Mind, Brain & Behavior Friday March 14, 2003

What to Study for the Final Exam  Chapters 26 & 28 – Motor Activity Know what kind of info the two main pathways carry, but not the names of the specific tracts. Class lecture is explained in detail in Chap 29.  Chapter 31 – Sex and the Brain Summary of sex differences and what they mean for cognition, discussed in class.  Chapter 32 – Emotion Know the differences in the two parts of the ANS

What to Study (Cont.)  Chapter 33 – Motivation Also know how the hypothalamus and pituitary control the endocrine system, from class.  Chapter 34 – Language  Chapter 35 – Learning and Memory Chapter 36 is optional Additional discussion of memory development, N.A. and Korsakoff’s syndrome, from class.

Where is Memory?  Both cortical and subcortical structures are involved in creating memories.  Although memories appear to be stored in the cortex, they are: Distributed – spread out in a network Redundant – represented in multiple ways  Hebbian cell assemblies (loops) permit access at various points in a network.

What is Memory?  Memory is a change in the synapses of the neurons comprising a network.  Memories are not static “records” but products of a change in the connections among nerve cells.  Memories extract and store the meanings of events, not their exact details. Sensory aspects are reexperienced not recalled. Recall is reconstructed, not just retrieved.

Stages of Memory  Sensory buffers – lasts seconds, one for each sense: Iconic – for visual information Echoic – for auditory information  Working memory/short term memory (STM): Lasts seconds to minutes Limited capacity – 7 plus or minus 2 Capacity can be expanded by chunking Executive functions  Long term memory (LTM) – permanent.

Amnesia  H.M.’s surgery removed parts of the temporal lobe, including hippocampus.  Severe anterograde amnesia – inability to form new memories of events in one’s life. Retrograde amnesia – loss of memory for the past.  With amnesia, some kinds of memory are spared, others impaired, suggesting there are different kinds of memory.

Explicit vs Implicit  Implicit memory – does not involve conscious awareness: Procedural memory (skills, how to do things) Priming, recognition tasks Classical & operant conditioning, habituation & sensitization Semantic memory (meanings of words, facts)  Explicit memory – involves conscious attention: Episodic and autobiographical memory, recall Sensory experiences

Working Memory  In humans, localized to frontal lobes.  Delayed development of frontal lobes in humans and monkeys: “A not B” task Can’t tolerate delays (8-10 sec) until 1-1/2 yrs old

Long Term Memory  Localized to temporal lobes: Hippocampus – memory formation and consolidation Entorhinal cortex (adjacent to hippocampus)  During memory storage the temporal region forms a connection between the relevant networked areas of the brain.

Infantile Amnesia  Inability to remember events of one’s childhood before ages year olds couldn’t remember preschool classmates Attributed to immaturity of memory systems in children.

Conditioning  A form of learning: Classical (Pavlovian) conditioning. Operant (instrumental) conditioning.  How are learned associations maintained? Amygdala (and emotional arousal) mediates activity of the hippocampus to form neural connections.

Types of Amnesia  Damage to Temporal Lobe – H.M.  Damage to Thalamic Structures – N.A. Most impaired with verbal material.  Korsakoff’s Syndrome Chronic alcoholics with thiamine deficiency Retrograde and anterograde amnesia.  Electroconvulsive Shock Therapy (ECT)

Amnesia and Forgetting  Forget at normal rate -- thalamic: N.A. Korsakoff’s patients Monkeys with medial thalamic lesions  Forget rapidly – hippocampus: H.M. Bilateral ECT Monkeys with amygdala/hippocampus lesions

Semantic Memory  Unimpaired by anterograde amnesia. Children with amnesia develop normal semantic memory. Intact entorhinal cortex may be used to store semantic memories despite hippocampal damage.  Context-rich, episodic memory impaired.

Cellular Mechanisms  Habituation involved suppression of action potentials through decreased release of neurotransmitter – change is at the synapse. Sensitization – increased neurotransmitter release  Explicit memory involves long-term potentiation, LTP (a physical changes to neurons) in hippocampus.  All mental processes result in changes to the brain, and vice versa. Social processes are also biological.