how-to-detect-amygdala-activity-with-magnetoencephalography-using

How to Detect Amygdala Activity with Magnetoencephalography using Source Imaging

In trace fear conditioning a conditional  stimulus (CS) predicts the occurrence of the unconditional stimulus (UCS),  which is presented after a brief ...

reducing-state-anxiety-using-working-memory-maintenance

Reducing State Anxiety Using Working Memory Maintenance

The purpose of this protocol is to explain how to examine the relationship between working memory processes and anxiety by combining the Sternberg Working ...

University of Wisconsin-Milwaukee

National Institutes of Health (NIH)

In Pavlovian fear conditioning, an aversive unconditional stimulus (UCS) is repeatedly paired with a neutral conditional stimulus (CS). As a consequence, the subject begins to show conditional responses (CRs) to the CS that indicate expectation and fear. There are currently two general models competing to explain the role of subjective awareness in fear conditioning. Proponents of the single-process model assert that a single propositional learning process mediates CR expression and UCS expectancy. Proponents of a dual-process model assert that these behavioral responses are expressions of two independent learning processes. We used backward masking to block perception of our visual CSs and measured the effect of this training on subsequent unmasked performance. In two separate experiments we show a dissociation between CR expression and UCS expectancy following differential delay conditioning with masked CSs. In Experiment I, we show that masked training facilitates CR expression when the same CSs are presented during a subsequent unmasked reacquisition task. In Experiment II we show that masked training retards learning when the CS+ is presented as part of a compound CS during a subsequent unmasked blocking task. Our results suggest that multiple memory systems operate in a parallel, independent manner to encode emotional memories.

Conditioning with masked stimuli affects the timecourse of skin conductance responses.

Dans pavlovien peur de conditionnement, un stimulus aversif inconditionnel (UCS) est &agrave; plusieurs reprises associ&eacute; &agrave; un stimulus conditionnel neutre (CS). En cons&eacute;quence, le sujet commence &agrave; r&eacute;agir de mani&egrave;re conditionnelle (CRs) au CS qui indiquent l&#39;espoir et la peur. Il existe actuellement deux mod&egrave;les g&eacute;n&eacute;raux en concurrence pour expliquer le r&ocirc;le de la conscience subjective dans le conditionnement de la peur. Les partisans du mod&egrave;le de processus unique affirment qu&#39;un simple apprentissage propositionnel m&eacute;die expression CR et l&#39;esp&eacute;rance de l&#39;UCS. Les partisans d&#39;un mod&egrave;le double-processus affirment que ces r&eacute;actions comportementales sont des expressions de deux processus d&#39;apprentissage autonome. Nous avons utilis&eacute; masquage vers l&#39;arri&egrave;re &agrave; la perception de bloc de notre CSs visuels et de mesurer l&#39;effet de cette formation sur l&#39;ex&eacute;cution ult&eacute;rieure de d&eacute;masqu&eacute;. Dans deux exp&eacute;riences distinctes, nous montrons une dissociation entre l&#39;expression de la CR et l&#39;esp&eacute;rance de UCS apr&egrave;s conditionnement retard diff&eacute;rentiel avec CSs masqu&eacute;s. En exp&eacute;rimenter je, nous montrons que masqu&eacute;e formation facilite l&#39;expression CR lorsque la m&ecirc;me CSs sont pr&eacute;sent&eacute;es au cours d&#39;une t&acirc;che ult&eacute;rieure r&eacute;acquisition d&eacute;masqu&eacute;. L&#39;exp&eacute;rience II, nous montrons que formation masqu&eacute;e retarde l&#39;apprentissage quand le CS + est pr&eacute;sent&eacute; dans le cadre d&#39;un Etat contractant compos&eacute; pendant une t&acirc;che bloquante d&eacute;masqu&eacute;e ult&eacute;rieure. Nos r&eacute;sultats sugg&egrave;rent que plusieurs syst&egrave;mes de m&eacute;moire fonctionnent d&#39;une mani&egrave;re parall&egrave;le, ind&eacute;pendante pour coder les m&eacute;moires &eacute;motionnelles.

Climatisation avec des stimuli masqu&eacute;s affecte la timecourse des r&eacute;ponses de la conductance de la peau.

