Chapter 15 - Temporal Lobes

symptoms of temporal-lobe disorder?

* transformed personality
* he got a left-temporal lobe tumor → was removed
* aphasic after surgery (clear after a few weeks)
* word-find difficulties
* verbal-memo probs
* including radical changes in affect (emotion) and personality, memory disturbance, and at least a transient disturbance of language

what does the temporal lobe comprise all of?

the tissue that lies below the lateral (Sylvian) fissure and anterior to the occipital cortex

* subcortical structs:
* limbic sys, amygdala, hippo formation

how many temporal areas did Brodmann identify?

* 10
* but recent studies found more areas in monkey brain

the divisions of temporal lobes?

* auditory (Brodmann’s area, 41, 42, 22)
* for the ventral visual stream on the lateral temporal lobe (area 20,21, 37, 38)

what are the visual regions referred to as?

inferotemporal cortex or area TE

what does the lateral (sylvian) fissure form?

insula → includes gustatory cortex + auditory association cortex

what does the STS seperate?

the superior and middle temporal gyri and houses a sig amount of neocortex

what is the medial temporal cortex?

* limbic cortex
* includes amygdala and adjacent cortex (uncus), hippo, and surrounding cortex (subiculum, entorhinal cortex, perirhinal cortex), and fufiform gyrus

bordmann’s area for entorhinal cortex?

area 28

what does area 35 and 36 correspond to?

perirhinal cortex

what are cortical areas TH and TF often referred to as?

parahippocampal cortex

what are the fusiform gyrus and inferior temporal gyrus functionally part of?

the lateral temporal cortex

what is the cortical region lying along the boundary of the temporal and parietal lobes often called?

temporal-parietal junction (TPJ)

when is TPJ shown to be active?

* attention
* memo
* language
* social processing
* so it proposed as central to decision making in a social context

what are the afferent projections involved?

sensory sys

where are the efferent projections involved?

* parietal and frontal associations regions
* limbic sys
* basal ganglia

how is the neocortex of the left and right temporal lobe connected ?

by corpus callosum

how is medial temporal cortex and amygdala connected?

anterior commissure

what are the types of cortical-cortical connections found?

1. hierarchical sensory pathway subserves stimulus recog
2. a dorsal auditory pathway is concerned with directing movements with respect to auditory info
3. a polymodal pathway prob underlies stimulus categorization
4. a medial temporal projection crucial to LTM
5. a frontal lobe projection necessary for various aspects of movement control, STM, and affect

what is the hierarchical sensory pathway subserves the stimulus recog?

* hierarchical progression of connections emanates from teh primary and secondary auditory and visual areas, ending in the temporal pole. T
* he visual projections form the ventral stream of visual processing, whereas the auditory projections form a parallel ventral stream of auditory processing

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expand on the second cortical-cortical connection :A dorsal auditory pathway is concerned with directing movements with respect to auditory information

* projections from the auditory areas to the posterior parietal cortex, this pathway is analogous to part of the dorsal visual pathway, which likely plays a role in detecting the spatial location of auditory inputs

expand on the third cortical-cortical connection :A polymodal pathway probably underlies stimulus categorization.

this series of parallel projections from teh visual and auditory association areas converges in the polymodal regions of the STS

expand on the forth find cortical-cortical connection :A medial temporal projection crucial to long-term memory

* the projection from the auditory and visual association areas into the medial temporal, or limbic, regions goes first to the perirhinal cortex, then to the entorhinal cortex, and finally into the hippo formation or the amygdala or both.
* the hippo projection forms the **perforant pathway** → when disrupted, results in major dysfunc of hippocampal activity

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expand of the fifth cortical-cortical connection: A frontal-lobe projection necessary for various aspects of movement control, short-term memory, and affect

this series of parallel projections reaches from the temporal association areas to the frontal lobe

how many cortical and subcortical pathways comprise the ventral stream?

at least 6

where are projections in the first set subcortical go (in ventral stream)?

* from every region of the occipitotemporal pathway to the neostriatum (striatum)
* projections for the occipitotemoral-neostriatial network to support types of habit and skill learning depedent on vision

what is the striatum comprised of?

caudate nucleus and plutamen of the basal ganglia

where are projections headed in second pathway of ventral stream go and do?

