Differences In Neural Processing Research Articles

Evaluating tastes and aromas of wine: a peek inside the “black box”

Purpose– Wine tasting is an integral method for engaging consumers. Producers go to great lengths to educate consumers on evaluating quality based on taste and aroma. Understanding the sensory and perceptual processes of wine tasting may offer insight into how consumers at different levels of wine expertise use their senses to evaluate wine.Design/methodology/approach– This study used functional near-infrared spectroscopy to examine processing in the frontal lobe of the brain during wine tasting and aroma evaluation. Sixty subjects evaluated the tastes and aromas of wine samples with various levels of sweetness, whereas 16 defined areas of their frontal lobes were measured with functional near infrared measurement.Findings– The subjects’ orbitofrontal cortices were activated during both olfaction (smelling) and tasting. Further, larger areas of the frontal lobes showed significant activation during the olfaction task than during the tasting task. The level of the subjects’ wine knowledge did not predict differences in neural processing when participants evaluated aroma of wine; however, subjects with higher wine knowledge did show significantly higher activation in specific frontal lobe regions when tasting. Differences in levels of product involvement among the subjects were not significant for the tasting task, but were significant for the olfaction task.Originality/value– Developing a better understanding of the biological processes involved in tasting may lead to understanding the differences in consumer preferences for wine. This, in turn, may assist tasting room managers to adjust their tasting procedure to be tailored to consumer-specific needs.

Towards understanding sex differences in visceral pain: Enhanced reactivation of classically-conditioned fear in healthy women

Sex differences in learned fear regarding aversive gastrointestinal stimuli could play a role in the female preponderance of chronic abdominal pain. In a fear conditioning model with rectal pain as unconditioned stimulus (US), we compared healthy males and females with respect to neural responses during aversive visceral learning, extinction and re-activation of fear memory (i.e., reinstatement). To do so, conditioned visual stimuli (CS+) were consistently paired with painful rectal distensions as US, while different visual stimuli (CS−) were presented without US. During extinction, both CSs were presented without US, whereas during reinstatement, a single, unpaired US was presented. In region-of-interest analyses, sexes were compared with respect to conditioned anticipatory neural activation (CS+>CS−). The results revealed that in late acquisition, CS+ presentation induced significantly greater anticipatory activation of the insula in women. During extinction, women demonstrated reduced activation of the posterior cingulate cortex. During reinstatement, the CS+ led to greater activation of the hippocampus, thalamus and cerebellum in women. These group effects in neural activation during learning and memory processes were not accounted for by sex differences in pain thresholds, pain ratings, or stress parameters. In conclusion, this is the first study to support sex differences in neural processes mediating aversive visceral learning. Our finding of enhanced neural responses during reinstatement in key brain areas relevant for memory suggests enhanced reactivation of old fear memory trace in women. Sex differences in “gut memories” could play a role in the female preponderance of chronic abdominal pain.

Striatal disorders dissociate mechanisms of enhanced and impaired response selection - Evidence from cognitive neurophysiology and computational modelling.

Paradoxically enhanced cognitive processes in neurological disorders provide vital clues to understanding neural function. However, what determines whether the neurological damage is impairing or enhancing is unclear. Here we use the performance of patients with two disorders of the striatum to dissociate mechanisms underlying cognitive enhancement and impairment resulting from damage to the same system. In a two-choice decision task, Huntington's disease patients were faster and less error prone than controls, yet a patient with the rare condition of benign hereditary chorea (BHC) was both slower and more error prone. EEG recordings confirmed significant differences in neural processing between the groups. Analysis of a computational model revealed that the common loss of connectivity between striatal neurons in BHC and Huntington's disease impairs response selection, but the increased sensitivity of NMDA receptors in Huntington's disease potentially enhances response selection. Crucially the model shows that there is a critical threshold for increased sensitivity: below that threshold, impaired response selection results. Our data and model thus predict that specific striatal malfunctions can contribute to either impaired or enhanced selection, and provide clues to solving the paradox of how Huntington's disease can lead to both impaired and enhanced cognitive processes.