Pavloviano paura condizionata, uno stimolo incondizionato aversive (UCS) &egrave; ripetutamente accoppiato con un neutro stimolo condizionato (CS). Di conseguenza, il soggetto comincia a mostrare le risposte condizionale (CRs) al CS che indicano l&#39;aspettativa e la paura. Ci sono attualmente due modelli generali in competizione per spiegare il ruolo della consapevolezza soggettiva nel condizionamento della paura. I fautori del modello di singolo-processo asserire che un processo unico di apprendimento proposizionale media CR espressione e aspettativa di UCS. I fautori di un modello dual-processo affermano che queste risposte comportamentali sono espressioni di due processi di apprendimento indipendente. Abbiamo usato di mascheramento all&#39;indietro alla percezione di blocco del nostro CSs visual e misurato l&#39;effetto di questa formazione sulle successive prestazioni smascherata. In due esperimenti separati mostriamo una dissociazione tra espressione di CR e l&#39;aspettativa di UCS seguito condizionata ritardo differenziale con CSs mascherato. Esperimento in I, mostriamo che formazione mascherato facilita l&#39;espressione CR quando lo stesso CSs vengono presentati durante un&#39;attivit&agrave; successiva riacquisizione smascherato. Nell&#39;esperimento II ci mostra che formazione mascherato ritarda l&#39;apprendimento quando il CS + viene presentato come parte di un composto CS durante una successiva attivit&agrave; blocca smascherata. I nostri risultati suggeriscono che sistemi multipli di memoria operano in maniera parallela, indipendente per codificare i ricordi emozionali.

Condizionata con stimoli mascherati colpisce il timecourse delle risposte di conduttanza della pelle.

The primary focus of research on the amygdala has been on the detection of and response to emotion but the amygdala also sometimes responds to new or unexpected stimuli without specific emotional content. Very little is currently known about why the amygdala responds to some new stimuli but not to others. Here we investigated the conditions that are necessary and sufficient for the expression of novelty specific amygdala responses by presenting novel and repeated images to human participants and varying the content of these images while measuring blood-oxygenation level dependent (BOLD) responses. In Experiment 1 we presented novel and repeated emotional and neutral images. Both emotional and neutral images of humans evoked more amygdala activity when novel than when repeated. In Experiment 2 we presented novel and repeated images of humans and scenes. Images of humans but not scenes evoked more amygdala activity when novel than when repeated. Our results suggest that the amygdala plays a stimulus-specific role in the brain's novelty detection network. Surprisingly, emotion was not necessary for amygdalar novelty responses, but the presence of a human representation was important. Amygdala responses evoked by novel faces may reflect our need to use others' faces as clues for important events in the environment.

The human amygdala plays a stimulus specific role in the detection of novelty.

L&#39;objectif principal de la recherche sur l&#39;amygdale a &eacute;t&eacute; sur la d&eacute;tection des et la r&eacute;ponse &agrave; l&#39;&eacute;motion, mais l&#39;amygdale aussi parfois r&eacute;pond aux stimuli nouveaux ou impr&eacute;vus sans contenu &eacute;motionnel sp&eacute;cifique. Tr&egrave;s on conna&icirc;t actuellement pourquoi l&#39;amygdale r&eacute;pond &agrave; certains nouveaux stimuli, mais pas &agrave; d&#39;autres. Ici, nous avons &eacute;tudi&eacute; les conditions qui sont n&eacute;cessaires et suffisantes pour l&#39;expression des r&eacute;ponses sp&eacute;cifiques amygdale nouveaut&eacute; en pr&eacute;sentant roman et images r&eacute;p&eacute;t&eacute;es &agrave; des participants humains et en variant le contenu de ces images tout en mesurant-l&#39;oxyg&eacute;nation du sang niveau d&eacute;pendant (BOLD) r&eacute;ponse. Dans l&#39;exp&eacute;rience 1, nous a pr&eacute;sent&eacute; le roman et r&eacute;p&eacute;t&eacute; images &eacute;motionnelles et neutres. Images &eacute;motionnels et neutres de l&#39;homme &eacute;voqu&eacute;e par plus d&#39;activit&eacute; amygdale lorsque roman que lorsque r&eacute;p&eacute;t&eacute;. Dans l&#39;exp&eacute;rience 2, nous avons pr&eacute;sent&eacute; les images nouvelles et r&eacute;p&eacute;t&eacute;es des humains et des sc&egrave;nes. Images de l&#39;homme, mais pas de sc&egrave;nes &eacute;voquent plus d&#39;activit&eacute; amygdale lorsque roman que lorsque r&eacute;p&eacute;t&eacute;. Nos r&eacute;sultats sugg&egrave;rent que l&#39;amygdale joue un r&ocirc;le de stimulation sp&eacute;cifique dans le r&eacute;seau de d&eacute;tection de nouveaut&eacute; du cerveau. &Eacute;tonnamment, &eacute;motion n&#39;&eacute;tait pas n&eacute;cessaire pour les r&eacute;ponses d&#39;amygdalar nouveaut&eacute;, mais la pr&eacute;sence d&#39;une repr&eacute;sentation humaine &eacute;tait importante. R&eacute;ponses amygdale &eacute;voqu&eacute;es par nouveaux visages peuvent refl&eacute;ter notre besoin d&#39;utiliser d&#39;autres visages comme indices pour des &eacute;v&eacute;nements importants dans l&#39;environnement.

L&#39;amygdale humaine joue un r&ocirc;le sp&eacute;cifique de la stimulation dans la d&eacute;tection de nouveaut&eacute;.

