scholarly journals Network-based asymmetry of the human auditory system

2018 ◽  
Author(s):  
Bratislav Mišić ◽  
Richard F. Betzel ◽  
Alessandra Griffa ◽  
Marcel A. de Reus ◽  
Ye He ◽  
...  
Keyword(s):  
Auditory Cortex ◽  
Shortest Paths ◽  
Network Configuration ◽  
Brain Areas ◽  
Opposite Hemisphere ◽  
Efficient Communication ◽  
Functional Lateralization ◽  
Left And Right ◽  
Auditory Cortices ◽  
The Right

Converging evidence from activation, connectivity and stimulation studies suggests that auditory brain networks are lateralized. Here we show that these findings can be at least partly explained by the asymmetric network embedding of the primary auditory cortices. Using diffusion-weighted imaging in three independent datasets, we investigate the propensity for left and right auditory cortex to communicate with other brain areas by quantifying the centrality of the auditory network across a spectrum of communication mechanisms, from shortest path communication to diffusive spreading. Across all datasets, we find that the right auditory cortex is better integrated in the connectome, facilitating more efficient communication with other areas, with much of the asymmetry driven by differences in communication pathways to the opposite hemisphere. Critically, the primacy of the right auditory cortex emerges only when communication is conceptualized as a diffusive process, taking advantage of more than just the topologically shortest paths in the network. Altogether, these results highlight how the network configuration and embedding of a particular region may contribute to its functional lateralization.

Contribution of auditory cortex to sound localization by the ferret (Mustela putorius)

1987 ◽  
Vol 57 (6) ◽  
pp. 1746-1766 ◽  
Author(s):  
G. L. Kavanagh ◽  
J. B. Kelly
Keyword(s):  
Auditory Cortex ◽  
Sound Localization ◽  
Horizontal Plane ◽  
Primary Auditory Cortex ◽  
Cortical Lesions ◽  
Mustela Putorius ◽  
Complete Destruction ◽  
Left And Right ◽  
The Right ◽  
Bilateral Lesions

Ferrets were tested in a semicircular apparatus to determine the effects of auditory cortical lesions on their ability to localize sounds in space. They were trained to initiate trials while facing forward in the apparatus, and sounds were presented from one of two loudspeakers located in the horizontal plane. Minimum audible angles were obtained for three different positions, viz., the left hemifield, with loudspeakers centered around -60 degrees azimuth; the right hemifield, with loudspeakers centered around +60 degrees azimuth; and the midline with loudspeakers centered around 0 degrees azimuth. Animals with large bilateral lesions had severe impairments in localizing a single click in the midline test. Following complete destruction of the auditory cortex performance was only marginally above the level expected by chance even at large angles of speaker separation. Severe impairments were also found in localization of single clicks in both left and right lateral fields. In contrast, bilateral lesions restricted to the primary auditory cortex resulted in minimal impairments in midline localization. The same lesions, however, produced severe impairments in localization of single clicks in both left and right lateral fields. Large unilateral lesions that destroyed auditory cortex in one hemisphere resulted in an inability to localize single clicks in the contralateral hemifield. In contrast, no impairments were found in the midline test or in the ipsilateral hemifield. Unilateral lesions of the primary auditory cortex resulted in severe contralateral field deficits equivalent to those seen following complete unilateral destruction of auditory cortex. No deficits were seen in either the midline or the ipsilateral tests.

scholarly journals The rodent hippocampus as a bilateral structure: A review of hemispheric lateralization

2017 ◽  
Author(s):  
Jake T. Jordan
Keyword(s):  
Brain Region ◽  
Spatial Information ◽  
Right Hemisphere ◽  
Neural Substrates ◽  
Hemispheric Lateralization ◽  
Hemispheric Differences ◽  
Functional Lateralization ◽  
Left And Right ◽  
The Right ◽  
Behavior And Cognition

