Neuroscience Exploring The Brain - Barry Connors  ## Metadata - Author: **Barry Connors** - Full Title: Neuroscience Exploring The Brain - Category: #articles - URL: https://readwise.io/reader/document_raw_content/2692228 ## Highlights - Descartes believed it could not possi- bly account for the full range of human behavior. He reasoned that unlike other animals, people possess intellect and a God-given soul. Thus, Descartes proposed that brain mechanisms control only human behavior that is like that of the beasts. ([View Highlight](https://read.readwise.io/read/01gw3wsb68x13bwq8xgkhznc76)) - The nervous system consists of two divisions, the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS consists of the brain and spinal cord. The three major parts of the brain are the cerebrum, the cerebellum, and the brain stem. The PNS consists of the nerves and nerve cells that lie outside the brain and spinal cord. ([View Highlight](https://read.readwise.io/read/01gw3wzf9es5abnyjyytbrwkv3)) - The study of the brain at this most elementary level is called molecular neuroscience. ([View Highlight](https://read.readwise.io/read/01gw3xypy869av7wq0b7edypa7)) - cellular neuroscience, which focuses on studying how all those molecules work together to give neurons their special properties. ([View Highlight](https://read.readwise.io/read/01gw3xzbsne0awhgmmkqfxkh3t)) - systems neuroscience, neuroscientists study how different neural circuits analyze sensory information, form perceptions of the ex- ternal world, make decisions, and execute movements. ([View Highlight](https://read.readwise.io/read/01gw3xzxef4h01hcxez2r8gy76)) - What neural systems account for gender-specifi c behaviors? Where are dreams created and what do they reveal? These questions are studied in behavioral neuroscience. ([View Highlight](https://read.readwise.io/read/01gw3y08vf32ctv3dqc66fc55z)) - cognitive neuroscience, studies how the activity of the brain creates the mind. ([View Highlight](https://read.readwise.io/read/01gw3y0gx4gygjp2j00k5txteg)) ## New highlights added March 23, 2023 at 7:43 AM - It is the neurons that sense changes in the environment, communicate these changes to other neurons, and command the body’s responses to these sensations. Glia , or glial cells , contribute to brain function mainly by insulating, supporting, and nourishing neighboring neurons. ([View Highlight](https://read.readwise.io/read/01gw6k8wgygtcqyrvk16zep27x)) - If the brain were a chocolate chip cookie and the neurons were chocolate chips, the glia would be the cookie dough that fi lls all the other space and suspends the chips in their appropriate locations. ([View Highlight](https://read.readwise.io/read/01gw6k9bv8amfdgcnpeceqhgdd)) ## New highlights added March 23, 2023 at 9:40 AM - The human eye can distinguish two points only if they are separated by more than about one-tenth of a millimeter (100 ␮ m). Thus, we can say that 100 ␮ m is near the limit of resolution for the unaided eye. Neurons have a diameter of about 20 ␮ m, and neurites can be as small as a frac- tion of a micrometer. The light microscope, therefore, was a necessary development before neuronal structure could be studied. But this type of microscopy has a theoretical limit imposed by the properties of microscope lenses and visible light. With the standard light microscope, the limit of resolu- tion is about 0.1 ␮ m. Because the space between neurons is only 0.02 ␮ m (20 nm), it’s no wonder that two esteemed scientists, Golgi and Cajal, disagreed about whether neurites were continuous from one cell to the next. This question could not be answered until about 70 years ago when the electron microscope was developed and applied to biological specimens. ([View Highlight](https://read.readwise.io/read/01gw6kp5pns4esrbxq5ceakmws)) - We begin our tour at the soma, the roughly spherical central part of the neuron. The cell body of the typical neuron is about 20 ␮ m in diameter. The watery fl uid inside the cell, called the cytosol , is a salty, potassium- rich solution that is separated from the outside by the neuronal mem- brane. Within the soma are a number of membrane-enclosed structures called organelles . ([View Highlight](https://read.readwise.io/read/01gw6kxff5c1d7jawnzfmm6qed)) - The