L&#39;obiettivo primario della ricerca sull&#39;amigdala &egrave; stata al rilevamento di e risposta all&#39;emozione ma l&#39;amigdala anche talvolta risponde a stimoli nuovi o imprevisti senza specifico contenuto emotivo. Attualmente molto poco &egrave; noto circa perch&eacute; l&#39;amigdala risponde ad alcuni stimoli nuovi, ma non per gli altri. Qui abbiamo studiato le condizioni che sono necessarie e sufficienti per l&#39;espressione delle risposte specifiche amigdala novit&agrave; presentazione romanzo e immagini ripetute ai partecipanti umani e variando il contenuto di queste immagini durante la misurazione le ossigenazione sanguigna livello dependent (BOLD) risposte. Nell&#39;esperimento 1 abbiamo presentato romanzo e ripetute immagini emotive e neutrale. Immagini sia emotive e neutrale degli esseri umani evocato pi&ugrave; attivit&agrave; amigdala quando romanzo rispetto a quando si ripete. Nell&#39;esperimento 2 abbiamo presentato romanzo e ripetute immagini di esseri umani e scene. Immagini di esseri umani ma non scene evocato pi&ugrave; attivit&agrave; amigdala quando romanzo rispetto a quando si ripete. I nostri risultati suggeriscono che l&#39;amigdala svolge un ruolo di stimolo specifico nella rete di rilevamento novit&agrave; del cervello. Sorprendentemente, emozione non era necessario per le risposte amygdalar novit&agrave;, ma la presenza di una rappresentazione umana era importante. Risposte amigdala evocate dal romanzo facce possono riflettere la nostra necessit&agrave; di utilizzare altri volti come indizi per eventi importanti nell&#39;ambiente.

L&#39;amigdala umana svolge un ruolo specifico di stimolo nella rilevazione di novit&agrave;.

Neural plasticity in the amygdala is necessary for the acquisition and storage of memory in Pavlovian fear conditioning, but most neuroimaging studies have focused only on stimulus-evoked responses during the conditioning session. This study examined changes in the resting-state functional connectivity (RSFC) of the amygdala before and after Pavlovian fear conditioning, an emotional learning task. Behavioral results from the conditioning session revealed that participants learned normally and fMRI data recorded during learning identified a number of stimulus-evoked changes that were consistent with previous work. A direct comparison between the pre- and post-conditioning amygdala connectivity revealed a region of dorsal prefrontal cortex (PFC) in the superior frontal gyrus that showed a significant increase in connectivity following the conditioning session. A behavioral measure of explicit memory performance was positively correlated with the change in amygdala connectivity within a neighboring region in the superior frontal gyrus. Additionally, an implicit autonomic measure of conditioning was positively correlated with the change in connectivity between the amygdala and the anterior cingulate cortex (ACC). The resting-state data show that amygdala connectivity is altered following Pavlovian fear conditioning and that these changes are also related to behavioral outcomes. These alterations may reflect the operation of a consolidation process that strengthens neural connections to support memory after the learning event.

Resting-state connectivity of the amygdala is altered following Pavlovian fear conditioning.

Plasticit&eacute; neuronale dans l&#39;amygdale est n&eacute;cessaire pour l&#39;acquisition et le stockage de la m&eacute;moire dans la crainte de pavlovien climatis&eacute;, mais la plupart des &eacute;tudes de neuro-imagerie ont mis l&#39;accent uniquement sur &eacute;voqu&eacute;e par la stimulation des r&eacute;ponses au cours de la session de la climatisation. Cette &eacute;tude a examin&eacute; les changements dans l&#39;&eacute;tat de repos de connectivit&eacute; fonctionnelle (RSFC) de l&#39;amygdale avant et apr&egrave;s pavlovien de peur conditionn&eacute;e, une t&acirc;che d&#39;apprentissage &eacute;motionnel. R&eacute;sultats comportements de la session de conditionnement a r&eacute;v&eacute;l&eacute; que normalement, les participants ont appris et donn&eacute;es IRMf enregistr&eacute;es au cours de l&#39;apprentissage identifi&eacute; un certain nombre de changements &eacute;voqu&eacute;e par le stimulus qui concordaient avec les travaux ant&eacute;rieurs. Une comparaison directe entre la connectivit&eacute; de l&#39;amygdale pr&eacute;- et post-conditioning ont montr&eacute; une r&eacute;gion du cortex pr&eacute;frontal dorsal (PFC) dans le gyrus frontal sup&eacute;rieur qui a montr&eacute; une augmentation significative en mati&egrave;re de connectivit&eacute;, issue de la session de conditionnement. Une mesure comportementale des performances de la m&eacute;moire explicite une corr&eacute;lation positive avec le changement de connectivit&eacute; amygdale dans une r&eacute;gion voisine dans le gyrus frontal sup&eacute;rieur. En outre, une mesure autonome implicite de conditionnement &eacute;tait positivement corr&eacute;l&eacute;e avec le changement de la connectivit&eacute; entre l&#39;amygdale et le cortex cingulaire ant&eacute;rieur (CCA). Les donn&eacute;es d&#39;&eacute;tat de repos montrent que la connectivit&eacute; de l&#39;amygdale est alt&eacute;r&eacute;e suite pavlovien peur conditionn&eacute; et que ces changements sont &eacute;galement li&eacute;s aux r&eacute;sultats comportements. Ces alt&eacute;rations peuvent refl&eacute;ter l&#39;exploitation d&#39;un processus de consolidation qui renforce les connexions neuronales pour soutenir la m&eacute;moire apr&egrave;s l&#39;&eacute;v&eacute;nement d&#39;apprentissage.

