Retaining Information in the Brain

1. 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.

2. 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).

3. 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.

4. 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)

5. 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.