DECLARATIVE MEMORY IN ANIMALS Research aims of animal models a. Neuropsychological aim

1. DECLARATIVE MEMORY IN ANIMALS • Research aims of animal models • a. Neuropsychological aim • Comparative aim • Neurobiological mechanisms • 2. Limitations and special challenges associated with the study of declarative memory in animals

2. 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?

8. 3. Cognitive processing in rodents • O’Keefe and Nadel’s (1978): • hippocampus mediates cognitive map • General findings • i. Rats with hippocampal system damage are severely impaired in many form of spatial exploration and learning.

9. 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

10. Spatial learning in rats (sample answer for an exam question) 1. water maze, developed by Morris (1981) a. Tank b. water c. platform d. extra maze cues 2. Demand of the task a. The animal swims around until it to find the platform to escape

12. Spatial learning in rats (continued) Variable-start-location a. 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-location H damage did not prevent rats from learning

14. Spatial learning in rats (continued) Interpretation a. Variable-start-location i. 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

15. Spatial learning in rats (continued) Interpretation b. Constant-start-location i. Lack of the demand for flexibility and relationality in the standard test ii. Emphasis on the representation of spatial relations among the distal cues is eliminated iii. learning a rigid approach trajectory guided toward a particular cue or cue complex iv. Procedural memory systems

16. 4 Visual recognition memory in nonhuman primates (DNMS) 1. The set of behavioural tests a. 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

19. 2. Monkeys with experimental lesions of the entire medial temporal area i. intact STM but impaired LTM ii. Retrograde amnesia iii. intact capacities for skill acquisition task

20. 3. Structures of the medial temporal lobe critical to supporting memory i. amygdala is not important ii. 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.

21. Monkey visual recognition task (DNMS) The representational flexibility and promiscuityare necessary to permit comparisons to be performed between stored representations of the sample phase cues and items actually present in the match phase displays and to support the expression of the stored memory in a test situation that is not a repetition of the original acquisition event. A description that operationalize fundamental properties of declarative memory

22. 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.

23. 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 the particular processing structures or procedures engaged by the learning tasks” compare and contrast vs. facilitation of particular routines support inferential use of memories in novel situations vs. rerunning more smoothly the same processes