DECLARATIVE MEMORY IN ANIMALS

1.Research aims of animal modelsa. Neuropsychological aimb. Comparative aimc. Neurobiological mechanisms

2. Limitations and special challenges associated with the study of declarative memory in animals

QUESTIONS for Multiple memory system in Animals:

• a. What is an animal model of amnesia? Why are such models valuable?

• b. What characteristics of amnesia are well modeled using animals?

• c. What advances led to breakthroughs in these model?

3. Cognitive processing in rodents

a.O’Keefe and Nadel’s (1978): a.hippocampus mediates cognitive map

b.General findingsi. Rats with hippocampal system damage

are severely impaired in many form of spatial exploration and learning.

ii. Place learning: Morris water-maze task(1) rats are trained to find a hidden escape platform submerged just below the surface in a pool of cloudy water (2) Hippocampal system damage impair the ability to lean the location of the escape platform

Spatial learning in rats (sample answer for an exam question)

1. water maze, developed by Morris (1981)

a. Tankb. waterc. platformd. extra maze cues

2. Demand of the taska. The animal swims around until it to find the platform to escape

Spatial learning in rats (continued)Variable-start-locationa. normal rats

Over trials, able to locate the platform increasingly rapidly, and eventually swim directly to the platform, produce very short latency.b. Hippocampal system damage

i. Impaired ability to learn, not able to swim directly to the platform, maintain long escape latency

Constant-start-locationH damage did not prevent rats from learning

Spatial learning in rats (continued)Interpretationa. Variable-start-locationi. The need of animals to build a representation of the position of the platform in relation to the various visual cues arrayed in the room, independent of particular swimming routes,ii. and to flexibly express this stored information regardless the start location.iii. The characteristics of the hippocampal-dependent declarative memory system: representational flexibility and relationality

Spatial learning in rats (continued)Interpretation b. Constant-start-locationi. Lack of the demand for flexibility and relationality in the standard testii. Emphasis on the representation of spatial relations among the distal cues is eliminatediii. learning a rigid approach trajectory guided toward a particular cue or cue complexiv. Procedural memory systems

4 Visual recognition memory in nonhuman primates (DNMS)

1. The set of behavioural testsa. delayed non-match-sample task

i. Ss are exposed to an object once and then,

ii. after a delay,iii. asked to recognize the object by

indicating the unfamiliar one in a two choice presentation

2. Monkeys with experimental lesions of the entire medial temporal area

i. intact STM but impaired LTMii. Retrograde amnesiaiii. intact capacities for skill acquisition

task

3. Structures of the medial temporal lobe critical to supporting memory

i. amygdala is not importantii. damage limited to the hippocampus

has only modest effect in monkeys (but bigger effect in humans)

iii. damage to the perirhinal and parahippocampal region can produce the full pattern of the amnesic deficit.

Monkey visual recognition task (DNMS)The representational flexibility and promiscuity are necessary to permit comparisons to be performed between stored representations of the sample phase cues and items actually present in the match phase displays andto support the expression of the stored memory in a test situation that is not a repetition of theoriginal acquisition event.

A description that operationalize fundamental properties of declarative memory

Cohen, 1984“a declarative code permits the ability to compare and contrast information from different processes or processing systems; and it enable the ability to make inferences from and generalizations across facts derived from multiple processing sources.

Procedural leaning was characterized as the acquisition of specific skills, adaptations, and biases and that such procedure knowledge is tied to and expressible only through activation of theparticular processing structures or procedures engaged by the learning tasks”compare and contrast vs. facilitation of particular routinessupport inferential use of memories in novel situations vs. rerunning more smoothly the same processes