Repos-&Eacute;tat connectivit&eacute; de l&#39;amygdale est alt&eacute;r&eacute;e pavlovien peur conditionn&eacute;e.

Plasticit&agrave; neurale nell&#39;amigdala &egrave; necessaria per l&#39;acquisizione e l&#39;archiviazione di memoria nel pavloviano paura condizionata, ma la maggior parte dei studi di neuroimaging si sono concentrati solo sulle risposte stimolo evocato durante la sessione di condizionamento. Questo studio ha esaminato le modifiche nella connettivit&agrave; funzionale allo stato di riposo (RSFC) di amigdala prima e dopo pavloviano paura condizionata, un&#39;attivit&agrave; di apprendimento emotivo. Risultati comportamentali dalla sessione condizionata rivelato che i partecipanti imparato normalmente e fMRI dati registrati durante l&#39;apprendimento ha individuato una serie di modifiche evocati stimolo che sono coerenti con il lavoro precedente. Un confronto diretto tra la connettivit&agrave; pre e post-conditioning amigdala ha rivelato una regione della corteccia prefrontale dorsale (PFC) in giro frontale superiore che ha mostrato un aumento significativo nella connettivit&agrave; dopo la sessione di condizionamento. Una misura del comportamento delle prestazioni di memoria esplicita &egrave; stata positivamente correlata con il cambiamento nella connettivit&agrave; amigdala all&#39;interno di una regione confinante in giro frontale superiore. Inoltre, un&#39;implicita misura autonomica di condizionamento &egrave; stata positivamente correlata con il cambiamento nella connettivit&agrave; tra l&#39;amigdala e la corteccia cingolata anteriore (ACC). Lo stato di riposo i dati Mostra che connettivit&agrave; amigdala &egrave; alterato in seguito pavloviano paura condizionata e che questi cambiamenti sono legati anche ad esiti comportamentali. Queste alterazioni possono riflettere il funzionamento di un processo di consolidamento che rinforza le connessioni neurali per supportare la memoria dopo l&#39;evento di apprendimento.

Connettivit&agrave; allo stato di riposo dell&#39;amigdala &egrave; alterato dopo pavloviano paura condizionata.

A number of recent papers have suggested that the amygdala plays a role in the brain's novelty detection circuit. In a recent study, we showed that this role may be specific to certain classes of biologically-relevant stimuli, such as human faces. The purpose of the present experiment was to determine whether other biologically-relevant stimuli also evoke novelty specific amygdala responses. To test this idea, we presented novel and repeated images of snakes and flowers while measuring BOLD. Surprisingly, we found that novel images of snakes and flowers evoke more amygdala activity than repeated images of snakes and flowers. Our results further confirm the robustness of the novelty evoked amygdala responses, even when compared with effects more traditionally associated with the amygdala. In addition, our results suggest that threatening stimuli may prime the amygdala to respond to other types of stimuli as well.

The effect of threat on novelty evoked amygdala responses.

Un certain nombre d&#39;&eacute;tudes plus r&eacute;centes ont sugg&eacute;r&eacute; que l&#39;amygdale joue un r&ocirc;le dans le circuit de d&eacute;tection de nouveaut&eacute; du cerveau. Dans une &eacute;tude r&eacute;cente, nous avons montr&eacute; que ce r&ocirc;le peut &ecirc;tre sp&eacute;cifique &agrave; certaines cat&eacute;gories de stimuli biologiquement pertinentes, telles que des visages humains. La pr&eacute;sente exp&eacute;rience visait &agrave; d&eacute;terminer si les autres stimuli biologiquement pertinente aussi &eacute;voque r&eacute;ponses amygdale sp&eacute;cifique nouveaut&eacute;. Pour tester cette id&eacute;e, nous vous pr&eacute;sentions nouvelles et r&eacute;p&eacute;t&eacute;es des images de serpents et de fleurs tout en mesurant &quot;BOLD&quot;. &Eacute;tonnamment, nous avons constat&eacute; que les nouvelles images de serpents et de fleurs &eacute;voquent plus d&#39;activit&eacute; amygdale que les images r&eacute;p&eacute;t&eacute;es des serpents et des fleurs. Nos r&eacute;sultats confirment la robustesse des r&eacute;ponses amygdale nouveaut&eacute; &eacute;voqu&eacute;e, m&ecirc;me par rapport aux effets plus traditionnellement associ&eacute;es &agrave; l&#39;amygdale. En outre, nos r&eacute;sultats sugg&egrave;rent que des stimuli en danger peut amorcer l&#39;amygdale pour r&eacute;pondre &agrave; d&#39;autres types de stimuli ainsi.