Neural differences in processing of case particles in Japanese: an fMRI study

IntroductionIn subject–object–verb (SOV) languages, such as Japanese, sentence processing proceeds incrementally to the late presentation of the head (verb). Japanese case particles play a crucial role in sentence processing; however, little is known about how these particles are processed. In particular, it is still unclear how the functional difference between case particles is represented in the human brain.MethodsIn this study, we conducted an fMRI experiment using an event-related design to directly compare brain activity during Japanese case particle processing among the nominative case ga, accusative case o, and dative case ni. Twenty five native Japanese speakers were asked to judge whether the presented character was a particle in a particle judgment task and whether the character ended with a specific vowel in a phonological judgment task, which was used as a control condition.ResultsA particle comparison demonstrated that the processing of ni was associated with significantly weaker brain activity than that of ga and o in the left middle frontal gyrus (MFG) and the inferior frontal gyrus (IFG). Significantly greater brain activity associated with ni relative to ga in the right IFG was also observed.ConclusionThese results suggest that the Japanese case particles ga, ni, and o are represented differently in the brain.

Altered cingulate and insular cortex activation during risk‐taking in methamphetamine dependence: losses lose impact

To determine if methamphetamine-dependent (MD) individuals exhibit behavioral or neural processing differences in risk-taking relative to healthy comparison participants (CTL). This was a cross-sectional study comparing two groups' behavior on a risk-taking task and neural processing as assessed using functional magnetic resonance imaging (fMRI). The study was conducted in an in-patient treatment center and a research fMRI facility in the United States. Sixty-eight recently abstinent MD individuals recruited from a treatment program and 40 CTL recruited from the community completed the study. The study assessed risk-taking behavior (overall and post-loss) using the Risky Gains Task (RGT), sensation-seeking, impulsivity and blood-oxygenation-level-dependent activation in the brain during the decision phase of the RGT. Relative to CTL, MD displayed decreased activation in the bilateral rostral anterior cingulate cortex (ACC) and greater activation in the left insula across risky and safe decisions (P < 0.05). Right mid-insula activation among CTL did not vary between risky and safe decisions, but among MD it was higher during risky relative to safe decisions (P < 0.05). Among MD, lower activation in the right rostral ACC (r = -0.39, P < 0.01) and higher activation in the right mid-insula (r = 0.35, P < 0.01) during risky decisions were linked to a higher likelihood of choosing a risky option following a loss. Methamphetamine-dependent individuals show disrupted risk-related processing in both anterior cingulate and insula, brain areas that have been implicated in cognitive control and interoceptive processing. Attenuated neural processing of risky options may lead to risk-taking despite experiencing negative consequences.

Neural Sensitivity to Absolute and Relative Anticipated Reward in Adolescents

Adolescence is associated with a dramatic increase in risky and impulsive behaviors that have been attributed to developmental differences in neural processing of rewards. In the present study, we sought to identify age differences in anticipation of absolute and relative rewards. To do so, we modified a commonly used monetary incentive delay (MID) task in order to examine brain activity to relative anticipated reward value (neural sensitivity to the value of a reward as a function of other available rewards). This design also made it possible to examine developmental differences in brain activation to absolute anticipated reward magnitude (the degree to which neural activity increases with increasing reward magnitude). While undergoing fMRI, 18 adolescents and 18 adult participants were presented with cues associated with different reward magnitudes. After the cue, participants responded to a target to win money on that trial. Presentation of cues was blocked such that two reward cues associated with $.20, $1.00, or $5.00 were in play on a given block. Thus, the relative value of the $1.00 reward varied depending on whether it was paired with a smaller or larger reward. Reflecting age differences in neural responses to relative anticipated reward (i.e., reference dependent processing), adults, but not adolescents, demonstrated greater activity to a $1 reward when it was the larger of the two available rewards. Adults also demonstrated a more linear increase in ventral striatal activity as a function of increasing absolute reward magnitude compared to adolescents. Additionally, reduced ventral striatal sensitivity to absolute anticipated reward (i.e., the difference in activity to medium versus small rewards) correlated with higher levels of trait Impulsivity. Thus, ventral striatal activity in anticipation of absolute and relative rewards develops with age. Absolute reward processing is also linked to individual differences in Impulsivity.

