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Questions and Answers
What is the primary function of mechanotransducers?
What is the primary function of mechanotransducers?
What triggers synaptic vesicles to fuse with the cell membrane?
What triggers synaptic vesicles to fuse with the cell membrane?
How does cortical magnification affect visual processing?
How does cortical magnification affect visual processing?
What role does top-down processing play in sensory perception?
What role does top-down processing play in sensory perception?
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What is the primary pathway for object identification in the brain?
What is the primary pathway for object identification in the brain?
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What does the McGurk Effect demonstrate about sensory processing?
What does the McGurk Effect demonstrate about sensory processing?
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Which type of cells is characterized as having separate on and off regions and respond to bars and edges?
Which type of cells is characterized as having separate on and off regions and respond to bars and edges?
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Local coding in visual processing refers to what?
Local coding in visual processing refers to what?
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What is the primary role of myelin sheaths in nerve cells?
What is the primary role of myelin sheaths in nerve cells?
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Which symptom is NOT commonly associated with multiple sclerosis?
Which symptom is NOT commonly associated with multiple sclerosis?
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What type of vision is characterized by color perception in bright light?
What type of vision is characterized by color perception in bright light?
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What is the function of amacrine cells in the retina?
What is the function of amacrine cells in the retina?
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What percentage of males and females is typically affected by color blindness?
What percentage of males and females is typically affected by color blindness?
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Which neurotransmitter activates Na+ channels to generate excitatory post-synaptic potentials (EPSP)?
Which neurotransmitter activates Na+ channels to generate excitatory post-synaptic potentials (EPSP)?
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Which of the following best describes the process of lateral inhibition?
Which of the following best describes the process of lateral inhibition?
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What biological process is regulated by light exposure in circadian rhythms?
What biological process is regulated by light exposure in circadian rhythms?
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What is the primary function of the somantic nervous system?
What is the primary function of the somantic nervous system?
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Which type of nerve carries sensory information into the spinal cord?
Which type of nerve carries sensory information into the spinal cord?
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What is the role of ion channels in neuronal information transmission?
What is the role of ion channels in neuronal information transmission?
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What happens during an excitatory postsynaptic potential (EPSP)?
What happens during an excitatory postsynaptic potential (EPSP)?
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Which division of the autonomic nervous system is characterized by calming the body after arousal?
Which division of the autonomic nervous system is characterized by calming the body after arousal?
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In the Hodgkin-Huxley cycle, what is the first event that occurs?
In the Hodgkin-Huxley cycle, what is the first event that occurs?
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What primarily determines whether a graded potential will trigger an action potential?
What primarily determines whether a graded potential will trigger an action potential?
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What is a key feature of the metencephalon in the hindbrain?
What is a key feature of the metencephalon in the hindbrain?
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What does the process of pattern separation primarily involve?
What does the process of pattern separation primarily involve?
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What characterizes sparse encoding in neural processing?
What characterizes sparse encoding in neural processing?
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Which brain area is primarily responsible for motion perception?
Which brain area is primarily responsible for motion perception?
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What does the term 'pareidolia' refer to?
What does the term 'pareidolia' refer to?
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How do cell assemblies function within the context of object representation?
How do cell assemblies function within the context of object representation?
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What is the main challenge posed by the binding problem in visual perception?
What is the main challenge posed by the binding problem in visual perception?
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What was a key finding of the Chang and Tsao experiment regarding facial representation?
What was a key finding of the Chang and Tsao experiment regarding facial representation?
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What role does the amygdala play in the fear response?
What role does the amygdala play in the fear response?
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Study Notes
Synaptic Transmission
- Calcium ions (Ca2+) trigger synapse vesicles to fuse with the cell membrane, releasing neurotransmitters into the synaptic cleft.
Brain Organization
- Topographic Organization: Neurons are clustered for efficient local processing.
- Axon Length: Shorter axons allow more neurons, conserve resources, and optimize brain volume.
- Dense Connectivity: Enables efficient local processing.
- Lateral Inhibition: Enhances contrast and sharpens sensory signals.
Auditory System
- Humans can hear frequencies from 20 to 20,000 Hz.
