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Special Senses
Published in Pritam S. Sahota, James A. Popp, Jerry F. Hardisty, Chirukandath Gopinath, Page R. Bouchard, Toxicologic Pathology, 2018
Kenneth A. Schafer, Oliver C. Turner, Richard A. Altschuler
Assessment of otopathology is often matched with the assessment of cochlear function. The simplest test in many animal models is snapping fingers and looking for movement of the animal’s ears (“Preyer’s reflex”). This test is only sensitive to large hearing deficits and will not be reliable in all animal species. The most common assessment in animal models is the ABR. The frequencies at which there is hearing loss can be determined, in addition to differentiating between only outer hair cell loss and the loss of outer and inner hair cells. The extent of inner and outer hair cell loss and changes in ABR are based on threshold shifts. Differentiation between hair cell loss (sensory) and auditory nerve dysfunction (neural) can also be determined (Liberman and Beil 1979). Outer hair cell function can also be tested by examining otoacoustic emissions. The acoustic startle reflex can be used to test hearing thresholds, gap detection, prepulse inhibition, and tinnitus. Further testing of the auditory nerve can be done by measuring round window noise and ensemble spontaneous activity of the auditory nerve or by placing electrodes into the nerve and recording compound action potentials. Loss of inner hair cell–auditory nerve synaptic connections can be detected by measuring suprathreshold ABR response as a measure of dynamic range and reduced suprathreshold responses have been shown to correlate with noise-induced loss of low sensitivity auditory nerve fibers (e.g., Furman et al. 2010).
Cocaine Increases Sensorimotor Gating and is Related to Psychopathy
Published in Journal of Dual Diagnosis, 2021
Iván Echeverria, Ana Benito, Alejandro Fuertes-Saiz, María Luisa Graña, Isabel Aleixandre, Gonzalo Haro
Prepulse inhibition (PPI) of the startle reflex is defined as a reduction in the magnitude of this reflex when a low-intensity auditory stimulus occurs which would normally be unable to generate a response by itself (prepulse) 30–300 ms (millisecond) before the onset of a startle stimulus (pulse). It has been described as an operational measure of a central inhibitory mechanism that regulates sensorimotor gating, reducing the impact of irrelevant sensory stimuli. Therefore, an impairment of this mechanism expressed as a lack of attenuation of the reflexive startle reaction after the onset of auditory stimulus (prepulse-pulse) can be used as an endophenotype or biological marker of vulnerability to certain mental disorders such as schizophrenia (Kohl et al., 2013). Furthermore, it has been well documented that the duration of the prepulse-pulse interval helps define the type of processing taking place. Shorter intervals like 30 ms, respond to pre-attentive and automatic perceptual processing whereas longer intervals like 120 ms are defined as partially automatic, meaning they are capable of proceeding automatically but also of controlled attentional modulation (Schell et al., 2000).
Effects of psychological or physical prenatal stress on attention and locomotion in juvenile rats
Published in International Journal of Neuroscience, 2021
Samaneh GhotbiRavandi, Mohammad Shabani, Sina Bakhshaei, Masoud Nazeri, Masoumeh Nozari
The startle reflex is a protective response that makes organisms ready for the fight or flight responses. This test has been used in animals as well as humans [5]. In rats, the startle response is characterized by muscle contractions in response to a sudden loud acoustic stimulus and appears in the post-natal day (PND) 10-12. When the audiogenic stimulus is preceded by a weaker stimulus, the severity of this reaction is diminished, which is known as the physiological phenomenon of prepulse inhibition (PPI) [6, 7]. PPI is usually considered as an operational measure of sensorimotor gating by which either excess or minor stimuli are screened or “gated out” of awareness so that an individual can focus its attention on the most prominent stimuli. The normal functioning of this mechanism is critical for normal cognitive processes [8]. In several psychiatric diseases such as schizophrenia, the sensorimotor gating is impaired, presenting as reduced PPI, while an increased amplitude of the response can be seen during post-traumatic stress disorder (PTSD) [9, 10].
Sensorimotor Gating in Cocaine-Related Disorder with Comorbid Schizophrenia or Antisocial Personality Disorder
Published in Journal of Dual Diagnosis, 2019
Alejandro Fuertes-Saiz, Ana Benito, César Mateu, Sonia Carratalá, Isabel Almodóvar, Abel Baquero, Gonzalo Haro
Cocaine is responsible for more hospital admissions for treatment (36.5%) and emergencies (43.7%) than any other drug (Observatorio Español de la Droga y las Toxicomanías (OEDT), 2016). Schizophrenia and antisocial personality disorder (ASPD) are very prevalent in cocaine users (Araos et al., 2014; Arias et al., 2013). Prepulse inhibition (PPI; Blumenthal, Reynolds, & Spence, 2015) is a robust measure of sensorimotor gating (Kohl, Heekeren, Klosterkötter, & Kuhn, 2013), is a cross-species phenomenon (Zhang, Forkstam, Engel, & Svensson, 2000), is significantly heritable (Greenwood et al., 2016), and is a useful schizophrenia endophenotype (Siegel, Talpos, & Geyer, 2013). PPI is reduced in patients with psychiatric disorders compared with healthy controls (Arenas, Caballero-Reinaldo, Navarro-Francés, & Manzanedo, 2017). Since animal studies suggest the unitary nature of the neurocircuits that govern both major psychiatric syndromes and enhanced addiction vulnerability, it is probable that many genetic and environmental risk factors for mental illness, substance use disorders, or dual diagnosis conditions could be identical (Chambers, 2007). PPI, given its usefulness as an endophenotype, seems a good starting point to study these common etiological bases.