Neuroscience: Brain Structure

• Neuroscience examines the nervous system, including the brain, spinal cord, and nerves.
• It investigates the nervous system's structure, function, development, genetics, biochemistry, physiology, and pathology.

Brain Structure

• The brain serves as the nervous system's control center, orchestrating thought, memory, emotion, movement, and vital life functions.
• The adult human brain weighs roughly 3 pounds (1.4 kilograms) and comprises billions of neurons.
• The cerebrum, cerebellum, diencephalon (thalamus and hypothalamus), and brainstem (midbrain, pons, and medulla oblongata) constitute the brain's major regions.
• The cerebrum is the brain's largest component, divided into left and right hemispheres interconnected by the corpus callosum.
• Each hemisphere further divides into four lobes: frontal, parietal, temporal, and occipital.
• The frontal lobe governs executive functions, planning, decision-making, and motor control.
• The parietal lobe handles sensory data, including touch, temperature, pain, and spatial awareness.
• The temporal lobe manages auditory processing, memory, and language comprehension.
• The occipital lobe processes visual input.
• The cerebellum coordinates movement and balance.
• The thalamus sends sensory and motor signals to the cerebral cortex.
• The hypothalamus regulates body temperature, hunger, thirst, sleep, and hormone secretion.
• The brainstem regulates fundamental life processes, such as breathing, heart rate, and blood pressure.
• The cerebral cortex, the cerebrum's outer layer, is in charge of higher-level cognitive functions.
• Its convoluted structure increases surface area, accommodating a greater number of neurons.
• Sulci are the grooves, and gyri are the ridges on the cerebral cortex's surface.

Neurotransmitters

• Neurotransmitters are chemical signals that travel across synapses from one neuron to the next.
• They are produced in neurons and kept in vesicles at the axon terminal.
• An action potential causes neurotransmitters to be released into the synaptic cleft when it reaches the axon terminal.
• Neurotransmitters attach to receptors on the postsynaptic neuron, resulting in either excitation or inhibition.
• Examples of neurotransmitters: acetylcholine, dopamine, serotonin, norepinephrine, glutamate, and GABA.
  • Acetylcholine facilitates muscular contraction, memory, and attention.
  • Dopamine influences reward, motivation, movement, and cognition.
  • Serotonin regulates mood, sleep, appetite, and social behavior.
  • Norepinephrine impacts alertness, arousal, and the stress response.
  • Glutamate serves as the brain's main excitatory neurotransmitter.
  • GABA (gamma-aminobutyric acid) functions as the brain's primary inhibitory neurotransmitter.
• Reuptake, enzymatic degradation, or diffusion terminates neurotransmitter activity.
• Neurotransmitters impact a variety of brain functions and are implicated in several neurological and psychiatric illnesses.

Cognitive Neuroscience

• Cognitive neuroscience explores the neural underpinnings of cognitive functions, including attention, memory, language, and decision-making.
• It integrates cognitive psychology and neuroscience approaches to investigate how the brain facilitates mental processes.
• Cognitive neuroscience employs techniques such as fMRI, EEG, TMS, and lesion studies.
  • Functional magnetic resonance imaging (fMRI) assesses brain activity by tracking alterations in blood flow.
  • Electroencephalography (EEG) captures electrical activity in the brain using electrodes positioned on the scalp.
  • Transcranial magnetic stimulation (TMS) uses magnetic pulses to activate or suppress specific brain regions.
  • Lesion studies examine how cognitive functions are affected by brain damage.
• Cognitive neuroscience aims to define the neural circuits and mechanisms that underpin cognitive processes.
• It seeks to elucidate how distinct brain regions interact to generate complex behaviors.
• Cognitive neuroscience research has improved the understanding and treatment of neurological and psychiatric disorders.

Neuroplasticity

• Neuroplasticity is the brain's capacity to adapt and reorganize itself throughout life in response to experiences, learning, or injury.
• It entails changes in the structure, function, and connections of neurons.
• Neuroplasticity manifests at multiple levels, including synaptic plasticity, structural plasticity, and functional reorganization.
• Synaptic plasticity involves alterations in the strength of synaptic connections between neurons.
• Long-term potentiation (LTP) and long-term depression (LTD) are two key types of synaptic plasticity.
  • LTP strengthens synaptic connections, whereas LTD weakens them.
• Structural plasticity encompasses modifications in the brain's physical structure, such as the formation of new neurons (neurogenesis) or synapses (synaptogenesis).
• Functional reorganization refers to the brain's ability to reassign functions from damaged to undamaged areas.
• Neuroplasticity is shaped by factors such as age, experience, genetics, and environment.
• Enriched environments and learning experiences can foster neuroplasticity.
• Neuroplasticity is critical for learning and memory, recovery from brain injury, and adaptation to changing conditions.

Neural Networks

• Neural networks are interconnected neuron networks in the brain that process information.
• They are the fundamental components of neural computation and cognitive processes.
• Neural networks can be structured in various ways, including feedforward, recurrent, and hierarchical networks.
• Feedforward networks feature unidirectional connections, with information flowing from input to output layers.
• Recurrent networks have self-looping connections, allowing for sequential information processing and internal state maintenance.
• Hierarchical networks are arranged into multiple processing levels, with lower levels processing basic features and higher levels processing more complex data.
• Neural networks learn by modifying the strength of neuron connections, a process known as synaptic plasticity.
• Hebbian learning, a synaptic plasticity principle, states that neurons that fire together wire together.
• Artificial neural networks are computational models inspired by the structure and function of biological neural networks.
• They find application in pattern recognition, machine learning, and artificial intelligence.