1. What Activates the Reward System?

The reward system is activated every time we experience something rewarding. For instance, the reward system is triggered when eating something we really enjoy or meeting people we like. The result is a sensation of pleasure and joy.

2. What Part of the Brain Processes Rewards?

There are several parts of the brain that processes rewards, however, the main ones involve the ventral tegmental area (VTA), the nucleus accumbens, the prefrontal cortex, the amygdala, and the hippocampus.  

Rewards are controlled by the reward system through the neurotransmitter dopamine.

2.1. What Is the Ventral Tegmental Area (VTA) and Its Role in the Reward System?

The ventral tegmental area (VTA) is a brain structure located in the midbrain that contains the cell bodies of the dopaminergic neurons where dopamine is released.

2.2. What Is the Nucleus Accumbens and Its Role in the Reward System?

The nucleus Accumbens is a brain structure that is part of the ventral striatum in the basal ganglia. It contains nerve cells that are sensitive to dopamine.

The nerve cells of the nucleus accumbens express on their surface the dopamine receptors, the D1-like (D₁, and D₅) and the D2-like (D₂, D₃, and D₄) family of receptors where dopamine binds. Once activated by dopamine, these cells cause feelings of pleasure.

2.3. What Is the Amygdala and Its Role in the Reward System?

The amygdala is an almond-shaped brain structure located deep in the cerebrum. It is made of a cluster of neurons (Nucleus) responsible for memory including reward-related memory.

For instance, if we had a good experience that led to a feeling of pleasure, this information is stored in the amygdala in the form of desirable memory.

2.5. What Is the Hippocampus and Its Role in the Reward System?

The hippocampus is a brain structure located in the thalamus which is part of the diencephalon (forebrain).

It is made of several clusters of neurons (Nuclei) responsible for coordinating interactions between the nervous system and the endocrine system through the pituitary gland.

Like the amygdala, the hippocampus is also responsible for memory including reward-related memory.

2.6. What Is the Prefrontal Cortex and Its Role in the Reward System?

The prefrontal cortex is the part of the brain that covers up the front of the frontal lobe. It is involved in executive functions such as planning, decision making, and short-term memory.

Within the reward system, the prefrontal cortex coordinates all reward-related information and decides on the type of behavior in response to the information available.

3. What Is Dopamine in the Brain?

Dopamine is a neurotransmitter that is released by dopaminergic neurons to control movement and reward-motivated behavior, such as pleasure, craving, rewards-related decision making, associative learning (learning new things), and short-term memory [2].

Dopamine is synthesized through the metabolism of an essential amino acid known as Phenylalanine. Phenylalanine first generates tyrosine (another amino acid), then tyrosine produces DOPA which finally produces dopamine.

After dopamine synthesis by the dopaminergic neurons, it is transported from the cytoplasm of the neurons all the way to the synapses by a cellular transporter named VMAT2 (Vesicular Monoamine transporter 2), where it is released through vesicles known as synaptic vesicles.

The release of dopamine vesicles in the synaptic cleft is triggered by action potentials, and once released, dopamine binds to the dopamine receptors, the D1-like (D₁, and D₅) and the D2-like (D₂, D₃, and D₄) family of receptors, found on the surface of dendrites of postsynaptic neurons.

The binding of dopamine to its receptors initiates action potentials in the receiving neurons known as neurotransmission.

After the binding activation, dopamine is recycled back to the presynapse by the dopamine transporter until the next activity.

4. What Are the Disorders of the Reward System?

They are several disorders associated with dysfunctions of the reward system, including addiction, mood disorders, schizophrenia, and attention deficit hyperactivity disorder (ADHD).

4.1. What Is Addiction?

Addiction is a compulsive engagement in rewarding stimuli that have adverse consequences. The affected individual is incapable of stopping using a substance or engaging in a behavior. An example of this is drugs addiction.

4.2. Mood Disorders

Mood disorders are emotional states or moods characterized by inconsistency or swings in expressing emotions such as sadness, irritability, aggressivity, impulsivity, and excessive happiness.

