ENTRIES A–Z
Philip Winn in Dictionary of Biological Psychology, 2003
Many stimuli, when presented to an animal for the first time, will elicit a response. Following repeated presentations of such stimuli, responding often declines. This decline in responding is termed HABITUATION. For example, a loud noise will, initially, elicit a startle response. Following repeated presentations of this noise, the startle response will decline and eventually disappear. True examples of habituation are typically thought not to be the result of either sensory adaptation or motor fatigue. Two characteristics, in particular, are often taken as support for this proposal, since they would appear to be uncharacteristic of sensory adaptation or motor fatigue. First, habituation proceeds more rapidly to weak stimuli rather than strong stimuli. Second, presentation of a strong, or motivationally significant, stimulus following habituation will result in restoration of the original response (see DISHABITUATION). Given that habituation is thought to be one of the most simple and primitive forms of LEARNING, it is not surprising that examples of it can be found throughout the animal kingdom. It has been observed, using a variety of stimuli and measuring a variety of responses, in such diverse creatures as leeches, molluscs, insects, birds, and of course mammals, including humans. For example, a snail will rapidly withdraw into its shell following a tap to the surface on which it is placed. Repeated presentations of the stimulus, however, will result in the decline, and eventual
Stress, Perceptual Distortions, and Human Performance
Darrell L. Ross, Gary M. Vilke in Guidelines for Investigating Officer-Involved Shootings, Arrest-Related Deaths, and Deaths in Custody, 2018
Fear can also cause someone to freeze, but in law enforcement, this is not always a viable option. Fear, however, can assist the officer as it can help him or her to maintain alertness, it can focus the attention to action and to respond to a perceived threat of danger, it can mobilize tremendous strength, information can still be processed, and it serves as a basic instinct to survive. The startle response to an unexpected stimulus provides an example of the adaptive response to fear. A sudden loud noise can create an automatic startle response and is often associated with a threat of danger. As the noise is picked up, the head rotates to the direction of the sound and the optic system scans to determine the source and the automatic response occurs. Instantaneously, the SNS has been activated, the amygdala screams, “DANGER,” and the person responds instinctively to protect him/herself.
The Traumatized Couple
Len Sperry, Katherine Helm, Jon Carlson in The Disordered Couple, 2019
Trauma is characterized as a direct experiencing, witnessing, or learning of an instance that involves the actual or threatened death, serious injury, or sexual violence to oneself or to others (American Psychiatric Association, 2013). Traumatization can occur when one’s perceived internal and external resources are incapable of helping them cope with an overwhelming or frightening experience (Oseland et al., 2016). This can include single incidents or a series of prolonged experiences that cause psychological and/or emotional distress that undermine the trauma survivor’s perceived sense of control, connection, and meaning. Trauma and stress-related disorders are based on the notion that many of the symptoms experienced by survivors are anhedonic and dysphoric in nature. In other words, symptoms are bothersome to the survivor and represent a loss of interest or change from previous functioning (Oseland et al., 2016). The diagnostic criteria for Post-Traumatic Stress Disorder (PTSD) consist of four symptom categories: intrusive re-experiencing, avoidance, negative alterations in cognition, and hyperarousal or hypervigilance (American Psychiatric Association, 2013). Hypervigilance presents as an individual’s persistent expectation of danger in the environment, causing survivors to be “stuck” in their previous traumatic experiences. This symptom can be further impacted by difficulty sleeping, irritable mood, trouble concentrating, and an exaggerated startle response (American Psychiatric Association, 2013; Oseland et al., 2016).
A-582941, cholinergic alpha 7 nicotinic receptor agonist, improved cognitive and negative symptoms of the sub-chronic MK-801 model of schizophrenia in rats
Published in Psychiatry and Clinical Psychopharmacology, 2018
Gokhan Unal, Feyza Aricioglu
The test procedure of PPI has been described in previous literature [20]. Briefly, before the testing day, rats were put in the chambers and exposed to a background noise for 5 min and five startle stimuli for adaptation to apparatus and for testing of hearing and startle function. On the test day, rats were placed in the chambers and exposed 70 dB of background noises for 5 min. After the acclimation period, rats were exposed to three trial blocks. Block 1 consisted of five presentations of 40 ms 120 dB pulse-alone trials. Block 2 had 50 pseudo-random trials (average intertrial intervals of 15s) which consisted of 10 presentations of each prepulse + pulse trials (74, 78, and 86 dB of 20 ms duration and 100 ms before 40 ms 120 dB pulse), 10 presentations of 120 dB pulse-alone and 10 presentations of no stimulus. Block 3 had five presentations of pulse-alone trials. Startle response was defined as the average of 100 readings collected every 1 ms beginning at the onset of the acoustic startle stimulus. Only Block 2 was taken into account for per cent prepulse inhibition. Per cent prepulse inhibition of startle response was calculated for each rat as per the following formula:
Sensorimotor and sensory gating in depression, anxiety, and their comorbidity
Published in The World Journal of Biological Psychiatry, 2021
Zinaida I. Storozheva, Roman V. Akhapkin, Olga V. Bolotina, Anna Korendrukhina, Vladimir Y. Novototsky-Vlasov, Irina V. Shcherbakova, Anna V. Kirenskaya
As a whole, the analysis allowed to identify specific and general characteristics of sensorimotor and sensory gating for depressive, anxiety and comorbid disorders. The startle response and its prepulse modification features revealed in comorbid group are shared rather with anxiety disorders. The study of P50 suppression paradigm showed up depression as a main contributor in the profile for co-occurrence. Thus, the profile for co-occurrence appears to diverge across response channels. Although, both paradigms used in the study, are thought to measure gating of incoming information, they are only weakly interrelated (Cadenhead et al. 2002), and reflect partly different neural mechanisms (Oranje et al. 2011). It is also important that startle stimuli can be interpreted as threatening, and neutral auditory stimuli are used in P50 paradigm.
Brain Environment Interactions: Stress, Posttraumatic Stress Disorder, and the Need for a Postmortem Brain Collection
Published in Psychiatry, 2022
Elizabeth Osuch, Robert Ursano, He Li, Maree Webster, Chris Hough, Carol Fullerton, Gregory Leskin
While not under conscious control, startle response is increased if a subject is afraid, and decreased if a subject is relaxed or has taken anxiolytic medication. Numerous studies have demonstrated that the acoustic startle response in rodents is enhanced by stressful stimuli such as intermittent tail shock (Garrick et al., 1997; Garrick et al., 2001), foot shock (Shi and Davis, 2001), and other stressful conditions, such as bright light (in a nocturnal species)(Walker and Davis, 2002). These studies demonstrate that acoustic startle is affected by environmental conditions, and can thus function as an interesting model for PTSD and the effects of stress on humans.
Related Knowledge Centers
- Brainstem
- Central Nervous System
- Cochlear Nerve
- Cochlear Nucleus
- Emotion
- Reflex
- Synapse
- Affect
- Fight-Or-Flight Response
- Specific Phobia