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J L Armony

Publications and source records attributed to J L Armony.

15 recordsLinked to original sources
PubMed2006

Affective response to one's own moral violations.

Morality depends on a set of cultural rules that regulate interpersonal behaviour and provide a basis for social cohesion. The interpretation of moral transgressions and their affective consequences depends on whether the action is intentional or accidental, and whether one is the agent of or witness to the action. We used event-related functional magnetic resonance imaging (fMRI) to investigate whether the amygdala is involved in judging one's own moral violation of social norms. In this study, participants (n = 12) were asked to make evaluations regarding the degree of inappropriateness of social behaviours described in stories in which they themselves, or someone else, transgressed social norms either intentionally or accidentally. Consistent with our hypothesis, the amygdala was activated when participants considered stories narrating their own intentional transgression of social norms. This result suggests the amygdala is important for affective responsiveness to moral transgressions.

Adult↗
PubMed2003

Activations related to "mirror" and "canonical" neurones in the human brain: an fMRI study.

In the macaque monkey ventral premotor cortex (F5), "canonical neurones" are active when the monkey observes an object and when the monkey grasps that object. In the same area, "mirror neurones" fire both when the monkey observes another monkey grasping an object and when the monkey grasps that object. We used event-related fMRI to investigate where in the human brain activation can be found that reflects both canonical and mirror neuronal activity. There was activation in the intraparietal and ventral limbs of the precentral sulcus when subjects observed objects and when they executed movements in response to the objects (canonical neurones). There was activation in the dorsal premotor cortex, the intraparietal cortex, the parietal operculum (SII), and the superior temporal sulcus when subjects observed gestures (mirror neurones). Finally, activations in the ventral premotor cortex and inferior frontal gyrus (area 44) were found when subjects imitated gestures and executed movements in response to objects. We suggest that in the human brain, the ventral limb of the precentral sulcus may form part of the area designated F5 in the macaque monkey. It is possible that area 44 forms an anterior part of F5, though anatomical studies suggest that it may be a transitional area between the premotor and prefrontal cortices.

Adult↗
PubMed2002

Neural response to emotional faces with and without awareness: event-related fMRI in a parietal patient with visual extinction and spatial neglect.

This study examined whether differential neural responses are evoked by emotional stimuli with and without conscious perception, in a patient with visual neglect and extinction. Stimuli were briefly shown in either right, left, or both fields during event-related fMRI. On bilateral trials, either a fearful or neutral left face appeared with a right house, and it could either be extinguished from awareness or perceived. Seen faces in left visual field (LVF) activated primary visual cortex in the damaged right-hemisphere and bilateral fusiform gyri. Extinguished left faces increased activity in striate and extrastriate cortex, compared with right houses only. Critically, fearful faces activated the left amygdala and extrastriate cortex both when seen and when extinguished; as well as bilateral orbitofrontal and intact right superior parietal areas. Comparison of perceived versus extinguished faces revealed no difference in amygdala for fearful faces. Conscious perception increased activity in fusiform, parietal and prefrontal areas of the left-hemisphere, irrespective of emotional expression; while a differential emotional response to fearful faces occurring specifically with awareness was found in bilateral parietal, temporal, and frontal areas. These results demonstrate that amygdala and orbitofrontal cortex can be activated by emotional stimuli even without awareness after parietal damage; and that substantial unconscious residual processing can occur within spared brain areas well beyond visual cortex, despite neglect and extinction.

Aged↗
PubMed2002

An fMRI study of intentional and unintentional (embarrassing) violations of social norms.

The aim of this investigation was to identify neural systems supporting the processing of intentional and unintentional transgressions of social norms. Using event-related fMRI, we addressed this question by comparing neural responses to stories describing normal behaviour, embarrassing situations or violations of social norms. Processing transgressions of social norms involved systems previously reported to play a role in representing the mental states of others, namely medial prefrontal and temporal regions. In addition, the processing of transgressions of social norms involved systems previously found to respond to aversive emotional expressions (in particular angry expressions); namely lateral orbitofrontal cortex (Brodmann area 47) and medial prefrontal cortex. The observed responses were similar for both intentional and unintentional social norm violations, albeit more pronounced for the intentional norm violations. These data suggest that social behavioural problems in patients with frontal lobe lesions or fronto-temporal dementia may be a consequence of dysfunction within the systems identified in light of their possible role in processing whether particular social behaviours are, or are not, appropriate.

Adult↗
PubMed2001

Modulation of auditory neural responses by a visual context in human fear conditioning.