Substance abuse such as alcoholism, cocaine, opioids (e.g., heroin) can cause mood disorders through addiction [3]. For instance, depression can be induced by substance abuse associated with an imbalance of neurotransmitters such as dopamine.

Besides addiction, mood disorders are also characterized by reduced motivation which may be associated with reduced activity of dopamine in the striatum [4].

4.3. Schizophrenia

Schizophrenia is a complex and severe mental health disorder that is classified as a type of psychosis. It is characterized by significant alterations in thoughts, perception, mood, and behaviors [5]. 

Like mood disorders, schizophrenia is also associated with a lack of motivation which may be due to abnormalities in the orbitofrontal cortex and striatum.

4.4. Attention Deficit Hyperactivity Disorder (ADHD)

Attention deficit hyperactivity disorder (ADHD) is a brain disorder that affects the behavior of affected individuals and is characterized by an impulsive and constant pattern of inattention and hyperactivity.

In ADHD individuals, there are alterations in motivation and reward which may be associated with the levels of dopamine [6].

These levels are high during the hyperactive phase which increases motivation and reward, while during the inattention phase the levels of dopamine decrease resulting in a lack of motivation and reward.

Conclusion

The reward system controls addictive behaviors, mood, feeding behaviors, positive emotions (e.g., pleasure), and learning.

It is a complex system that involves several brain structures, including the ventral tegmental area (VTA), the nucleus accumbens, the prefrontal cortex, the amygdala, and the hippocampus.

The neurotransmission of information with the reward system is ensured by the neurotransmitter, dopamine.

Dopamine is released by the dopaminergic neurons in the ventral tegmental and excites neurons in the nucleus accumbens. Memory related to reward is stored in the amygdala and the hippocampus. Finally, the behavior associated with motivation and reward is coordinated by the prefrontal cortex.

Anomalies of the reward system result in disorders including addiction, mood disorders, schizophrenia, and attention deficit hyperactivity disorder (ADHD).

The post What Is the Reward System of the Brain? appeared first on .

• The limbic Lobe
• Hippocampal Formation
• The Amygdala
• The Septal Area
• The Hypothalamus

1. What Is the Function of the Limbic Lobe?

The limbic lobe is a vital region of the brain involved in emotion, learning, memory, and motivation [2]. It is a C-shaped brain region that includes:

• Cingulate gyrus
• Parahippocampal gyrus
• Subcallosal Gyrus

1.1. What Is Cingulate Gyrus and Its Function?

The cingulate gyrus is a brain structure located toward the middle (medial aspect) of the cerebral hemisphere and is involved in the formation and processing of emotions, memory, and learning.

1.2. What Is Parahippocampal Gyrus and Its Function?

The parahippocampal gyrus is a brain structure located toward the middle of the temporal lobe and is involved in-memory processing, storage, and recall.

1.3. What Is Subcallosal Gyrus and Its Function?

The subcallosal gyrus is a thin layer (lamina) located towards the middle of the hemisphere involved in the regulation of stress responses by suppressing the amygdala’s responsiveness to fear.

2. What Is Hippocampal Formation?

The hippocampal formation is located towards the middle of the temporal lobe of the brain and is made of 4 structures [3]:

• The Dentate Gyrus
• The Hippocampus Proper
• The Subiculum Complex
• The Entorhinal Cortex

2.1. What Is Dentate Gyrus?

The dentate gyrus is a structure located toward the middle of the temporal lobe that receives fibers from the entorhinal cortex and may be involved in episodic memory (Type of long-term memory).

2.2. What is Hippocampus?

The hippocampus proper is the structure of the brain where episodic memories are formed and stored.

In addition to its role in long-term memory, the hippocampus is also involved in learning, flexible and goal-oriented behavior, navigation, and spatial orientation.

2.3. What Is Subiculum Complex and Its Function?

The subiculum complex is a structure located toward the middle of the temporal lobe involved in working memory and drug addiction.

2.4. What Is Entorhinal Cortex and Its Function?

The entorhinal cortex is a structure located toward the middle of the temporal lobe which connects the hippocampus and the neocortex and is involved in navigation, perception of time, and memory formation, consolidation, and optimization during sleep.

