Retaining Information in the Brain Explicit memories are language-based facts and experiences that can be brought to conscious awareness. The network: left and right frontal lobes <--> hippocampus. Fig. 24.1 With left-hippocampus damage, people have trouble remembering verbal information, but they have no trouble recalling visual designs and locations. With right-hippocampus damage, the reverse is true. (Schacter, 1996). Memories are not permanently stored in the hippocampus. If a rat's hippocampus is removed 3 hours after it learns the location of food, long-term storage is disrupted; 48 hours later does not .(Tse et al. 2007). During deep sleep, the hippocampus processes memories for later retrieval. Frontal cortex and hippocampus appear to be having a dialogue during sleep. (Euston et. al. 2007). Cortex areas surrounding the hippocampus support the processing and storing of explicit memories.

Retaining Information in the Brain Fig. 24.2 Implicit memories, created by classical conditioning, are laid down in the cerebellum. The movie 'Memento' borrows the LeDoux (1996) experiment. With a damaged cerebellum, the conditioned reflexes of classical conditioning cannot occur. (Daum & Schugens, 1996). The basal ganglia are deep brain structures involved in motor movement, facilitating formation of procedural memories for skills. The basal ganglia receive input from the cortex but do not return signals for conscious awareness of procedural learning. We all experience infantile amnesia primarily because the hippocampus is one of the last brain structures to mature. This leads evolutionary psychologists to theorize that explicit (language-based) memories are relatively new. (Bauer et. al. 2007).

Retaining Information in the Brain Fig. 24.3: Memorize for the next exam. Stress hormones provoke the amygdala (two limbic system, emotion-processing clusters) to intitiate a memory trace in the frontal lobes and basal ganglia and to boost activity in the brain's memory-forming areas. (Buchanan, 2007). Emotional arousal can sear certain events into the brain, while disruptuing memory for neutral events around the same time. (Birnbaum et al. 2004). Emotions can persist without our conscious memory of what caused them. (Feinstein et al., 2010). Memory serves to predict the future and to alert us to potential dangers. Weaker emotions mean weaker memories. (Cahill, 1994). Flashbulb memories are noteworthy for their vividness and the confidence with which we can recall them. They are, however, susceptible to the misinformation effect.

Retaining Information in the Brain Fig. 24.4 Long Term Potentiation is the Holy Grail of Neuroscience. It is an increased efficiency of potential neural firing. Drugs that block LTP interfere with learning. (Lynch & Staubli, 1991) Mutant mice engineered to lack an enzyme needed for LTP can learn a maze. (Silva et al., 1992) Rats given a drug that enhances LTP with learn a maze in half the time. (Service, 1994). Injecting rats with a chemical the blocks the preservation of LTP erases recent learning. (Pastalkova et al., 2006). LTP can be disrupted by electroconvulsive therapy. LTP can be disrupted by head trauma. (Yarnell & Lynch, 1970). LTP can be enhanced by glutamate, or CREB. (Fields, 2005)

Retaining Information in the Brain Boosting CREB production might trigger increased production of other proteins that help reshape synapses and transfer short- term memories into long-term memories. Sea slugs (Aplysia), mice and fruit flies with enhanced CREB production have displayed enhanced learning. Blocking CREB-producing amygdala neurons can permanently erase an intrusive auditory fear memory. (Han et al., 2009). Propranolol can remove the traumatic memories that lead to a stress disorder. (Pitman et al., 2005). You will be using this section of the Myers text for your long essay work on the movie 'Memento'. Memorize Fig. 24.5 for the next exam.