AbstractThe left and right rodent hippocampi exhibit striking lateralization in some of the very neural substrates considered to be critical for hippocampal cognitive function. Despite this, there is an overwhelming lack of consideration for hemispheric differences in studies of the rodent hippocampus. Asymmetries identified so far suggest that a bilateral model of the hippocampus will be essential for an understanding of this brain region, and perhaps of the brain more widely. Although hypotheses have been proposed to explain how the left and right hippocampi contribute to behavior and cognition, these hypotheses have either been refuted by more recent studies or have been limited in the scope of data they explain. Here, I will first review data on human and rodent hippocampal lateralization. The implications of these data suggest that considering the hippocampus as a bilateral structure with functional lateralization will be critical moving forward in understanding the function and mechanisms of this brain region. In exploring these implications, I will then propose a hypothesis of the hippocampus as a bilateral structure. This discrete-continuous (DC) hypothesis proposes that the left and right hippocampi contribute to spatial memory and navigation in a complementary manner. Specifically, the left hemisphere stores spatial information as discrete, salient locations and that the right hemisphere represents space continuously, contributing to route computation and flexible spatial navigation. Consideration of hippocampal lateralization in designing future studies may provide insight into the function of the hippocampus and resolve debates concerning its function.

scholarly journals Neural support of manual preference revealed by BOLD variations during right and left finger-tapping in a sample of 287 healthy adults balanced for handedness

2020 ◽  
Author(s):  
Nathalie Tzourio-Mazoyer ◽  
Loïc Labache ◽  
Laure Zago ◽  
Isabelle Hesling ◽  
Bernard Mazoyer
Keyword(s):  
Finger Tapping ◽  
Brain Areas ◽  
Left Hand ◽  
Left Handedness ◽  
Somatosensory Cortices ◽  
Hand Control ◽  
Left And Right ◽  
The Right ◽  
The Brain ◽  
Somatosensory Areas

AbstractWe have identified the brain areas involved in Manual Preference (MP) in 143 left-handers (LH) and 144 right-handers (RH)). First, we selected the pairs of homotopic regions of interest (hROIs) of the AICHA atlas with significant contralateral activation and asymmetry during the right-hand and the left-hand Finger-Tapping (FT) both in RH and LH. Thirteen hROIs were selected, including the primary and secondary sensorimotor, and premotor cortices, thalamus, dorsal putamen and cerebellar lobule IV. Both contralateral activations and ipsilateral deactivations (reversed for the cerebellum) were seen in primary motor and somatosensory areas, with stronger asymmetries when the preferred hand was used. Comparing the prediction of MP with different combinations of BOLD variations in these 13 hROIs, the differences between movement of the preferred hand versus that of the non-preferred hand within the contralateral and/or ipsilateral cortices of 11 hROIS performed best at explaining handedness distribution, Handedness is thus supported by: 1-between-hand variations of ipsilateral deactivations of hand primary sensorimotor and secondary somatosensory cortices and 2-variations in regions showing the same profile in left and right-handers during the right or left FT. The present study demonstrates that right and left-handedness are not based on mirrored organization of hand control areas.

scholarly journals Asymmetric Lateralization during Pain Processing

Symmetry ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2416
Author(s):  
Carolina Roza ◽  
Anabel Martinez-Padilla
Keyword(s):  
Chronic Pain ◽  
Right Hemisphere ◽  
Emotional Experience ◽  
Cellular Level ◽  
Pain Processing ◽  
Brain Areas ◽  
Functional Studies ◽  
Functional Lateralization ◽  
Pain Symptoms ◽  
The Right

Pain is defined as “an unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage”. This complex perception arises from the coordinated activity of several brain areas processing either sensory–discriminative or affective–motivational components. Functional studies performed in healthy volunteers revealed that affective–emotional components of pain are processed bilaterally but present a clear lateralization towards the right hemisphere, regardless of the site of stimulation. Studies at the cellular level performed in experimental animal models of pain have shown that neuronal activity in the right amygdala is clearly pronociceptive, whilst activation of neurons in the left amygdala might even exert antinociceptive effects. A shift in lateralization becomes evident during the development of chronic pain; thus, in patients with neuropathic pain symptoms, there is increased activity in ipsilateral brain areas related with pain. These observations extend the asymmetrical left–right lateralization within the nervous system and provide a new hypothesis for the pathophysiology of chronic forms of pain. In this article, we will review experimental data from preclinical and human studies on functional lateralization in the brain during pain processing, which will help to explain the affective disorders associated with persistent, chronic pain.

scholarly journals Metabolic Lateralization in the Hypothalamus of Male Rats Related to Reproductive and Satiety States

