![]() ![]() d | In addition to having a normal ability to ignore auditory distractors, patients with schizophrenia show normal retention of auditory tonal information once a correction is made for the increased overall thresholds. Individuals with schizophrenia show elevated tone matching thresholds even in the absence of distraction, but are no more susceptible to distraction than controls, supporting the concept of auditory cortex-level dysfunction. By contrast, individuals with lesions that affect the prefrontal cortex do not have elevated thresholds in the absence of distraction even at relatively long interstimulus intervals (for example, 5 seconds), but show increased susceptibility to distraction effects. ![]() Individuals with lesions that affect the auditory cortex show elevated thresholds even in the absence of distractors, but no increased susceptibility to distraction. c | In all individuals, presentation of distractor tones between the reference and test tones leads to an elevation in discrimination thresholds, which are expressed as the difference in tone frequency between stimuli (Δ f). a,b | Stimuli can be presented either in a no-distractor condition in which the interval between tones is silent, or in a distractor condition in which irrelevant auditory stimuli or visual stimuli are presented in the intervening period. The difficulty of the task is defined by altering the pitch difference between the reference and test tones. In this paradigm, tones are presented sequentially, and subjects must report whether the second tone is the same or different from the first or higher or lower in pitch. Tpt, heteromodal temporoparietal region.Īlthough the majority of cognitive studies in schizophrenia use relatively complex paradigms, such as those investigating executive processing or working memory, deficits are observed even in relatively simple auditory paradigms, such as the ability to match tones following a brief delay. The view is from above the STG, after removing the overlying cortex, revealing the superior temporal plane. In monkeys, the auditory association cortex is subdivided into lateral belt and parabelt cortices, which together comprise BA42 in humans, in a location extending from the lateral portion of the HG onto the planum temporale (PT). In humans, BA41 is located in the posterior medial two-thirds of Heschl’s gyrus (HG). ![]() The primary auditory cortex, denoted as the auditory core in monkeys, and as Brodmann’s area 41 (BA41) in humans, is indicated. ![]() Diagrams of the regions that make up macaque (part d) and human (part e) auditory cortices are shown. Because of this orientation, human auditory event-related potentials show a characteristic topography over the surface of the scalp, with inversion of activity between frontocentral scalp regions and mastoids (for example, see FIG. The blue dashed line shows the orientation of electrical currents generated within the auditory cortex. Inferiorly, the STG is bordered by the superior temporal sulcus (STS) in both monkeys and humans. The superior temporal gyrus (STG) is bordered superiorly by the lateral sulcus (LS) in monkeys and the Sylvian fissure (SF) in humans. The auditory cortex location (in grey) in monkeys is shown in part b and in humans is shown in part c. Neurons of the inferior colliculus project to the medial geniculate nucleus of the thalamus, which provides innervation to the auditory cortex. Projections from the dorsal cochlear nucleus cross the midline and travel through the lateral lemniscus to synapse in the inferior colliculus. The ascending auditory pathway in humans begins as the auditory nerve enters the brainstem, where it forms synapses in the dorsal and ventral cochlear nuclei (part a). ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |