PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 17081712

Complex tone processing and critical band in the human auditory cortex.

Yoshiharu Soeta·Seiji Nakagawa
View original source ↗Export metadata ↓

Abstract

Psychophysical experiments in humans have indicated that the auditory system has a well-defined bandwidth for resolution of complex stimuli. This bandwidth is known as the critical bandwidth (CBW). Physiological correlates of the CBW were examined in the human auditory cortex. Two- and three-tone complexes were used as the sound stimuli with all signals presented at 55 dB sound pressure level (SPL). The duration of stimulation was 500 ms, with rise and fall ramps of 10 ms. Ten normal-hearing subjects took part in the study. Auditory-evoked fields were recorded using a 122-channel whole-head magnetometer in a magnetically shielded room. The latencies, source strengths, and coordinates of the N1m waves, which were found above the left and right temporal lobes approximately 100 ms after the onset of stimulation, were analyzed. The results indicated that N1m amplitudes were approximately constant when the frequency separation of a two-tone complex or the total bandwidth of a three-tone complex was less than the CBW; however, the N1m amplitudes increased with increasing frequency separation or total bandwidth when these were greater than the CBW. These findings indicate critical band-like behavior in the human auditory cortex. The N1m amplitudes in the right hemisphere were significantly greater than those in the left hemisphere, which may reflect a right-hemispheric dominance in the processing of tonal stimuli.

Explore related subjects

Acoustic StimulationAdultAuditory CortexAuditory PerceptionDominance, CerebralEvoked Potentials, AuditoryHumansMagnetoencephalographyPsychophysicsReaction TimeJournal ArticleResearch Support, Non-U.S. Gov't

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Yoshiharu Soeta, Seiji Nakagawa. 2006-11-01. Complex tone processing and critical band in the human auditory cortex.. https://doi.org/10.1016/j.heares.2006.09.005

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2008

Sensory filtering phenomenology in PTSD.

Disrupted sensory filtering, or problems with suppressing irrelevant environmental sensory stimuli, has been reported in individuals with posttraumatic stress disorder (PTSD). However, the relationship of sensory filtering deficits to specific PTSD symptoms versus an association with general trauma exposure is unclear. These relationships were examined by administering self-report measures of trauma exposure, PTSD, and sensory gating phenomenology to undergraduate participants with PTSD (n=32), with trauma history but without PTSD (n=144), and with minimal trauma history (n=153). Subjects with PTSD reported greater filtering disruption than individuals in the trauma only and low trauma groups, who did not differ. Individuals endorsing reexperiencing and numbing symptoms, and females endorsing hypervigilance, reported disrupted sensory filtering phenomenology. These results suggest that impaired filtering differentiates between individuals with PTSD symptoms and asymptomatic individuals exposed to multiple traumas and low-trauma controls.

Acoustic Stimulation↗
PubMed2007

Hypoglycemia reduces the blood-oxygenation level dependent signal in primary auditory and visual cortex: a functional magnetic resonance imaging study.

Studies of the effects of hypoglycemia on the brain using neurocognitive testing have suggested that mainly complex functions subserved by secondary and tertiary cortex are affected by mild to moderate hypoglycemia and that intensively treated patients with Type I diabetes mellitus (T1DM) may have altered sensitivity to the central nervous system effects of hypoglycemia. Functional magnetic resonance imaging provides a sensitive, regionally-specific probe of possible neurophysiologic changes related to hypoglycemia in the brain. Eleven intensively-treated T1DM patients and 11 matched non-diabetic controls took part in a 2-day protocol in which functional magnetic resonance imaging (MRI) was used to measure changes in the patterns of brain activation produced by simple auditory and visual stimuli in different conditions. On one day, participants were euglycemic the entire time. On the other day, an initial 50-min euglycemic period was followed by a 50-min hypoglycemic period. Results indicated that hypoglycemia reduced the amplitude of the blood-oxygenation level dependent response in primary auditory and visual cortex to simple auditory and visual stimuli. The latency and duration of the transient hemodynamic response function were not affected. Responses to hypoglycemia were similar in diabetic and non-diabetic participants. These results suggest that mild to moderate hypoglycemia may alter the balance of blood flow and oxygen extraction when glucose levels are lowered. Intensively-treated T1DM, with its attendant frequent hypoglycemic episodes, did not seem to alter hypoglycemic responses in primary visual and auditory cortex.

Acoustic Stimulation↗
PubMed2007

Song discrimination learning in zebra finches induces highly divergent responses to novel songs.

Perceptual biases can shape the evolution of signal form. Understanding the origin and direction of such biases is therefore crucial for understanding signal evolution. Many animals learn about species-specific signals. Discrimination learning using simple stimuli varying in one dimension (e.g. amplitude, wavelength) can result in perceptual biases with preferences for specific novel stimuli, depending on the stimulus dimensions. We examine how this translates to discrimination learning involving complex communication signals; birdsongs. Zebra finches (Taeniopygia guttata) were trained to discriminate between two artificial songs, using a Go/No-Go procedure. The training songs in experiment 1 differed in the number of repeats of a particular element. The songs in experiment 2 differed in the position of an odd element in a series of repeated elements. We examined generalization patterns by presenting novel songs with more or fewer repeated elements (experiment 1), or with the odd element earlier or later in the repeated element sequence (experiment 2). Control birds were trained with only one song. The generalization curves obtained from (i) control birds, (ii) experimental birds in experiment 1, and (iii) experimental birds in experiment 2 showed large and systematic differences from each other. Birds in experiment 1, but not 2, responded more strongly to specific novel songs than to training songs, showing 'peak shift'. The outcome indicates that learning about communication signals may give rise to perceptual biases that may drive signal evolution.

Acoustic Stimulation↗