11 - Learning, Memory, and Amnesia

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learning

neuroplastic process that deals with how experience changes the brain

memory

neuroplastic process that deals with how these changes are stored and subsequently reactivated

H.M.

the person who’s memory deficits were instrumental in the achievement of our current understanding of the neural bases of memory

lobectomy

an operation in which a lobe, or a major part of one, is removed from the brian

lobotomy

an operation in which a lobe, or a major part of one, is separated from the rest of the brain by a large cut but is not removed

digit span + 1 test

H.M.’s inability to form certain long-term memories was objectively illustrated by his performance on the_________ test, a classic test of verbal long-term memory. H.M. was asked to repeat 5 digits that were read to him at 1-second intervals. He repeated the sequence correctly. On the next trial, the same 5 digits were presented in the same sequence with 1 new digit added on the end. This same 6-digit sequence was presented a few times until he got it right, and then another digit was added to the end of it, and so on. After 25 trials, H.M. had not managed to repeat the 8-digit sequence. Most people can correctly repeat about 15 digits after 25 trials of the _________ test

global amnesia

amnesia for information presented in all sensory modalities

block-tapping memory-span test

H.M. had global amnesia, it was demonstrated that H.M.’s amnesia was not restricted to verbal material by assessing his performance on the + 1 version of the ____________ test. An array of 9 blocks was spread out on a board in front of H.M., and he was asked to watch the neuropsychologist touch a sequence of them and then to repeat the same sequence of touches. H.M. had a block-tapping span of 5 blocks, which is in the normal range; but he could not learn to correctly touch a sequence of 6 blocks, even when the same sequence was repeated 12 times.

mirror-drawing test

The first indication that H.M.’s anterograde amnesia did not involve all long-term memories from the results of a _______ test. H.M.’s task was to draw a line within the boundaries of a star-shaped target by watching his hand in a mirror. H.M. was asked to trace the star 10 times on each of 3 consecutive days, and the number of times he went outside the boundaries on each trial was recorded. As Figure 11.2 shows, H.M.’s performance improved over the 3 days, which indicates retention of the task. However, despite his improved performance, H.M. could not recall ever having completed the task before.

incomplete-pictures test

The discovery that H.M. was capable of forming long-term memories for mirror drawing suggested that sensorimotor tasks were the one exception to his inability to form long-term memories. However, this view was challenged by the demonstration that H.M. could also form new long-term memories for the ________ test—a nonsensorimor test of memory that employs five sets of fragmented drawings. Each set contains drawings of the same 20 objects, but the sets differ in their degree of completeness: Set 1 contains the most fragmented drawings, and set 5 contains the complete drawings. The subject is asked to identify the 20 objects from the most fragmented set (set  1); then, those objects that go unrecognized are presented in their set 2 versions, and so on, until all 20 items have been identified. Despite his improved performance, H.M. could not recall previously performing the task.

pavlovian conditioning

H.M. learned an eye-blink __________ task, albeit at a retarded rate. A tone was sounded just before a puff of air was administered to his eye; these trials were repeated until the tone alone elicited an eye blink. Two years later, H.M. retained this conditioned response almost perfectly, although he had no conscious recollection of the training.

memory consolidation

the translation of short-term memories into long-term memories

1. changed the way memory function distribution in the brain was viewed.

2. supported the theory that there are different modes of storage for short-term, long-term, and remote memory.

3. first to reveal that an amnesic patient might claim no recollection of a previous experience while demonstrating memory for it by improved performance.

the three major scientific contributions of H.M.’s case

explicit

H.M.’s case was the first to reveal that an amnesic patient might claim no recollection of a previous experience while demonstrating memory for it by improved performance (e.g., on the mirror-drawing and incomplete-pictures tests). This discovery led to the creation of two distinct categories of long-term memories: Conscious long-term memories became known as _______ memories (or declarative memories)

implicit

H.M.’s case was the first to reveal that an amnesic patient might claim no recollection of a previous experience while demonstrating memory for it by improved performance (e.g., on the mirror-drawing and incomplete-pictures tests). This discovery led to the creation of two distinct categories of long-term memories: Conscious long-term memories became known as explicit memories (or declarative memories), and long-term memories demonstrated by improved test performance without conscious awareness became known as _______ memories.

medial temporal lobe amnesia

Neuropsychological patients with a profile of mnemonic deficits similar to those of H.M., with preserved intellectual functioning, and with evidence of medial temporal lobe damage are said to suffer from

repetition priming tests

tests that assess implicit memory

semantic memories

explicit memories for general facts or information

episodic memories

explicit memories for particular life events

autobiographical memory

episodic memory is also called

global cerebral ischemia

Patients who have experienced _________— that is, have experienced an interruption of blood supply to their entire brains—often suffer from medial temporal lobe amnesia

transient global amnesia

defined by its sudden onset in the absence of any obvious cause in otherwise normal adults and is transient, typically lasting only 4 to 6 hours

korsakoff’s syndrome

a disorder of memory common in people who have consumed large amounts of alcohol; the disorder is largely attributable to the brain damage associated with the thiamine deficiency that often accompanies heavy alcohol consumption

alzheimer’s disease

________ is another major cause of amnesia. The first sign of ________ is often a mild deterioration of memory. However, the disorder is progressive: Eventually, dementia develops and becomes so severe that the patient is incapable of even simple activities (e.g., eating, speaking, recognizing a spouse, or bladder control). ________ is terminal.

