Search results
Sep 2, 2020 · Plants have a rich variety of interactions with their environment, including adaptive responses mediated by electrical signaling. This has prompted claims that information processing in plants is similar to that in animals and, hence, that plants are conscious, intelligent organisms. In several recent reports, the facts that general anesthetics cause plants to lose their sensory responses and ...
- Metrics
We would like to show you a description here but the site...
- Metrics
Studies indicate 0.5-3.5 mg of cyanide per kg of body weight can be lethal. Therefore, based on the amounts of amygdalin typically present in raw apricot kernels, it is estimated that adults could ingest only three small apricot kernels (370 mg), before seeing harmful effects. And for toddlers the amount would be much smaller – only 60 mg ...
Nov 21, 2023 · The amygdala is a small structure located in the temporal lobes of the brain. It plays an important role in emotion and memory. There are two amygdalae in the brain. One is in the right hemisphere ...
- The amygdala is a small, almond-shaped cluster of neurons located deep in the temporal lobe. It is part of the limbic system and plays a significan...
- Damage to the amygdala may lead to impaired social functioning and decision-making, as well as the inability to recognize and respond to threats.
- The amygdala is located in the temporal lobe, with one amygdala in each hemisphere of the brain. The function of the amygdala centers on emotions a...
- Stimulation of the amygdala, especially when related to stress or fear, increases blood flow to the region and initiates chemical changes that infl...
- The amygdala modulates responses related to fear and perceived dangers by attaching emotions to memories and sensations. It also interacts with the...
- The amygdala is stimulated by processed sensory input, such as sights, sounds, and sensations. It also responds to memories of unpleasant or fright...
- Overview
- Anatomy of the amygdala
- Function of the amygdala
- Role in innate and learned emotional behaviour
- Regulation of emotion
- The amygdala, cognition, and social behaviour
- Amygdala dysfunction
amygdala, region of the brain primarily associated with emotional processes. The name amygdala is derived from the Greek word amygdale, meaning “almond,” owing to the structure’s almondlike shape. The amygdala is located in the medial temporal lobe, just anterior to (in front of) the hippocampus. Similar to the hippocampus, the amygdala is a paired...
The amygdala comprises a group of nuclei, or clusters of neurons. The basolateral complex, the largest of the clusters and located roughly in the lateral and middle parts of the amygdala, includes the lateral, basal, and accessory-basal nuclei. The lateral nucleus is the major recipient of input from sensory cortices (cortical brain regions that represent information about sensory stimuli) of all modalities (e.g., vision, hearing). In addition, it has been established that in rodents information about auditory stimuli arrives in the amygdala directly from a subcortical (beneath the cortex) area of the brain known as the medial geniculate nucleus, which is located in the thalamus.
The cortical and medial nuclei of the amygdala form the so-called cortico-medial group. Olfactory (smell) information flows directly into the cortico-medial amygdala from the olfactory bulb and pyriform cortex, both of which function in the sense of smell. The intercalated masses are a ribbon of inhibitory neurons that gate information flow from the basolateral complex to the central nucleus of the amygdala.
In addition to sensory input, the amygdala receives input from a number of cortical and subcortical brain systems. Most prominently, the amygdala receives dense input from the prefrontal cortex, especially from the anterior cingulate and orbitofrontal cortices. The amygdala also receives prominent input from the insula and from the hippocampus and rhinal (olfactory) cortices. Subcortical information flows to the amygdala from numerous nuclei, including every neuromodulatory system.
Output from the amygdala can be directed to both subcortical and cortical brain structures. The central nucleus is directed to numerous subcortical structures known to mediate different autonomic, physiologic, and behavioral expressions of emotional state. The basal and accessory-basal nuclei are the major outputs of the amygdala directed to the cerebral cortex. Those anatomical projections may underlie the role of the amygdala in modulating cognitive processes such as decision making, attention, and memory.
The amygdala plays a prominent role in mediating many aspects of emotional learning and behaviour. There exist a vast array of human emotions, ranging from joy to sadness, disgust to excitement, and regret to satisfaction. Most emotions possess a valence (positive or negative) and an intensity (low to high) that reflects emotional arousal. Studies of the neural basis of emotion in animal models, including those focusing on the amygdala, typically have utilized physiological (e.g., autonomic) or behavioral (e.g., approach or defense) measures that likely reflect the valence and intensity of an emotional experience.
Exclusive academic rate for students! Save 67% on Britannica Premium.