A functional neuroimaging study assessing gender differences in the neural mechanisms underlying the ability to resist impulsive desires

There is ample evidence of gender differences in neural processes and behavior. Differences in reward-related behaviors have been linked to either temporary or permanent organizational influences of gonadal hormones on the mesolimbic dopamine system and reward-related activation. Still, little is known about the association between biological gender and the neural underpinnings of the ability to resist reward-related impulses. Here we assessed with functional magnetic resonance imaging which neural processes enable men and women to successfully control their desire for immediate reward when this is required by a higher-order goal (i.e., during a ‘desire-reason dilemma’; Diekhof and Gruber, 2010). Thirty-two participants (16 females) were closely matched for age, personality characteristics (e.g., novelty seeking) and behavioral performance in the ‘desire-reason task’. On the neural level, men and women showed similarities in the general response of the nucleus accumbens and of the ventral tegmental area to predictors of immediate reward, but they differed in additional brain mechanisms that enabled self-controlled decisions against the preference for immediate reward. Firstly, men exhibited a stronger reduction of activation in the ventral pallidum, putamen, temporal pole and pregenual anterior cingulate cortex during the ‘desire-reason dilemma’. Secondly, connectivity analyses revealed a significant change in the direction of the connectivity between anteroventral prefrontal cortex and nucleus accumbens during decisions counteracting the reward-related impulse when comparing men and women. Together, these findings support the view of a sexual dimorphism that manifested in the recruitment of gender-specific neural resources during the successful deployment of self-control.

Reduced Cortical Motor Potentials Underlie Reductions in Memory-Guided Reaching Performance

We used the event-related potential (ERP) methodology to examine differences in neural processing between visually and memory-guided reaches. Consistent with previous findings (e.g., Westwood, Heath, & Roy, 2003), memory-guided reaches undershot veridical target location to a greater extent than their visually guided counterparts. Analysis of the ERP data revealed that memory-guided reaches were associated with reduced potentials over medial-frontal cortex at target presentation and following movement onset. Further, we found that the amplitudes of the potentials over medial-frontal cortex for visually and memory-guided reaches were significantly correlated with the peak accelerations and decelerations of the reaching movements. Our results suggest that memory-guided reaches are mediated by a motor plan that is generated while a target is visible, and then stored in memory until needed--a result counter to recent behavioral theories asserting that memory-guided reaches are planned just before movement onset via a stored, sensory-based target representation.

Striatum processes reward differently in adolescents versus adults

Adolescents often respond differently than adults to the same salient motivating contexts, such as peer interactions and pleasurable stimuli. Delineating the neural processing differences of adolescents is critical to understanding this phenomenon, as well as the bases of serious behavioral and psychiatric vulnerabilities, such as drug abuse, mood disorders, and schizophrenia. We believe that age-related changes in the ways salient stimuli are processed in key brain regions could underlie the unique predilections and vulnerabilities of adolescence. Because motivated behavior is the central issue, it is critical that age-related comparisons of brain activity be undertaken during motivational contexts. We compared single-unit activity and local field potentials in the nucleus accumbens (NAc) and dorsal striatum (DS) of adolescent and adult rats during a reward-motivated instrumental task. These regions are involved in motivated learning, reward processing, and action selection. We report adolescent neural processing differences in the DS, a region generally associated more with learning than reward processing in adults. Specifically, adolescents, but not adults, had a large proportion of neurons in the DS that activated in anticipation of reward. More similar response patterns were observed in NAc of the two age groups. DS single-unit activity differences were found despite similar local field potential oscillations. This study demonstrates that in adolescents, a region critically involved in learning and habit formation is highly responsive to reward. It thus suggests a mechanism for how rewards might shape adolescent behavior differently, and for their increased vulnerabilities to affective disorders.

Multisensory processing in synesthesia — differences in the EEG signal during uni- and multimodal processing

Synesthesia is a condition in which stimulation in one processing stream (e.g., letters or music) leads to perception in an unstimulated processing stream (e.g., colors). Behavioral differences in mutisensory processing have been shown for multimodal illusions, but the differences in neural processing are still unclear. In the present study, we examined uni- and multimodal processing in 14 people with synesthesia and 13 controls using EEG recordings and a simple detection task. Stimuli were either presented acoustically, visually or multimodaly (simultaneous visual and auditory stimulation). In the multimodal condition, auditory and visual stimuli were either matching or mismatching (e.g., a lion either roaring or ringing). The subjects had to press a button as soon as something was presented visually or acoustically. Results: ERPs revealed occipital group differences in the negative amplitude between 100 and 200 ms after stimulus presentation. Relative to controls, synesthetes showed an increased negative component peaking around 150 ms. This group difference is found in all visual conditions. Unimodal acoustical stimulation leads to increased negative amplitude in synesthetes in the same time window over parietal and visual electrodes. Overall this shows that processing in the occipital lobe is different in synesthetes independent of the stimulated modality. In addition, differences in the negative amplitude between processing of incongruent and congruent multimodal stimuli could be detected in the same time window between synesthetes and controls over left frontal sites. This shows that also multimodal integration processes are different in synesthetes.

