scholarly journals Lack of tonotopic organization of the auditory cortex in schizophrenia

2014 ◽  
Author(s):  
Thomas Ragole ◽  
Erin Slason ◽  
Peter Teale ◽  
Martin Reite ◽  
Donald C. Rojas
Keyword(s):  
Magnetic Field ◽  
Auditory Cortex ◽  
Cognitive Processes ◽  
Spatial Organization ◽  
Primary Auditory Cortex ◽  
Auditory Stimuli ◽  
Healthy Controls ◽  
Equivalent Current Dipole ◽  
Current Dipole ◽  
Tonotopic Organization

Background: Disorganization of tonotopy in the auditory cortex has been described in schizophrenia. Subjects with schizophrenia show little to no spatial organization of responses to different tone frequencies in the auditory cortex. Previous studies have called into question the use of MEG and the M100 response to assess tonotopy. This study seeks to replicate prior results of tonotopic disorganization in schizophrenia compared to healthy controls. Methods: The tonotopic organization for 400 Hz and 4,000 Hz sound in 19 patients with schizophrenia and 11 comparison subjects was determined using MEG by examining the M100 auditory-evoked magnetic field dipole in primary auditory cortex. The equivalent current dipole locations were then mapped and compared. Results: The previous result of a lack of tonotopy in subjects with schizophrenia was partly replicated. In control subjects, the 400 Hz tone auditory evoked field was found anterior to the 4000 Hz in the primary auditory cortex. Conclusions: The lack of tonotopic organization of the auditory cortex is replicable in patients with schizophrenia and suggests that the architecture underlying tonotopy in the auditory cortex is disordered. This result suggests possible alteration in the organization of the auditory cortex, which may in turn influence higher order cognitive processes by altering the perception of incoming auditory stimuli.

scholarly journals Lack of tonotopic organization of the auditory cortex in schizophrenia

2014 ◽  
Author(s):  
Thomas Ragole ◽  
Erin Slason ◽  
Peter Teale ◽  
Martin Reite ◽  
Donald C. Rojas
Keyword(s):  
Magnetic Field ◽  
Auditory Cortex ◽  
Cognitive Processes ◽  
Spatial Organization ◽  
Primary Auditory Cortex ◽  
Auditory Stimuli ◽  
Healthy Controls ◽  
Equivalent Current Dipole ◽  
Current Dipole ◽  
Tonotopic Organization

Background: Disorganization of tonotopy in the auditory cortex has been described in schizophrenia. Subjects with schizophrenia show little to no spatial organization of responses to different tone frequencies in the auditory cortex. Previous studies have called into question the use of MEG and the M100 response to assess tonotopy. This study seeks to replicate prior results of tonotopic disorganization in schizophrenia compared to healthy controls. Methods: The tonotopic organization for 400 Hz and 4,000 Hz sound in 19 patients with schizophrenia and 11 comparison subjects was determined using MEG by examining the M100 auditory-evoked magnetic field dipole in primary auditory cortex. The equivalent current dipole locations were then mapped and compared. Results: The previous result of a lack of tonotopy in subjects with schizophrenia was partly replicated. In control subjects, the 400 Hz tone auditory evoked field was found anterior to the 4000 Hz in the primary auditory cortex. Conclusions: The lack of tonotopic organization of the auditory cortex is replicable in patients with schizophrenia and suggests that the architecture underlying tonotopy in the auditory cortex is disordered. This result suggests possible alteration in the organization of the auditory cortex, which may in turn influence higher order cognitive processes by altering the perception of incoming auditory stimuli.

Functional Organization of Squirrel Monkey Primary Auditory Cortex: Responses to Pure Tones

2001 ◽  
Vol 85 (4) ◽  
pp. 1732-1749 ◽  
Author(s):  
Steven W. Cheung ◽  
Purvis H. Bedenbaugh ◽  
Srikantan S. Nagarajan ◽  
Christoph E. Schreiner
Keyword(s):  
Receptive Field ◽  
Auditory Cortex ◽  
Squirrel Monkey ◽  
Spatial Organization ◽  
Functional Organization ◽  
Primary Auditory Cortex ◽  
Complex Sound ◽  
Sound Coding ◽  
Field Gradients ◽  
Pure Tones