L&#39;effet de la menace sur la nouveaut&eacute; &eacute;voqu&eacute;e par r&eacute;ponses amygdale.

Un certo numero di documenti recenti hanno suggerito che l&#39;amigdala svolge un ruolo nel circuito di rilevamento novit&agrave; del cervello. In un recente studio, abbiamo dimostrato che questo ruolo potrebbe essere specifico a determinate classi di stimoli biologicamente rilevanti, come ad esempio volti umani. Lo scopo dell&#39;esperimento presente era di determinare se altri stimoli biologicamente rilevanti anche evocano risposte specifiche amigdala novit&agrave;. Per verificare questa idea, abbiamo presentato il romanzo e ripetute immagini di serpenti e di fiori mentre misura BOLD. Sorprendentemente, abbiamo trovato che romanzo immagini di serpenti e fiori evocano pi&ugrave; attivit&agrave; amigdala rispetto alle immagini ripetute di serpenti e di fiori. Ulteriormente i nostri risultati confermano l&#39;affidabilit&agrave; delle risposte amigdala novit&agrave; evocato, anche se confrontato con gli effetti pi&ugrave; tradizionalmente associati con l&#39;amigdala. Inoltre, i nostri risultati suggeriscono che minacciosi stimoli pu&ograve; prime amigdala per rispondere ad altri tipi di stimoli come bene.

L&#39;effetto della minaccia su novit&agrave; evocato le risposte amigdala.

Psychopathic behavior has long been attributed to a fundamental deficit in fear that arises from impaired amygdala function. Growing evidence has demonstrated that fear-potentiated startle (FPS) and other psychopathy-related deficits are moderated by focus of attention, but to date, no work on adult psychopathy has examined attentional modulation of the amygdala or concomitant recruitment of relevant attention-related circuitry. Consistent with previous FPS findings, here we report that psychopathy-related differences in amygdala activation appear and disappear as a function of goal-directed attention. Specifically, decreased amygdala activity was observed in psychopathic offenders only when attention was engaged in an alternative goal-relevant task prior to presenting threat-relevant information. Under this condition, psychopaths also exhibited greater activation in selective-attention regions of the lateral prefrontal cortex (LPFC) than did nonpsychopaths, and this increased LPFC activation mediated psychopathy's association with decreased amygdala activation. In contrast, when explicitly attending to threat, amygdala activation did not differ in psychopaths and nonpsychopaths. This pattern of amygdala activation highlights the potential role of LPFC in mediating the failure of psychopathic individuals to process fear and other important information when it is peripheral to the primary focus of goal-directed attention.

The interplay of attention and emotion: top-down attention modulates amygdala activation in psychopathy.

Comportement psychopathe a longtemps &eacute;t&eacute; attribu&eacute;e &agrave; un d&eacute;ficit fondamental dans la crainte qui r&eacute;sulte de la fonction de l&#39;amygdale avec facult&eacute;s affaiblies. Plus en plus &eacute;vident a d&eacute;montr&eacute; que sursaut peur potentialis&eacute;e (FPS) et autres d&eacute;ficits li&eacute;s psychopathie sont mod&eacute;r&eacute;s par le centre d&#39;attention, mais &agrave; ce jour, aucun travail sur la psychopathie adulte n&#39;a examin&eacute; attentionnelle modulation du recrutement amygdale ou concomitante des circuits d&#39;attention-associ&eacute;s pertinents. Conform&eacute;ment aux conclusions ant&eacute;rieures de FPS, nous rapportons ici que les diff&eacute;rences li&eacute;es &agrave; la psychopathie dans l&#39;activation de l&#39;amygdale apparaissent et disparaissent en fonction de l&#39;attention cibl&eacute;. Plus pr&eacute;cis&eacute;ment, amygdale une diminution activit&eacute; a &eacute;t&eacute; observ&eacute;e chez les d&eacute;linquants psychopathes seulement lorsque l&#39;attention se livrait &agrave; une t&acirc;che alternative objectif pertinente avant la pr&eacute;sentation des informations pertinentes &agrave; la menaces. Sous cette condition, psychopathes expose aussi une plus grande activation dans les r&eacute;gions de l&#39;attention s&eacute;lective du cortex pr&eacute;frontal lat&eacute;ral (LPFC) que nonpsychopaths et la liaison de cette augmentation LPFC activation m&eacute;di&eacute;e psychopathie avec activation de l&#39;amygdale une diminution. En revanche, lorsque pr&eacute;sents explicitement &agrave; la menace, activation de l&#39;amygdale ne diff&egrave;re pas en psychopathes et nonpsychopaths. Ce mod&egrave;le d&#39;activation de l&#39;amygdale met en &eacute;vidence le r&ocirc;le potentiel de LPFC dans la m&eacute;diation de l&#39;incapacit&eacute; des individus psychopathiques &agrave; peur de processus et d&#39;autres informations importantes lorsqu&#39;il est &agrave; l&#39;attention primaire de cibl&eacute; la p&eacute;riph&eacute;rie.