3. What Is the Amygdala and What It Controls?

The Amygdala is an almond-shaped structure located toward the middle of the temporal lobe involved in emotional response (fear, anxiety, and anger), decision making, and memory (emotional and fear associated memories) [4].

4. What Is Septal Area and Its function?

The septal area is a structure located in the inferior and posterior part of the middle of the frontal lobe involved in emotional, motivational, and spatial behavior through its nuclei connections with the hypothalamus, amygdala, olfactory bulb, cingulate gyrus, thalamus, habenula, and midbrain.

5. What Is the Hypothalamus and What It Controls?

The hypothalamus is a structure located in the diencephalon below the thalamus and is involved in functional linking between the nervous system and the endocrine system [5].

It is divided into three regions, the anterior region (supraoptic), the middle region (tuberal), and the posterior region (mammillary), and each region is subdivided into areas containing specialized nuclei.

The anterior region has 3 areas known as preoptic, medial, and lateral, involved in thermoregulation, circadian rhythms (suprachiasmatic nucleus), and endocrine secretion of hypothalamic hormones (e.g., corticotropin-releasing hormone).

The meddle region (tuberal) has 2 areas, medial and lateral, involved in the control of blood pressure, heart rate, gastrointestinal stimulation, hunger, secretion of the growth hormone-releasing hormone (GHRH), and neuroendocrine control.

The posterior region has also 2 areas, medial and lateral, involved in memory, learning, arousal, sleep, shivering, pupillary dilatation, and energy balance.

6. What Happens If the Limbic System Is Damaged?

Damage in the structures of the limbic system can result in the following disorders [1]:

• Epilepsy
• Dementia
• Limbic Encephalitis
• Schizophrenia
• Anxiety Disorders
• Affective Disorders
• ADHD
• Korsakoff’s Psychosis
• Klüver-Bucy Syndrome
• Autism

6.1. Epilepsy

Hippocampal sclerosis (tissue stiffening) can result in temporal lobe epilepsy which can be further complicated when other structures, including the amygdala and the parahippocampal gyrus, are also involved (Mesial Temporal Sclerosis).

6.2. Dementia

Alzheimer’s’ disease is associated with senile plaques and neurofibrillary tangles affecting the hippocampus and the dentate gyrus.

6.3. Limbic Encephalitis

Limbic encephalitis is an inflammation that affects parts of the limbic structures due to an autoimmune disorder (non-paraneoplastic limbic encephalitis) or a tumor (Paraneoplastic limbic encephalitis).

6.4. Schizophrenia

Schizophrenia is a complex and severe mental health disorder that is classified as a type of psychosis. It is characterized by significant alterations in thoughts, perception, mood, and behaviors.

The causes are not well known; however, it was suggested that the causes may be associated with a cognitive decline due to alterations in brain development, particularly of the cerebral cortex.

The reduced volumes of the limbic system structures including the hippocampus and the entorhinal cortex in schizophrenia patients may be one of the causes of this disorder.

6.5. Anxiety Disorders

Failure of the hippocampus and the cingulate gyrus in modulating the activity of the amygdala can result in anxiety disorders.

6.6. Affective Disorders

Variation in the volumes of the frontal lobes, amygdala, hippocampus, and basal ganglia, have been associated with affective disorders. 

6.7. ADHD

Loss of connections between the orbitofrontal cortex and the amygdala may explain the disinhibition behavior observed in ADHD individuals.

6.8. Korsakoff’s Psychosis

Korsakoff’s psychosis is caused by damage to mammillary bodies, the thalamus (e.g., tumors, ischemia, or stroke), and hypothalamus resulting in amnesia, the deficit in explicit memory, and confabulation.

6.9. Klüver-Bucy Syndrome

This disease is associated with symptoms including hypersexuality, hyperphagia, placidity, visual agnosia, and hyperorality. It is due to bilateral lesions affecting the amygdala and the inferior prefrontal cortex.

6.10. Autism

Alterations in limbic structures, including the amygdala and the cingulate gyrus, have been associated with autism and Asperger’s syndrome.

Conclusion

Although its involvement in the control of emotions, long-term memory, behavior, and olfaction is known, the complexity of the limbic system makes its clinical study difficult.

