Case Report: Stimulation of the Right Amygdala Induces Transient Changes in Affective Bias

Bijanki, Kelly R.; Kovach, Christopher K.; McCormick, Laurie M.; Kawasaki, Hiroto; Dlouhy, Brian J.; Feinstein, Justin S.; Jones, Robert; Howard, Matthew A.

doi:10.1016/j.brs.2014.05.005

Cited by 24 publications

(22 citation statements)

References 28 publications

(26 reference statements)

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“…We also confirmed these behavioural results with a logistic mixed model (Supplementary Notes). Together, our results suggest that amygdala lesion patients had an abnormally low threshold for reporting fear, a finding consistent with prior reports2233 (see Discussion section).…”

Section: Resultssupporting

confidence: 92%

The human amygdala parametrically encodes the intensity of specific facial emotions and their categorical ambiguity

et al. 2017

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The human amygdala is a key structure for processing emotional facial expressions, but it remains unclear what aspects of emotion are processed. We investigated this question with three different approaches: behavioural analysis of 3 amygdala lesion patients, neuroimaging of 19 healthy adults, and single-neuron recordings in 9 neurosurgical patients. The lesion patients showed a shift in behavioural sensitivity to fear, and amygdala BOLD responses were modulated by both fear and emotion ambiguity (the uncertainty that a facial expression is categorized as fearful or happy). We found two populations of neurons, one whose response correlated with increasing degree of fear, or happiness, and a second whose response primarily decreased as a linear function of emotion ambiguity. Together, our results indicate that the human amygdala processes both the degree of emotion in facial expressions and the categorical ambiguity of the emotion shown and that these two aspects of amygdala processing can be most clearly distinguished at the level of single neurons.

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Section: Resultssupporting

confidence: 92%

The human amygdala parametrically encodes the intensity of specific facial emotions and their categorical ambiguity

et al. 2017

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“…Further, most of these postencoding memory-enhancement effects have been demonstrated for stimuli that already have an emotional meaning (30,32,33), making it difficult to dissociate the possible roles of the amygdala in emotion and memory. Finally, none of these studies of emotional memory in humans has involved directly stimulating the amygdala, and those that have stimulated the amygdala apart from memory testing have found that subjective emotional responses and autonomic responses are elicited infrequently and only at relatively high levels of stimulation (34)(35)(36). Thus, it remains unknown whether direct electrical stimulation of the human amygdala would be sufficient to enhance memory and whether any such modulation would depend upon eliciting a subjective or physiological emotional response.…”

Section: Significancementioning

confidence: 99%

Direct electrical stimulation of the amygdala enhances declarative memory in humans

Inman

Manns

Bijanki

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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144

102

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Emotional events are often remembered better than neutral events, a benefit that many studies have hypothesized to depend on the amygdala's interactions with memory systems. These studies have indicated that the amygdala can modulate memory-consolidation processes in other brain regions such as the hippocampus and perirhinal cortex. Indeed, rodent studies have demonstrated that direct activation of the amygdala can enhance memory consolidation even during nonemotional events. However, the premise that the amygdala causally enhances declarative memory has not been directly tested in humans. Here we tested whether brief electrical stimulation to the amygdala could enhance declarative memory for specific images of neutral objects without eliciting a subjective emotional response. Fourteen epilepsy patients undergoing monitoring of seizures via intracranial depth electrodes viewed a series of neutral object images, half of which were immediately followed by brief, low-amplitude electrical stimulation to the amygdala. Amygdala stimulation elicited no subjective emotional response but led to reliably improved memory compared with control images when patients were given a recognition-memory test the next day. Neuronal oscillations in the amygdala, hippocampus, and perirhinal cortex during this next-day memory test indicated that a neural correlate of the memory enhancement was increased theta and gamma oscillatory interactions between these regions, consistent with the idea that the amygdala prioritizes consolidation by engaging other memory regions. These results show that the amygdala can initiate endogenous memory prioritization processes in the absence of emotional input, addressing a fundamental question and opening a path to future therapies.

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“…Most prominently, amygdala stimulation can induce negative (unpleasant) emotions such as fear, tension and nervousness [40, 64]. However, positive emotions can be evoked as well, depending on stimulation site [14, 52], mirroring fMRI studies that generally find amygdala activation to unpleasant and well as pleasant stimuli. It is notable that several studies attempted but failed to induce feelings of aggression by amygdala stimulation [40, 64], except in patients who had pathological aggression to begin with.…”

Section: The Amygdala Emotion and Social Cognitionmentioning

confidence: 99%

The primate amygdala in social perception – insights from electrophysiological recordings and stimulation

Rutishauser

Mamelak

Adolphs

2015

Trends in Neurosciences

121

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The amygdala’s role in emotion and social perception has been intensively investigated primarily through studies using fMRI. Recently, this topic has been examined using single-unit recordings in both humans and monkeys, with a focus on face processing. The findings provide novel insights, including several surprises: amygdala neurons have very long response latencies, show highly nonlinear responses to whole faces, and can be exquisitely selective for very specific parts of faces such as the eyes. In humans, the responses of amygdala neurons correlate with internal states evoked by faces, rather than with their objective features. Current and future studies extend the investigations to psychiatric illnesses such as autism, in which atypical face processing is a hallmark of social dysfunction.

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Case Report: Stimulation of the Right Amygdala Induces Transient Changes in Affective Bias

Cited by 24 publications

References 28 publications

The human amygdala parametrically encodes the intensity of specific facial emotions and their categorical ambiguity

The human amygdala parametrically encodes the intensity of specific facial emotions and their categorical ambiguity

Direct electrical stimulation of the amygdala enhances declarative memory in humans

The primate amygdala in social perception – insights from electrophysiological recordings and stimulation

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