Blood oxygenation level-dependent functional magnetic resonance imaging of bilateral but asymmetrical responses to gustatory stimulation in the rat insular cortex

Kida, Ikuhiro; Iguchi, Yoshinobu; Hoshi, Yoko

doi:10.1016/j.neuroimage.2011.03.007

Cited by 12 publications

(7 citation statements)

References 38 publications

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“…Of particular relevance to the current study, significant correlations ( r = 0.65 to r = .75) between the numbers of quinine-stimulated gapes and Fos positive neurons in regions approximating DI and AI throughout GC were found. Moreover, numerous electrophysiological studies in the rat (Allen et al, 1991; Cechetto and Saper, 1987; de Araujo and Simon, 2009; Hanamori et al, 1998; Katz et al, 2001, 2002; Kosar et al, 1986a; Norgren and Wolf, 1975; Sadacca et al, 2012; Saper, 1982; Yamamoto et al, 1980, 1985, 1989), as well as optical imaging studies in the rat (Accolla and Carleton, 2008; Accolla et al, 2007,) and mouse (Chen et al, 2011), and functional magnetic resonance imaging in the rat (Kida et al, 2011) have also shown that the GC, as traditionally defined, contains neurons that respond to various features of taste stimuli, possibly including their hedonic impact. Katz and colleagues (Sadacca et al, 2012), for instance, contend that palatability processing in the GC actually occurs in advance of palatability processing in the amygdala, and possibly in advance of brainstem neural activity associated with TR behaviors (Travers and Norgren, 1986).…”

Section: Discussionmentioning

confidence: 99%

Unconditioned oromotor taste reactivity elicited by sucrose and quinine is unaffected by extensive bilateral damage to the gustatory zone of the insular cortex in rats

et al. 2015

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Rats display stereotypical oromotor and somatic responses to small volumes of intraorally infused taste solutions. These behaviors, known as taste reactivity, are categorized by their association with ingestion or rejection and are thought to reflect the palatability of the stimulus. Because supracollicular decerebrate rats display normal taste reactivity responses, it would appear that forebrain structures are not necessary for generating them. However, because moving the plane of transection rostrally, or damaging or manipulating specific ventral forebrain sites disrupts normal taste reactivity behavior, lesions of the gustatory cortex, a region that has been suggested to be involved with palatability processing, may do the same. In the current study, rats received two injections of either ibotenic acid (N=12) or vehicle (N=8), targeting the conventionally defined gustatory cortex in each hemisphere, and were implanted with intraoral cannulae. Following recovery, their responses to intraoral infusions (0.23 ml in 1 min) of dH20, sucrose (1.0M and 0.1M), and quinine hydrochloride (3 mM and 0.3 mM) were video recorded. Analysis of brains with sufficient bilateral lesions (N=10) revealed that, on average, approximately 94% of the gustatory cortex was destroyed. These extensive bilateral lesions had no significant effect on taste reactivity; the numbers of ingestive and aversive responses to sucrose and quinine were similar between groups. Though these findings do not rule out involvement of the gustatory cortex in palatability processing, they make evident that the region of insular cortex destroyed is not necessary for the normal expression of unconditioned affective behavioral responses to taste stimuli.

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Section: Discussionmentioning

confidence: 99%

Unconditioned oromotor taste reactivity elicited by sucrose and quinine is unaffected by extensive bilateral damage to the gustatory zone of the insular cortex in rats

et al. 2015

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“…In rodents, the gustatory cortex (GC) is conventionally defined as a subregion of insular cortex surrounding the intersection of the middle cerebral artery and the rhinal fissure. Electrophysiological recordings have revealed taste-responsive neurons distributed in this brain region and tracing studies have confirmed projections from the gustatory zone of the thalamus [ 1 – 12 ]. Although the GC is highly integrated with other taste pathways, its role in taste function, including qualitative discrimination, affect, and physiological reflexes remains in its infancy.…”