* amygdala-bound projections from inferotemporal regions
* allow processing of emotionally salient stimuli

where are projections headed in third pathway of ventral stream go and do?

* travels from inferotemporal cortex to ventral striatum (nucleus accumbens)
* support the assignments of stimulus valence (potency)

where do three remaining pathways in ventral stream project and do?

* from inferotemporal cortex to other cortical regions
* medial temporal → LTM
* orbitofrontal pathway → object-reward associations
* ventrolateral prefrontal → object WM

what does the temporal cortex house?

* primary auditory cortex
* secondary auditory and visual cortex
* limbic cortex
* amygdala
* hippo

what are the three basic sensory func of temporal cortex?

1. processing auditory input
2. visual obj recog
3. LTM of sensory input → memo

what is the func of ventral stream pathway?

* obj recog by characteristics such as shape, colour, size
* categorization

what does obj categorization depend on (region)?

inferortemporal cortex, area TE

what does damage to temporal cortex lead to?

deficits in identifying and categorizing stimuli

what is cross-modal matching and depends on what region?

* matching visual and auditory info
* depends on the cortex of the superior temporal sulcus

LTM depends on what?

ventral stream and paralimbic cortex of the medial temporal region

affective response is a func of what?

amygdala

Associating sensory input and emotion is crucial for learning because stimuli become associated with their positive, negative, or neutral consequences, and behavior is modified accordingly.

what happens in absence of affective system?

* all stimuli would be treated equivalently → can be consequential
* e.g., fail to associate rattle snake with consequence of being bitten

what happens when amygdala gets lesion?

become very placid and do not react emotionally to threatening stimuli.

what subcortical region helps us use spatial nagivation?

hippo → contains cells that code places in space

what is biological motion?

movements that have particular relevance to a species

what region analyzes movement?

STS

what is social cog?

theory of mind that allows us to dev hypotheses abt other people’s intentions

what info in important for social cog?

social perception

what area play a key role in social cog?

cells in STS

what could also be involved in perceiving species-typical sounds (vocalization)?

STS and cells in superior temporal gyrus

what can talking and signing be perceived as?

* a complex form of biological motion
* so activation of STS in response to mouth movement too

if people have temporal lobe injuries that lead to impairments in analyzing biological motion, there is likely a correlated deficit in _________ ________________

social awareness

what do neurons in STS may be particularly responsive to?

* faces seen head-on
* faces viewed in profile
* posture of the head
* particular facial expressions

what cells are maximally sensitive to primate bodies moving in a particular direction?

STS cells

what did scientist notice in experiment of watching the good, the bad and the ugly?

1. extensive activity throughout the entire temporal lobe was highly correlated across participants → same for auditory and visual areas in temporal lobe, STS and cingulate regions → shows stereotypic response to naturalistic audiovisual stimuli
2. selective activation related to the film’s precise moment-to-moment content
* close up for face → FFA highly active
* broad scene → enhance activity of PPA
3. no intersubject coherence → they have widely diff thought patters beyond the sensory processing, related to past experience.

in study, what do activation for most cells in area TE require?

* complex features containing a combo of characteristics such as orientation, size, colour, and texture

what do cells with similar, although slightly diff, selectively tend to do?

cluster vertically in columns

how would obj be likely represented in columnar organization in area TE?

by the activation of many cells within a columnar module

→ they largely overlap to minimize the effect of small changes in input images and lead to the categorization of similar obj

what did study on inferotemporal find that experience alters?

the stimulus specificity → is a experience-dependent characteristic

what does experience-dependent characteristic allow us to do?

allows the visual sys to adapt to diff demands in a changing visual enviro → important for human visual recog abilities that face differing demands depending on the type of eviro they are confronting

inferotemporal neurons not only may process visual input but also may provide what?

a mechanism for internally representing images of obj → may provide basis for WM and visual imagery

what are evidence that a special pathway exists in visual sys for analyzing faces?

1. study sows that neurons in temporal lobe specifically tuned to diff faces, with some cells attuned to facial identity and others to facial expression
2. inverted photographs of any obj that has a usual right side up makes it harder to recog, but the effect on faces in disproportionate

what illusion shows the importance of an upright orientation for facial perception?

Thatcher Illusion

are inverted faces and upright faces processed in the same regions?