2020 ◽  
Vol 27 (5) ◽  
pp. 1197-1205 ◽  
Author(s):  
David S. Kiss ◽  
Istvan Toth ◽  
Gergely Jocsak ◽  
Tibor Bartha ◽  
Laszlo V. Frenyo ◽  
...  
Keyword(s):  
Food Intake ◽  
Right Hemisphere ◽  
Ex Vivo ◽  
Functional Asymmetry ◽  
Male Rats ◽  
Reproductive Control ◽  
State Dependent ◽  
Functional Lateralization ◽  
Left And Right ◽  
The Right

AbstractThe hypothalamus is the main regulatory center of many homeostatic processes, such as reproduction, food intake, and sleep-wake behavior. Recent findings show that there is a strongly interdependent side-linked localization of hypothalamic functions between the left and right hemispheres. The goal of the present study was to trace functional asymmetry of the hypothalamus related to the regulation of food intake and reproduction, in male rodents. Subjects were examined through measurements of mitochondrial metabolism ex vivo. Impact of gonadectomy and scheduled feeding was tested on the modulation of hypothalamic metabolic asymmetry. Results show that in male rats, functional lateralization of the hypothalamus can be attributed to the satiety state rather than to reproductive control. Fasting caused left-sided metabolic dominance, while satiety was linked to the right hemisphere; trends and direction in sided dominance gradually followed the changes in satiety state. Our findings revealed satiety state-dependent metabolic differences between the two hypothalamic hemispheres. It is therefore concluded that, at least in male rats, the hypothalamic hemispheres control the satiety state-related functions in an asymmetric manner.

scholarly journals Neurophysiological Evaluation of Right-Ear Advantage During Dichotic Listening

2021 ◽  
Vol 12 ◽  
Author(s):  
Keita Tanaka ◽  
Bernhard Ross ◽  
Shinya Kuriki ◽  
Tsuneo Harashima ◽  
Chie Obuchi ◽  
...  
Keyword(s):  
Steady State ◽  
Auditory Cortex ◽  
Dichotic Listening ◽  
Steady State Response ◽  
State Response ◽  
Auditory Steady State Response ◽  
Left And Right ◽  
Ear Advantage ◽  
Right Ear Advantage ◽  
The Right

Right-ear advantage refers to the observation that when two different speech stimuli are simultaneously presented to both ears, listeners report stimuli more correctly from the right ear than the left. It is assumed to result from prominent projection along the auditory pathways to the contralateral hemisphere and the dominance of the left auditory cortex for the perception of speech elements. Our study aimed to investigate the role of attention in the right-ear advantage. We recorded magnetoencephalography data while participants listened to pairs of Japanese two-syllable words (namely, “/ta/ /ko/” or “/i/ /ka/”). The amplitudes of the stimuli were modulated at 35 Hz in one ear and 45 Hz in the other. Such frequency-tagging allowed the selective quantification of left and right auditory cortex responses to left and right ear stimuli. Behavioral tests confirmed the right-ear advantage, with higher accuracy for stimuli presented to the right ear than to the left. The amplitude of the auditory steady-state response was larger when attending to the stimuli compared to passive listening. We detected a correlation between the attention-related increase in the amplitude of the auditory steady-state response and the laterality index of behavioral accuracy. The right-ear advantage in the free-response dichotic listening was also found in neural activities in the left auditory cortex, suggesting that it was related to the allocation of attention to both ears.

Applying Frequency Bands to Explore the Identification of Two Dimensional Figures

2013 ◽  
Vol 311 ◽  
pp. 196-201
Author(s):  
Chia Ju Liu ◽  
Chin Fei Huang ◽  
Chia Yi Chou ◽  
Ming Chi Lu ◽  
Yung Yi Chang ◽  
...  
Keyword(s):  
Mental Rotation ◽  
Left Hemisphere ◽  
Cognitive Processing ◽  
Right Hemisphere ◽  
Brain Activity ◽  
Brain Areas ◽  
Opposite Hemisphere ◽  
Frequency Bands ◽  
The Right ◽  
Hemisphere Specialization

The aim of this study was to apply frequency bands to explore how mental rotation strategies affect the identification of 2D figures. Eighteen adults were recruited for this study. In the ERP experiments, the participants were required to identify 2D figures with mental rotation. The results showed the differences between the high-achieving (HA) and low-achieving (LA) spatial ability participants in their use of mental rotation for identifying 2D figures. At 300-380 ms, the HA participants showed higher brain activity in the right hemisphere than in other brain areas, whereas the LA participants showed activity in the whole brain. At 520 to 620 ms, the areas of brain activity were in the opposite hemisphere for the HA and LA participants. The highest brain activity was shown in the left hemisphere of the HA participants and in the right hemisphere for the LA participants at 520 to 620 ms. The implication of this study is that right hemisphere specialization for mental rotation might appear in early cognitive processing, but in late cognitive processing, the left hemisphere specialization form of mental rotation might show an advantage.