The spatial organization of response parameters in squirrel monkey primary auditory cortex (AI) accessible on the temporal gyrus was determined with the excitatory receptive field to pure tone stimuli. Dense, microelectrode mapping of the temporal gyrus in four animals revealed that characteristic frequency (CF) had a smooth, monotonic gradient that systematically changed from lower values (0.5 kHz) in the caudoventral quadrant to higher values (5–6 kHz) in the rostrodorsal quadrant. The extent of AI on the temporal gyrus was ∼4 mm in the rostrocaudal axis and 2–3 mm in the dorsoventral axis. The entire length of isofrequency contours below 6 kHz was accessible for study. Several independent, spatially organized functional response parameters were demonstrated for the squirrel monkey AI. Latency, the asymptotic minimum arrival time for spikes with increasing sound pressure levels at CF, was topographically organized as a monotonic gradient across AI nearly orthogonal to the CF gradient. Rostral AI had longer latencies (range = 4 ms). Threshold and bandwidth co-varied with the CF. Factoring out the contribution of the CF on threshold variance, residual threshold showed a monotonic gradient across AI that had higher values (range = 10 dB) caudally. The orientation of the threshold gradient was significantly different from the CF gradient. CF-corrected bandwidth, residual Q10, was spatially organized in local patches of coherent values whose loci were specific for each monkey. These data support the existence of multiple, overlying receptive field gradients within AI and form the basis to develop a conceptual framework to understand simple and complex sound coding in mammals.

scholarly journals Temporal Nonlinearity During Recovery From Sequential Inhibition by Neurons in the Cat Primary Auditory Cortex

2006 ◽  
Vol 95 (3) ◽  
pp. 1897-1907 ◽  
Author(s):  
Kyle T. Nakamoto ◽  
Jiping Zhang ◽  
Leonard M. Kitzes
Keyword(s):  
Auditory Cortex ◽  
Recovery Rate ◽  
Primary Auditory Cortex ◽  
Auditory Stimuli ◽  
Time Interval ◽  
Large Set ◽  
Strong Response ◽  
Preceding Stimulus ◽  
Sequential Inhibition ◽  
Response Area

Auditory stimuli occur most often in sequences rather than in isolation. It is therefore necessary to understand how responses to sounds occurring in sequences differ from responses to isolated sounds. Cells in primary auditory cortex (AI) respond to a large set of binaural stimuli when presented in isolation. The set of responses to such stimuli presented at one frequency comprises a level response area. A preceding binaural stimulus can reduce the size and magnitude of level response areas of AI cells. The present study focuses on the effects of the time interval between a preceding stimulus and the stimuli of a level response area in pentobarbital-anesthetized cats. After the offset of a preceding stimulus, the ability of AI cells to respond to succeeding stimuli varies dynamically in time. At short interstimulus intervals (ISI), a preceding stimulus can completely inhibit responses to succeeding stimuli. With increasing ISIs, AI cells respond first to binaural stimuli that evoke the largest responses in the control condition, i.e., not preceded by a stimulus. Recovery rate is nonlinear across the level response area; responses to these most-effective stimuli recover to 70% of control on average 187 ms before responses to other stimuli recover to 70% of their control sizes. During the tens to hundreds of milliseconds that a level response area is reduced in size and magnitude, the selectivity of AI cells is increased for stimuli that evoke the largest responses. This increased selectivity results from a temporal nonlinearity in the recovery of the level response area which protects responses to the most effective binaural stimuli. Thus in a sequence of effective stimuli, a given cell will respond selectively to only those stimuli that evoke a strong response when presented alone.

Tonotopic organization of responses reflecting stop consonant place of articulation in primary auditory cortex (A1) of the monkey

1995 ◽  
Vol 674 (1) ◽  
pp. 147-152 ◽  
Author(s):  
Mitchell Steinschneider ◽  
David Reser ◽  
Charles E. Schroeder ◽  
Joseph C. Arezzo
Keyword(s):  
Auditory Cortex ◽  
Stop Consonant ◽  
Primary Auditory Cortex ◽  
Tonotopic Organization ◽  
Place Of Articulation

Note on tonotopic organization of primary auditory cortex in the cat

1975 ◽  
Vol 100 (1) ◽  
pp. 188-191 ◽  
Author(s):  
Moise H. Goldstein ◽  
Moshe Abeles
Keyword(s):  
Auditory Cortex ◽  
Primary Auditory Cortex ◽  
Tonotopic Organization

scholarly journals Local Homogeneity of Tonotopic Organization in the Primary Auditory Cortex of Marmosets

2018 ◽  
Author(s):  
Huan-huan Zeng ◽  
Jun-feng Huang ◽  
Ming Chen ◽  
Yun-qing Wen ◽  
Zhi-ming Shen ◽  
...  
Keyword(s):  
Auditory Cortex ◽  
Large Scale ◽  
Frequency Tuning ◽  
Primary Auditory Cortex ◽  
Primate Species ◽  
Tonotopic Organization ◽  
Brain Structure And Function ◽  
A1 Neurons ◽  
Cortical Regions

