page_title: Methods used to study memory
section_title: Primates
hierarchical_section_title: Methods used to study memory / Animal subjects / Experimental designs / Primates
caption_attribution_description: Stumptail Monkeys. Stumptail monkeys (Macaca arctoides) are among the most conciliatory members of the genus Macaca. They are heavily built, yet remarkably friendly and tolerant, such as here: the alpha male is eating attractive food unperturbed by an entire audience around him. When stumptail monkeys were housed with a less tolerant macaque, they modified the latter species' behavior into a more pacific direction.
context_page_description: The study of memory incorporates research methodologies from neuropsychology, human development and animal testing using a wide range of species. The complex phenomenon of memory is explored by combining evidence from many areas of research. New technologies, experimental methods and animal experimentation have led to an increased understanding of the workings of memory.
context_section_description: The textbook Fundamentals of Human Neuropsychology by Kolb and Whishaw describes some designs used to study memory in the macaque monkey. Elizabeth Murray and her colleagues trained monkeys to reach through the bars of their cage after a brief delay in order to displace objects under which a reward may be located. During the brief delay the monkey had to use either object recognition memory, or contextual memory to remember where the reward was located. Object recognition is tested with a matching-to-sample task where the monkey had to remember visual characteristics of the object in order to obtain the reward. Alternatively, in the non-matching-to-sample design the monkey must remember the location of the previously seen object. The monkey must then use context and spatial memory in order to correctly displace an object in the same location as previous, in order to obtain the food reward. These two tasks can be used to differentiate between object recognition memory and contextual memory. Murray and her colleagues were able to show that hippocampal lesions impaired contextual memory whereas rhinal cortex lesions impaired object recognition memory. This experimental design allowed for the dissociation of two mutually exclusive brain regions devoted to specific types of memory.
  In experiments with the macaque monkey, Earl Miller and his colleagues used the delayed matching to sample (DMS) task to assess working memory in monkeys. The monkey was required to fixate on a computer screen while coloured images were displayed serially for 0.5 seconds, and separated by a one-second delay. The first image shown was the sample, and the monkey was trained to pull a lever when the sample object was shown a second time. In this experiment single-cell recordings were taken from the prefrontal cortex, an area thought to be involved with working memory. In order to verify the location of the recording device, MRI and stereotaxic instruments were used. The ability to use single cell recordings solely for experimental purposes is exclusive to animal testing and has greatly increased our understanding of memory systems.
caption: Macaques of the primate genus.
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