However, advances in behavioral studies, functional magnetic resonance imaging (MRI), deep brain stimulation, and perfusion studies, have allowed a better understanding of this system, and future functional imaging techniques will certainly uncover more hidden functions of this fascinating part of the brain.

The post What Is the Limbic System and What Is Its Function? appeared first on .

Explicit Memories are long-term memories that are stored in the following brain structures:

• Hippocampus
• Neocortex
• Amygdala

Implicit Memories are long-term memories that are stored in the following brain structures:

• Basal Ganglia
• Cerebellum

Working Memory and short-term memory are stored in the following brain structure:

• Prefrontal Cortex

1. What Is Memory?

Memory is the faculty of processing, storing, and remembering experiences and knowledge. It is what makes us and what makes our identity.

Memories are processed, stored, and reactivated in specific neurons that interact with each other through synapses which are known as synaptic plasticity.

Memories are made stronger or weaker depending on dynamic interactions between these groups of specialized neurons.

Memory is divided into short-term memory or working memory and long-term memory which includes explicit and implicit memories.

2. What Does It Mean to Have an Explicit Memory?

Explicit memories are conscious memories that recall events that happen to us (episodic memories) or that recall general knowledge of the world (semantic memories).

They are formed and stored in a specific group of neurons found in the hippocampus, neocortex, and amygdala.

2.1. What Does the Hippocampus Do for Memory?

The hippocampus is the structure of the brain where episodic memories are formed and stored. It is situated in the temporal lobe of the brain.

In addition to its role in long-term memory, the hippocampus is also involved in learning, flexible and goal-oriented behavior, navigation, and spatial orientation.

The hippocampus is also one of the two areas of the adult brain where there is still the production of new neurons (hippocampal neurons) due to the presence of neural stem cells.

2.2. What Does the Neocortex Do for Memory?

The neocortex serves as a storage area for temporary memories provided by the hippocampus and that are stored in a form of semantic memories.

It is the largest part of the cerebral cortex and is also involved in sensory perception (perception of outside stimuli), spatial reasoning, language, and the planning, control, and execution of voluntary movement.

2.3. What Does the Amygdala Do for Memory?

The amygdala is an almond-shaped structure of the brain’s temporal lobe involved in the formation and storage of emotional and fear-associated memories.

In addition to its role in memory, the amygdala is also involved in emotional responses (e.g., fear and anxiety) and decision-making in response to external stimuli.

3. What is Implicit Memory?

Implicit memories are unconscious or automatic memories that do not require conscious or voluntary recall to influence our behavior.

Implicit memories are divided into priming memories and procedural memories:

• Priming Memories

A priming memory is an unconscious improvement or change in dealing with a stimulus because of a previous experience with the same or a related stimulus [2].

• Procedural Memories

Procedural memory is associated with performing tasks without being consciously aware of doing them. An example is the capacity of riding a bike even if we did not cycle for a long period.

Implicit memories are formed and stored in a specific group of neurons found in the basal ganglia and cerebellum.

3.1. What Does Basal Ganglia Do for Memory?

Basal ganglia are structures resting deep within the brain and are involved in the storage of procedural memories [3].

Basal ganglia are also involved in many functions of the brain, including cognition, emotion, procedural learning, conditional learning, habit learning, and control of voluntary motor movements.

3.2. What Does the Cerebellum Do for Memory?

The cerebellum is situated at the back of the brain and is involved in procedural memory but also in motor learning and classical conditioning.

In addition, the cerebellum is involved in controlling the body balance, coordination, movement, and motor skills.

4. What Is Working Memory?

Working memory is a temporary storage of a small amount of information ready for immediate mental use [4].

5. What Is Short-Term Memory?

Working memory is a temporary storage of a small amount of information without manipulation of the information stored [5].

Theoretical concepts differentiate between working memory and short-term memory as short-term memory is suggested to refer to the maintenance while working memory involves a combination of maintenance and manipulation of information.

However, correlational studies have not been able to separate between working memory and short-term memory [5].

Working memory and short-term memory are mediated by the prefrontal cortex.

