 many can describe any episode, including the day of the week and the date increased gray matter in the temporal and parietal lobes increased size in the fiber projection between the temporal and frontal lobes still vulnerable to distortions

Question 29

What did Karl Lashley study regarding memory circuits?

Answer 29

searched in vain for the neural circuits underlying memories severity of memory disturbance related to size, not location, of injury

Question 30

What was discovered through the bilateral medial temporal lobe resection of H.M.?

Answer 30

seizures originated in the region of the amygdala, hippocampal formation, and associated subcortical structures, so Scoville removed them bilaterally following surgery, H.M. had severe amnesia, lacking any explicit memory he could not recall anything that happened after the surgery despite this deficit, H.M. had an above-average IQ, performed well on perceptual tests, and could recall events from his childhood H.M.'s performance on implicit memory tests was left intact

Question 31

What is the parahippocampal cortex?

Answer 31

receives connections from the parietal cortex believed to take part in visuospatial processing

Question 32

What is the perirhinal cortex?

Answer 32

receives connections from the visual regions of the ventral stream believed to take part in visual object memory

Question 33

What is the entorhinal cortex?

Answer 33

located on the medial temporal lobe surface provides a major route for neocortical input to the hippocampal formation often degenerates in Alzheimer disease

Question 34

What is visuospatial memory?

Answer 34

using visual information to identify an object's location in space laboratory animals and human patients with selective hippocampal injury have severe deficits in various forms of spatial memory monkeys with hippocampal lesions have difficulty learning the location of objects

Question 35

What does the hippocampus and spatial memory look like in animals?

Answer 35

animals with especially good spatial memory should have bigger hippocampi than do species with poorer spatial memories the hippocampal formation in food-storing birds and rodents is larger than that of birds and rodents that do not store food

Question 36

What are the three classes of spatial cells in the rat and mouse hippocampus?

Answer 36

place cells head direction cells grid cells

Question 37

What are place cells in the rat and mouse hippocampus?

Answer 37

discharge when rats are in a spatial location regardless of orientation (hippocampus)

Question 38

What are head direction cells in the rat and mouse hippocampus?

Answer 38

cells discharge whenever a rat's head points in a particular direction

Question 39

What are grid cells in the rat and mouse hippocampus?

Answer 39

discharge at many locations, forming a virtual grid invariant to changes in the rat's direction, movement, or speed (entorhinal cortex)

Question 40

How are connections for explicit memory in the temporal lobe pathway reciprocal?

Answer 40

connections from the neocortex run to the entorhinal cortex and then back to the neocortex signals from the medial temporal regions to the cortical sensory regions keep the sensory experience alive in the brain, the neural record outlasts the actual experience pathway back to the neocortex means it is kept apprised of the information being processed in medial temporal regions

Question 41

What is the relationship between the frontal lobe and short term memory?

Answer 41

the frontal love appears to participate in many forms of short-term memory all sensory systems project to the frontal lobes during tasks in which monkeys must keep information in short-term memory over a delay, certain cells in the frontal cortex will fire throughout the delay (animals that have not learned the task show no such cell activity)

Question 42

What is Korsakoff syndrome?

Answer 42

permanent loss of the ability to learn new information (anterograde amnesia) and to retrieve old information (retrograde amnesia) caused by diencephalic damage from chronic alcoholism or malnutrition that produces a vitamin B1 deficiency 80% of these patients show loss of frontal lobe cells

Question 43

What is the explicit memory circuit?

Answer 43

sensory/motor AREAS --> temporal regions --> medial thalamus & prefrontal cortex temporal lobe/pfc are central to LTM formation PFC central for ST explicit memories and recency of events

Question 44

How does the hippocampus consolidate memory?

Answer 44

in consolidation, or stabilizing a memory trace after learning, memories move from the hippocampus to diffuse regions in the neocortex once memories move, hippocampal involvement is no longer needed

Question 45

What is distributed reinstatement theory?

Answer 45

a learning episode rapidly produces a stored memory representation that is strong in the hippocampus but weak elsewhere the memory is replayed on the time scale of hours or days after learning, leading to enhanced representation outside the hippocampus

Question 46

What is reconsolidation?

