Co-Planar Stereotaxic Atlas of the Human Brain—3-Dimensional Proportional System: An Approach to Cerebral Imaging, J. Talairach, P. Tournoux. Georg Thieme Verlag, New York (1988), 122 pp., 130 figs. DM 268

Mini Mental State

http://mriquestions.com/uploads/3/4/5/7/34572113/language_review1-s2.0-s1053811912004703-main.pdf

A review and synthesis of the first 20 years of PET and fMRI studies of heard speech, spoken language and reading

Speech and language are considered uniquely human abilities: animals have communication systems, but they do not match human linguistic skills in terms of recursive structure and combinatorial power. Yet, in evolution, spoken language must have emerged from neural mechanisms at least partially available in animals. In this paper, we will demonstrate how our understanding of speech perception, one important facet of language, has profited from findings and theory in nonhuman primate studies. Chief among these are physiological and anatomical studies showing that primate auditory cortex, across species, shows patterns of hierarchical structure, topographic mapping and streams of functional processing. We will identify roles for different cortical areas in the perceptual processing of speech and review functional imaging work in humans that bears on our understanding of how the brain decodes and monitors speech. A new model connects structures in the temporal, frontal and parietal lobes linking speech perception and production.

/pdf/maps-and-streams-in-the-auditory-cortex-nonhuman-primates-4a7cmw3941.pdf

Maps and streams in the auditory cortex: nonhuman primates illuminate human speech processing.

Ever since Pliny the Elder coined the term tinnitus, the perception of sound in the absence of an external sound source has remained enigmatic. Traditional theories assume that tinnitus is triggered by cochlear damage, but many tinnitus patients present with a normal audiogram, i.e., with no direct signs of cochlear damage. Here, we report that in human subjects with tinnitus and a normal audiogram, auditory brainstem responses show a significantly reduced amplitude of the wave I potential (generated by primary auditory nerve fibers) but normal amplitudes of the more centrally generated wave V. This provides direct physiological evidence of "hidden hearing loss" that manifests as reduced neural output from the cochlea, and consequent renormalization of neuronal response magnitude within the brainstem. Employing an established computational model, we demonstrate how tinnitus could arise from a homeostatic response of neurons in the central auditory system to reduced auditory nerve input in the absence of elevated hearing thresholds.

https://www.jneurosci.org/content/jneuro/31/38/13452.full.pdf

Tinnitus with a normal audiogram: physiological evidence for hidden hearing loss and computational model.

Tuning out the noise: limbic-auditory interactions in tinnitus.

https://www.cell.com/neuron/pdf/S0896-6273(10)00987-6.pdf

Dysregulation of Limbic and Auditory Networks in Tinnitus

How the brain processes complex sounds, like voices or musical instrument sounds, is currently not well understood. The features comprising the acoustic profiles of such sounds are thought to be represented by neurons responding to increasing degrees of complexity throughout auditory cortex, with complete auditory "objects" encoded by neurons (or small networks of neurons) in anterior superior temporal regions. Although specialized voice and speech-sound regions have been proposed, it is unclear how other types of complex natural sounds are processed within this object-processing pathway. Using functional magnetic resonance imaging, we sought to demonstrate spatially distinct patterns of category-selective activity in human auditory cortex, independent of semantic content and low-level acoustic features. Category-selective responses were identified in anterior superior temporal regions, consisting of clusters selective for musical instrument sounds and for human speech. An additional subregion was identified that was particularly selective for the acoustic-phonetic content of speech. In contrast, regions along the superior temporal plane closer to primary auditory cortex were not selective for stimulus category, responding instead to specific acoustic features embedded in natural sounds, such as spectral structure and temporal modulation. Our results support a hierarchical organization of the anteroventral auditory-processing stream, with the most anterior regions representing the complete acoustic signature of auditory objects.

https://www.jneurosci.org/content/jneuro/30/22/7604.full.pdf

Cortical representation of natural complex sounds: effects of acoustic features and auditory object category.

Structural Plasticity of the Hippocampus and Amygdala Induced by Electroconvulsive Therapy in Major Depression.

Music consists of sound sequences that require integration over time. As we become familiar with music, associations between notes, melodies, and entire symphonic movements become stronger and more complex. These associations can become so tight that, for example, hearing the end of one album track can elicit a robust image of the upcoming track while anticipating it in total silence. Here, we study this predictive "anticipatory imagery" at various stages throughout learning and investigate activity changes in corresponding neural structures using functional magnetic resonance imaging. Anticipatory imagery (in silence) for highly familiar naturalistic music was accompanied by pronounced activity in rostral prefrontal cortex (PFC) and premotor areas. Examining changes in the neural bases of anticipatory imagery during two stages of learning conditional associations between simple melodies, however, demonstrates the importance of fronto-striatal connections, consistent with a role of the basal ganglia in "training" frontal cortex (Pasupathy and Miller, 2005). Another striking change in neural resources during learning was a shift between caudal PFC earlier to rostral PFC later in learning. Our findings regarding musical anticipation and sound sequence learning are highly compatible with studies of motor sequence learning, suggesting common predictive mechanisms in both domains.

https://www.jneurosci.org/content/jneuro/29/8/2477.full.pdf

Amber M. Leaver

Papers

Tuning out the noise: limbic-auditory interactions in tinnitus.

Dysregulation of Limbic and Auditory Networks in Tinnitus

Cortical representation of natural complex sounds: effects of acoustic features and auditory object category.

Structural Plasticity of the Hippocampus and Amygdala Induced by Electroconvulsive Therapy in Major Depression.

Brain Activation during Anticipation of Sound Sequences