Lecture 6.5 Flashcards
Primary Sensory Cortex
Receives input from thalamus
Secondary Sensory Cortex
Receives input from primary
Association Cortex
Receives input from more than one sensory system
Input mostly from secondary
Three characteristics of sensory systems
Hierarchical organization
Functional segregation
Parallel processing
Ranking of hierarchical organization
Receptors –> Thalamic relay –> Primary sensory cortex –> Secondary –> Association
Each level receives input from lower levels and adds a level of analysis before passing up
Damage to lower levels
Loss of function
Damage to higher levels
Specific sensory deficit
Sensation
Detection of stimuli
Perception
Interpretation of stimuli
Agnosias
Perceptual problems
Functional segregation
Primary, secondary and association cortices are not functionally homogeneous
Different analysis within each hierarchical level
Do not act together to perceive sensation
Parallel processing
Different levels of sensory hierarchy are not serial
Simultaneous analysis of a signal in different ways by multiple parallel pathways of neural networks
Two types of parallel processing
Influence behaviour without conscious awareness
Influence behaviour by engaging conscious awareness
Claustrum
Thin layer of neurons under neocortex
Receive input from all lower sensory areas to form perception
Sound
Vibration of air molecules
Range of frequencies heard by humans
20 to 20 000 Hz
Amplitude of sound wave
Loudness
Frequency of sound wave
Pitch
Complexity of sound wave
Timbre
Pure tone
Can't localize Generally uncomfortable Sine waves Do not occur naturally (computer or lab) Close relationship between the tone and pitch
Fourier analysis
Mathematically break down complex waves into component sine waves of different frequencies and amplitudes
Theory that fourier analysis occurs in the brain
Outer ear
Sound waves travel down the auditory canal
Tympanic membrane
Ear drum
Vibrations transferred to ossicles
Ossicles
Malleus
Incus
Stapes
Trigger vibrations in oval window
Inner ear
Transfers vibrations to endolymph of cochlea
Cochlea
Long coiled tube with internal membrane to tip
Organ of Corti
Each pressure change in the oval window travels along the organ of Corti as a wave
Basilar membrane
Hair cells (auditory receptors) mounted
Tectorial membrane
Rests on hair cells
Round window
Dissipates vibrations
Endolymph
High in K+
Surrounds the hair cells
Ionic imbalance = energy storage - no need for Na+/K+ pumps - trigger AP when hair cells move
Tight junctions between hair cells maintain ion imbalance