Answer 46

restabilizing a memory trace after the memory is revisited whenever a memory is replayed in the mind, it is open to further consolidation new information is constantly being integrated into existing memory networks it is possible to erase negative memories by using amnesic agents when the memory is revisited (e.g. in PTSD)

Question 47

What is the proposed neural circuit for explicit memory?

Answer 47

1. temporal lobe structures 2. frontal lobe structures 3. medial thalamus 4. basal forebrain - activating systems

Question 48

What is the proposed neural circuit for implicit memory?

Answer 48

basal ganglia ventral thalamus substantia nigra premotor cortex

Question 49

What does the basal ganglia do in the neural circuit for implicit memories?

Answer 49

basal ganglia receive input from the entire neocortex and send projections first to the ventral thalamus and then to the premotor cortex basal ganglia also receive widely and densely distributed projection from dopamine-producing cells in the substantia nigra dopamine appears necessary for basal ganglia circuits to function and may indirectly participate in implicit memory formation

Question 50

What is the unconscious nature of implicit memory?

Answer 50

Mishkin believes that implicit memories are unconscious because the connections between the basal ganglia and cortex are unidirectional basal ganglia receive information from the cortex but do not project back to the cortex for memories to be conscious, there must be feedback to the cortex the medial temporal lobe projects back to the cortex, so explicit memories are conscious

Question 51

What is emotional memory?

Answer 51

memory for the affective properties of stimuli or events can be implicit or explicit amygdala is critical for emotional memory damage to the amygdala abolishes emotional memory but has little effect on implicit or explicit memory we tend to remember emotionally arousing experiences vividly emotionally driven neurochemical and hormonal activating systems (probably cholinergic and noradrenergic) stimulate the amygdala

Question 52

What does the amygdala do in the neural circuit for implicit memories?

Answer 52

the amygdala has close connections with medial temporal cortical structures as well as with the rest of the cortex

Question 53

Where does the amygdala send projections to in the neural circuit for implicit memory?

Answer 53

brainstem structures that control autonomic responses such as blood pressure and heart rate the hypothalamus, which control hormonal system periaqueductal gray matter (PAG), which affects pain perception the basal ganglia, to tap into the implicit memory system

Question 54

What is the structural basis of memory?

Answer 54

at the neural level, memory is associated with changes that take place at the synapse the synapse is where one neuron influences another neuron

Question 55

How do we find the neural correlated of memory?

Answer 55

determine how synaptic changes are correlated with memory in the mammalian brain localize the synaptic changes to specific neural pathways analyze the nature of the synaptic changes themselves

Question 56

What is associative learning?

Answer 56

linkage of two or more unrelated stimuli to elicit a behavioral response neurons that fire together, wire together

Question 57

What is long-term potentiation (LTP)?

Answer 57

in response to stimulation at a synapse, changed amplitude of an excitatory postsynaptic potential that lasts for hours to days or longer plays a part in associative learning a strong burst of electrical stimulation applied to the presynaptic neuron produces an increase in the amplitude of the EPSP in the postsynaptic neuron

Question 58

What is field potential?

Answer 58

EPSPs from many neurons; recorded with extracellular electrodes

Question 59

What must happen for an EPSP to increase in size?

Answer 59

more neurotransmitter must be released from the presynaptic membrane postsynaptic membrane must become more sensitive to the same amount of transmitter

Question 60

What is long-term depression (LTD)?

Answer 60

decrease in EPSP size if LTP is a mechanism for forming memories, perhaps LTD is a mechanism for clearing out old memories

Question 61

What are the two types of receptors that glutamate acts on in the postsynaptic membrane?

Answer 61

AMPA (alpha-amino-3-hydroxy-5-methylisoxazole-4-proprionic acid) normally responds to glutamate NMDA (N-methyl-D-aspartate) doubly gated channels, normally blocked by magnesium (Mg2+) ions

Question 62

What two events must occur together for NMDA receptors to open?

Answer 62

depolarization of postsynaptic membrane, which displaces Mg2+ from pore (strong electrical stimulus) activation by glutamate from the presynaptic neuron (weak electrical stimulus) strong and weak stimuli have been paired

Question 63

What happens after NMDA receptors open and Ca2+ enters the postsynaptic neuron?

Answer 63

increased responsiveness of AMPA receptors to glutamate formation of new AMPA receptors retrograde messengers that trigger more glutamate release from presynaptic neuron

Question 64

What neural processes underlie the persistent long-term changes of learning?