Responses to a stimulus signaling danger depend not only on the nature of that stimulus, but also on the context in which it is presented. A large body of work has been conducted in experimental animals investigating the neural correlates of contextual modulation of fear responses. However, much less is known about this process in humans. In this study we used functional MRI in a fear conditioning paradigm to explore this phenomenon. Responses to acoustic conditioned stimuli in auditory cortex were modulated by the presence of a visual context which signaled the likelihood of receiving an aversive unconditioned stimulus. Furthermore, the presence of the aversive visual context was associated with enhanced activity in parietal cortex, which may reflect an increase in attention to the presence of environmental threat stimuli.

Acoustic Stimulation↗
PubMed2001

Effects of attention and emotion on face processing in the human brain: an event-related fMRI study.

We used event-related fMRI to assess whether brain responses to fearful versus neutral faces are modulated by spatial attention. Subjects performed a demanding matching task for pairs of stimuli at prespecified locations, in the presence of task-irrelevant stimuli at other locations. Faces or houses unpredictably appeared at the relevant or irrelevant locations, while the faces had either fearful or neutral expressions. Activation of fusiform gyri by faces was strongly affected by attentional condition, but the left amygdala response to fearful faces was not. Right fusiform activity was greater for fearful than neutral faces, independently of the attention effect on this region. These results reveal differential influences on face processing from attention and emotion, with the amygdala response to threat-related expressions unaffected by a manipulation of attention that strongly modulates the fusiform response to faces.

Adult↗
PubMed2000

Auditory processing across the sleep-wake cycle: simultaneous EEG and fMRI monitoring in humans.

We combined fMRI and EEG recording to study the neurophysiological responses associated with auditory stimulation across the sleep-wake cycle. We found that presentation of auditory stimuli produces bilateral activation in auditory cortex, thalamus, and caudate during both wakefulness and nonrapid eye movement (NREM) sleep. However, the left parietal and, bilaterally, the prefrontal and cingulate cortices and the thalamus were less activated during NREM sleep compared to wakefulness. These areas may play a role in the further processing of sensory information required to achieve conscious perception during wakefulness. Finally, during NREM sleep, the left amygdala and the left prefrontal cortex were more activated by stimuli having special affective significance than by neutral stimuli. These data suggests that the sleeping brain can process auditory stimuli and detect meaningful events.

Acoustic Stimulation↗
PubMed1999

Amygdala-hippocampal involvement in human aversive trace conditioning revealed through event-related functional magnetic resonance imaging.

Previous functional neuroimaging studies have characterized brain systems mediating associative learning using classical delay conditioning paradigms. In the present study, we used event-related functional magnetic resonance imaging to characterize neuronal responses mediating aversive trace conditioning. During conditioning, neutral auditory tones were paired with an aversive sound [unconditioned stimulus (US)]. We compared neuronal responses evoked by conditioned (CS+) and nonconditioned (CS-) stimuli in which a 50% pairing of CS+ and the US enabled us to limit our analysis to responses evoked by the CS+ alone. Differential responses (CS+ vs CS-), related to conditioning, were observed in anterior cingulate and anterior insula, regions previously implicated in delay fear conditioning. Differential responses were also observed in the amygdala and hippocampus that were best characterized with a time x stimulus interaction, indicating rapid adaptation of CS+-specific responses in medial temporal lobe. These results are strikingly similar to those obtained with a previous delay conditioning experiment and are in accord with a preferential role for medial temporal lobe structures during the early phase of conditioning. However, an additional activation of anterior hippocampus in the present experiment supports a view that its role in trace conditioning is to maintain a memory trace between the offset of the CS+ and the delayed onset of the US to enable associative learning in trace conditioning.

Amygdala↗
PubMed1998

Differential effects of amygdala lesions on early and late plastic components of auditory cortex spike trains during fear conditioning.

In auditory fear conditioning, pairing of a neutral acoustic conditioned stimulus (CS) with an aversive unconditioned stimulus (US) results in an enhancement of neural responses to the CS in the amygdala and auditory cortex. It is not clear, however, whether cortical plasticity governs neural changes in the amygdala or vice versa, or whether learning in these two structures is determined by independent processes. We examined this issue by recording single-cell activity in the auditory cortex (areas Te1, Te1v, and Te3) of freely behaving, amygdalectomized rats using a movable bundle of microwires. Amygdala damage did not affect short-latency (0-50 msec) tone responses, nor did it interfere with conditioning-induced increases of these onset responses. In contrast, lesions of the amygdala interfered with the development of late (500-1500 msec) conditioned tone responses that were not present before conditioning. Furthermore, whereas onset conditioned responses in the control group remained elevated after 30 extinction trials (presentation of CS alone), onset responses in lesioned animals returned to their preconditioning firing level after approximately 10 extinction trials. These results suggest that the amygdala enables the development of long-latency (US anticipatory) responses and prevents the extinction of short-latency onset responses to threatening stimuli. The findings further suggest that auditory cortex cells may participate differently in explicit and implicit memory networks.

