neuro-ang

[neuro-ang]

Falling in love is a wonder of our world, but what exactly happens to our brains when we reach the emotional state of being in love? 

When one falls in love, their brain undergoes different processes from chemicals and hormones which affect how we behave. Neurotransmitters, dopamine, serotonin, norepinephrine, and oxytocin all play a unique role in one’s experience with love. To begin with, neuroscientists have developed a three stage categorization to determine which hormones and brain networks are active in different stages of love: Sex drive, romantic love, and long-term bonding. 

To begin with, our sex drive is controlled by androgens and estrogens, which are both produced in the sex hormones. Androgens, such as testosterone found in primarily males, and ovaries found in females, are regulated by the hypothalamus and pituitary gland through hormonal signals. The mechanism for the production of androgens are: the hypothalamus will release the gonadotropin-releasing hormone (GnRH), which will then prompt the pituitary gland to produce luteinizing hormone (LH). LH will then allow for the stimulation of testosterone in testes or ovaries to be produced. In males, androgens are crucial for the development of reproductive tissue, as well as body hair and muscle growth. For females, androgens are important for sexual desire and the regulation of the reproductive system. 

Estrogen is a female sex hormone important for the reproductive system and libido. Estrogen is produced in the ovaries and is regulated by the hypothalamus and pituitary gland. Estradiol, a primary form of estrogen, is involved in the menstrual cycle and pregnancies. A balance between androgens and estrogens are essential for healthy libido, as well as psychological states. 

The next categorization of love is romantic love, where high dopamine and norepinephrine kicks in; this stage allows for the focused attraction of an individual. Dopamine plays an important role in the brain’s reward system, during an attraction phase dopamine levels will surge and motivation, addiction, and pleasure will arise. The increase in dopamine during love activates several brain areas, such as the prefrontal cortex, ventral tegmental area, and nucleus accumbens– allowing for romance to be an intensely rewarding and enjoyable interaction. Dopamine can also alter one’s focus, which contributes to the focused attention one may give and heightened memory surrounding getting to know someone one is interested in; this strengthens the human emotional connection. Norepinephrine, another romantic-attraction neurotransmitter, plays a part in the fight or flight response, where meeting someone new and feeling attracted can relay physical symptoms that are vitally important to feeling good when being around someone. These physical symptoms include sweaty hands, rapid heart rates, and rushes of energy. In addition, this heightened physical state can affect one’s memory and can vividly encode memories to enhance the emotional salience of a relationship. 

The last characterization of love is long term bonding which is dominated by oxytocin and vasopressin. The attachment phase of relationships is crucial for romantic partners to foster connection and contentment with a partner. During any physical response, such as sexual intercourse, hugs, and kissing, oxytocin is released, which enhances trust and empathy from partner to partner. Oxytocin releases stress and anxiety, while fostering mutual support. Oxytocin affects the amygdala and the ventral tegmental area, which are areas involved in emotion regulation and reward circuitry; this reinforces ‘feel good’ behavior and makes it more pleasurable. Vasopressin is equally important in promoting bonding and supportive relationships; vasopressin assists in regulating social behavior and aggression by interacting with specific receptors in the brain that play roles in the development of monogamous attachments. Both oxytocin and vasopressin are important for deep emotional bonds,  while oxytocin promotes trust and relaxation, vasopressin allows for behaviors that safeguard the relationship against external threats. 

Understanding the hormonal underpinnings of love emphasizes the importance of relationships in shaping one’s well-being.

[neuro-ang]

[neuro-ang]

Alzheimer’s disease (AD) is a neurodegenerative disease significantly impacting cognitive function; the pathogenesis of Alzheimer’s is complex and is due to the interplay of genetic, biochemical, and inflammatory factors. Afflicted individuals typically exhibit severe memory loss, confusion, difficulty with problem-solving and language, and disorientation. The excessive accumulation of β-amyloid proteins is caused by mutations in genes such as amyloid precursor protein (APP), presenilin 1 (PS-1), and presenilin 2 (PS-2)– which cause glial damage and amyloid plaques. Plaques are significant for being pathological markers of disease,

Amyloid plaques, neurofibrillary tangles, and significant neuronal loss are the three features that signify Alzheimer’s presence. The tau protein, known for forming a structure of the microtubule, maintains the health of neurons; in Alzheimer’s, tau is phosphorylated abnormally, causing microtubule structures to collapse. Without any structural integrity, no neurotransmitter pathway can work properly. This degeneration of neural systems affects the cholinergic system, which is linked to memory and learning systems– more specifically, the basal forebrain which is a contributor to the cognitive critical area. 

Cholinergic systems are significant for modulating the brain’s processing of information, acetylcholine facilitates synaptic plasticity, which measures the ability for the brain to adapt to new information. In Alzheimer’s specifically, there is a deficiency of cholinergic neurons, resulting in the deterioration of cognitive function.

The monoaminergic system, consisting of monoamines such as serotonin, dopamine, and norepinephrine, plays an important role in neurological behavior, and the degradation of any of these, contribute to the significant degradation of the disease. To begin with, the serotonergic system, involved in mood regulation, cognitive function, and sleep, interact with amyloidogenic processes, which play a major role in behavior, along with depression symptoms. Serotonergic neurons are typically found in the raphe nuclei in the brainstem. Next, dopaminergic neurons, located mostly in the substantia nigra and ventral tegmental area, mostly affect motor function and motivation– affecting one’s cognitive control, degenerated dopaminergic neurons will affect one’s physical function and influence the spread of neurofibrillary tangles (tau protein instability.) Lastly, norepinephrine is critical for stress responses and arousal. Located primarily in the locus coeruleus, noradrenergic neurons can affect energy levels, and normal anti-inflammatory properties; if this system is damaged, the disease process may be accelerated. 

The recognition of the cholinergic, serotonergic, dopaminergic, and noradrenergic neurons in Alzheimer’s pathophysiology can lead to drugs to help treat the degenerative disease. To begin with, using cholinesterase inhibitors can inhibit the enzyme that breaks down acetylcholine, in order to protect its degradation and increase its availability in the brain. Increasing cholinergic function can slow down the progression of cognitive decline and foster temporary mitigation of symptoms. Next, focusing on the monoaminergic systems, one can improve quality of life through the focus of mood regulation and stability. Currently, serotonin and norepinephrine reuptake inhibitors (SSRIs and SNRIs) are used to assist with mood and depressive symptoms. SSRIs work through the natural releasing of serotonin into the presynaptic neuron into the synaptic cleft. Once neurotransmission occurs, serotonin binds to specific receptors that allow for cellular responses to influence mood, SSRIs block the natural reuptake of serotonin by blocking the serotonin transporters; by preventing the reuptake of serotonin, more serotonin is left in the synaptic cleft, causing an enhanced and prolonged effect of improved mood. SNRIs are similar, in that they influence both serotonin and norepinephrine. Enhanced levels of neurotransmission help alleviate symptoms of depression, which is incredibly important to manage the symptoms of Alzheimer’s and slow down degeneration.  Lastly, using dopaminergic agonists and antagonists, drugs can mimic dopamine by binding to receptors (agonists), or they can block dopamine receptors (antagonists) in order to treat comorbid conditions. 

The cholinergic and monoaminergic systems both play key roles in the degradation of cognitive function seen in Alzheimer’s. Alzheimer’s disease affects multiple neural pathways and it is important to understand the interplay between systems and markers of disease.

[neuro-ang]

#alzheimer #neurodegenerativedisease #amygdala