scholarly journals Causal relationship between the right auditory cortex and speech-evoked frequency-following response: Evidence from combined tDCS and EEG

2020 ◽  
Author(s):  
Guangting Mai ◽  
Peter Howell
Keyword(s):  
Auditory Cortex ◽  
Causal Relationship ◽  
Right Hemisphere ◽  
Clinical Importance ◽  
Auditory Brainstem ◽  
After Effects ◽  
Frequency Following Response ◽  
Clinical Biomarkers ◽  
Auditory Cortices ◽  
The Right

AbstractSpeech-evoked frequency-following response (FFR) reflects the neural encoding of speech periodic information in the human auditory systems. FFR is of fundamental importance for pitch and speech perception and serves as clinical biomarkers for various auditory and language disorders. While it is suggested that the main neural source of FFR is in the auditory brainstem, recent studies have shown a cortical contribution to FFR predominantly in the right hemisphere. However, it is still unclear whether auditory cortex and FFR are causally related. The aim of this study was to establish this causal relationship using a combination of transcranial direct current stimulation (tDCS) and scalp-recorded electroencephalography (EEG). We applied tDCS over the left and right auditory cortices in right-handed normal-hearing participants and examined the after-effects of tDCS on FFR using EEG during monaural listening to a repeatedly-presented speech syllable. Our results showed that: (1) before tDCS was applied, participants had greater FFR magnitude when they listened to speech from the left than the right ear, illustrating right-lateralized hemispheric asymmetry for FFR; (2) anodal and cathodal tDCS applied over the right, but not left, auditory cortex significantly changed FFR magnitudes compared to the sham stimulation; specifically, such after-effects occurred only when participants listened to speech from the left ear, emphasizing the right auditory cortical contributions along the contralateral pathway. The current finding thus provides the first causal evidence that validates the relationship between the right auditory cortex and speech-evoked FFR and should significantly extend our understanding of speech encoding in the brain.Significance StatementSpeech-evoked frequency-following response (FFR) is a neural activity that reflects the brain’s encoding of speech periodic features. The FFR has great fundamental and clinical importance for auditory processing. Whilst convention maintains that FFR derives mainly from the brainstem, it has been argued recently that there are additional contributions to FFR from the auditory cortex. Using a combination of tDCS, that altered neural excitability of auditory cortices, and EEG recording, the present study provided the first evidence to validate a causal relationship between the right auditory cortex and speech-evoked FFR. The finding supports the right-asymmetric auditory cortical contributions to processing of speech periodicity and advances our understanding of how speech signals are encoded and analysed along the central auditory pathways.

Cortical Response to Auditory Motion Suggests an Asymmetry in the Reliance on Inter-Hemispheric Connections Between the Left and Right Auditory Cortices

2007 ◽  
Vol 97 (2) ◽  
pp. 1649-1655 ◽  
Author(s):  
Katrin Krumbholz ◽  
Nicola Hewson-Stoate ◽  
Marc Schönwiesner
Keyword(s):  
Hemispheric Lateralization ◽  
Spatial Processing ◽  
Auditory Motion ◽  
Motion Onset ◽  
Opposite Hemisphere ◽  
Response Latencies ◽  
Left And Right ◽  
Auditory Cortices ◽  
Onset Response ◽  
To Receive

The aim of the current study was to measure the brain's response to auditory motion using electroencephalography (EEG) to gain insight into the mechanisms by which hemispheric lateralization for auditory spatial processing is established in the human brain. The onset of left- or rightward motion in an otherwise continuous sound was found to elicit a large response, which appeared to arise from higher-level nonprimary auditory areas. This motion onset response was strongly lateralized to the hemisphere contralateral to the direction of motion. The response latencies suggest that the ipsilateral response to the leftward motion was produced by indirect callosal projections from the opposite hemisphere, whereas the ipsilateral response to the rightward motion seemed to receive contributions from direct thalamocortical projections. These results suggest an asymmetry in the reliance on inter-hemispheric projections between the left and right auditory cortices for auditory spatial processing.

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