Discuss the research evidence of where in the cortex memories are stored.

Question

What will be an ideal response?

Answer 1

Several lines of research have examined where in the brain long-term memories are stored once the information has been consolidated in the hippocampus. Such studies are as follows:
a. Bontempi et al. (1999) - used a mouse model showing that over the course of several days of retention testing of a spatial discrimination task, there was a progressive decrease in activity in the hippocampus and simultaneous progressive increase in activity in other cortical areas.
b. Remondes and Schuman (2004) - using a rat model, severed the communication pathway between the CA1 and cortex, which did not impair their memory of the task 24 hours later (short-term memory), but impaired their memory of the task 4 weeks later (long-term memory). One group of rats whose pathway was severed 3 weeks after training showed no deficits, showing that it takes around that time for consolidation and long-term storage to occur in the rat model.
c. Smith and Squire (2009) - using human participants, recorded brain activity via fMRI when participants recorded events from the past 30 years. Hippocampal activity was greatest for recollection of recent events, with declines in hippocampal activity for events occurring as far back as 12 years prior. Concurrently, activity progressively increased with older memories in areas such as the prefrontal, temporal, and parietal cortices.
d. Wheeler et al. (2000) - memories for sounds activate auditory areas of the brain, and memories for pictures activate the occipital lobe.
e. Martin et al. (1995) - naming colors activates temporal lobe areas; identifying pictures of tools activates the hand motor area and a part of the left temporal lobe.
f. Rosler et al. (1995) - spatial memories activate the parietal lobe area, and verbal memories activate the left frontal lobe.