P.1 Audition, Temp, Touch and Pain

What is the geniculostriate pathway?

It’s the primary visual pathway: retinal ganglion cells → lateral geniculate nucleus (LGN) → primary visual cortex (V1). V1 performs basic visual processing.

What does V2 do in the visual cortex?

V2 is adjacent to V1, connected bidirectionally, and elaborates on the visual information from V1.

What is the function of the ventral stream?

Known as the "what" pathway, it processes object identity, form, and color. Route: V1 → V2 → V4 → Inferior Temporal Cortex.

What does area V4 do and what happens if it's damaged?

V4 is involved in color processing. Damage can cause cerebral achromatopsia—loss of color perception despite normal retinas.

What is the role of the Inferior Temporal Cortex?

Processes complex visual features and object identity, houses category-specific cells like the Fusiform Face Area (FFA) for faces and Parahippocampal Place Area (PPA) for places.

What is visual agnosia?

A disorder where individuals can't recognize objects visually. Types include apperceptive (poor copying), associative (can copy but not name), and prosopagnosia (can't recognize faces holistically).

→ Common Result of Damage to the Temporal Cortex

What does patient D.F.'s case demonstrate?

D.F. had visual form agnosia due to ventral stream damage. She couldn’t perceive orientation but could act on it—showing a dissociation between perception (ventral) and action (dorsal).

What is the function of the dorsal stream?

Also called the "where/how" pathway, it processes spatial location and guides visually-based actions.

→ Parietal Cortex

What roles do Middle Temporal Cortex (MT) and Medial Superior Temporal Cortex (MST) areas play in motion perception?

MT detects direction and speed of motion (small receptive fields). MST processes more complex motion like expansion/contraction (large receptive fields).

What is optic ataxia?

A dorsal stream disorder where individuals can recognize objects but can’t reach for them accurately, especially in peripheral vision.

What is akinetopsia?

Motion blindness due to MT damage. People can't see movement—objects appear frozen, and tasks like pouring liquid or crossing the street become difficult.

What is a sound wave?

A mechanical pressure wave created by vibrating objects that propagate through air via compression and rarefaction.

What wave properties correspond to which auditory perceptions?

Amplitude = loudness, frequency = pitch, complexity = timbre.

What does the outer ear do?

The pinna collects sound, and the auditory canal funnels it to the tympanic membrane.

What is the function of the middle ear ossicles?

They transmit and amplify sound vibrations from the tympanic membrane to the oval window.

What happens in the cochlea?

Fluid waves move the basilar membrane, deflect hair cells, opening mechanically-gated ion channels which lead to neurotransmitter release and auditory nerve activation.

What are inner and outer hair cells?

Inner hair cells transduce sound, outer hair cells amplify and tune sensitivity.

What happens when cilia deflect toward the longest cilia?

Tip links stretch, K⁺ and Ca²⁺ channels open, leading to more depolarization and increased glutamate release.

What happens when cilia deflect toward the shortest cilia?

Tip links slacken, ion channels close, leading to hyperpolarization and reduced firing.

How is pitch perceived according to place theory?

Each frequency produces a vibration that peaks at one point along the basil membrane base = high, apex = low.

Apperceptive Visual Agnosia

poor copying of objects

Associative Visual Agnosia

associative can copy objects but not name

Prosopagnosia Visual Agnosia

individual can't recognize faces holistically

How do we identify a low or high pitched sound

Each frequency produces a vibration that peaks at one point along the basil membrane