Answer 64

Ca2+ enters postsynaptic neuron and activates a second messenger (e.g. cyclic AMP) cAMP alters gene expression in nucleus, which physically alters synapse, structural changes in the synapse (dendritic spines), formation or loss of synapses

Question 65

How does the brain modify existing circuits?

Answer 65

neurons change their structure in response to their changing experiences changes in the number of dendrites can be used to infer synaptic changes, more dendrites provide more connections new synapses can form between neurons that are already connected or between neurons that were not previously connected

Question 66

What is the evidence of the brain creating novel circuits?

Answer 66

predominant view prior to the mid-1990s, the mammalian brain does not make new neurons in adulthood there is evidence that neurogenesis does occur in the mammalian brain: olfactory bulb, hippocampal formation, and possibly neocortex reason for neurogenesis still unclear

Question 67

What is raising rats in enriched enclosures associated with?

Answer 67

increased brain weight more dendrites more astrocytes more blood capillaries more synapses per neuron increased mitochondrial volume (marker of greater metabolic activity)

Question 68

How did Chang and Greenough (1982) manipulate experience experimentally?

Answer 68

placed patches over one eye of each rat so that the contralateral hemisphere was deprived of visual input trained rats on a maze the visual cortex of the trained hemisphere (the one that received input from the eye without the patch) had more extensive dendrites

Question 69

How did Nudo and colleagues (1997) manipulate experience experimentally?

Answer 69

had monkeys retrieve food from small or large food wells small wells required dexterous movements of one or two fingers, whereas the monkeys could put their entire hand in the large wells the digit representation on the motor cortex was larger for animals that had to retrieve food from the smaller wells

Question 70

What is an example of life experiences altering dendritic morphology?

Answer 70

career word processors have greater differences between finger and trunk neurons than do salesperson

Question 71

What is the epigenetic of memory?

Answer 71

specific sites in the DNA of neurons involved in specific memories might exist in either a methylated or nonmethylated state fear conditioning is associated with rapid methylation, but if methylation was blocked, there was no memory epigenetic mechanisms mediate synaptic plasticity broadly, especially in learning and memory

Question 72

What is the relationship between hormones and plasticity?

Answer 72

high levels of estrogen: more dendritic spines in the hippocampus low levels of estrogen: more dendritic spines in neocortex but fewer in hippocampus low levels of testosterone: more dendritic spines in neocortex

Question 73

What are glucocorticoids?

Answer 73

released from the adrenal cortex in times of stress steady levels of glucocorticoids that are seen with prolonged stress may be neurotoxic glucocorticoids can kill hippocampal cells

Question 74

What is nerve growth factor?

Answer 74

neurotrophic factor that stimulates neurons to grow dendrites and synapses and in some cases promotes the survival of neurons

Question 75

What is the brain-derived neurotrophic factor (BDNF)?

Answer 75

may enhance plastic changes, such as the growth of dendrites and synapses increased levels when animals learn to solve problems

Question 76

What is behavioral sensitization?

Answer 76

escalating behavioral response to the repeated administration of a psychomotor stimulant sensitization is associated with an increased number of receptors, synapses, and dendrites drug exposure alters brain response to experience

Question 77

What are the guiding principles of brain plasticity?

Answer 77

behavioral change reflects brain change all nervous systems are plastic in the same general way plastic changes are age specific prenatal events can influence brain plasticity throughout life plastic changes are brain-region dependent experience-dependent changes interact (metaplasticity) plasticity has pros and cons

Question 78

What are the three possible ways to recover from brain injury?

Answer 78

learn new ways to solve problems recognize the brain to do more with less generate new neurons to produce new circuits

Question 79

What is the three-legged cat solution to brain injury?

Answer 79

when a cat loses a leg, it usually can compensate, not by growing a new leg but rather by learning how to walk with only three legs the same ability to compensate is also present in humans a person who loses a certain ability, such as being able to write with the right hand, may be able to compensate by learning to write with the left hand

Question 80

What is the new-circuit solution to brain injury?

Answer 80

in response to injury, the brain can form new connections and do more with less the amount of recovery is increased significantly if the person also engages in some form of intervention behavioral therapy: speech or physiotherapy pharmacological therapy: nerve growth factor, amphetamine