16 Notes: Temporal Lobe – biologicalpsych.com

Temporal Lobe
- Ventral = high level visual process
- Medial = memory
- Superior = cochlea
- Posterior = audio-motor proces
- Temporal-parietal = Wernicke
I. Ventral area of temporal lobe
- ventral = toward the tummy; under part of temporal lobe
- Ventral Stream
  - Occipital to temporal
  - Under part of temporal lobe
  - Main input from LGN
  - Parvocellular cells of V4
- As info moves thru temporal lobe
  - Processes larger receptive fields
  - Takes longer to process
  - Analyses more complex
- Representation of entire visual field
  - Uses cues to judge significance
  - Attention
  - Stimulus salience
  - Working memory
  - High-level visual processing
  - Complex stimuli
  - Faces (fusiform gyrus)
  - Scenes (parahippocampal)
  - Surrounds hippocampus
- Inferior temporal gyrus
  - Visual processing
  - Complex object features
    - global shape
    - face perception?
  - Fusiform gyrus = faces
  - Parahippocampal = scenes
  - Lingual gyrus
    - Word recognition
    - Dreaming
II. Medial Temporal Lobe
- Medial = toward median; toward middle
  - Declarative memory
  - Facts you know – L hemisphere
  - Events you’ve experienced – R
- Interacts with frontal lobes
  - Create long-term memories
  - Maintain long-term memories
  - Long-term memory
    - Becomes independent of encoding process
  - Hippocampus & adjacent areas work together
    - No simple dichotomies
    - associative vs. nonassociative
    - episodic vs. semantic memory
    - recollection vs. familiarity
- Transfer from STM to LTM
- Control spatial memory
- Damage causes
  - anterograde amnesia
- Declarative (explicit) memory
  - Semantic memory
    - Left hemisphere
    - Facts
  - Episodic memory
    - Right hemisphere
    - What I did on my vacation
III. Superior Temporal Lobe
- superior = upper
- Cochlea to auditory cortex
A. Primary auditory cortex = sound
- Anatomy of the Ear
- 1. Outer Ear
- 2. Middle Ear
- 3. Inner Ear
1. Outer Ear = pinna
- Pinna (pinnae) – visible ear
  - funnels sound to ear drum
  - helps in sound localization
- Tympanic membrane
  - Connects pinna to ear drum
  - Vibrates to sound wave
- Eustachian tube = equalizes pressure
2. Middle Ear
- Ossicular Chain
  - Pre-amplifier
    - amplifies vibrations 20x
    - 3 small bones
  - Malleus
  - Incus
  - Stapes
- Attenuation reflex
  - brain senses loud sound
  - tenses up muscles
  - To prevent damage
    - Bones don’t move
    - Greater for low frequencies
      - (higher freq. easier to discern)
3. Inner Ear
- A fluid-filled structure
  - fluid is called endolymph
  - similar to intracellular fluid
  - high in potassium
  - low in sodium
- Composed of
  - Bony labyrinth
  - Membranous labyrinth
    - suspended within bony labyrinth
    - delicate continuous membrane
  - Space between membranous & bony labyrinths
  - Filled with perilymph, similar to cerebral spinal fluid
2 outlets to air-filled middle ear
- Oval window
  - Filled by plate of stapes
  - Fluid pressure
- Round window
  - Pressure valve
Cochlea
- Spiral-shaped tube
- Has 2 connected canals
- Upper vestibular canal
- Lower tympanic canal
- Separate at large end
  - continuous at the apex
- Fluid filled (perilymph)
  - Has a middle canal
  - Cochlear duct
  - Filled with endolymph
- Contains the Organ of Corti
Organ of Corti
- “spiral organ”
- Contains hair cells for hearing (cilia)
- Basilar membrane with hair cells rest on it
- The basilar membrane separates the cochlear duct from the tympanic canal
- The tectorial membrane lies above the hair cells
Stereocilia
- Connected by extracellular links
- Graded in height
- Arranged in bundles
- Pseudo-hexagonal symmetry
How cochlea works
- Contains fluid
- Moving fluid $ hair cells, signals sent to brain, perceived as sound
- Arranged from high to low notes
  - low notes travel farther
Hearing Loss
- Bad bone conduction
  - Hearing aids
- Bad cochlea
  - Implant
- Dead cilia
  - ?
