Neuroscience
This page contains abridged crux of lecture topics covered during the course.
Brain Anatomy:
The brain consists of four main lobes:
Frontal lobes which coordinates voluntary movements and speech, memory, emotion, as well as cognitive skills such as problem solving;
Parietal lobes which integrate sensory signals from skin and processes taste and some visual stimulus;
Occipital lobes which processes visual stimulus;
Temporal lobes which interpret auditory information.
Within this segmentation are more specific regions such as the medulla or pons. The brain itself consists of glial cells (which help to regulate and maintain nerve cells) and nerve cells (which, through ion channels and synapses and neurotransmitters, send signals throughout the brain).
Genetics of Neurological disease
DNA and the genes within it are the encoding instructions for protein production. Since proteins are the molecules that allow cells to carry out their various functions and regulate themselves, the genes that code for proteins become extremely important, especially in the context of neurological diseases. If a mutation in a gene leads to a change in protein shape, this can impact the function of the protein.
A gain-of-function or loss-of-function mutation could potentially cause drastic results such as excessive proliferation leading to brain cancers or create toxic events that degrade neurons leading to Alzheimer's Disease.
Senses, Perception and Movement
Our eyes, ears, nose, mouth, and skin allows us to process sensory information. The retina is the specific bundle of nerves that converts light to electrical signals that get transmitted to the visual cortex. Hearing occurs in a similar fashion in which small hair-like cells in the inner ear convert vibration movement to electrical signals.
Our tongue and olfactory bulbs have receptors that send signals based on the molecules the receptors encounter, thus allowing differentiation between different tastes and smells. Finally, the skin has touch receptor signals that transmit information to sensory nerve fibers which transmits to the thalamus and somatosensory cortex to translate into touch perception.
Learning, Encoding, Retrieval and Discrimination of Memories
The different forms of memory process and store memories at varying duration. Learning occurs as newer connections between neurons are established and strengthened. Encoding and storage of memories (in the long term) depends on the attention level at the moment of the memories “creation”.
Retrieval requires being able to access the long term memory (reactivating the neural network that makes up that memory) and bringing it forth to the conscious working memory. Discrimination of memories becomes difficult over time as the neuron connections weaken, so the memory becomes less and less clear.
Aging and Memory
Because unused neuron connections undergo synaptic pruning, the memories the connections “stored” essentially begin to fade away. Working memory, due to cell loss and shrinkage, begins to decline as aging occurs.
Changes in the speed of neurotransmission also are attributed to slower processing speed. Finally, because of hippocampus cell loss, there appears to be more overlap between which neurons represent which memories, causing differentiation between memories to weaken overtime.
Neuronal cell determination & Brain development
There are two main forms of neuronal cell determination: autonomous specification in which cells differentiate based on the genetic components activated or inhibited after division, or conditional specification in which cell-to-cell signaling causes certain genes to activate and cause differentiation. Throughout life, the brain develops, with the two major spurts occurring where the cerebral cortex develops and then the next spurt in which the frontal lobes develop. As a result, genes and environment play a critical role during these critical periods.
Infancy is when the cerebral cortex and neuron connections are established and strengthened. Adolescence is when the frontal lobe and prefrontal cortex develops. The adult brain develops more slowly, where intelligence and processing peaks between 25 to 60 years of age. Aging then occurs in which cells degenerate and there is a decline in memory and cognitive functions.
Homeostasis
Homeostasis is the process of maintaining balance in the body’s tissues. The suprachiasmatic nucleus is a bundle of nerves in the hypothalamus that helps regulate the circadian rhythm in the body (a synchronized body clock coordinated in a 24 hour day cycle). Hormones also play a key role in regulating the body, and events that increase stress will cause the body to compensate to return back to homeostasis.
Childhood disorders
Childhood disorders are disorders typically diagnosed at a young age. A common childhood disorder to Autism Spectrum Disorder, in which a child expresses impaired social communication or interaction as well as repetitive behaviors/obsessive interests. Another disorder is ADHD which presents as severe attention and behavioral problems that interfere with everyday functioning. Other childhood disorders include down syndrome (Trisomy-21), dyslexia (difficulty reading), and epilepsy (repetitive seizures without any other medical reason).
Psychiatric disorders
Psychiatric disorders are caused by a combination of both genetics and environmental influences. Anxiety disorder is characterized as excessive fear or anxiety without any perceivable reason. PTSD is also a common anxiety disorder due to trauma from past events. While major depression is marked by long periods of sadness or tiredness, bipolar disorder is seen with intense mood changes (manic to depressive moods for example).
Neurodegenerative Disease
Neurodegeneration is the continued loss of nerve structures and function, which leads to the cognitive ability loss. Some neurodegenerative diseases include Alzheimer's disease (the most common form of dementia), Parkinson’s disease, and Huntington’s Disease.
Neurodegenerative diseases typically have genetic mutations that cause proteins to degrade neurons. One example of this in Alzheimer's Disease in which amyloid beta (Aβ) protein plaques build up and Tau protein over expression and accumulation in neurons.
Molecular Neuroscience
Molecular neuroscience is the study of molecular concepts in relation to the nervous system in animals. Because so many neurological conditions have a genetically underlying cause, the study of molecules in the nervous system becomes extremely important to better understand these conditions.
More importantly, since the functions and structures of the brain deal with molecules, molecular neuroscience allows better understanding of the brain, the control center of the body.