AbstractMarmoset has emerged as a useful non-human primate species for studying the brain structure and function. Previous studies on the mouse primary auditory cortex (A1) showed that neurons with preferential frequency tuning responses are mixed within local cortical regions, despite a large-scale tonotopic organization. Here we found that frequency tuning properties of marmoset A1 neurons are highly uniform within local cortical regions. We first defined tonotopic map of A1 using intrinsic optical imaging, and then used in vivo two-photon calcium imaging of large neuronal populations to examine the tonotopic preference at the single-cell level. We found that tuning preferences of layer 2/3 neurons were highly homogeneous over hundreds of micrometers in both horizontal and vertical directions. Thus, marmoset A1 neurons are distributed in a tonotopic manner at both macro- and microscopic levels. Such organization is likely to be important for the organization of auditory circuits in the primate brain.

scholarly journals Competition for neuronal resources: how hallucinations make themselves heard

2007 ◽  
Vol 190 (1) ◽  
pp. 57-62 ◽  
Author(s):  
Daniela Hubl ◽  
Thomas Koenig ◽  
Werner K. Strik ◽  
Lester Melie Garcia ◽  
Thomas Dierks
Keyword(s):  
Auditory Cortex ◽  
Evoked Potentials ◽  
Auditory Evoked Potentials ◽  
Primary Auditory Cortex ◽  
Auditory Attention ◽  
Auditory Hallucinations ◽  
Auditory Stimuli ◽  
Simultaneous Occurrence ◽  
Auditory Verbal Hallucinations ◽  
External Stimuli

BackgroundHallucinations are perceptions in the absence of a corresponding external sensory stimulus. However, during auditory verbal hallucinations, activation of the primary auditory cortex has been described.AimsThe objective of this study was to investigate whether this activation of the auditory cortex contributes essentially to the character of hallucinations and attributes them to alien sources, or whether the auditory activation is a sign of increased general auditory attention to external sounds.MethodThe responsiveness of the auditory cortex was investigated by auditory evoked potentials (N100) during the simultaneous occurrence of hallucinations and external stimuli. Evoked potentials were computed separately for periods with and without hallucinations; N100 power, topography and brain electrical sources were analysed.ResultsHallucinations lowered the N100 amplitudes and changed the topography, presumably due to a reduced left temporal responsivity.ConclusionsThis finding indicates competition between auditory stimuli and hallucinations for physiological resources in the primary auditory cortex. The abnormal activation of the primary auditory cortex may thus be a constituent of auditory hallucinations.

scholarly journals Antidromic Activation Reveals Tonotopically Organized Projections From Primary Auditory Cortex to the Central Nucleus of the Inferior Colliculus in Guinea Pig

2007 ◽  
Vol 97 (2) ◽  
pp. 1413-1427 ◽  
Author(s):  
Hubert H. Lim ◽  
David J. Anderson
Keyword(s):  
Auditory Cortex ◽  
Inferior Colliculus ◽  
Spatial Organization ◽  
Medial Geniculate Body ◽  
Primary Auditory Cortex ◽  
Central Nucleus ◽  
Antidromic Activation ◽  
Antidromic Stimulation ◽  
Medial Geniculate ◽  
Layer V

The inferior colliculus (IC) is highly modulated by descending projections from higher auditory and nonauditory centers. Traditionally, corticofugal fibers were believed to project mainly to the extralemniscal IC regions. However, there is some anatomical evidence suggesting that a substantial number of fibers from the primary auditory cortex (A1) project into the IC central nucleus (ICC) and appear to be tonotopically organized. In this study, we used antidromic stimulation combined with other electrophysiological techniques to further investigate the spatial organization of descending fibers from A1 to the ICC in ketamine-anesthetized guinea pigs. Based on our findings, corticofugal fibers originate predominantly from layer V of A1, are amply scattered throughout the ICC and only project to ICC neurons with a similar best frequency (BF). This strict tonotopic pattern suggests that these corticofugal projections are involved with modulating spectral features of sound. Along the isofrequency dimension of the ICC, there appears to be some differences in projection patterns that depend on BF region and possibly isofrequency location within A1 and may be indicative of different descending coding strategies. Furthermore, the success of the antidromic stimulation method in our study demonstrates that it can be used to investigate some of the functional properties associated with corticofugal projections to the ICC as well as to other regions (e.g., medial geniculate body, cochlear nucleus). Such a method can address some of the limitations with current anatomical techniques for studying the auditory corticofugal system.

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