4.1. What Does the Prefrontal Cortex Do for Memory?

The prefrontal cortex is situated at the front part of the frontal lobe and is involved in the storage of a small amount of information.

In addition, the prefrontal cortex is involved in many functions of the brain, including executive processes (differentiating between conflicting thoughts), information processing, attention, judgment, behavioral organization, and certain aspects of language and speech [6].

5. What Are the Types of Memory Loss?

Memory loss is known as amnesia which can be caused by head or emotional trauma, Alzheimer’s disease, brain tumor, alcoholism, seizures, encephalitis, or stroke [7]. There are several types of amnesia:

• Retrograde Amnesia
• Anterograde Amnesia
• Post-Traumatic Amnesia
• Transient Global Amnesia
• Dissociative Amnesia
• Infantile Amnesia

5.1. What Is Retrograde Amnesia?

Retrograde amnesia is the incapacity to recall events or information from the past.

5.2. What Is Anterograde Amnesia?

Anterograde amnesia is the incapacity to recall new events or information following an amnesia incident.

5.3. What Is Post-Traumatic Amnesia?

Post-traumatic amnesia is a state of confusion associated with to incapacity to recall new events or information immediately after a traumatic incident.

5.4. What Is Transient Global Amnesia?

Transient global amnesia is a temporary sudden and total loss of short-term memory.

5.4. What Is Dissociative Amnesia?

Dissociative amnesia is the incapacity to recall personal information following trauma or stress.

5.5. What Is Infantile Amnesia?

Infantile amnesia is the incapacity to recall events or information from childhood.

Conclusion

Memory is a complex process that involves several parts of the brain that process, store, and reactivate conscious and unconscious information from the past and when we need them. Without memories, it is impossible to know who we are, what we are doing, and what we are planning to do.

The post What Part of the Brain Controls Memory? appeared first on .

• Odour sensing by receptors of the olfactory sensory neurons in the nose.
• The olfactory sensory neurons in the nose transmit the odour information (olfactory information) to the olfactory nerves through a process known as neurotransmission.
• The olfactory nerves transmit the olfactory information to the olfactory bulb, a neural structure responsible of olfaction (Smell).
• The olfactory bulb transmits the olfactory information to specific areas of the brain for processing and identification of the smell.

1. What Part of the Brain Is Most Responsible for Smell?

There are several and important parts of the brain that are responsible for smell; however, the olfactory bulb is responsible for transmitting the olfactory (smell) information from the olfactory nerves to the brain for processing.

This olfactory information is chemically identified and coded by a part of the olfactory bulb known as the glomeruli. This process is known as the odor map [1].

2. What Happens in the Brain When You Smell?

When the olfactory information is transmitted from the olfactory bulb to the brain, there are parts of the brain responsible for the processing of this information including the amygdala, the piriform cortex, and the entorhinal cortex [2].

• The Amygdala and Olfaction

The amygdala is the central hub for the management of fear within a network that involves other brain organs including the thalamus, the neocortex, the hypothalamus, the pituitary gland, the hippocampus, and the adrenal glands located on the top of the kidneys.

When the amygdala receives the olfactory information for processing it interrogates the memory siege, the hippocampus, for previous similar stimuli (e.g., olfactory stimuli).

Once the information is received from the hippocampus, the amygdala triggers the hypothalamus-pituitary-adrenal axis to initiate an adaptative reaction [3].

Depending on the nature of the smell which can be pleasant or unpleasant, associated or not with potential danger, a reaction such as robust approach (pleasant olfaction) or withdrawal if unpleasant or linked with potential danger (e.g., the smell of smoke due to fire) [4].

• The Olfactory Tubercle and Olfaction

The olfactory tubercle is part of the olfactory cortex found in the frontal lobe of the brain where is connected to the amygdala and the hippocampus.

It is involved in recognizing one’s body odor from the environment odors (sensory integration), motivated behaviors in response to odor (attractiveness or repulsion), and reward recognition [1].

• The Piriform Cortex and Olfaction

The piriform cortex is part of the brain known as the rhinencephalon located in the cerebrum. It is involved in odor perception and its differentiation from other odors and from a mixture of odors, and in odor memory [5].