L&#39;interaction d&#39;attention et d&#39;&eacute;motion : activation de l&#39;amygdale dans psychopathie module l&#39;attention de haut en bas.

Comportamento psicopatico lungo &egrave; stato attribuito a un deficit fondamentale nel timore che nasce dalla funzione alterata amigdala. Crescente evidenza ha dimostrato che il trasalimento di paura-potenziate (FPS) e altri deficit correlati a psicopatia sono moderati da focus di attenzione, ma ad oggi, nessun lavoro sull&#39;adulto psicopatia ha esaminato attenzione modulazione di amigdala o concomitante assunzione di rilevanti attenzione relativi circuiti. Coerente con le precedenti conclusioni FPS, riportiamo che correlati a psicopatia differenze di attivazione amigdala appaiono e scompaiono in funzione dell&#39;obiettivo-diretta attenzione. Specificamente, amigdala diminuita attivit&agrave; &egrave; stata osservata in delinquenti psicopatici solo quando l&#39;attenzione fu impegnato in un compito rilevante obiettivo alternativo prima di presentare le informazioni rilevanti per la minaccia. Sotto questa condizione, psicopatici esposta anche una maggiore attivazione nelle regioni di attenzione selettiva della corteccia prefrontale laterale (LPFC) che ha fatto nonpsychopaths, associazione di questo aumento LPFC attivazione mediata psicopatia e con l&#39;attivazione di amigdala &egrave; diminuito. Al contrario, quando esplicitamente assistere alla minaccia, attivazione di amigdala non differiscono in psicopatici e nonpsychopaths. Questo pattern di attivazione amigdala mette in evidenza il potenziale ruolo della LPFC nella mediazione il fallimento degli individui psicopatici per timore di processo e altre informazioni importanti quando &egrave; periferico per l&#39;obiettivo primario di attenzione obiettivo-diretto.

L&#39;interazione di attenzione ed emozione: top-down attenzione modula l&#39;attivazione amigdala in psicopatia.

The nature of the relationship between explicit and implicit learning is a topic of considerable debate. To investigate this relationship we conducted two experiments on postconditioning revaluation of the unconditional stimulus (UCS) in human fear conditioning. In Experiment 1, the intensity of the UCS was decreased after acquisition for one group (devaluation) and held constant for another group (control). A subsequent test revealed that even though both groups exhibited similar levels of UCS expectancy, the devaluation group had significantly smaller conditional skin conductance responses. The devaluation effect was not explained by differences in the explicit estimates of UCS probability or explicit knowledge that the UCS intensity had changed. In Experiment 2, the value of the UCS was increased after acquisition for one group (inflation) and held constant for another group (control). Test performance revealed that UCS inflation did not alter expectancy ratings, but the inflation group exhibited larger learned skin conductance responses than the control group. The inflation effect was not explained by differences in the explicit estimates of UCS probability or explicit knowledge that the UCS intensity had changed. The SCR revaluation effect was not dependent on explicit memory processes in either experiment. In both experiments we found differences on an implicit measure of learning in the absence of changes in explicit measures. Together, the differences observed between expectancy measures and skin conductance support the idea that these responses might reflect different types of memory formed during the same training procedure and be supported by separate neural systems.

Dissociation between implicit and explicit responses in postconditioning UCS revaluation after fear conditioning in humans.

The role of consciousness in learning has been debated for nearly 50 years. Recent studies suggest that conscious awareness is needed to bridge the gap when learning about two events that are separated in time, as is true for trace fear conditioning. This has been repeatedly shown and seems to apply to other forms of classical conditioning as well. In contrast to these findings, we show that individuals can learn to associate a face with the later occurrence of a shock, even if they are unable to perceive the face. We used a novel application of magnetoencephalography (MEG) to non-invasively record neural activity from the amygdala, which is known to be important for fear learning. We demonstrate rapid (∼ 170-200 ms) amygdala responses during the stimulus free period between the face and the shock. These results suggest that unperceived faces can serve as signals for impending threat, and that rapid, automatic activation of the amygdala contributes to this process. In addition, we describe a methodology that can be applied in the future to study neural activity with MEG in other subcortical structures.

Rapid amygdala responses during trace fear conditioning without awareness.

The prefrontal cortex regulates the expression of fear based on previously learned information. Recently, this brain area has emerged as being crucial in the initial formation of fear memories, providing new avenues to study the neurobiology underlying aberrant learning in anxiety disorders. Here we review the circumstances under which the prefrontal cortex is recruited in the formation of memory, highlighting relevant work in laboratory animals and human subjects. We propose that the prefrontal cortex facilitates fear memory through the integration of sensory and emotional signals and through the coordination of memory storage in an amygdala-based network.

