Damage to the hippocampal system disrupts recent memory but leaves remote memory intact. The account presented here suggests that memories are first stored via synaptic changes in the hippocampal system, that these changes support reinstatement of recent memories in the neocortex, that neocortical synapses change a little on each reinstatement, and that remote memory is based on accumulated neocortical changes. Models that learn via changes to connections help explain this organization. These models discover the structure in ensembles of items if learning of each item is gradual and interleaved with learning about other items. This suggests that the neocortex learns slowly to discover the structure in ensembles of experiences. The hippocampal system permits rapid learning of new items without disrupting this structure, and reinstatement of new memories interleaves them with others to integrate them into structured neocortical memory systems.

Why there are complementary learning systems in the hippocampus and neocortex: insights from the successes and failures of connectionist models of learning and memory.

Degeneration and regeneration of the nervous system

http://whoville.ucsd.edu/PDFs/384_Squire_%20NeurobiolLearnMem2004.pdf

Memory systems of the brain: A brief history and current perspective

Goal-directed instrumental action: Contingency and incentive learning and their cortical substrates

Research indicates that people value music primarily because of the emotions it evokes. Yet, the notion of musical emotions remains controversial, and researchers have so far been unable to offer a satisfactory account of such emotions. We argue that the study of musical emotions has suffered from a neglect of underlying mechanisms. Specifically, researchers have studied musical emotions without regard to how they were evoked, or have assumed that the emotions must be based on the "default" mechanism for emotion induction, a cognitive appraisal. Here, we present a novel theoretical framework featuring six additional mechanisms through which music listening may induce emotions: (1) brain stem reflexes, (2) evaluative conditioning, (3) emotional contagion, (4) visual imagery, (5) episodic memory, and (6) musical expectancy. We propose that these mechanisms differ regarding such characteristics as their information focus, ontogenetic development, key brain regions, cultural impact, induction speed, degree of volitional influence, modularity, and dependence on musical structure. By synthesizing theory and findings from different domains, we are able to provide the first set of hypotheses that can help researchers to distinguish among the mechanisms. We show that failure to control for the underlying mechanism may lead to inconsistent or non-interpretable findings. Thus, we argue that the new framework may guide future research and help to resolve previous disagreements in the field. We conclude that music evokes emotions through mechanisms that are not unique to music, and that the study of musical emotions could benefit the emotion field as a whole by providing novel paradigms for emotion induction.

/pdf/emotional-responses-to-music-the-need-to-consider-underlying-592kszluvl.pdf

Emotional responses to music: The need to consider underlying mechanisms

Electrophysiological recording of neuronal unit activity during paired training trials from various regions of the ipsilateral cerebellum in rabbits well trained in the classically conditioned eyelid/nictitating membrane response have revealed both stimulus-evoked responses and responses that form an amplitude/temporal model of the learned behavioral response Ablation of the ipsilateral, lateral cerebellum completely and permanently abolished the behavioral conditioned response in well-trained animals but had no effect at all on the unconditioned reflex response In marked contrast, conditioned responses were easily trained in the eye contralateral to the cerebellar lesion We suggest that at least part of the essential neuronal plasticity that codes the learned response may be localized to the cerebellum

https://www.pnas.org/content/pnas/79/8/2731.full.pdf

Initial localization of the memory trace for a basic form of learning

Effects of lesions of cerebellar nuclei on conditioned behavioral and hippocampal neuronal responses

Electrophysiological recording of neural unit activity during paired training trials from the ipsilateral cerebellum in rabbits well trained in short-delay classical conditioning of the nictitating membrane (NM) and eyelid responses showed CS- and UCS-evoked responses and a pattern of increased neural activity that correlates with the learned behavioral response. Large ablations of the ipsilateral cerebellum completely and permanently abolished the conditioned response in well trained animals, as did more localized stereotaxic lesions. These lesions had no effect at all on the unconditioned reflex response. In marked contrast, conditioned responses were easily trained in the eye contralateral to the cerebellar lesion. We suggest that at least a part of the “engram,” the essential neuronal plasticity that codes the learned response, may be localized to the cerebellum.

/pdf/the-engram-found-role-of-the-cerebellum-in-classical-1lpbmb4qs6.pdf

The engram found? Role of the cerebellum in classical conditioning of nictitating membrane and eyelid responses

In this review, we have examined recent studies that have successfully identified neural circuits necessary for nonspecific and specific conditioned responses. This success is due in large part to the advantages of the classical conditioning paradigm for controlling stimuli and responses. Clearly, this research does not attempt to account for all forms of memory. The power of this approach is demonstrated by the distinction between essential and nonessential memory traces or engrams. Essential memory traces represent the circuitry responsible for forming the association in classical conditioning. Nonessential memory traces do not represent the essential association, but they are important for facilitating, adapting, and modifying the final performance of the learned behavior. The search for the engram for any learned behavior has been viewed with skepticism by some investigators who quote Karl Lashley: "This series of experiments has yielded a good bit of information about what and where the memory is not. It has discovered nothing directly of the real nature of the engram" (1950, pp. 477-78). However, these authors neglect to quote Lashley fully, for even he was less pessimistic about that search than in normally recognized. He continued, "I sometimes feel, in reviewing the evidence on the localization of the memory trace, that the necessary conclusion is that learning just is not possible. It is difficult to conceive of a mechanism which can satisfy the conditions set for it. Nevertheless, in spite of such evidence against it, learning does sometimes occur" (1950, pp. 477-78, emphasis added). Learning does indeed occur, and its neurobiological substrates can be localized.

David G. Lavond

Papers

Initial localization of the memory trace for a basic form of learning

Effects of lesions of cerebellar nuclei on conditioned behavioral and hippocampal neuronal responses

The engram found? Role of the cerebellum in classical conditioning of nictitating membrane and eyelid responses

Mammalian brain substrates of aversive classical conditioning.

Acquisition of classical conditioning without cerebellar cortex.