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

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

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

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Behavioral Learning Curve % Correct Responses Training Sessions PretrainingFirst ExposureFirst Significant Discrimination Continued Training CriterionOvertraining CS+ CS- 5

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. US CS Aud. Ctx MGN Amygdala Neural Circuit for Avoidance Learning tone footshock 6

Two Types of Neuronal Plasticity Excitation Discrimination ExcitationDiscrimination 7

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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. US CS Aud. Ctx MGN Amygdala Neural Circuit for Avoidance Learning tone footshock 9 X X X Talk et al., 2004 Poremba and Gabriel, 1999, 2001 Poremba and Gabriel, 1997

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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. ACC PCC MDN AVN MB LDTN MGN Amygdala Aud. Ctx CR US CS Neural Circuit for Avoidance Learning 11 Cingulate Cortex Limbic Thalamus

12 ACC PCC MDN AVN Cingulate Cortex Limbic Thalamus AcquisitionOvertraining % Correct Responses ACC MDN

13 ACC PCC MDN AVN Cingulate Cortex Limbic Thalamus AcquisitionOvertraining % Correct Responses PCC AVN

14 ACC PCC MDN AVN Cingulate Cortex Limbic Thalamus AcquisitionOvertraining % Correct Responses ACC PCC MDN AVN

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. ACC PCC MDN AVN MB LDTN MGN Amygdala Aud. Ctx CR US CS Neural Circuit for Avoidance Learning 15 Cingulate Cortex Limbic Thalamus EARLYLATE

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. ACC PCC MDN AVN MB LDTN MGN Amygdala Aud. Ctx CR US CS Neural Circuit for Avoidance Learning 16 EARLYLATE LAST?

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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. ACC PCC MDN AVN MB LDTN MGN Amygdala Aud. Ctx CR US CS 18 Neural Circuit for Avoidance Learning and ?

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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. HippocampusHippocampus ACC PCC MDN AVN MB LDTN MGN Amygdala Aud. Ctx CR US CS Neural Circuit for Avoidance and Approach Learning 21 EARLYLATE X

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. HippocampusHippocampus ACC PCC MDN AVN MB LDTN MGN Amygdala Aud. Ctx CR US CS Neural Circuit for Avoidance and Approach Learning 22 INPUT EARLYLATE CONTEXT Memory Filter

Summary for Simple Auditory Learning 2123 CONTEXT HippocampusHippocampus ACC PCC MDN AVN MB LDTN MGN Amygdala Aud. Ctx CR US CS INPUT EARLYLATE Memory Filter 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. 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. 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.