Prefrontal cortical regulation of fear learning.

Although the amygdala is often directly linked with fear and emotion, amygdala neurons are activated by a wide variety of emotional and non-emotional stimuli. Different subregions within the amygdala may be engaged preferentially by different aspects of emotional and non-emotional tasks. To test this hypothesis, we measured and compared the effects of novelty and fear on amygdala activity. We used high-resolution blood oxygenation level-dependent (BOLD) imaging and streamline tractography to subdivide the amygdala into three distinct functional subunits. We identified a laterobasal subregion connected with the visual cortex that responds generally to visual stimuli, a non-projecting region that responds to salient visual stimuli, and a centromedial subregion connected with the diencephalon that responds only when a visual stimulus predicts an aversive outcome. We provide anatomical and functional support for a model of amygdala function where information enters through the laterobasal subregion, is processed by intrinsic circuits in the interspersed tissue, and is then passed to the centromedial subregion, where activation leads to behavioral output.

Functionally distinct amygdala subregions identified using DTI and high-resolution fMRI.

Behavioural pattern separation (BPS), the ability to distinguish among similar stimuli based on subtle physical differences, has been used to study the mechanism underlying stimulus generalisation. Fear overgeneralisation is often observed in individuals with posttraumatic stress disorder and other anxiety disorders. However, the relationship between anxiety and BPS remains unclear. The purpose of this study was to determine the effect of anxiety (threat of shock) on BPS, which was assessed across separate encoding and retrieval sessions. Images were encoded/retrieved during blocks of threat or safety in a 2 × 2 factorial design. During retrieval, participants indicated whether images were new, old, or altered. Better accuracy was observed for altered images encoded during periods of threat compared to safety, but only if those images were also retrieved during periods of safety. These results suggest that overgeneralisation in anxiety may be due to altered pattern separation.

Effect of anxiety on behavioural pattern separation in humans.

Psychopathy is a personality disorder characterized by emotional deficits and a failure to inhibit impulsive behavior and is often subdivided into "primary" and "secondary" psychopathic subtypes. The maladaptive behavior related to primary psychopathy is thought to reflect constitutional "fearlessness," while the problematic behavior related to secondary psychopathy is motivated by other factors. The fearlessness observed in psychopathy has often been interpreted as reflecting a fundamental deficit in amygdala function, and previous studies have provided support for a low-fear model of psychopathy. However, many of these studies fail to use appropriate screening procedures, use liberal inclusion criteria, or have used unconventional approaches to assay amygdala function. We measured brain activity with BOLD imaging in primary and secondary psychopaths and non-psychopathic control subjects during Pavlovian fear conditioning. In contrast to the low-fear model, we observed normal fear expression in primary psychopaths. Psychopaths also displayed greater differential BOLD activity in the amygdala relative to matched controls. Inverse patterns of activity were observed in the anterior cingulate cortex (ACC) for primary versus secondary psychopaths. Primary psychopaths exhibited a pattern of activity in the dorsal and ventral ACC consistent with enhanced fear expression, while secondary psychopaths exhibited a pattern of activity in these regions consistent with fear inhibition. These results contradict the low-fear model of psychopathy and suggest that the low fear observed for psychopaths in previous studies may be specific to secondary psychopaths.

Psychopaths Show Enhanced Amygdala Activation during Fear Conditioning.

Anxiety patients exhibit deficits in cognitive tasks that require prefrontal control of attention, including those that tap working memory (WM). However, it is unclear whether these deficits reflect threat-related processes or symptoms of the disorder. Here, we distinguish between these hypotheses by determining the effect of shock threat versus safety on the neural substrates of WM performance in anxiety patients and healthy controls.

Anxiety Patients Show Reduced Working Memory Related dlPFC Activation During Safety and Threat.

According to the attentional control theory (ACT) proposed by Eysenck and colleagues, anxiety interferes with cognitive processing by prioritizing bottom-up attentional processes over top-down attentional processes, leading to competition for access to limited resources in working memory, particularly the central executive (Eysenck, Derakshan, Santos, & Calvo, ). However, previous research using the n-back working memory task suggests that working memory load also reduces state anxiety. Assuming that similar mechanisms underlie the effect of anxiety on cognition, and the effect of cognition on anxiety, one possible implication of the ACT would suggest that the reduction of state anxiety with increasing working memory load is driven by activation of central executive attentional control processes. We tested this hypothesis using the Sternberg working memory paradigm, where maintenance processes can be isolated from central executive processes (Altamura et al., ; Sternberg, ). Consistent with the n-back results, subjects showed decreased state anxiety during the maintenance period of high-load trials relative to low-load trials, suggesting that maintenance processes alone are sufficient to achieve this state anxiety reduction. Given that the Sternberg task does not require central executive engagement, these results are not consistent with an implication of the ACT where the cognition/anxiety relationship and anxiety/cognition relationship are mediated by similar central executive mechanisms. Instead, we propose an extension of the ACT such that engaging working memory maintenance suppresses state anxiety in a load-dependent manner. Furthermore, we hypothesize that the efficacy of this effect may moderate the effect of trait anxiety on cognition.