- Sound waves travel from the outer ear to the eardrum, then to the cochlea.
- The cochlea transforms pressure waves into electrical signals.
- Mechanotransducers: Amplify cellular responses to membrane movement.
- Tonotopic Representation: Different frequencies activate specific cochlear zones.
Visual System
- 90% of optic nerve fibers terminate in the lateral geniculate nucleus (LGN).
- Retinotopic Mapping: Visual field is mapped onto LGN and V1 neurons.
- Simple Cells: Orientation selective, respond to bars and edges, have separate on and off regions, and can be monocular or binocular.
- Complex Cells: Orientation selective, no ON/OFF subregions, nearly all binocular.
- Cortical Magnification: Processing of the fovea (center of visual field) is more extensive than that of peripheral vision. This results in a larger representation of the fovea on the cortical map than its actual size in the retinal image.
Top-Down vs. Bottom-Up Processing
- Top-Down Processing: Uses prior knowledge to interpret sensory input.
- Bottom-Up Processing: Processes sensory information from receptors.
- 6% of visual input helps understand distorted images.
- Cortical Connectivity: Predominantly top-down, integrating multisensory input.
- McGurk Effect: Visual cues influence auditory speech perception.
- Retinotopy: Remapping of retinal image onto cortical surface.
Top-Down Auditory Processing
- Allows content and procedural demands to bias perception.
- Enables integration of multi-sensory input.
Ventral Stream
- Temporal lobe pathway for object identification.
- MTL Responses: Firing rates vary with familiarity of faces.
- Grandmother Cells: Hypothetical cells firing for specific familiar faces (debunked).
- Gnostic Cells: Cells processing simple features to form images.
- Local Coding: Specific features combined for object recognition.
- Object Discrimination: Ability to distinguish between different objects.
- Cell Ensemble: Group of cells firing together for image representation.
Nervous System
- Somatic Nervous System: Transmits information between the central nervous system and the sensory organs and muscles (external environment).
- Autonomic Nervous System: Controls the body's internal environment.
- Afferent Nerves: Input.
- Efferent Nerves: Output.
- Sympathetic Nervous System: Arouses the body (fight or flight).
- Parasympathetic Nervous System: Returns the body to a normal resting state (relaxed).
Spinal Nerves
- Cervical, thoracic, lumbar, sacral, coccygeal.
- Sensory information enters the spinal cord via the dorsal root, traveling along unipolar sensory neurons.
- Motor commands exit the spinal cord through the ventral horn, traveling along multipolar motor neurons.
Adult Human Forebrain
- Telencephalon
- Diencephalon
Midbrain
- Mesencephalon
Hindbrain
- Metencephalon: Forms the cerebellum.
- Myelencephalon: Forms the medulla.
- Pons
Neuron Structure
- External Features: Cell body, dendrites, axon, ions (sodium and chloride).
- Internal Features: Membrane potential (-70mV), ions potassium and proteins.
Neuron Function
- Ion Channels: Allow ions to flow across the membrane, leading to changes in membrane potential.
- Graded Potential: Varies in size.
- Action Potential: All-or-nothing response.
- Threshold: The level of depolarization needed to trigger an action potential.
- Receptor Activation: Triggers the opening of ion channels by signaling molecules (neurotransmitters) or environmental events (e.g., light, touch, sound).
- EPSP (Excitatory Postsynaptic Potential): Caused by inward flow of sodium (Na⁺) ions.
- Depolarization: Increase in membrane potential.
-
Hodgkin-Huxley Cycle:
- Synaptic or receptor potential
- Depolarization of the membrane
- Opening of voltage-gated Na⁺ channels
- Na⁺ flows into the neuron.
Myelin
- Acts as electrical insulation for faster signal transmission and reduces interference from nearby axons.
- Composed of fat and protein.
Multiple Sclerosis
- Demyelination/damage to the myelin sheath disrupts nerve impulse flow.
- Symptoms include:
- Numbness or weakness in limbs
- Vision loss
- Double vision
- Tingling or pain
- Fatigue
- Dizziness
Visual Perception
- Photopic Vision: High acuity color vision in bright light.
- Scotopic Vision: Low acuity achromatic vision in dim light.