* no
* upright has separate face-perception sys that includes regions in the occipital lobe as well as several different temporal lobe regions

what do right temporal lesions lead to?

greater effect on facial processing than left

what are results of split face test?

* participants consistently chose the left-side of photography A when asked which resembled photo A the most.
* did this when photos were inverted, or upright
* patients w/ either right temporal or parietal removals consistently failed to match any conditions

would the person in photograph chose the same as someone else in split-faces test?

* no it will be reversed → we will chose right side
* bc we see ourselves differently in mirror than others see

sound wave path to brain?

cochlea → brainstem → auditory cortex → perception of sound

what kind of map do auditory regions have?

tonotopic maps → gol is to perceive sound making obj, locate sound, and make movements in relation to sounds

many cells in auditory cortex respond to specific _________?

frequencies

another word for frequencies?

sound pitch

what are the two most interesting sounds to human?

lang + music

how does speech differ from other auditory inputs?

1. speech sounds come largely from three restricted frequency ranges known as formants
* syllables differ both in onset frequency of the second (higher) formant and in the onset time of the consonant
* vowel sounds occupy a const f band
* consonants show rapid change in f
2. the same speech sounds vary from one context in which they are heard to another, yet all are perceived as being the same
* auditory sys must have mecha for categorizing varying sounds as equivalent, and this mecha must be affected by experience, bc obstacle learning lang as adult
3. speech sounds change vv rapidly in relation to one another, and the sequence of the sounds is critical to understanding

what does music rely on?

* relations between auditory ele

what does lang depend on?

individual auditory ele

what is tune defined by?

arrangement of the pitches’ durations and interval between them

what do musical sounds differ from one another by?

* loudness
* timber
* pitch

what is loudness refer to?

subjective magnitude of an auditory sensation judged by a given person as “vv loud”, “soft”, “very soft”, etc.

what is intensity measured in?

decibels → intensity

what does timbre refer to?

* the distinctive character of a sound, the quality that distinguishes it from all other sounds of similar pitch and loudness
* e.g., can distinguish trombone and violin by sound even if play same note

what is pitch?

position of a sound in a musical scale

what is pitch related to ?

frequency → vibration of sound wave

what does pitch contribute to in regards of speech?

prosody → “tone” of voices

what is the lowest component of a note called?

fundamental f

what are f above fundamental called?

overtones or partials → they are multiples of fundamentals → harmonics

what is periodicity pitch?

when a fundamental f is removed from a note by means of electronic filters, overtones are sufficient to determine the pitch of the fundamental f

what is an important aspect of pitch perception?

although we can generate (and perceive) the fundamental f, we still perceive the complex tones of the harmonics, or spectral pitch

what region seems to make periodicity - pitch discrimination?

auditory cortex of the right temporal lobe

patients with right temporal lobectomies that include primary auditory cortex are impaired at what?

* making pitch discrimination when the fundamental is absent but make discrimination normally when fundamental is present
* also impaired at identifying the direction of a pitch change

other name for primary auditory cortex?

area 41 → Heschl’s gyrus

what types of time relations are fundamental to the ryth musical sequences?

* segmentation of sequences of pitches into groups based on the duration of the sounds and identification of temporal regularity (beat)

other word for beat?

meter

what regions plays role in temporal grouping for rhythm?

left temporal lobe

what region plays role in meter?

right temporal lobe

what regions play a role in motor component of rhythm?

* supplementary motor cortex
* premotor cortex
* cerebellum
* basal ganglia

injury where impairs learning melodies?

* either temporal lobes

what region injured leads to impairment of melody retention?

right temporal

the right temporal lobe has a special func of extracting ______ from sounds, whether sound is speech or music

pitch

there is a moch larger volume of what in Heschl’s gyrus in both temporal lobes in musicians?

grey and white matter

what does the gray-matter difference positively correlate to?

musical aptitude → the greater aptitude, the larger the gray-matter volume

what do fundamental-pitch listeners exhibit?

pronounced leftward asymmetry of gray matter volume in Heschl’s gyrus

what do spectral-pitch listeners exhibit?

rightward asymmetry, independent of music training

what do innate differences in brain morphology relate to?

the way in which pitch is processed and that some innate differences are related to music ability