Differences in neural activation between preterm and full term born adolescents on a sentence comprehension task: Implications for educational accommodations

Adolescent survivors of preterm birth experience persistent functional problems that negatively impact academic outcomes, even when standardized measures of cognition and language suggest normal ability. In this fMRI study, we compared the neural activation supporting auditory sentence comprehension in two groups of adolescents (ages 9–16 years); sentences varied in length and syntactic difficulty. Preterms (n = 18, mean gestational age 28.8 weeks) and full terms (n = 14) had scores on verbal IQ, receptive vocabulary, and receptive language tests that were within or above normal limits and similar between groups. In early and late phases of the trial, we found interactions by group and length; in the late phase, we also found a group by syntactic difficulty interaction. Post hoc tests revealed that preterms demonstrated significant activation in the left and right middle frontal gyri as syntactic difficulty increased. ANCOVA showed that the interactions could not be attributed to differences in age, receptive language skill, or reaction time. Results are consistent with the hypothesis that preterm birth modulates brain–behavior relations in sentence comprehension as task demands increase. We suggest preterms’ differences in neural processing may indicate a need for educational accommodations, even when formal test scores indicate normal academic achievement.

Brain Stem Responses to Speech in Younger and Older Adults

This experiment was designed to evaluate whether neural encoding of speech features at the brain stem level is altered in the aging auditory system. In addition, the effect of minimal peripheral hearing loss on the auditory brain stem response (ABR) evoked by speech stimuli and interactions with aging were examined. Speech-evoked ABRs (S-ABRs) were recorded using a synthetic 40-msec /da/ stimulus from both ears of participants in two groups: normal-hearing younger adults (n = 19) and normal-hearing older adults (n = 18). Latencies and amplitude for S-ABR peaks representing neural responses to the onset and offset of the speech syllable as well as a sustained frequency following response to the vowel content were analyzed. The role of hearing threshold differences between groups and the reduced overall stimulus level on the S-ABR were also examined. In addition, click-evoked ABRs (C-ABRs) were obtained from all participants, and age-group differences in the neural response to both types of stimuli at the brain stem level were compared. S-ABR latencies, amplitudes, and sustained response mean data were obtained for younger adults and older adults. Older adults were found to have significantly smaller C-ABRs with longer latencies, despite all latencies falling within normal limits. Older adults also had significantly smaller onset and offset responses for the S-ABR, with significantly delayed offset latencies in response to this synthetic consonant-vowel syllable. Many of the C-ABR and S-ABR variables were found to significantly correlate with high-frequency audiometric thresholds, and few of the group differences remained significant when this was taken into account. The remaining significant S-ABR effects were decreased amplitude at the onset and significantly delayed offset responses in the older group. These effects were different from those of simply decreasing the overall stimulus level, which caused significant shifts in latency across the entire S-ABR. Results of this study partially supported the hypothesis of age-related differences in neural processing of speech at the brain stem level. There were significant delays in the timing of the offset portion of the S-ABR in older listeners compared with their younger counterparts, even after accounting for the differences in peripheral hearing threshold between groups. There were also significant reductions in amplitude of the S-ABR at the onset. These results are consistent with a reduction in neural synchrony in older adults to transient components of both speech and nonspeech sounds. However, sustained components of the S-ABR, which follow the harmonic components of the syllable, showed group differences but were not significant after adjusting for peripheral hearing loss, suggesting that they may be more affected by hearing sensitivity and other peripheral changes. These results support further investigation into the ability of the aging auditory system to encode temporal cues at the brain stem level, particularly the response to speech stimulus offset and its relationship to speech perception and temporal processing abilities.

