Neuroscience

• Dendrites receive signals from other neurons and transmit them towards the cell body.
• The brain is the "nerve center" of the body, containing billions of neurons that transmit information from the body and the outside world
• The brain programs our responses, including conscious and unconscious movements, thoughts, emotions, and memories
• The brain can perform multiple tasks simultaneously, such as throwing a ball while talking to a friend or daydreaming while driving to work
• The cerebrum is the largest part of the human brain, divided into two large, separate hemispheres connected by the corpus callosum
• The cerebral cortex is a deeply folded layer of nerve tissue on the surface of the cerebrum, increasing the brain's processing power
• The frontal lobes coordinate voluntary movements, speech, memory, emotions, cognitive skills like planning and problem-solving, and aspects of personality
• The parietal lobes integrate sensory signals from the skin, process taste, and some types of visual information
• The occipital lobes process visual information, recognize colors and shapes, and integrate them into complex visual understanding
• The temporal lobes carry out some visual processing and interpret auditory information, including encoding new memories
• The hippocampus encodes new memories, while the amygdala integrates memory and emotion, both part of the limbic system that helps regulate emotion and motivation
• The limbic system includes structures like the thalamus, which integrates sensory information, and the hypothalamus, which sends hormonal signals to the rest of the body through the pituitary gland
• The forebrain, consisting of the limbic system, thalamus, hypothalamus, and cerebral cortex, regulates emotion, motivation, and sensory information processing
• The midbrain coordinates eye movements, reflexes to sounds, and inhibits unwanted body movements, helping manage fine motor control
• The midbrain also helps coordinate sensory input and motor output for tasks like writing or playing a musical instrument
• Brain lobes and their functions:

  • Blue (frontal lobe): responsible for attention, planning, and decision-making
  • Green (temporal lobe): associated with language, memory, and emotion
  • Yellow (parietal lobe): integrates information from the senses
  • Pink (occipital lobe): responsible for vision
• Basal ganglia:

  • Collection of structures that help regulate complex body movements
• Hindbrain:

  • Plays roles in glucose regulation and sleep
  • Contains regions that help control movement
  • Cerebellum:
  • Second-largest part of the brain in volume
  • Coordinates voluntary movements
  • Helps the brain learn new motor skills
  • Roles in spatial and temporal perception
  • Damage to the cerebellum can result in jerky movements or difficulty touching finger to nose
• Parts of the hindbrain:

  • Pons: influences breathing and posture
  • Medulla: contains nerve pathways connecting the brain to the spinal cord and helps control basic functions like swallowing, heart rate, and breathing
• Brainstem:

  • Comprised of the midbrain, pons, and medulla
• Brain evolution:

  • Human brain evolved from a simple tube
  • Early vertebrates had brains similar to the modern lancelet
  • Human brain began as a simple tube and evolved into regions similar to ancestral brains
  • Forebrain, midbrain, and hindbrain developed distinct bulges for sensory and motor processing
  • Over time, new types of neurons led to the expansion of the forebrain into cerebral hemispheres
  • Cortical tissues in the cerebrum and cerebellum expanded further in early mammals, increasing processing power
• Neural networks:

  • Information moves between brain regions via chains of neurons
  • Nerve fibers of region-spanning neurons form distinct bundles called nerve tracts
  • Examples of major nerve tracts include the corpus callosum and the anterior commissure
• Neural networks transmit signals between the left and right temporal lobes
• A group of nerve tracts connecting a series of regions in the brain is called a neural network
• Neural networks route signals through the brain along a linear pathway, analyzing and organizing different types of information within fractions of a second
• When watching a movie, the brain turns moving shapes into recognizable characters and scenery
• The process starts with photoreceptors in the retina triggering electrical signals in response to specific wavelengths of light
• Signals then travel through the optic nerve, optic tract, and thalamus to the primary visual cortex in the occipital lobe at the back of the brain
• Neurons in the primary visual cortex detect the edges of objects within the field of vision and integrate signals from each eye to create a three-dimensional representation of the outside world
• Neurons in the temporal lobe recognize and identify objects, while neurons in the parietal lobe detect the spatial location of those objects
• The visual cortex sends signals back to the thalamus to be integrated with other sensory information, forming a thalamocortical loop
• Neuronal signals loop through the thalamus and cortex, producing rhythmic, oscillating electrical patterns known as brain waves
• There are four distinct types of brain waves: alpha waves, beta waves, theta waves, and delta waves
• Alpha waves originate mainly in the parietal and occipital lobes when the brain is relaxed and eyes are closed, characterized by frequencies between 8 and 13 Hz
• Beta waves are somewhat faster, with frequencies ranging from 14 to 30 Hz, typically produced by the frontal and parietal regions of the brain when processing sensory input or concentrating on a task
• Theta waves and delta waves are typical of sleep, with theta waves slower than alpha waves (4 to 7 Hz) and delta waves very slow (less than 3.5 Hz)
• Alpha and delta waves have higher amplitudes than beta or theta waves, but all these signals are in the microvolt range when measured with electrodes on the scalp
• Neurons are organized into distinct layers spanning the thickness of the cortex like shelves in a bookcase
• The brain and spinal cord contain many distinct neural networks, including spinal tracts that pass signals through the brainstem and spinal cord
• Signals either travel upward from sensory receptors in skin and muscles to the thalamus and parts of the cortex that interpret touch and pressure, or they travel downward from brain regions that induce movement