• The Entorhinal Cortex and Olfaction

The Entorhinal cortex is part of the cerebral cortex where it plays a role as an interface between the hippocampus that is involved in memory and the neocortex involved in sensory perception (e.g., olfaction) spatial reasoning, and navigation, and cognition [6].

4. Can Smells Trigger Emotions?

There are common brain areas that are involved in both olfaction and emotion such as the amygdala, the hippocampus, the orbitofrontal cortex, the insula, and the cingulate cortex.

When the amygdala receives the olfactory information for processing it interrogates the memory siege, the hippocampus, for previous similar stimuli (e.g., olfactory stimuli).

Depending on the nature of the smell which can be pleasant or unpleasant, associated or not with potential danger, a reaction such as robust approach (pleasant olfaction) or withdrawal if unpleasant or linked with potential danger (e.g., the smell of smoke due to fire) [7].

The orbitofrontal cortex is involved in the reward value of taste but also in the reward value of odors which initiate an emotion [8].

The insula is a part of the cerebral cortex involved in emotion and in the processing of unpleasant odors [9].

The cingulate cortex is also part of the cerebral cortex that is involved in the formation and processing of emotions related to pleasant and unpleasant odors [10].

5. Does Smell Affect Memory?

Olfaction requires the involvement of the hippocampus, the brain part that controls memory. The amygdala processing of the olfactory information involves interrogating the hippocampus about previous experiences with the olfactory information.

6. What Is It Called When a Smell Triggers a Memory?

This effect is known as the Proustian effect based on the name of the novelist Marcel Proust.

7. Why Do Smells Make Me Angry?

The smell can trigger anger if that smell was associated with a past situation that caused anger to an individual.

The amygdala processing of the olfactory information involves interrogating the hippocampus about previous experiences with the olfactory information.

The olfactory information can also trigger emotions of anger through parts of the brain such as the amygdala, the hippocampus, the orbitofrontal cortex, the insula, and the cingulate cortex.

8. What Causes Loss of Smell?

The loss of smell can be complete and is known as anosmia or diminished and is known as hyposmia. These alterations in olfaction are due to physical or mental health disorders, viral infections, inflammation, environmental exposure, or aging [2].

Disorders or conditions such as Alzheimer’s disease, Parkinson’s disease, meningiomas, facial trauma or schizophrenia, may affect the function of the olfactory system leading to a loss of smell.

Upper respiratory viral infections and neurotropic viruses can also cause a loss of smell.

Neurotoxins found in some industrial workplaces such as solvents, metals, and particulate matter can cause a loss of smell [11].

9. What Is Aromatherapy and Its Benefits?

Aromatherapy is the use of plant essential oils through skin application or olfaction for the management of chronic pain, anxiety, some cognitive disorders, depression, insomnia, and stress-related disorders [12].

However, the clinical evidence is limited, and further research and clinical trials are required.

These are some of the essential plant oils that were used in different studies:

• Bergamot
• Chamomile-Roman
• Geranium
• Jasmine
• Juniper
• Lavender
• Lemon
• Mandarin
• Marjoram
• Melissa
• Neroli
• Patchouli
• Rose
• Rosemary
• Sage
• Spearmint
• Ylang-Ylang
• Vetiver

Conclusion

Olfaction is a complex process that involves the transmission of the olfactory information (smell) by specialized sensory neurons in the nose, the olfactory nerves, the olfactory bulb, and its processing by several regions of the brain.

Meanwhile, let’s enjoy the smell of a nice dish of food and a delicate perfume.

The post How Does Smell Get from the Nose to the Brain? appeared first on .

The central organ that controls and regulates fear is the amygdala, an almond-chapped structure located deep within the brain’s temporal lobes.

1. What Is the Function of the Amygdala in Fear?

The amygdala is the central hub for the management of fear within a network that involves other brain organs including the thalamus, the neocortex, the hypothalamus, the pituitary gland, the hippocampus, and the adrenal glands located on the top of the kidneys.

When stimuli (e.g., environmental changes) are received by the thalamus, they are sent to the amygdala for processing which involves interrogating the memory siege, the hippocampus, for previous similar stimuli.