Sex differences in neural responses to stress and alcohol context cues

Stress and alcohol context cues are each associated with alcohol-related behaviors, yet neural responses underlying these processes remain unclear. This study investigated the neural correlates of stress and alcohol context cue experiences and examined sex differences in these responses. Using functional magnetic resonance imaging, brain responses were examined while 43 right-handed, socially drinking, healthy individuals (23 females) engaged in brief guided imagery of personalized stress, alcohol-cue, and neutral-relaxing scenarios. Stress and alcohol-cue exposure increased activity in the cortico-limbic-striatal circuit (P < 0.01, corrected), encompassing the medial prefrontal cortex (mPFC), orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), left anterior insula, striatum, and visuomotor regions (parietal and occipital lobe, and cerebellum). Activity in the left dorsal striatum increased during stress, while bilateral ventral striatum activity was evident during alcohol-cue exposure. Men displayed greater stress-related activations in the mPFC, rostral ACC, posterior insula, amygdala, and hippocampus than women, whereas women showed greater alcohol-cue-related activity in the superior and middle frontal gyrus (SFG/MFG) than men. Stress-induced anxiety was positively associated with activity in emotion-modulation regions, including the medial OFC, ventromedial PFC, left superior-mPFC, and rostral ACC in men, but in women with activation in the SFG/MFG, regions involved in cognitive processing. Alcohol craving was significantly associated with the striatum (encompassing dorsal, and ventral) in men, supporting its involvement in alcohol "urge" in healthy men. These results indicate sex differences in neural processing of stress and alcohol-cue experiences and have implications for sex-specific vulnerabilities to stress- and alcohol-related psychiatric disorders.

Culture differences in neural processing of faces and houses in the ventral visual cortex

Behavioral and eye-tracking studies on cultural differences have found that while Westerners have a bias for analytic processing and attend more to face features, East Asians are more holistic and attend more to contextual scenes. In this neuroimaging study, we hypothesized that these culturally different visual processing styles would be associated with cultural differences in the selective activity of the fusiform regions for faces, and the parahippocampal and lingual regions for contextual stimuli. East Asians and Westerners passively viewed face and house stimuli during an functional magnetic resonance imaging experiment. As expected, we observed more selectivity for faces in Westerners in the left fusiform face area (FFA) reflecting a more analytic processing style. Additionally, Westerners showed bilateral activity to faces in the FFA whereas East Asians showed more right lateralization. In contrast, no cultural differences were detected in the parahippocampal place area (PPA), although there was a trend for East Asians to show greater house selectivity than Westerners in the lingual landmark area, consistent with more holistic processing in East Asians. These findings demonstrate group biases in Westerners and East Asians that operate on perceptual processing in the brain and are consistent with previous eye-tracking data that show cultural biases to faces.

Auditory space perception in left- and right-handers

Several studies have shown that handedness has an impact on visual spatial abilities. Here we investigated the effect of laterality on auditory space perception. Participants (33 right-handers, 20 left-handers) completed two tasks of sound localization. In a dark, anechoic, and sound-proof room, sound stimuli (broadband noise) were presented via 21 loudspeakers mounted horizontally (from 80° on the left to 80° on the right). Participants had to localize the target either by using a swivel hand-pointer or by head-pointing. Individual lateral preferences of eye, ear, hand, and foot were obtained using a questionnaire. With both pointing methods, participants showed a bias in sound localization that was to the side contralateral to the preferred hand, an effect that was unrelated to their overall precision. This partially parallels findings in the visual modality as left-handers typically have a more rightward bias in visual line bisection compared with right-handers. Despite the differences in neural processing of auditory and visual spatial information these findings show similar effects of lateral preference on auditory and visual spatial perception. This suggests that supramodal neural processes are involved in the mechanisms generating laterality in space perception.

Sex differences in neural processing of language among children

Why females generally perform better on language tasks than males is unknown. Sex differences were here identified in children (ages 9–15) across two linguistic tasks for words presented in two modalities. Bilateral activation in the inferior frontal and superior temporal gyri and activation in the left fusiform gyrus of girls was greater than in boys. Activation in the left inferior frontal and fusiform regions of girls was also correlated with linguistic accuracy irregardless of stimulus modality, whereas correlation with performance accuracy in boys depended on the modality of word presentation (either in visual or auditory association cortex). This pattern suggests that girls rely on a supramodal language network, whereas boys process visual and auditory words differently. Activation in the left fusiform region was additionally correlated with performance on standardized language tests in which girls performed better, additional evidence of its role in early sex differences for language.