Working memory maintenance is sufficient to reduce state anxiety.

The habenula, a portion of the epithalamus, is implicated in the pathophysiology of depression, anxiety and addiction disorders. Its small size and connection to other small regions prevent standard human imaging from delineating its structure and connectivity with confidence. Resting state functional connectivity is an established method for mapping connections across the brain from a seed region of interest. The present study takes advantage of 7T fMRI to map, for the first time, the habenula resting state network with very high spatial resolution in 32 healthy human participants. Results show novel functional connections in humans, including functional connectivity with the septum and bed nucleus of the stria terminalis (BNST). Results also show many habenula connections previously described only in animal research, such as with the nucleus basalis of Meynert, dorsal raphe, ventral tegmental area (VTA), and periaqueductal grey (PAG). Connectivity with caudate, thalamus and cortical regions such as the anterior cingulate, retrosplenial cortex and auditory cortex are also reported. This work, which demonstrates the power of ultra-high field for mapping human functional connections, is a valuable step toward elucidating subcortical and cortical regions of the habenula network.

Resting state connectivity of the human habenula at ultra-high field.

novelty; bed nucleus of the stria terminalis; BNST; amygdale; fMRI; BST.

The effects of stimulus novelty and negativity on BOLD activity in the amygdala, hippocampus, and bed nucleus of the stria terminalis.

Anxiety disorders affect approximately 1 in 5 (18%) Americans within a given 1 year period, placing a substantial burden on the national health care system. Therefore, there is a critical need to understand the neural mechanisms mediating anxiety symptoms. We used unbiased, multimodal, data-driven, whole-brain measures of neural activity (magnetoencephalography) and connectivity (fMRI) to identify the regions of the brain that contribute most prominently to sustained anxiety. We report that a single brain region, the intraparietal sulcus (IPS), shows both elevated neural activity and global brain connectivity during threat. The IPS plays a key role in attention orienting and may contribute to the hypervigilance that is a common symptom of pathological anxiety. Hyperactivation of this region during elevated state anxiety may account for the paradoxical facilitation of performance on tasks that require an external focus of attention, and impairment of performance on tasks that require an internal focus of attention.

ArticleTotal : 2	Year
Publication title Cited by 27	2013
Publication title Cited by 7	2017

Article	Year
Conditioning with masked stimuli affects the timecourse of skin conductance responses. Behavioral neuroscience\| PubMed ID: 20695647	2010
The human amygdala plays a stimulus specific role in the detection of novelty. NeuroImage\| PubMed ID: 21256226	2011
Resting-state connectivity of the amygdala is altered following Pavlovian fear conditioning. Frontiers in human neuroscience\| PubMed ID: 22936906	2012
The effect of threat on novelty evoked amygdala responses. PloS one\| PubMed ID: 23658813	2013
The interplay of attention and emotion: top-down attention modulates amygdala activation in psychopathy. Cognitive, affective & behavioral neuroscience\| PubMed ID: 23712665	2013
Dissociation between implicit and explicit responses in postconditioning UCS revaluation after fear conditioning in humans. Behavioral neuroscience\| PubMed ID: 23731073	2013
Rapid amygdala responses during trace fear conditioning without awareness. PloS one\| PubMed ID: 24823365	2014
Prefrontal cortical regulation of fear learning. Trends in neurosciences\| PubMed ID: 24929864	2014
Functionally distinct amygdala subregions identified using DTI and high-resolution fMRI. Social cognitive and affective neuroscience\| PubMed ID: 25969533	2015
Effect of anxiety on behavioural pattern separation in humans. Cognition & emotion\| PubMed ID: 26480349	2017
Psychopaths Show Enhanced Amygdala Activation during Fear Conditioning. Frontiers in psychology\| PubMed ID: 27014154	2016
Anxiety Patients Show Reduced Working Memory Related dlPFC Activation During Safety and Threat. Depression and anxiety\| PubMed ID: 27110997	2017
Working memory maintenance is sufficient to reduce state anxiety. Psychophysiology\| PubMed ID: 27434207	2016
Resting state connectivity of the human habenula at ultra-high field. NeuroImage\| PubMed ID: 27780778	2017
The effects of stimulus novelty and negativity on BOLD activity in the amygdala, hippocampus, and bed nucleus of the stria terminalis. Social cognitive and affective neuroscience\| PubMed ID: 28008079	2017
Threat of shock increases excitability and connectivity of the intraparietal sulcus. eLife\| PubMed ID: 28555565	2017

Nicholas L. Balderston

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