- Cone-fed Circuits: Low convergence; one ganglion cell per cone.
- Rod-fed Circuits: High convergence; one ganglion cell feeds multiple rods.
- ipRGC (Intrinsically Photosensitive Retinal Ganglion Cells): Contain melanopsin.
- Melanopsin: Photopigment sensitive to blue light in ipRGC.
- Circadian Rhythms: Biological processes regulated by light exposure.
- Blind Spot: Located 15 degrees from the center of the fovea.
Neurotransmitters
- Vesicle Steps: Loading, storage, mobilization, docking, priming, fusion.
- Glutamate: Neurotransmitter activating Na+ channels for EPSP.
- GABA: Neurotransmitter activating K+ channels for IPSP.
Retinal Cells
- Amacrine Cells: Release GABA to inhibit retinal signals.
- Horizontal Cells: Support cells releasing GABA in the retina.
- Lateral Inhibition: Surrounding cells inhibit a cell's response.
Color Vision
- Monochromatic View: Vision limited to shades of gray.
- Dichromatic View: Vision limited to blues and greens.
- Trichromatic View: Vision including blues, greens, and reds.
- Tetrachromatic Vision: A visual system with four different types of cone cells.
-
Color Blindness: Affects 5-10% of males and 0.1% of females.
- Deuteranomaly: Weakness in green perception.
- Protanopia: Inability to perceive red color.
- Opponent-Process Theory: Color perception is controlled by opposing color systems.
Homeostasis
- Self-regulation to maintain internal stability.
- Hot: Sweating
- Cold: Shivering
Presynaptic Calcium Influx
- Ca2+ arrives at the pre-synaptic terminal and depolarization occurs, causing the action potential to drive the voltage-gated ion Ca2+ channel to open.
Pattern Recognition
- Pattern Completion: Recognizing incomplete patterns based on context.
- Pattern Separation: Distinguishing between similar patterns or objects.
- Generalization: Recognizing objects in varied contexts and positions.
- Trade-off in Processing: Balancing pattern completion, separation, and generalization.
- Dense Encoding: Requires overlap for pattern completion and generalization.
- Sparse Encoding: Requires separation for distinct object representation.
Facial Recognition
- Face Patches: Specific areas in the brain (middle lateral, middle fundus, and anterior medial) contain cells that respond when certain facial features are altered.
- Chang and Tsao Experiment: Demonstrated distributed facial representation in cells.
- Face Space: Dimensional space representing facial features.
- Selective Cells: Cells responding to specific features in faces.
- Pareidolia: Perceiving familiar patterns, like faces or animals, in objects.
Brain Statistics
- 86 Billion Neurons: Total number of neurons in the human brain.
- 40 Million Neurons: Number of neurons in the hippocampus.
- Chang and Tsao Experiment: Found that single cells are linked to one axis of face space and are blind to changes orthogonal to this axis. Multiple cells are active for a particular face, each coding a particular feature dimension.
Dorsal Stream
- Parietal lobe pathway for object location and movement.
Learning
- Hebbian Learning: Cells that fire together strengthen their connections.
Motion Perception
- Akinetopsia: Inability to perceive motion.
Visual Processing Areas
- V4 Area: Brain region for color detection and processing.
- V5 Area: Responsible for motion perception in the visual system.
Binding Problem
- Linking features to form a unified object.
- Temporal Binding: Synchronization of neural firing links features together.
- Cell Assemblies: Groups of neurons firing together to represent objects.
Visual Perception
- Ambiguous Figure: Visual illusion where perception shifts between interpretations.
- Foreground-Background Segmentation: Distinguishing main objects from their surroundings.
- 3D Shape Computation: Determining the shape of objects in three dimensions.
- Looming: Perception of approaching objects based on visual angle.
Fear Response
- Activation of the amygdala due to perceived threats.
Memory
- Short Term Memory: Retention of information for 10-20 seconds.
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Description
This quiz explores key concepts in neuroscience, focusing on synaptic transmission, brain organization, and sensory systems, including auditory and visual processes. Test your understanding of how neurotransmitters function, the structure of the brain, and the mechanics of hearing and vision.
