Learning and Memory in the Auditory System

1. Learning and Memory in the Auditory System Amy Poremba, Ph.D. The University of Iowa Department of Psychology Behavioral and Cognitive Neuroscience 1

2. Introduction Examples of learning about auditory cues will be used to infer some general learning principles. 2

3. CS+ Tone 1 US Footshock UCR Run CR Run CS- Tone 2 Danger/Fear X Training Rules for Discriminative Active Avoidance Conditioning Safety 3

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5. 100 CS+ CS- 75 % Correct Responses 50 25 0 Pretraining First Exposure First Significant Discrimination Continued Training Criterion Overtraining Training Sessions Behavioral Learning Curve 5

6. Neural Circuit for Avoidance Learning Aud. Ctx Amygdala MGN CR – conditioned response CS – conditioned stimulus US – unconditioned stimulus ACC – anterior cingulate cortex PCC – posterior cingulate cortex MGN – medial geniculate n. MDN – medial dorsal n. AVN – anterior ventral n. MB – mammillary bodies LDTN – lateral dorsal tegmental n. footshock tone US CS 6

7. Two Types of Neuronal Plasticity Discrimination Excitation Excitation Discrimination 7

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9. Neural Circuit for Avoidance Learning Aud. Ctx Amygdala MGN X Talk et al., 2004 X Poremba and Gabriel, 1999, 2001 X Poremba and Gabriel, 1997 CR – conditioned response CS – conditioned stimulus US – unconditioned stimulus ACC – anterior cingulate cortex PCC – posterior cingulate cortex MGN – medial geniculate n. MDN – medial dorsal n. AVN – anterior ventral n. MB – mammillary bodies LDTN – lateral dorsal tegmental n. footshock tone US CS 9

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11. Neural Circuit for Avoidance Learning Aud. Ctx CR ACC PCC Cingulate Cortex Amygdala AVN MDN Limbic Thalamus MB MGN CR – conditioned response CS – conditioned stimulus US – unconditioned stimulus ACC – anterior cingulate cortex PCC – posterior cingulate cortex MGN – medial geniculate n. MDN – medial dorsal n. AVN – anterior ventral n. MB – mammillary bodies LDTN – lateral dorsal tegmental n. LDTN US CS 11

12. MDN ACC Acquisition Overtraining ACC PCC Cingulate Cortex % Correct Responses AVN MDN Limbic Thalamus 12

13. AVN PCC Acquisition Overtraining ACC PCC Cingulate Cortex % Correct Responses AVN MDN Limbic Thalamus 13

14. MDN AVN ACC PCC Acquisition Overtraining ACC PCC Cingulate Cortex % Correct Responses AVN MDN Limbic Thalamus 14

15. Neural Circuit for Avoidance Learning EARLY LATE Aud. Ctx CR ACC PCC Cingulate Cortex Amygdala AVN MDN Limbic Thalamus MB MGN CR – conditioned response CS – conditioned stimulus US – unconditioned stimulus ACC – anterior cingulate cortex PCC – posterior cingulate cortex MGN – medial geniculate n. MDN – medial dorsal n. AVN – anterior ventral n. MB – mammillary bodies LDTN – lateral dorsal tegmental n. LDTN US CS 15

16. Neural Circuit for Avoidance Learning Aud. Ctx EARLY LATE CR ACC PCC LAST? Amygdala AVN MDN MB MGN CR – conditioned response CS – conditioned stimulus US – unconditioned stimulus ACC – anterior cingulate cortex PCC – posterior cingulate cortex MGN – medial geniculate n. MDN – medial dorsal n. AVN – anterior ventral n. MB – mammillary bodies LDTN – lateral dorsal tegmental n. LDTN US CS 16

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18. Neural Circuit for Avoidance Learning and ? Aud. Ctx CR ACC PCC Amygdala AVN MDN MB MGN CR – conditioned response CS – conditioned stimulus US – unconditioned stimulus ACC – anterior cingulate cortex PCC – posterior cingulate cortex MGN – medial geniculate n. MDN – medial dorsal n. AVN – anterior ventral n. MB – mammillary bodies LDTN – lateral dorsal tegmental n. LDTN US CS 18

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21. Neural Circuit for Avoidanceand Approach Learning Aud. Ctx CR EARLY LATE ACC PCC Hippocampus X Amygdala AVN MDN MB MGN CR – conditioned response CS – conditioned stimulus US – unconditioned stimulus ACC – anterior cingulate cortex PCC – posterior cingulate cortex MGN – medial geniculate n. MDN – medial dorsal n. AVN – anterior ventral n. MB – mammillary bodies LDTN – lateral dorsal tegmental n. LDTN US CS 21

22. Neural Circuit for Avoidance and Approach Learning Hippocampus Aud. Ctx CR EARLY LATE ACC PCC CONTEXT Amygdala Memory Filter AVN MDN INPUT MB MGN CR – conditioned response CS – conditioned stimulus US – unconditioned stimulus ACC – anterior cingulate cortex PCC – posterior cingulate cortex MGN – medial geniculate n. MDN – medial dorsal n. AVN – anterior ventral n. MB – mammillary bodies LDTN – lateral dorsal tegmental n. LDTN US CS 22

23. Summary for Simple Auditory Learning Aud. Ctx CR EARLY LATE ACC PCC Hippocampus Amygdala CONTEXT AVN MDN Memory Filter INPUT MB MGN LDTN US CS This type of learning is better with trials spread across days rather than massed trials on one or two days. After a certain number of training trials, continued trials are no longer necessary for consolidation, i.e., moving the memory to long term storage. There are multiple brain circuits for different stages of the learning. Brain structures that are important for acquisition are not always necessary for long term memory storage. Types of learning may be layered, i.e., the input system in this case is similar to the fear conditioning system. Here the animals learn to avoid the footshock and other brain areas are then involved in the learning. The context surrounding the important signals to be learned helps attentional processing and the learning of more than one task. There may be multiple brain circuits even for this simple type of task perhaps creating a filter for which memories will be remembered. 21 23