Once the information is received from the hippocampus indicating a potential threat, the amygdala triggers the hypothalamus-pituitary-adrenal axis to initiate an adaptative reaction [1].

2. What Is the Role of the Hypothalamus-Pituitary-Adrenal Axis in Fear?

In this event, the hypothalamus secretes CRH (corticotropin-releasing hormone) to stimulate the secretion of ACTH (Adrenocorticotropic hormone) by the pituitary gland leading to the secretion of cortisol by the adrenal glands as part of the “Fight-or-Flight” mechanism [2].

3. How Fear Is Biologically Controlled?

When stimuli (e.g., environmental changes) are received by the thalamus, parts of the stimuli are also sent to the neocortex, a brain structure responsible for thinking and rationality, which processes this information and informs the amygdala of the absence of threat.

4. What Causes Fear?

To better understand the fear and cope with it, it is essential to understand its causes. Several theories suggest the origin of fear such as individuals’ personality, social construction, anxiety sensitivity, modularity of the mind, basic emotion, and evolutionary [1].

A. What Is the Link Between Personality and Fear?

A study that analyzed more than 4892 studies on the relationship between anxious personality traits and fear, found that individuals who score high on anxious personality tend to generalize fear to safe or novel situations [3]. 

B. What Is the Link Between Social Construction and Fear?

Fear can be socially constructed through mass media, horror movies, and news. For instance, as media is an integral daily part of our lives, they can lead to the production and constitution of emotions and feelings, including fear, which can be socially shared due to the media-wide social outreach [4].

C. What is the Link Between Anxiety Sensitivity and Fear?

Anxiety sensitivity (AS) describes individual differences in cognitive and affective risk factors of fear of bodily sensations such as pain, pleasure, headaches, nausea, itches, and tickles.

A study investigated the effects of an anxiety-based smoking cessation treatment on 579 adults and found that 35.6% had at least one emotional distress disorder diagnosis, and 11.9% of individuals had at least two emotional distress disorder diagnoses [5].

D. What Is the Link Between Modularity of the Mind and Fear?

According to the theory of modularity of the mind, the mind is comprised of innate neural structures or mental modules. It was suggested that a module of fear also exists and controls threat-related stimuli through some specialized neural structures [6].

E. What Is Basic Emotional Fear?

This theory states that fear is an emotion that evolved from adaptations to fundamental life tasks through signals, physiology, and previous events. Using neuroimaging techniques, a study showed that basic emotions such as fear, happiness, anger, sadness, and disgust, have specific regional brain activations [7].

F. What Is Evolutionary Fear?

This theory suggests that fear is evolutionary and is associated with survival circuits that are found in all animal species.

Due to the presence of sensory receptors and motor effectors within the central nervous system, that coordinates the interface between bodily functions and the environment, these survival capacities increased in complexity during evolution [8].

5. How is Fear Measured?

There are two types of tests used to measure the fear index: behavioral and psychophysiological measures [1].

A. What Are the Behavioral Measures for the Fear Index?

Behavioral measures assess the correlation between self-report questionnaires and behavioral responses:

• –  Skin-conductance response 
• – Pupillometry
• – Facial electromyography
• – Potentiation of auditory startle
• – Heart rate and respiration
• – Salivary cortisol

B. What Are the Psychophysiological Measures for the Fear Index?

Psychophysiological Measures are used to evaluate attention and emotional responses to stimuli:

• – State-Trait Anxiety Inventory
• – Beck Anxiety Inventory
• – Anxiety Sensitivity Index
• – Fear Survey Schedule
• – Fear Questionnaire
• – Social Avoidance/Distress Scale
• – Albany Panic and Phobia Q
• – PANAS-X Fear
• – Fear of Negative Evaluation Scale

6. How to Deal with Fear?

Fear can lead to stress, anxiety, and panic attacks and several measures could be used to overcome fear such as taking some time off, facing our fears, and learning about our fears to better face them.

However, there are some debilitating fear conditions where therapy is required. In this case, therapies such as medications, psychotherapy, and hypnosis are used to treat specific phobias [9].