cell body of the neuron contains the same organelles found in all animal cells. The most important ones are the nucleus, the rough endo- plasmic reticulum, the smooth endoplasmic reticulum, the Golgi appara- tus, and the mitochondria. Everything contained within the confi nes of the cell membrane, including the organelles but excluding the nucleus, is referred to collectively as the cytoplasm . ([View Highlight](https://read.readwise.io/read/01gw6kxhwjc3dsm577fphcjr1q)) - Within the nucleus are chromosomes which contain the genetic ma- terial DNA ( deoxyribonucleic acid ). Your DNA was passed on to you from your parents and it contains the blueprint for your entire body. The DNA in each of your neurons is the same, and it is the same as the DNA in the cells of your liver and kidney and other organs. What distinguishes a neuron from a liver cell are the specifi c parts of the DNA that are used to assemble the cell. These segments of DNA are called genes . ([View Highlight](https://read.readwise.io/read/01gw6ky73yg53wrm6c59zpjmke)) ## New highlights added March 24, 2023 at 9:05 AM - Protein synthesis , the assembly of protein molecules, occurs in the cytoplasm. Because the DNA never leaves the nucleus, an intermediary must carry the genetic message to the sites of protein synthesis in the cytoplasm. This function is performed by another long molecule called messenger ribonucleic acid , or mRNA ([View Highlight](https://read.readwise.io/read/01gw97176b4ptqaw765gmfab0t)) - At one end of the gene is the promoter , the region where the RNA-synthesizing enzyme, RNA polymerase , binds to initiate transcription. The binding of the polymerase to the promoter is tightly regulated by other proteins called transcription factors . ([View Highlight](https://read.readwise.io/read/01gw99xr2q0wwm30ybwbavxgah)) - Initial transcripts con- tain both introns and exons, but then, by a process called RNA splicing ([View Highlight](https://read.readwise.io/read/01gw99y25174n71bxfp28713pm)) ## New highlights added March 25, 2023 at 10:10 AM - But what fascinated me most was our observation that when many copies of a gene were injected into a cell nucleus, all of these molecules ended up in an ordered head-to-tail arrangement, called a concatemer (Figure B). This was as- tonishing and could not have occurred as a random event. We went on to unequivocally prove that homologous recom- bination, the process by which chromosomes share genetic information during cell division, was responsible for the in- corporation of the foreign DNA (Folger et al., 1982). These experiments demonstrated that all mammalian somatic cells contain a very effi cient machinery for swapping segments of DNA that have similar sequences of nucleotides. Injection of a thousand copies of a gene sequence into the nucleus of a cell resulted in chromosomal insertion of a concatemer con- taining a thousand copies of that sequence, all oriented in the same direction. ([View Highlight](https://read.readwise.io/read/01gwbrx9vkyyj8g7n5e7r1swcw)) - Gene targeting has taken us in many new directions, including most recently pursuing the role of microglia, cells that migrate into the brain after being generated in the bone marrow along with immune and blood cells. Mutating these cells in mice results in a pathology remarkably similar to the human condition called trichotillomania, a type of obsessive- compulsive disorder characterized by strong urges to pull out one’s hair. Amazingly, transplanting normal bone mar- row into mutant mice permanently cures them of this path- ological behavior (Chen et al., 2010). ([View Highlight](https://read.readwise.io/read/01gwbs1sw67nhp07pb10krz20f)) - Neurons make use of the information in genes by synthesizing proteins ([View Highlight](https://read.readwise.io/read/01gwbsyyqdxwhd7pthz00g0zjt)) - Protein synthesis occurs at dense globular structures in the cytoplasm called ribosomes . mRNA transcripts bind to the ribosomes, and the ribosomes translate the instructions contained in the mRNA to assemble a protein molecule. In other words, ribosomes use the blueprint provided by the mRNA to manufacture proteins from raw material in the form of amino acids. ([View Highlight](https://read.readwise.io/read/01gwbsz485r7qhwa3zjgxz8jsw))