- The typical areas that have been subject to study are the nuclei clusters comprising the amygdalae and the prefrontal cortex (PFC) as their functionality and activation is abnormal relative to healthy controls.
   - The amygdalae constitute part of the limbic system and play a role in the emotional response to a stimulus, most notably inducing physiological reactions to fear, anger, anxiety, and aggression.
      - Hyperarousal of the amygdalae give rise to the intense emotional responses that are characteristic of BPD.
   - The PFC is a major contributor to our executive control, influencing emotional and motivational behaviors.
      - Diminished efficacy of top-down cortical modulation—wherein the brain uses models, ideas, and expectations to interpret sensory information—is observed in BPD, as misinterpretation of events often invokes the onset of a crisis. 
- Both the amygdalae and the PFC are associated with different neural networks.
   - Within the SN, a network that detects and incorporates emotional and sensory stimuli, the amygdalae are considered a subcortical node.
   - Subsections of the PFC are classified as cortical nodes in the DFN, a network involved in various functions but guessed at being the primary determinant of the neurological basis for the self.
- Abnormal neuronal connectivity of the amygdalae and the PFC may be an underlying cause of the impaired communication between the aforementioned neural networks often reported in BPD.

Functional Connectivity in BPD

- Neuroimaging studies have used changes in blood flow or chemistry to examine parts of the brain active while normal adults perform tasks.
- These studies have provided a general picture of where cognitive and emotional processing is carried out by the brain. They give hope of helping us understand how genetics and experience work together to produce the behavior patterns of the adult.
- Neuroimaging studies have examined in the brains of normal adults such processes as perception, working memory, language, spatial attention, attentional selection, arousal, and happy and sad emotional states.

Neuroimaging Studies

fMRI studies have demonstrated increased activation of the insula and amygdala in individuals with SAD. However, these studies were all done independent of one another, and the two brain regions were treated as independent of each other. It has been demonstrated that individuals with anxiety have greater functional connectivity between the amygdala and (right) insula during the anticipation of aversive stimuli, suggesting a greater role of the insula in emotional processing of pathological anxiety.

Functional Connectivity in SAD: Insula & amygdala

Functional connectivity (FC) is defined as the temporal coincidence of spatially distant neurophysiological events, wherein two regions are considered to show functional connectivity if there is a statistical relationship between the measures of activity recorded for them. Extensions of this include both static and dynamic FC.

University of Minnesota - Twin Cities

Biological systems, cascades, processes, and factors that are modulated by the anatomy, physiology, and pathology of the nervous system.

Neurobiological Mechanisms

Everything that defines you as a person is controlled by the neural structures within your brain and body. There are a variety of ways to identify the structures in the brain, starting with cellular and leading into major anatomical divisions. 

Functional Neural Anatomy

Functional neuroimaging has identified several brain regions and circuits involved in pathological anxiety, such as the amygdala, insula, and prefrontal cortex. Neural dysfunction associated with SAD varies from reduced regional volume to increased or decreased activation and functional connectivity.

The Neural Basis of Social Anxiety Disorder

Eickhoff, S. B. & Müller, V. I. (2015). Functional connectivity. Brain mapping: An encyclopedic reference, 2. 187-201. https://doi.org/10.1016/B978-0-12-397025-1.00212-8

Functional connectivity

Neurobiological Mechanisms Library

Functional Connectivity

The Hypothalamic-Pituitary-Adrenal (HPA) axis is a crucial neuroendocrine system that orchestrates the body's response to stress. While highly active during a stress response, its hormonal cascade operates more slowly than the immediate reaction of the sympathetic nervous system. The process begins when the hypothalamus releases corticotropin-releasing factor (CRF), which signals the pituitary gland to secrete adrenocorticotropic hormone (ACTH). ACTH then travels to the adrenal glands, stimulating them to release hormones like cortisol into the bloodstream. This hormonal sequence ultimately provides the body with the energy needed to manage the stressor.

Hypothalamic-Pituitary-Adrenal (HPA) Axis

- specialized cells
- synapses
- central and peripheral nervous system
- neurotransmitters
- hormones
- brain region and their specialized functions
- brain support systems

Structures of Functional Neural Anatomy

- Electroencephalogram (EEG)
- Golgi stain
- Nissl stain
- Optogenetics
- Functional magnetic resonance imaging (fMRI)

Methods of Brain Mapping

Based *only* on the information provided in this case, what is the most logical conclusion you can draw about how different abilities, like understanding language and producing speech, are organized in the brain? Explain your reasoning.

Interpreting Brain Injury Effects

- Amygdala
- Insula
- Prefrontal cortex
- Anterior cingulate cortex

Brain Regions Involved in SAD

Functional magnetic resonance imaging (fMRI) is an effective tool for analyzing brain functionality. It is capable of tracking the functional response of the brain through Blood Oxygen Level Dependent (BOLD) contrast. Increased neuronal activity leads to local increase in energy and oxygen consumption. Essentially, the BOLD effect is a contrast caused by the relative decrease in the magnetic field irregularities due to relative increase in the oxyHb level contributed by the blood flowing in the brain region with increased activity.

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