Section: Introductionmentioning

confidence: 99%

Extensive Gustatory Cortex Lesions Significantly Impair Taste Sensitivity to KCl and Quinine but Not to Sucrose in Rats

et al. 2015

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Recently, we reported that large bilateral gustatory cortex (GC) lesions significantly impair taste sensitivity to salts in rats. Here we extended the tastants examined to include sucrose and quinine in rats with ibotenic acid-induced lesions in GC (GCX) and in sham-operated controls (SHAM). Presurgically, immediately after drinking NaCl, rats received a LiCl or saline injection (i.p.), but postsurgical tests indicated a weak conditioned taste aversion (CTA) even in controls. The rats were then trained and tested in gustometers to discriminate a tastant from water in a two-response operant taste detection task. Psychometric functions were derived for sucrose, KCl, and quinine. Our mapping system was used to determine placement, size, and symmetry of the lesions (~91% GC damage on average). For KCl, there was a significant rightward shift (ΔEC50 = 0.57 log10 units; p<0.001) in the GCX psychometric function relative to SHAM, replicating our prior work. There was also a significant lesion-induced impairment (ΔEC50 = 0.41 log10 units; p = 0.006) in quinine sensitivity. Surprisingly, taste sensitivity to sucrose was unaffected by the extensive lesions and was comparable between GCX and SHAM rats. The fact that such large bilateral GC lesions did not shift sucrose psychometric functions relative to SHAM, but did significantly compromise quinine and KCl sensitivity suggests that the neural circuits responsible for the detection of specific taste stimuli are partially dissociable. Lesion-induced impairments were observed in expression of a postsurgical CTA to a maltodextrin solution as assessed in a taste-oriented brief-access test, but were not reflected in a longer term 46-h two-bottle test. Thus, deficits observed in rats after extensive damage to the GC are also dependent on the test used to assess taste function. In conclusion, the degree to which the GC is necessary for the maintenance of normal taste detectability apparently depends on the chemical and/or perceptual features of the stimulus.

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“…In contrast, the rat subcortex occupies a significantly larger portion of the brain and some subcortical structures, such as the inferior colliculus of the midbrain, are located close to the skull [34]. Rat fMRI is a new field, although progress has been made in studying the somatosensory [35]–[39], olfactory [40]–[43], visual [44]–[47], and recently, the gustatory [48] and auditory [20]–[22] systems. Another functional imaging technique that has been used to study the rat auditory system is based on optical signals [49].…”

Section: Introductionmentioning

confidence: 99%

Noninvasive fMRI Investigation of Interaural Level Difference Processing in the Rat Auditory Subcortex

et al. 2013

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ObjectiveInteraural level difference (ILD) is the difference in sound pressure level (SPL) between the two ears and is one of the key physical cues used by the auditory system in sound localization. Our current understanding of ILD encoding has come primarily from invasive studies of individual structures, which have implicated subcortical structures such as the cochlear nucleus (CN), superior olivary complex (SOC), lateral lemniscus (LL), and inferior colliculus (IC). Noninvasive brain imaging enables studying ILD processing in multiple structures simultaneously.MethodsIn this study, blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) is used for the first time to measure changes in the hemodynamic responses in the adult Sprague-Dawley rat subcortex during binaural stimulation with different ILDs.Results and SignificanceConsistent responses are observed in the CN, SOC, LL, and IC in both hemispheres. Voxel-by-voxel analysis of the change of the response amplitude with ILD indicates statistically significant ILD dependence in dorsal LL, IC, and a region containing parts of the SOC and LL. For all three regions, the larger amplitude response is located in the hemisphere contralateral from the higher SPL stimulus. These findings are supported by region of interest analysis. fMRI shows that ILD dependence occurs in both hemispheres and multiple subcortical levels of the auditory system. This study is the first step towards future studies examining subcortical binaural processing and sound localization in animal models of hearing.

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Blood oxygenation level-dependent functional magnetic resonance imaging of bilateral but asymmetrical responses to gustatory stimulation in the rat insular cortex

Cited by 12 publications

References 38 publications

Unconditioned oromotor taste reactivity elicited by sucrose and quinine is unaffected by extensive bilateral damage to the gustatory zone of the insular cortex in rats

Unconditioned oromotor taste reactivity elicited by sucrose and quinine is unaffected by extensive bilateral damage to the gustatory zone of the insular cortex in rats

Extensive Gustatory Cortex Lesions Significantly Impair Taste Sensitivity to KCl and Quinine but Not to Sucrose in Rats

Noninvasive fMRI Investigation of Interaural Level Difference Processing in the Rat Auditory Subcortex

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