Auditory sensitivity
Stanley A. Gelfand in Hearing, 2017
The phenomenon under discussion is called temporal integration or temporal summation. It demonstrates that the ear operates as an energy detector that samples the amount of energy present within a certain time frame (or window). A certain amount of energy is needed within this time window for the threshold to be attached. This energy may be obtained by using a higher intensity for less time or a lower intensity for more time. The ear integrates energy over time within an integration time frame of roughly 200 ms. This interval might also be viewed as a period during which energy may be stored, and can be measured as a time constant τ (Plomp and Bouman, 1959). Energy available for longer periods of time is not integrated with the energy inside the time window. This additional energy thus does not contribute to the detection of the sound, so that the threshold does not change durations longer than 200 ms. Photographers might think of this situation as analogous to the interaction of a camera's f-stop (intensity) and shutter speed (duration) in summating the light energy for a certain film speed (integration time): the lens opening and shutter speed may be traded against one another as long as the same amount of light is concentrated upon the film. The trade-off between intensity and duration is illustrated conceptually in Figure 9.5.
Neuronal Function
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal in Principles of Physiology for the Anaesthetist, 2020
A synapse permits the transmission of a neural impulse in one direction from one nerve to another. A typical neuron in the CNS may receive inputs from several other neurons (convergence), or make synaptic contact with many other neurons (divergence). The postsynaptic potentials of neurons may be integrated by a process called summation. Temporal summation therefore occurs when a second postsynaptic potential (excitatory or inhibitory) arrives before the membrane has returned to its resting level (Figure 4.13). A typical postsynaptic potential may last about 15 ms and ion channels are open for less than 1 ms, and there is usually sufficient time for several channels to open over the course of a single postsynaptic potential. The effects of these two potentials are additive over time. Spatial summation occurs when a number of axon terminals over the surface of a neuron are active simultaneously and their combined postsynaptic potential is greater than any one individual potential (Figure 4.14). Commonly, the magnitude of a single EPSP may be 0.5–1 mV, far less than the 10–20 mV required to reach threshold. Spatial summation enables the combined EPSP to exceed threshold.
Physiology of the nervous system
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal in Principles of Physiology for the Anaesthetist, 2015
A synapse is a specialized junction between the axon of one neuron (presynaptic) and another (postsynaptic) neuron. The presynaptic neuron releases neurotransmitters into the synaptic cleft via calcium-dependent exocytosis of synaptic vesicles. The neurotransmitter binds to receptors in the postsynaptic membrane to cause a transient change in the membrane of the postsynaptic cell. Depolarization of the postsynaptic membrane results in an EPSP, whereas hyperpolarization of the postsynaptic membrane leads to an IPSP. EPSPs and IPSPs are not all or none potentials. As a result, postsynaptic potentials can be superimposed on one another, resulting in temporal and spatial summation.
Pro-nociceptive pain modulation profile in patients with acute and chronic shoulder pain: a hypothesis-generating topical review
Published in Physical Therapy Reviews, 2021
Rani Othman, Nicola Swain, Steve Tumilty, Prasath Jayakaran, Ramakrishnan Mani
Conditioned pain modulation (CPM) is a commonly used protocol to measure descending control mechanisms in humans [80]. CPM is believed to represent the human behaviour correlate of diffuse noxious inhibitory controls mechanism. In contrast, temporal summation (TS) reflects the wind-up process within the dorsal horn wide-dynamic range neuron [31, 72, 81]. Further, MEP is a form of sensitivity testing and it might link to QST outcomes [82, 83]. MEP paradigms such as sensitivity to physical activity can be used in addition to QST measure, which assesses natural pain reactions in response to repeated functional movement [82, 83]. Outcomes of such testing protocols (i.e. QST, MEP, and CSI) can provide insights into the mechanisms behind persistent pain experience. They can be a useful clinical tool in which it can predict future pain [79, 84, 85].
Timing matters: the interval between acute stressors within chronic mild stress modifies behavioral and physiologic stress responses in male rats
Published in Stress, 2018
Sonia A. Cavigelli, Alexander D. Bao, Rebecca A. Bourne, Michael J. Caruso, Jasmine I. Caulfield, Mary Chen, Joshua M. Smyth
We tested three hypotheses: (i) the temporal summation hypothesis, (ii) the anticipatory hypothesis, and (iii) the null hypothesis. The temporal summation hypothesis proposes that health consequences are more extensive when daily acute stressors occur in rapid succession as opposed to spread out over the day. This is based on the assumption that biologic responses to temporally clustered acute stressors summate over time if there is not enough time between stressors to allow for return to basal activity. If supported, we expected that rats exposed to daily stressors in rapid succession (“Clustered”) would show the greatest evidence of slowed growth, dampened hedonic behavior, glucocorticoid dysregulation (slower daily decline, dampened acute response, and/or slower recovery following acute stressor), and increased inflammatory responses compared to Control rats. The anticipatory hypothesis proposes that health consequences are worse when daily stressors are dispersed across the day because the organism must maintain elevated physiologic preparedness throughout the day. If this hypothesis is accurate, we expected that rats exposed to daily acute stressors throughout the day (“Dispersed”) would show the greatest evidence of slowed growth, decreased hedonic behavior, greater glucocorticoid dysregulation, and increased peripheral inflammatory responses. Under the null hypothesis, the temporal pattern of acute stressors within chronic stress is of no consequence, and both forms of chronic stress (“Clustered” versus “Dispersed”) will lead to similar outcomes.
Rate pitch discrimination in cochlear implant users with the use of double pulses and different interpulse intervals
Published in Cochlear Implants International, 2019
Sabrina H. Pieper, Andreas Bahmer
Because of the facilitation, we additionally assume a loudness summation effect due to temporal interaction by presenting double pulses. This was already shown by Karg et al. (2013). They investigated the relation of loudness between double-pulse trains with different IPI and single-pulse trains. The loudness summation effect of double pulses with various IPIs (0, 0.1, 0.2, 0.3, 0.8, 1.3, 1.8 ms) was also investigated by Landsberger and Galvin (2011). Instead of double-pulse trains at one single electrode they stimulated adjacent electrodes for virtual channel discrimination. Assuming an overlap of electrical fields induced by these adjacent electrodes, their stimulation approach is similar to our study using only one electrode. They showed that the current required for equal loudness had to be slightly increased with increasing IPI due to a summation effect in the facilitation range between 0 and 0.3 ms (Figure 1 top in their paper).
Related Knowledge Centers
- Action Potential
- Axon Terminal
- Excitatory Postsynaptic Potential
- Inhibitory Postsynaptic Potential
- Neurotransmitter Receptor
- Synapse
- Threshold Potential
- Neurotransmitter
- Ion Channel
- Neuron