Lecture 15 - Temporal lobes 1
How does the 'theory of object perceptions" in the slides match up (very generally) with the functions in the various parts of the primary, secondary visual cortex, what may be happening in the (ventral) visual stream? (V1 to hippocampus)?
They match up very well. There are discrete areas specified by the theory that more or less correlate to the various parts of the ventral visual stream. Ventral Visual Stream -Object perception -Biological motion -Face perception Theory of Object Perception - first thing done in a Ventral Visual Stream -Edges and bars of lengths, contrasts and orientations -Grouping elements into higher-order units, separating figure and ground -Viewer-centered description matched onto stored 3D descriptions of structure of objects -(rotation if needed)? -Meaning attributed to the stimulus -Naming of different items Notes: -Shapes is the important thing, not color/pattern (pink elephant, plaid apple, etc.) -"Theory" - best guess to stages how we take in information and then see -First, we see edges - further processes put together edges and orientations to get objects -Certain areas light up when thinking/seeing them (persons, animals, tools) -Lateral occipital cortex - most function here
What is the difference between view-dependent and view-invariant shape perception?
View dependent means that you need to see a particular object from a particular vantage point, or at a particular viewpoint, in order to be able to identify said object. View Invariant means that viewpoint does not matter i.e. common components of bicycle (handlebars, wheels, pedals) allows you to identify as bicycle regardless of viewpoint.
What is the progression and transformation of information from the pinna onwards to the primary auditory cortex (i.e. outer, middle, inner ear (w/ details) to n. VIII to Cochlear nucleus (dorsal & ventral), superior olivary nucleus, inferior colliculus, medial geniculate nucleus to A1)
eardrum-> hammer-> anvil-> stirrup -> oval window -> cochlea-> N8 -> ipsilateral cochlear nucleus -> superior olivary nucleus -> inferior colliculus -> MGN -> A1
tonotopic
means that cells responsive to different frequencies are found in different places at each level of the central auditory system, and that there is a standard (logarithmic) relationship between this position and frequency.
What is the relationship between the basilar membrane and tonotopic organization?
the basilar membrane is organized tonotopically - meaning each segment has a frequency of greatest sensitivity. essentially the 4 main tonotopic areas move from closest to the oval window (high frequency) to farthest away (low frequency).
Cochlea
the sound goes thru oval window and in the cochlea there is fluid basilar membrane has hair cells - actual receptors for sound - sit on basilar membrane when pressure wave makes hair cells move there's an action potential - then you have completed the transduction the pressure wave moves the hair cells and the hair cells trigger an action potential
How does the hierarchical sensory pathway run in the temporal lobe, what is its function?
A1+2, V1+2 -> lateral temporal cortex -> temporal pole (BA 38) -> medial aspects of the temporal lobe. Audio: Travels through the Superior Temporal Gyrus Visual: Travels through the Inferior Temporal Gyrus Function: integrate auditory and visual info.
Where is the secondary auditory cortex?
Anterior region of the Superior Temporal Gyrus
How does the polymodal pathway pathway run in the temporal lobe, what is its function?
Connections emerging from the auditory and visual hierarchical pathways are directed to neurons enfolded within the Superior Temporal Sulcus It is a polymodal region - i.e. multiple sensory modalities Auditory and visual information are coming in (connections and interactions) Probably important in categorical organization (chair furniture nature living/nonliving) - region for quickly assigning things to categories Believed to be involved in assigning stimuli to categorical classes.
How does the dorsal auditory pathway pathway run in the temporal lobe, what is its function?
Connections with the posterior parietal cortex Processing of sound for spatial information (to then look and act in relation to the sounds) Effect -Enables location of sounds in space -Promotes orienting and initiation of movements relative to sound location
What are other names for A1?
Heschl's gyrus/i Brodmann's 41 and 42 Transverse Temporal Gyri
What does it mean that the primary auditory cortex has a tonotopic organization?
It is arranged based on frequency. Tone map - sound is mapped tonotopically on the hair cell as they are distributed on the basilar membrane
How does the medial temporal projection pathway run in the temporal lobe, what is its function?
Major Destinations: Amygdala and Hippocamus This results in the integration of information into Memory Emotional tone Direction of projections: Perirhinal cortex → Entorhinal cortex → amygdala/hippocampus (performant pathway)
What is the name(s) of the nerve that transmits information from the cochlea?
N.VIII: Vestibucochlear, Statoacoustic, Auditory-vestibular, nerve
The perforant pathway runs from the entorhinal cortex to the hippocampus, what appears to be its function?
Perforant pathway forms the main projection to the hippocampus Damage in this region severely affects memory Ultimate Effect -Stimulus recognition -The familiar conscious experience of knowing, assimilating and feeling Memory: Stimulus recognition & conscious experience of knowing, assimilating, and feeling. (see guide for pictures)
What are some of the problems with hypothesizing object-specific neurons in shape perception?
Said neurons can be triggered, or not triggered by seemingly insignificant variables (a hand in multiple orientations triggers one particular neuron, hand in mitten does not). Makes it difficult to form a cohesive hypothesis on how precisely humans identify certain objects.
What is biological motion perception and what parts of the temporal lobe seems to be involved in this? What is the role of biological motion perception in social cognition?
The movement of animals, including people, but not rocks or cranes. It appears to take place in the Superior temporal sulcus (sts) between the superior and the middle gyrii. Biological motion perception is the basis of social perception and development of social cognition. (seeing where others are moving their eyes, body language, etc).
What are the receptors for hearing, and how are they situated with respect to the basilar membrane and the cochlea?
The receptors are hair cells and they are situated in the fluid of the cochlea and around the basilar membrane. They carry information for the cochlea.
How does the temporal cortex connect with the frontal lobes?
They are strongly connected. Posterior temporal cortex projects to the dorsolateral prefrontal cortex. Anterior temporal cortex projects to orbitofrontal cortex.