Learn More
In the early part of the 20th century, psychologist Heinrich Klüver and neurosurgeon Paul C. Bucy studied monkeys with lesions of the temporal lobe that included the amygdala and observed changes in emotional, feeding, and sexual behaviour. Subsequent studies established that the amygdala was a critical structure mediating those effects.
Pheromones and innately appetitive and aversive stimuli, including certain odours, tastes, or sexual imagery, can produce physiological and behavioral expressions of emotional state. For olfactory stimuli, the cortico-medial amygdala is known to mediate innate emotional behaviour. For other innately reinforcing stimuli, including some drugs of abuse, circuitry within the basolateral complex likely also contributes to emotional responses.
Emotional learning most commonly has been studied in both animal models and humans, using Pavlovian conditioning, in which an otherwise neutrally conditioned stimulus is paired with an innately aversive unconditioned stimulus. This type of paradigm, often referred to as fear conditioning, can result in robust learning, owing to the convergence of sensory information about the conditioned stimulus and the unconditioned stimulus. Neuromodulatory input may also contribute to this learning. As an animal learns, the responses of amygdala neurons to conditioned stimuli change, reflecting the learning process. Furthermore, the activation of neurons in the basolateral amygdala can induce learning, suggesting that those neurons play a causal role in emotional learning. After learning, input from the basolateral complex to the central nucleus of the amygdala leads to the orchestration of a range of physiological and behavioral responses that are correlated with emotional states. Measures of fear conditioning include the cessation of movement (“freezing”), a defensive behaviour, and increased skin conductance responses or increased blood pressure (autonomic measures that reflect arousal level). Lesions of the amygdala impair the acquisition and expression of this learning.
Emotional responses to sensory stimuli not only arise through innate mechanisms and through learning but also can be altered by extinction and cognitive control mechanisms. Both extinction and cognitive control involve interactions between the prefrontal cortex and the amygdala. Extinction, which itself is a learning process, is induced by the repeated presentation of a conditioned stimulus in the absence of a previously associated unconditioned stimulus, resulting in the elimination of a previously elicited response. Projections from the prefrontal cortex to the amygdala mediate extinction, with complex circuitry involving the central nucleus, the basolateral complex, and the intercalated masses playing a role in the modification of responses to previously conditioned stimuli.
The cognitive control of emotion is an important process to understand, given its critical role in normal adaptive emotional behaviour. Human studies using functional magnetic resonance imaging have implicated prefrontal-amygdala interactions in these processes, though the precise mechanisms remain poorly understood, in part owing to the difficulty in studying those processes in animal models.
Emotions influence cognitive processes such as attention, memory formation, and decision making, and they play a prominent role in social behaviour. A large body of literature supports a role for the amygdala in those functions, presumably by virtue of amygdalar projections to the prefrontal and sensory cortices, to the hippocampus and rhinal corti...
Dysfunction within the amygdala and the neural circuits connecting the amygdala with a variety of cortical and subcortical structures likely contributes to the pathophysiology (disease-associated physiological processes) of a number of neuropsychiatric disorders. However, the precise mechanisms responsible for those disorders remain poorly understood. The anatomical interconnections between the amygdala and the prefrontal cortex, which likely are critical for normal adaptive emotional behaviour, do not fully develop until early adulthood. Many neuropsychiatric disorders emerge during or before that time.
Work in animals and studies of clinical populations suggest a role for amygdalar dysfunction in anxiety disorders, addiction, and complex neuropsychiatric disorders such as autism, where clinical features include social, cognitive, and affective components. As research on the amygdala and related structures advances, the precise disturbances in circuit mechanisms that underlie those and other psychiatric disorders are likely to be elucidated, opening the way to the development of new therapeutic interventions that transform the treatment of psychiatric disorders.
Amygdala. Your amygdala is a small part of your brain, but it has a big job. It’s a major processing center for emotions. It also links your emotions to many other brain abilities, especially memories, learning and your senses. When it doesn’t work as it should, it can cause or contribute to disruptive feelings and symptoms.
Jan 14, 2015 · The amygdala is a brain region that is important for emotional processing, the circuitry and function of which has been well-conserved across evolution , although species differences do exist 1.
People also ask
What does the amygdala do?
Where is the amygdala located in the brain?
Is the amygdala a paired structure?
How does the amygdala connect to the brain?
Why is the amygdala important to survival?
Does exposure to nature reduce amygdala activity?
Sep 5, 2022 · The same pattern of amygdala activity after the exposure to the natural environment observed in both tasks, the FFT and the MIST, suggests that a one-hour walk in nature may have had a global ...