Differences in neural processing between nouns and verbs in Chinese: Evidence from EEG

Differences in neural processing between nouns and verbs in Chinese: Evidence from EEG

Morphological characteristics and electrophysiological properties of CA1 pyramidal neurons in macaque monkeys

Little is known about the morphological characteristics and intrinsic electrophysiological properties of individual neurons in the nonhuman primate hippocampus. We have used intracellular recording and biocytin-labeling techniques in the in vitro hippocampal slice preparation to provide quantitative evaluation of the fundamental morphological and intrinsic electrophysiological characteristics of macaque monkey CA1 pyramidal neurons. These neurons have previously been studied in the rat in our laboratory. Monkey CA1 pyramidal neurons have an average soma volume of 3578μm 3, 4.71 basal dendrites with 53 terminal branches for a dendritic length of about 10,164μm, 1.13 apical dendrites with 47 terminal branches for a dendritic length of about 10,678μm. In comparison, rat CA1 pyramidal neurons have an average soma volume of 2066μm 3, 3.35 basal dendrites with 29 terminal branches for a dendritic length of about 4,586μm, 1.43 apical dendrites with 62 terminal branches for a dendritic length of about 8,838μm. The basic intrinsic electrophysiological properties of CA1 pyramidal cells are similar in monkeys and rats. Monkey CA1 pyramidal neurons have a resting membrane potential of about −62 mV (rat: −62 mV), an input resistance of 35 MΩ (rat: 34–49 MΩ), a rheobase of 0.17 nA (rat: 0.12–0.20 nA) and an action potential amplitude of 83 mV (rat: 71–89 mV). Although morphological differences such as the increased dendritic length may translate into differences in neural processing between primates and rodents, the functional significance of these morphological differences is not yet clear. Quantitative studies of the primate brain are critical in order to extrapolate information derived from rodent studies into better understanding of the normal and pathological function of the human hippocampus.

551 Relationship of phantom phenomena and somatosensory cortical reorganization in amputees

The present study was designed to investigate differences in neural processing of pain-related semantic information in amputees with and without chronic phantom limb pain and healthy controls. One-hundred-and-twenty words (40 neutral, 40 body-related, 40 pain-related) were presented in pseudorandom order to probe group differences in the perception of pain-related information. Visual evoked potentials (VEP) to the words were recorded from 11 scalp locations, EMG was measured at the stump and the contralateral side and bilaterally from the M. corrugator. In addition, heart rate and skin conductance responses were obtained. Both early and late VEP components were altered. Pain-free amputees showed a reduced N100 amplitude compared to phantom limb pain patients and healthy controls whereas the phantom limb pain patients displayed a significantly enhanced late positivity (500–800 msec after word onset). VEP components were unaffected by word type. The peripheral EMG responses were significantly different among the groups: phantom limb pain patients showed larger EMG reactions on the stump than on the contralateral side, whereas pain-free amputees showed the opposite effect. The data suggest an enhanced central and peripheral processing of visual stimuli in phantom limb pain patients.

Evidence for a change in neural processing in phantom limb pain patients

The present study was designed to investigate differences in neural processing of pain-related semantic information in amputees with and without chronic phantom limb pain and healthy controls. One-hundred-and-twenty words (40 neutral, 40 body-related, 40 pain-related) were presented in pseudorandom order to probe group differences in the perception of pain-related information. Visual evoked potentials (VEP) to the words were recorded from 11 scalp locations, EMG was measured at the stump and the contralateral side and bilaterally from the M. corrugator. In addition, heart rate and skin conductance responses were obtained. Both early and late VEP components were altered. Pain-free amputees showed a reduced N100 amplitude compared to phantom limb pain patients and healthy controls whereas the phantom limb pain patients displayed a significantly enhanced late positivity (500–800 msec after word onset). VEP components were unaffected by word type. The peripheral EMG responses were significantly different among the groups: phantom limb pain patients showed larger EMG reactions on the stump than on the contralateral side, whereas pain-free amputees showed the opposite effect. The data suggest an enhanced central and peripheral processing of visual stimuli in phantom limb pain patients.