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"Conditioned response."
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Memory formation in the absence of experience
Memory is coded by patterns of neural activity in distinct circuits. Therefore, it should be possible to reverse engineer a memory by artificially creating these patterns of activity in the absence of a sensory experience. In olfactory conditioning, an odor conditioned stimulus (CS) is paired with an unconditioned stimulus (US; for example, a footshock), and the resulting CS–US association guides future behavior. Here we replaced the odor CS with optogenetic stimulation of a specific olfactory glomerulus and the US with optogenetic stimulation of distinct inputs into the ventral tegmental area that mediate either aversion or reward. In doing so, we created a fully artificial memory in mice. Similarly to a natural memory, this artificial memory depended on CS–US contingency during training, and the conditioned response was specific to the CS and reflected the US valence. Moreover, both real and implanted memories engaged overlapping brain circuits and depended on basolateral amygdala activity for expression.Pairing an odor conditioned stimulus (CS) with an unconditioned stimulus (US) induces memory formation. Vetere et al. replace the real CS and US with direct optogenetic stimulation of the brain and create a fully artificial odor memory in mice.
Journal Article
Mechanisms in classical conditioning : a computational approach
\"What mechanisms are involved in enabling us to generate predictions of what will happen in the near future? Although we use associative mechanisms as the basis to predict future events, such as using cues from our surrounding environment, timing, attentional, and configural mechanisms are also needed to improve this function. Timing mechanisms allow us to determine when those events will take place. ... Written for graduates and researchers in neuroscience, computer science, biomedical engineering and psychology, the author presents neural network models that incorporate these mechanisms and shows, through computer simulations, how they explain the multiple properties of associative learning\"--Provided by publisher.
Book
Examination of a Response–Effect Compatibility Task With Continuous Mouse Movements: Free- Versus Forced-Choice Tasks and Sequential Modulations
According to ideomotor theory, we select actions by recalling and anticipating their sensory consequences, that is, their action effects. Compelling evidence for this theory comes from response–effect compatibility (REC) experiments, in which a response produces an effect with which it is either compatible or incompatible. For example, pressing a left/right response key is faster if it is predictably followed by an action effect on the same, compatible side compared with the other, incompatible side, even though the effect itself appears only after response time is measured. Recent studies investigated this effect with continuous responses (i.e., computer mouse movements) and reported an REC effect in a forced-choice but not in a free-choice task. From the keypressing literature, the opposite result pattern or no differences would have been expected. To clarify this issue, we report 3 experiments with mouse movement responses. Experiment 1 used a simpler scenario than in prior studies and found a similar result: The REC effect was evident in a forced- but not in a free-choice task. Also, sequential modulations of the REC effect were exploratorily analyzed and replicated with higher power in Experiment 2. However, Experiment 3 demonstrated that at least part of the REC effect with mouse movements can be attributed to stimulus–response compatibility (SRC), with a much smaller compatibility effect evident with a procedure for which SRC was reduced. We conclude that a sequentially modulated compatibility effect can be observed with mouse movements, but previous studies may have underestimated the contribution from SRC. The results are also discussed in terms of why the compatibility effect was observed in forced- but not free-choice tasks with mouse movement responses.
Journal Article
Neuronal Activity Related to Reward Value and Motivation in Primate Frontal Cortex
In several areas of the macaque brain, neurons fire during delayed-response tasks at a rate determined by the value of the reward expected at the end of the trial. The activity of these neurons might be related to the value of the expected reward or to the degree of motivation induced by expectation of the reward. We describe results indicating that the nature of reward-dependent activity varies across areas. Neuronal activity in orbitofrontal cortex represents the value of the expected reward, whereas neuronal activity in premotor cortex reflects the degree of motivation.
Journal Article
Impulsive Choice Induced in Rats by Lesions of the Nucleus Accumbens Core
Impulsive choice is exemplified by choosing a small or poor reward that is available immediately, in preference to a larger but delayed reward. Impulsive choice contributes to drug addiction, attention-deficit/hyperactivity disorder, mania, and personality disorders, but its neuroanatomical basis is unclear. Here, we show that selective lesions of the nucleus accumbens core induce persistent impulsive choice in rats. In contrast, damage to two of its afferents, the anterior cingulate cortex and medial prefrontal cortex, had no effect on this capacity. Thus, dysfunction of the nucleus accumbens core may be a key element in the neuropathology of impulsivity.
Journal Article
Cerebellar LTD and Learning-Dependent Timing of Conditioned Eyelid Responses
Mammals can be trained to make a conditioned movement at a precise time, which is correlated to the interval between the conditioned stimulus and unconditioned stimulus during the learning. This learning-dependent timing has been shown to depend on an intact cerebellar cortex, but which cellular process is responsible for this form of learning remains to be demonstrated. Here, we show that protein kinase C-dependent long-term depression in Purkinje cells is necessary for learning-dependent timing of Pavlovian-conditioned eyeblink responses.
Journal Article
Into the Mind’s Eye: Exploring the Fast-Same Effect in the Same-Different Task
The fast-same effect is the observation that “same” responses are much faster than “different” responses in the same-different task. Moreover, identical stimuli are responded to faster than stimuli that are the same in name only (e.g., B and b). We examine Bamber’s (1969) identity reporter model (a two-stage model predicting load effects), Proctor’s (1981) facilitation framework, and Krueger and Shapiro’s (1981) priming framework, proposed to account for these effects. Facilitation and priming are strong for identical and repeated stimuli, for phonological associates, and, in principle, for any form of association. We thus manipulated two types of associations: nominal (changing the letter case, preserving phonology) and learned (matching arbitrary symbols to letters) associations and used extended training to see variations in load effects. We found that overall performance benefits from phonological information and from training, although training did not change load effects. Additionally, the results from a transfer phase show capacity limitation for learned associates, which severely constrains facilitation. This finding is inconsistent with a priming framework. The results are discussed using an expanded version of Bamber’s identity reporter model, which is also compatible with Proctor’s facilitation framework.
Journal Article
The implausibility of response shifts in dementia patients
Dementia patients may express wishes that do not conform to or contradict earlier expressed preferences. Our understanding of the difference between their prior preferences and current wishes has important consequences for the way we deal with advance directives. Some bioethicists and gerontologists have argued that dementia patients change because they undergo a ‘response shift’. In this paper we question this assumption. We will show that proponents of the response shift use the term imprecisely and that response shift is not the right model to explain what happens to dementia patients. We propose a different explanation for the changed wishes of dementia patients and conclude that advance directives of dementia patients cannot be simply put aside.
Journal Article