Acoustic Stimulation↗
PubMed1997

Fear conditioning enhances different temporal components of tone-evoked spike trains in auditory cortex and lateral amygdala.

Single neurons were recorded in freely behaving rats during fear conditioning from areas of auditory cortex that project to the lateral nucleus of the amygdala (LA). The latency and rate of conditioning and extinction were analyzed, and the results were compared to previous recordings from LA itself. Auditory cortex neurons took more trials to learn, and they responded more slowly than LA neurons within trials. Short-latency plasticity in LA, therefore, reflects inputs from the auditory thalamus rather than the auditory cortex. Unlike LA cells, some auditory cortex cells showed late conditioned responses that seemed to anticipate the unconditioned stimulus, while others showed extinction-resistant memory storage. Thus, rapid conditioning of fear responses to potentially dangerous stimuli depends on plasticity in the amygdala, while cortical areas may be particularly involved in higher cognitive (mnemonic and attentional) processing of fear experiences.

Acoustic Stimulation↗
PubMed1997

Stimulus generalization of fear responses: effects of auditory cortex lesions in a computational model and in rats.

The conditioning of fear responses to a simple acoustic stimulus (pure tone) paired with footshock can be mediated by the transmission of auditory information to the lateral nucleus of the amygdala from either the auditory thalamus or the auditory cortex. We examined the processing capacity of the thalamo-amygdala pathway by making lesions of the auditory cortex and testing the extent to which conditioned fear responses generalized to tones other than the one paired with footshock. Two studies were performed, one in an anatomically constrained computational model of the fear conditioning network and the other in rats. Stimulus generalization was unaffected in both. These findings support the validity of the model as an approach to studying the neural basis of conditioned fear learning, and in addition suggest that the thalamo-amygdala pathway, possibly by the use of population coding, is capable of performing at least crude stimulus discriminations.

Acoustic Stimulation↗
PubMed1996

GABAA and GABAB receptors differentially regulate synaptic transmission in the auditory thalamo-amygdala pathway: an in vivo microiontophoretic study and a model.

Stimulation of the medical geniculate body elicits extracellular single unit responses in the lateral nucleus of the amygdala that are dependent upon glutamatergic neurotransmission [Li et al. (1995) Exp. Brain Res., 105-87-100]. In the present study, we examined the contribution of inhibitory amino acid transmission to these excitatory responses. Antagonists of GABAA or GABAB receptors were delivered microiontophoretically to cells activated by stimulation of the medial geniculate body. Blockade of GABAA receptors with bicuculline resulted in a pronounced increase in evoked short latency unit responses (4-8 ms). In some cases, cells that were not responsive to the stimulation became responsive in the presence of bicuculline. In contrast, delivery of GABAB antagonists, Phaclofen or 2-OH-saclofen, did not affect these short-latency responses. Using paired-pulse stimulation, both short (< 30 ms) and longer (> 50 ms) latency inhibitory processes were revealed. GABAA blockade eliminated the short latency inhibition and GABAB blockade eliminated the longer latency inhibition in most cells. These results suggest that the activation of GABAA and GABAB receptors differentially regulate glutamatergic synaptic transmission in the auditory thalamo-amygdala pathway. Moreover, our findings suggest that at least part of this regulation is via a feedforward mechanism. We tested the sufficiency of feedforward inhibition to account for the data using a simple computational model that incorporates the results presented here.

Amygdala↗
PubMed1995

An anatomically constrained neural network model of fear conditioning.

Conditioning of fear reactions to an auditory conditioned stimulus (CS) paired with a footshock unconditioned stimulus (US) involves CS transmission to the amygdala from the auditory thalamus, the auditory cortex, or both. This article presents a simple neural network model of this neural system. The model consists of modules of mutually inhibitory nonlinear units representing the different relevant anatomical structures of the thalamo-amygdala and thalamo-corticoamygdala circuitry. Frequency-specific changes produced by fear conditioning were studied at the behavioral level (stimulus generalization) and the single-unit level (receptive fields). The findings mirror effects observed in conditioning studies of animals. This computational model provides an initial grounding for explorations of how emotional information and behavior are related to anatomical and physiological observations.

Acoustic Stimulation↗