7. Frequently Asked Questions about What Is the Biology of Fear and Anxiety?

What is fear and anxiety from a biological perspective?

Fear and anxiety are natural responses to perceived threats or dangers. Biologically, they involve complex interactions between various brain regions, neurotransmitters, and hormones.

What brain regions are involved in processing fear and anxiety?

The amygdala, prefrontal cortex, and hippocampus are key brain regions involved in the processing and regulation of fear and anxiety.

The amygdala plays a central role in detecting threats and initiating fear responses, while the prefrontal cortex helps regulate and contextualize these responses. The hippocampus is involved in memory formation and emotional regulation.

What neurotransmitters are involved in fear and anxiety?

Neurotransmitters such as serotonin, dopamine, and gamma-aminobutyric acid (GABA) play crucial roles in modulating fear and anxiety. Imbalances in these neurotransmitter systems can contribute to the development of anxiety disorders.

How do hormones influence fear and anxiety?

Hormones like cortisol and adrenaline are released in response to stress and play important roles in the body’s fight-or-flight response.

Chronic stress and dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, which governs the release of these hormones, can contribute to the development of anxiety disorders.

Can genetics influence susceptibility to anxiety disorders?

Yes, genetics can predispose individuals to anxiety disorders. Certain genetic variations may impact the functioning of neurotransmitter systems or the regulation of stress response pathways, increasing vulnerability to anxiety.

How does the environment contribute to the development of anxiety disorders?

Environmental factors such as early-life experiences, trauma, chronic stress, and substance abuse can all contribute to the development of anxiety disorders. These factors can interact with genetic predispositions and alter brain function and chemistry in ways that promote anxiety.

Are there effective treatments for anxiety disorders targeting the biology of fear and anxiety?

Yes, several treatments target the biological underpinnings of anxiety disorders, including medication (e.g., selective serotonin reuptake inhibitors, benzodiazepines) that modulate neurotransmitter activity, and psychotherapy techniques (e.g., cognitive-behavioral therapy) that help individuals reframe their thoughts and behaviors related to fear and anxiety.

Additionally, lifestyle interventions such as exercise and mindfulness practices can help regulate stress response systems and alleviate symptoms of anxiety.

Conclusion

Several theories are suggested to explain the origin of fear; however, fear is likely to originate from a combination of all those theories as most of them appear to overlap in some respects.

One of the points that raises attention is the social construct theory where large media outlets can create a large-scale state of fear within a population, a country, or globally, that can lead to unforeseen consequences.

References

[1] Adolphs, R., 2013. The biology of fear. Current biology, 23(2), pp.R79-R93.

[2] Miller, W.L., 2018. The hypothalamic-pituitary-adrenal axis: a brief history. Hormone research in paediatrics, 89(4), pp.212-223.

[3] Sep, M.S., Steenmeijer, A. and Kennis, M., 2019. The relation between anxious personality traits and fear generalization in healthy subjects: a systematic review and meta-analysis. Neuroscience & Biobehavioral Reviews, 107, pp.320-328.

[4] Renda, C.D., 2019. Watching” Insidious”–On the Social Construction of Fear. The Qualitative Report, 24(7), pp.1784-1804.

[5] Allan, N.P., Norr, A.M., Capron, D.W., Raines, A.M., Zvolensky, M.J. and Schmidt, N.B., 2015. Specific associations between anxiety sensitivity dimensions and fear and distress dimensions of emotional distress disorders. Journal of psychopathology and behavioral assessment, 37(1), pp.67-78.

[6] Gross, C.T. and Canteras, N.S., 2012. The many paths to fear. Nature Reviews Neuroscience, 13(9), pp.651-658.

[7] Vytal, K. and Hamann, S., 2010. Neuroimaging support for discrete neural correlates of basic emotions: a voxel-based meta-analysis. Journal of cognitive neuroscience, 22(12), pp.2864-2885.

[8] LeDoux, J., 2012. Rethinking the emotional brain. Neuron, 73(4), pp.653-676.

[9] Antony, M.M., Craske, M.G. and Barlow, D.H., 2006. Mastering your fears and phobias. Oxford University Press.

The post What Is the Biology of Fear and Anxiety? appeared first on .