HD 2140 Prelim2

HD 2140 Prelim2 - Week 7: memory 1 Memory: A man sets...

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Week 7: memory 1 Memory: A man set’s himself the task of portraying the world…shortly before death he discovers this patient labyrinth of lines is a drawing of is own face – Borges I. What is memory? And what is it for? a. Classical view: memory is for STORING information=functional metaphor b. Better idea: memory is for INTERACTING with the world - possibility of progress depends on finding patterns in data II. What is memory for? a. VALUE: Simple memories of interaction with entire stimuli (Items/”objects”) only kinds of stimuli that have intrinsic value are those that directly cause pain (for example, a tactile encounter with a sharp object, ex: leopards teeth b. NAVIGATION: memories of interaction with structured environments (episodes/”events”) c. CONCEPTS: memories of interaction with structured situations d. EPISODIC/NARRIATIVE SELF: Autobiographical memories e. THEORY OF MIND: memories of interaction with other agents III. Simple memory: data to be stored is treated as a whole, and no attempt to analyze it (does not mean that data cannot be analyze, just that function of simple memory does not extend beyond holistic storage and retrieval) a. Simple memory is found in all animals – and any device that has computations b. Is for snapshots (arrays of pixels) i. Create and store records of the pixel array ii. Mark each record for value (“to be retained/deleted” etc) iii. c. A single- pixel memory cell made of two “formal neurons” i. A signal arriving on the START line stores one bit of info in the storage neuron (lower left) by turning it ON ii. The neuron subsequently remains ON due to the FEEDBACK connection, until a STOP signal is received. iii. The state of the memory cell (ON or OFF) is queried by sending a signal down the INPUT line to the “readout” neuron: 1. If the OUTPUT is ON, the state is ON; 2. If the OUTPUT IS OFF, the state is OFF. 3. Reminder: the number inside the “neuron” signifies the threshold. The small circle on an input line denotes inhibition (the unmarked input are excitatory) view 3.2-7 Gating network with memory d. Multiple realizability of memory (mouse trap and pliers= two different implementations of the same computational functionality) e. A 1-bit memory cell (see slide for examples on this or figure 6.3) i. Two kinds of memory in Aplysia – has just one modifiable synapse. Can then be viewed as a simple memory with a 1-bit capacity. 1. Jaw control system of Aplysia californica is controlled by neural circuit with two stable states 2. The gill withdrawal system in Aplysia (Lec. 2.2) exhibits another kind of memory 3. f. HIPPOCAMPUS: simple memory is a function that is carried out in mammalian brain by the hippocampus g. Conceptual tool for thinking about memory maintenance: DYNAMICAL SYSTEM with ATTRACTOR states (figure 6.4 right illustrates the energy surface over a two-dimensional state space) h. Using simple memory:
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This note was uploaded on 10/06/2010 for the course PSYCH 2140 taught by Professor Edelman during the Spring '08 term at Cornell.

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HD 2140 Prelim2 - Week 7: memory 1 Memory: A man sets...

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