Most common causes
- Age (presbycusis)
  - Gradual, steady loss
- Noise
  - Motorcycles, lawn mower
  - Music in headphones
  - Gun shots
- db
  - 0 barely audible
  - 20 leaves ruffling
  - 40 quiet suburbia
  - 60 speaking voice
  - 100 subway train
  - 140 jet taking off
- Obstructions
  - Earwax
  - Objects
- Chemicals
  - Some antibiotics
  - Arsenic, mercury, tin, lead
- Head injury
  - Structural damage
- Infections
  - Middle ear (otitis media)
  - Swimmer’s ear (otitis externa
  - Fluid (cold or flu)
Preventing Loss
- Good genes
- Cover your ears
  - Lawn movers
  - Guns
- Don’t smoke
  - Correlation, cause unknown
  - Oxygen
  - Neurotransmitters
  - Developing brain
- No loud music
Processing Sound
- Vestibulocochlear nerve
- Cochlea but stops at cochlear nuclei
Neural Path
- Cochlei
- Cochlear nuclei
- Superior olivary complex
- Inferior colliculus
- Thalamus (medial geniculate nuclie)
- Primary auditory cortex
Cochlear nucleus
- 1st processing
Dorsal cochlear nucleus
Ventral cochlear nucleus
Superior olivary complex
- In the pons
- Input: ventral cochlear nucleus
  - Lateral superior olive (LSO)
    - Detecting ineraural level
  - Medial superior olive (MSO)
    - Interaural time difference
Inferior colliculi
- Just below superior colliculi
- Visual processing centers
- Integrates sound source info
Medial geniculate nucleus
- Thalamic relay system
- The LGN of sound
Auditory Cortex
- Highly organized into 3 parts
- Concentrically with primary in the middle
  - Primary auditory cortex
  - Secondary auditory cortex
  - Tertiary auditory cortex
1. Primary Auditory
- Direct input from MGN
- Tonotopically organized
- Identifies loudness, pitch, rhythm
- Neurons are organized:
- Frequencies respond best to
- Low frequencies at one end
- Complete “frequency map”
- Tonotopic map
  - Maps for vision & hearing
    - Reina to cortex
    - Cochlea to cortex
2. Secondary Auditory
- Surrounds primary cortex
- Interconnect
- Further processing
- Process patterns of
- Harmony
- Melody
- Rhythm
3. Tertiary Auditory Cortex
- Integrates musical experience
What it all does
- Analyses
- Identifying auditory objects
- Segmenting streams
- Identifying location of a sound
- How it all works
- Unclear
Inputs
- Multiple sounds
- Occur simultaneously
Tasks
Which components go together
- location of sounds
- groupings based on
  - Harmony
  - Timing
  - Pitch
Connects to Frontal & Parietal lobes too
- Why each note played by different instrument in orchestra sounds different
- Same pitch
Gamma waves
- Ss exposed to three or four cycles of 40 hertz click
- Spike in EEG
- Hallucination 12-30 Hz
- Left auditory cortex of schiz.
When remember song in mind
- Don’t perceive sound
- Experience melody, rhythm & overall experience
B. Wernicke’s Area
- Where temporal & parietal lobes meet
- Understanding of written
- Understanding speech
- Auditory word recognition
- Mimicking words
- Dominant Side
  - Usually left hemisphere
  - Resolve associative meanings
  - Bank———teller
- Non-Dominant Side
  - Usually right hemisphere
  - Resolve subordinate meanings
  - Ambiguous word meaning
  - River bank
  - Money bank
- Damage to Wernicke’s Area
  - Receptive aphasia
  - Also called
    - Fluent aphasia
    - Jargon aphasia
  - Impairs language comprehend
  - Natural-sounding rhythm
  - Normal syntax
  - Gibberish
  - Nonverbal sound problems
  - Animal noises
  - Machine sounds

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