An Apparent New Instance of Stimulus Intensity Dynamism during Discrimination of Duration of Repeating Auditory Stimuli

Macmillan, Alastair; Gray, Jeffrey A.; Ison, James R.

doi:10.1080/14640747308400323

Cited by 28 publications

(4 citation statements)

References 14 publications

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“…There was no lesion effect when the tone signaled the positive trials, though there was an effect when the tone signaled negative trials (Freeman, Kramarcy & Lee 1973). The tendency to respond on negative trials when a tone is sounding has also been observed in normal rats and is taken to demonstrate stimulus-intensity dynamism rather than any influence on learning or memory (Macmillan, Gray & Ison 1973). Hence the sensory nature of the cue is a critical determinant of the lesion effect.…”

Section: Task Classificationmentioning

confidence: 95%

Associations across time: The hippocampus as a temporary memory store

1985

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All recent memory theories of hippocampal function have incorporated the idea that the hippocampus is required to process items only of some qualitatively specifiahle kind, and is not required to process items of some complementary set. In contrast, it is now proposed that the hippocampus is needed to process stimuli of all kinds, but only when there is a need to associate those stimuli with other events that are temporally discontiguous. In order to form or use temporally discontiguous associations, it is essential to maintain some memory of the first component until the second component has occurred. When the temporal gap to he spanned is small, and the number of items to be temporarily retained is low, a limited-capacity, short-term store is sufficient to allow associations to be formed. Such a store is presumed to operate in parallel with the hippocampus in normal animals. Hippocampal damage disrupts a much higher-capacity store that has a slower decay rate, and so leaves animals with only a very limited ability to form temporally discontiguous associations. Hippocampal damage, however, is not held to affect the long-term storage of associations of any kind, if they can be formed. Analyses of both new and existing data are presented to show that by classifying tasks in terms of the need to use a temporary memory store to retain temporally discontiguous information one can cut right across existing classifications as well as achieve a better fit to the data. The hippocampus thus seems best described as a high-capacity, intermediate-term memory store.

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Section: Task Classificationmentioning

confidence: 95%

Associations across time: The hippocampus as a temporary memory store

1985

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“…Interestinlgy, when we compared behavioral performance for proficient mice between sessions rewarded for high vs. low concentrations we noticed that the number of FAs increased when the rewarded stimulus was the low odorant group (Figure 7A). The increased FAs could be due to the effect of stimulus strength on behavioral responsiveness (Macmillan et al, 1973;Sun and Landy, 2016). The increased FA in the low concentration condition increased the variance of percent correct performance revealing a substantial correlation between decoding the reinforced stimulus from tPRP and behavioral performance for the proficient animal (Figures 7F,G).…”

Section: Discussionmentioning

confidence: 94%

The Olfactory Bulb Facilitates Use of Category Bounds for Classification of Odorants in Different Intensity Groups

Losacco

George

Hiratani

et al. 2020

Front. Cell. Neurosci.

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Signal processing of odor inputs to the olfactory bulb (OB) changes through top-down modulation whose shaping of neural rhythms in response to changes in stimulus intensity is not understood. Here we asked whether the representation of a high vs. low intensity odorant in the OB by oscillatory neural activity changed as the animal learned to discriminate odorant concentration ranges in a go-no go task. We trained mice to discriminate between high vs. low concentration odorants by learning to lick to the rewarded group (low or high). We recorded the local field potential (LFP) in the OB of these mice and calculated the theta-referenced beta or gamma oscillation power (theta phase-referenced power, or tPRP). We found that as the mouse learned to differentiate odorant concentrations, tPRP diverged between trials for the rewarded vs. the unrewarded concentration range. For the proficient animal, linear discriminant analysis was able to predict the rewarded odorant group and the performance of this classifier correlated with the percent correct behavior in the odor concentration discrimination task. Interestingly, the behavioral response and decoding accuracy were asymmetric as a function of concentration when the rewarded stimulus was shifted between the high and low odorant concentration ranges. A model for decision making motivated by the statistics of OB activity that uses a single threshold in a logarithmic concentration scale displays this asymmetry. Taken together with previous studies on the intensity criteria for decisions on odorant concentrations, our finding suggests that OB oscillatory events facilitate decision making to classify concentrations using a single intensity criterion.

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“…The optimal point is in the approximate range of 60-75 dB (SPL), and further increases in ambient noise thereafter have a deleterious effect. The increasing early part of the function may reflect an arousal consequence of the noise, a consequence which may be noted similarly in a variety of reflexive and nomeflexive behaviors (for example, Ison & Leonard, 1971;MacMillan, Gray, & Ison, 1973;Sheard, Astrachan, & Davis, 1975). The reason for the terminal downturn is not unambiguous but it may be produced by the increasingly unfavorable signal/noise ratio as the background level noise approaches the intensity of the eliciting stimulus signal (Ison & Hammond, 1971).…”

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confidence: 99%