Overview
This lecture reviews the anatomy, boundaries, and functions of the temporal lobe of the cerebral cortex, with detailed discussion of auditory and olfactory processing, language comprehension (Wernicke’s area), and the insula’s sensory roles.
Temporal Lobe Boundaries
- The lateral sulcus (Sylvian fissure) separates the temporal lobe from the frontal and parietal lobes.
- The preoccipital notch and an imaginary line separate the temporal lobe from the occipital lobe.
Auditory Cortices
- The primary auditory cortex provides conscious awareness of sound, including frequency, pitch, and localization.
- Sound signals cross in the brainstem and usually project to the contralateral primary auditory cortex.
- A lesion in the primary auditory cortex affects the ability to localize and interpret contralateral sound.
Auditory Association Cortex
- Receives input from the primary auditory cortex and assigns meaning to sounds by comparing them to memory.
- Helps interpret the purpose, source, and emotional tone of sound stimuli.
Wernicke’s Area
- Responsible for comprehension of spoken and written language by integrating auditory and visual input.
- Communicates with Broca’s area (speech production) via the arcuate fasciculus.
- Damage causes Wernicke’s aphasia (receptive aphasia): fluent but nonsensical speech with impaired understanding.
Olfactory Cortex
- The primary olfactory cortex (medial temporal lobe) provides conscious awareness of smell.
- The olfactory association cortex enables recognition and analysis of smells and connects odors to memories and emotions via the limbic system.
Insula
- Not a part of the temporal lobe; considered the fifth lobe of the cerebral cortex.
- Processes visceral sensations (from organs), vestibular sensations (equilibrium), and gustatory sensations (taste).
- Supports awareness of bodily sensations, taste discrimination, and some equilibrium functions.
Key Terms & Definitions
- Lateral sulcus (Sylvian fissure) — boundary separating temporal lobe from frontal and parietal lobes.
- Primary auditory cortex — area responsible for conscious sound awareness.
- Auditory association cortex — area giving meaning to sounds based on memory.
- Wernicke’s area — region for comprehension of language.
- Broca’s area — region for speech production.
- Wernicke’s aphasia (receptive aphasia) — fluent but nonsensical speech; poor comprehension.
- Primary olfactory cortex — area for conscious smell awareness.
- Olfactory association cortex — area for smell identification and linking odors to emotion/memory.
- Insula — cerebral cortex region for taste, visceral, and vestibular sensation.
Action Items / Next Steps
- Review the pathways and functions of auditory, olfactory, and insular cortices.
- Study the clinical implications of lesions in language and sensory areas, especially Wernicke’s aphasia.