acetylcholine

The level of _______ is greatly reduced in the brains of Alzheimer’s patients. This reduction results from the degeneration of the basal forebrain (a midline area located just above the hypothalamus), which is the brain’s main source of _______.

basal forebrain

The level of acetylcholine is greatly reduced in the brains of Alzheimer’s patients. This reduction results from the degeneration of the _______ (a midline area located just above the hypothalamus;), which is the brain’s main source of acetylcholine.

concussion

a temporary disturbance of consciousness produced by a nonpenetrating head injury

posttraumatic amnesia (PTA)

Blows to the head that do not penetrate the skull but are severe enough to produce concussion (a temporary disturbance of consciousness produced by a nonpenetrating head injury) are the most common causes of amnesia. Amnesia following a nonpenetrating blow to the head is called ________________.

coma

pathological state of unconsciousness

islands of memory

surviving memories for isolated events that occurred during periods for which other memories have been wiped out

standard consolidation theory/dual-trace theory

theory that suggests that memories are temporarily stored in the hippocampus until they can be transferred to a more stable cortical storage system

engram

a change in the brain that stores a memory

reconsolidated

each time a memory is retrieved from long term storage, it is temporarily held in labile (changeable or unstable) short-term memory, where it is once again susceptible to posttraumatic amnesia until it is ________.

monkey version delayed nonmatching-to-sample test

In this test, a monkey is presented with a distinctive object (the sample object), under which it finds food (e.g., a banana pellet). Then, after a delay, the monkey is presented with two test objects: the sample object and an unfamiliar object. The monkey must remember the sample object so that it can select the unfamiliar object to obtain food concealed beneath it

David Mumby; Mumby box

The version of the delayed nonmatching-to-sample test for rats that most closely resembles that for monkeys was developed by ______ using an apparatus that has become known as the _______

morris water maze test

intact rats placed at various locations in a circular pool of murky water rapidly learn to swim to a stationary platform hidden just below the surface. Rats with hippocampal lesions learn this task with great difficulty.

reference memory

memory for the general principles and skills that are required to perform a task

working memory

temporary memory that is necessary for the successful performance of a task on which one is currently working

radial arm maze test

in this test, several (e.g., eight) arms radiate out from a central starting chamber, and the same few arms are baited with food each day. Intact rats readily learn to visit the same arm more than once each day. The ability to visit only the baited arms of the radial arm maze is a measure of reference memory, and the ability to refrain from visiting an arm more than once in a given day is a measure of working memory. Rats with hippocampal lesions display major deficits on both the reference and working memory measures of this test

place cells

neurons that respond only when a subject is in specific locations (their place fields)

entorhinal cortex

area of the medial temporal cortex that is a major source of neural signals to the hippocampus

grid cells

_____ cells are entorhinal neurons that each have an extensive array of evenly spaced place fields, producing a pattern reminiscent of graph paper

jennifer aniston neurons

neurons that fire in response to images of jennifer aniston

concept cells

the most remarkable feature of Jennifer Aniston neurons is that they respond to ideas or concepts rather than to particulars, which is why they are also known as

inferotemporal cortex

plays an important role in storing memories of visual input

amygdala

plays a special role in memory for emotional significance of experiences, however, there is little evidence that it stores memories; it appears to be involved in strengthening emotionally significant memories stored in other structures. it might be the reason why emotion-provoking events are remembered better than neutral events

prefrontal cortex

patients with __________ damage often have difficulty performing tasks that involve a series of responses (i.e., A cook who before brain damage, had been an excellent cook; and afterward, she still remembered her favorite recipes and how to perform each individual cooking technique. However, she was incapable of preparing even simple meals because she could not carry out the various steps in proper sequence)

cerebellum

is thought to participate in the storage of memories of learned sensorimotor skills through its various neuroplastic mechanisms

striatum

is thought to store memories for consistent relationships between stimuli and responses—the type of memories that develop incrementally over many trials (habit formation)

long-term potentiation (LPT)

the effect where there is facilitation of synaptic transmission following high-frequency electrical stimulation applied to presynaptic neurons

long-term depression (LDP)

the flip side of LTP and occurs in response to prolonged low-frequency stimulation of presynaptic neurons

metaplasticity

refers to the fact that LTP and/or LTD induction can be modulated by prior synaptic activity

infantile amnesia

amnesia where we remember virtually nothing of the events of our infancy

nootropics or smart drugs

substances that are thought to improve memory