The basic and core concepts of cognitive neuroscience
DEFINATION of Cognitive NEUROSCINCE
Exploring how brain activity underpins mental processes such as perception, memory, and decision-making.
NEURONS
A neuron, or nerve cell, is the fundamental unit of the nervous system, specialized to transmit information throughout the body. Neurons communicate using electrical and chemical signals, making them essential for processes like sensation, thought, movement, and emotion.
Key Parts of a Neuron:
Cell Body (Soma): The central part of the neuron containing the nucleus and organelles. It processes incoming signals and maintains the neuron's health.
Dendrites:Branch-like structures that extend from the cell body. They receive signals from other neurons and convey them toward the cell body.
Axon:A long, thin projection that transmits signals away from the cell body to other neurons, muscles, or glands. It can be covered in a fatty substance called myelin, which speeds up signal transmission.
Axon Terminals (Synaptic Boutons):The endpoints of an axon where it forms connections, or synapses, with other neurons or target cells. These terminals release chemical messengers called neurotransmitters.
Synapse:The junction between two neurons or between a neuron and another cell, where communication occurs via neurotransmitters.
How we measure or see neural activity
1. EEG and ERP:
EEG (Electroencephalogram)
How It Works: EEG measures electrical activity in the brain using electrodes placed on the scalp. It records brain wave patterns created by neurons' electrical impulses.
What It Can Tell Us:
Brain activity during specific states (e.g., sleep, alertness).
Detection of abnormalities such as seizures or brain damage.
Temporal resolution is high, meaning EEG is excellent for tracking rapid changes in brain activity over time.
ERP (Event-Related Potential)
How It Works: ERP is a subset of EEG, focusing on electrical responses to specific sensory, cognitive, or motor events. The brain’s electrical response is averaged over multiple trials to isolate the signal associated with a specific event.
What It Can Tell Us:
Cognitive processes such as attention, decision-making, and language comprehension.
Time-locked brain activity related to specific stimuli (e.g., how long it takes to process a word or sound).
2. CT (CAT Scan)
How It Works: CT (Computed Tomography) uses X-rays to take multiple images of the brain or body from different angles. A computer combines these images to create cross-sectional "slices" of the structure.
What It Can Tell Us:
Structural details, such as the presence of tumors, fractures, or blood clots.
Useful for detecting damage after strokes, injuries, or hemorrhages.
Provides good spatial resolution but no information about brain activity.
3. MRI: (Magnetic Resonance Imaging)
How It Works:
Uses a powerful magnetic field and radio waves to create detailed images of the brain or body.
The magnetic field aligns hydrogen atoms in the body, and the radio waves disturb this alignment. As the atoms realign, they emit signals that are converted into detailed images.
What It Can Tell Us:
High-resolution images of soft tissues, making it excellent for detecting structural abnormalities such as tumors, lesions, or brain shrinkage.
Does not provide functional information about brain activity.
fMRI (Functional MRI)
How It Works: fMRI measures changes in blood flow (via oxygenation levels) in the brain, which serves as an indirect measure of neural activity. Active brain regions use more oxygen, causing detectable changes in the magnetic properties of the blood.
What It Can Tell Us:
Identifies brain regions involved in specific tasks (e.g., memory, decision-making, or emotion).
Maps functional connectivity between brain regions.
Excellent spatial resolution, but slower than EEG for tracking real-time changes.
4. PET (Positron Emission Tomography):
How It Works:
A small amount of radioactive tracer (usually glucose tagged with a radioactive isotope) is injected into the bloodstream.
As active brain regions use glucose, the tracer accumulates in those areas and emits gamma rays, which are detected by the PET scanner.
What It Can Tell Us:
Measures metabolic activity in the brain, showing which areas are most active during specific tasks.
Can identify abnormalities in brain function, such as in Alzheimer's disease or schizophrenia.
Useful for studying neurotransmitter systems by tagging specific molecules.
The Subtraction Technique
What It Is: A method used in fMRI and PET studies to isolate specific brain activity.
Brain activity during a "control" task is subtracted from brain activity during an "experimental" task.
This reveals regions uniquely activated by the experimental condition, filtering out unrelated activity.
Example: Comparing brain activity while resting versus solving a math problem to identify areas involved in problem-solving.
Each technique has unique strengths and applications, making them valuable for studying both brain structure and function.
1. Structures of the Forebrain
The forebrain is the largest and most complex part of the brain, responsible for higher-order functions like thinking, decision-making, and emotion regulation. Its key structures include:
Cerebrum (Cerebral Cortex)
Divided into two hemispheres (left and right), with four lobes:
Frontal Lobe: Involved in decision-making, problem-solving, planning, and motor control.
