Post-Traumatic Stress Disorder and Deception
Harold V. Hall, Joseph G. Poirier in Detecting Malingering and Deception, 2020
The CNS activity of abused and non-abused children, measured by the impact of acoustic startle tones on EEG-evoked potentials, reflected significant differences between the two groups (McPherson, Newton, Ackerman, Oglesby, & Dykman, 1997). Essentially, the children with PTSD had greater EEG intensity gradients compared with the non-abused subjects. Auditory-evoked EEG potentials were recorded with male Vietnam combat veterans with PTSD (Gillette et al., 1997). Diminished EEG latencies were significantly correlated with the intensity of re-experiencing symptoms, e.g., nightmares and flashbacks. The authors suggested that the finding was supportive of a “sensory gating effect at the brainstem level,” and that the suppression effect may similarly influence other psychophysiological measures. In a study employing magnetic resonance imaging, Gurvits, Shenton, Hokama, and Ohta (1996) observed that both right and left hippocampi were significantly smaller in subjects with PTSD compared with combat control and normal subjects. There were no significant differences in intracranial cavity, whole brain, ventricles, brain ratio, or amygdala. The two combat groups did evidence increased subarachnoid cerebrospinal fluid. The authors suggested that since hippocampal volume was directly correlated with combat, traumatic stress might cause damage to the hippocampus.
Mesolimbic Interactions with Mesopontine Modulation of Locomotion
Peter W. Kalivas, Charles D. Barnes in Limbic Motor Circuits and Neuropsychiatry, 2019
Deficits in sensory gating also have been reported. In a paired stimuli paradigm, schizophrenic patients do not inhibit the response to the second stimulus under conditions in which normal subjects do inhibit such responses.186–188 Because the PPN appears to generate the auditory evoked P1 wave, these data are suggestive of enhanced activity in this nucleus in schizophrenia. Recently, we reported that the brain stems of schizophrenic patients have on average twice as many PPN neurons as those of normal controls or of psychiatric (non-schizophrenic) controls.189 Even though these findings appear to be holding up with the addition of more brains to this study, caution is necessary because this is a small sample (7–8 brains in each group) and the population of schizophrenic patients was limited to extremely chronic (>30 years of institutionalization), fairly intractable cases.
Neuropharmacologic considerations in the treatment of vegetative state and minimally conscious state following brain injury
Mark J. Ashley, David A. Hovda in Traumatic Brain Injury, 2017
Dorsal projections from the brain stem ARAS reach the thalamus. The thalamus serves as the main relay and filtering station for ascending sensory information. Without the thalamus, most sensory input would not reach the cortex. Activation of the thalamic nuclei by cholinergic and glutaminergic fibers of the ARAS facilitates transmission of sensory input to higher cortical regions. The thalamic nuclei have both afferent and efferent connections with the cerebral cortex and brain stem. The thalamic reticular nucleus, in particular, is involved in the process of sensory gating. Gating of the stream of sensory data allows attention to be selectively focused on some aspects of sensory input and not others. The ascending pathways from the thalamus to the primary sensory areas of the cerebral cortex are predominantly glutaminergic. From the primary sensory areas, collateral connections proceed to the sensory association areas, where information is processed, interpreted, and consciously experienced.
EEG reveals deficits in sensory gating and cognitive processing in asymptomatic adults with a history of concussion
Published in Brain Injury, 2022
Anthony Tapper, W. Richard Staines, Ewa Niechwiej-Szwedo
Relatively fewer studies have investigated sensory ERPs in individuals with a history of concussion. For example, the P50 and N100 are two sensory ERPs elicited following an auditory stimulus and may reflect a multistage sensory gating process that protects higher-order cognitive areas from being bombarded with sensory stimuli (18–21). The sensory gating process entails selection of incoming relevant information and/or suppression of irrelevant stimuli (22). Studies examining sensory ERPs during the auditory oddball task in individuals with a history of concussion have yielded mixed results (3,6,9–12). For instance, some studies reported smaller N100 ERP amplitudes in groups with previous concussion compared to controls (9–12); in contrast, other studies reported no differences between groups (3,6). The mixed findings could arise due to different analytic procedures as studies reporting no N100 amplitude differences only analyzed target trials whereas those showing smaller amplitudes in participants with concussion compared target to non-target trials. This is particularly important because sensory gating is often calculated using the difference between target and non-target ERP amplitudes; thus, studies reporting smaller N100 amplitudes could reflect poorer target facilitation, non-target inhibition or a combination of the two.
Clinical correlates of noise sensitivity in patients with acute TBI
Published in Brain Injury, 2019
Daniel Shepherd, Jason Landon, Mathew Kalloor, Alice Theadom
An alternative approach, the information-processing hypothesis of NS (20), relies on known neuroanatomical correlates of auditory-related top-down and bottom-up cognitive processes, and how physical insults to these areas degrade vital auditory processes such as filtering, attention, and memory. For example, individuals with NS may not possess the ability to adaptively process auditory distractors (25–27). Cognitive deficits are prevalent in those diagnosed with PCS, including impaired attentional processes and reduced information-processing speed (2). It has been proposed that attentional impairment in people with a TBI could be accounted for by dysfunctional sensory gating processes arising from the thalamus failing to filter out irrelevant stimuli (28). In this situation, the failure to inhibit task-irrelevant sounds results in information overload of working memory (29). In documenting the neurological markers of NS, two studies have indicated differences in the auditory evoked potentials of noise sensitive individuals vs. matched controls (30,31), and the likelihood that noise sensitive individuals have degraded pre-attentive filtering processes and experience higher cognitive loads when processing auditory information.
COMT Genotype and Sensory and Sensorimotor Gating in High and Low Hypnotizable Subjects
Published in International Journal of Clinical and Experimental Hypnosis, 2018
Zinaida I. Storozheva, Anna V. Kirenskaya, Mikhail N. Gordeev, Maria E. Kovaleva, Vladimir Yu Novototsky-Vlasov
The positive correlation between P50 S1 amplitude and the first ASR amplitude in the HH group can be regarded as evidence that ASR amplitude strongly depends on sensory processing of auditory stimuli, and supposes the greater integrity of sensory processing and executive networks in HH subjects. The implication of temporal lobes and auditory cortex in mediating the sensory gating response was consistently reported in animal and invasive human studies (Korzyukov et al., 2007; Oranje, Geyer, Bocker, Leon Kenemans, & Verbaten, 2006; Weisser et al., 2001). It is worth noting that the sensory motor integrity evidenced by the correlation between amplitudes of P50 and ASR reflects mainly automatic preattentive processes.