Parietal Lobe: Processes sensory information like touch, temperature, and spatial orientation.
Temporal Lobe: Responsible for auditory processing and memory.
Occipital Lobe: Handles visual information.
Thalamus
Acts as a relay station, transmitting sensory information (except smell) to the appropriate areas of the cerebral cortex.
Hypothalamus
Regulates homeostasis, including temperature, hunger, thirst, sleep, and hormonal control via the pituitary gland.
Basal Ganglia
A group of nuclei involved in motor control, habit formation, and reward-based learning.
Limbic System
A network of interconnected structures associated with emotion, memory, and motivation.
3. Structures of the Limbic System
The limbic system is a set of interconnected structures that process emotions, memory, and motivation. Its key structures include:
Amygdala
Involved in processing emotions, particularly fear and aggression, and forming emotional memories.
Hippocampus
Crucial for forming new long-term memories and spatial navigation.
Hypothalamus
Regulates emotional responses and physiological states, such as stress and arousal.
Thalamus
Acts as a sensory relay station and integrates sensory inputs with emotional responses.
Cingulate Gyrus
Processes emotions and regulates behavior and autonomic responses.
Fornix
A white matter tract that connects the hippocampus to other parts of the limbic system, facilitating communication.
The forebrain, with its diverse structures, integrates sensory, motor, and cognitive functions, making it the control center of human experience and behavior.
2. Roles of the Hippocampus, Amygdala, Septum, and Thalamus
Hippocampus
Role: Essential for forming new long-term memories and spatial navigation.
Clinical Relevance: Damage can result in memory loss (e.g., anterograde amnesia).
Amygdala
Role: Processes emotions like fear and anger and forms emotional memories.
Clinical Relevance: Dysfunction is linked to anxiety disorders, PTSD, and emotional dysregulation.
Septum
Role: Involved in regulating emotions, particularly those related to pleasure and inhibition of aggression.
Clinical Relevance: Damage can lead to emotional instability or increased aggression.
Thalamus
Role: Acts as a sensory relay station, directing sensory information (except smell) to the appropriate cortical areas.
Clinical Relevance: Damage can cause sensory processing issues or disruptions in consciousness (e.g., coma).
3. What Is the Frontal Lobe in Charge Of?
The frontal lobe is responsible for a wide range of higher-order cognitive and motor functions:
Executive Functions: Planning, decision-making, problem-solving, and impulse control.
Motor Control: Primary motor cortex coordinates voluntary movements.
Language: Broca’s area (in the left hemisphere) is involved in speech production.
Social Behavior: Regulates emotions, social interactions, and personality.
4. Why Is the Frontal Lobe the Most Frequently Damaged Part of the Brain?
Location: The frontal lobe is positioned at the front of the skull, making it more vulnerable in accidents (e.g., car crashes or falls).
High Exposure: It absorbs much of the impact in traumatic brain injuries (TBI).
Development: The frontal lobe matures last (into the mid-20s), leaving it more susceptible to injury during adolescence and early adulthood.
5. What Types of Deficits Do We See in Patients with Frontal Lobe Damage?
Damage to the frontal lobe can cause a range of physical, cognitive, and emotional deficits:
Cognitive Deficits
Impaired problem-solving, planning, and decision-making.
Difficulty maintaining attention and organizing thoughts.
Reduced working memory capacity.
Motor Deficits
Loss of fine motor skills or paralysis (if the motor cortex is affected).
Speech difficulties, such as Broca’s aphasia (difficulty producing speech).
Emotional and Social Deficits
Emotional instability or inappropriate emotional responses.
Reduced ability to empathize or understand social cues.
Changes in personality, such as increased impulsivity or apathy.
Behavioral Deficits
Poor impulse control and increased risk-taking behaviors.
Difficulty adhering to social norms or inhibiting inappropriate actions.
References
Simply Psychology. (n.d.). Language acquisition theory. Simply Psychology. Retrieved December 3, 2024, from https://www.simplypsychology.org/language.html
National Human Neural Stem Cell Resource. (n.d.). Choosing the right brain scan: A comprehensive guide to brain scan types. Retrieved December 3, 2024, from https://www.nhnscr.org/blog/choosing-the-right-brain-scan-a-comprehensive-guide-to-brain-scan-types/​:contentReference[oaicite:0]{index=0}​:contentReference[oaicite:1]{index=1}​:contentReference[oaicite:2]{index=2}.
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