Ni- Part 2ck Flashcards
(29 cards)
Why action perception is importunate
Humans are social- need to make sense o fathers actions, affords evolutionary advantage, we interact in a complex social environment threat detection, building friendships, interactions w potential mates, happens fast so have dedicated system
Functional specialisation in the visual cortex - v5
V4 responds electively to colour, and v5 for direction- zeki, noticed they had diff layouts of neurones. Eye info goes to lgn in thalamus, then v1, v5 (movement)v5 rf larger than v1, cells respond to moving dots/bars, direction, speed (each has an optimum), has retinotopic map of visual world, not sensitive to colour. If stim the cells in a spec direction, the monkey sees movement in that direction. V5 linked to medial superioir temp cells MST,
MST
Larger rf than v5, sensitive to translation, most respond to optic flow like expansion, contraction, rotation. Get combos of rotation and expansion and we walk around . Stimulating them influences perception of movement.
Bio motion background
Johnasson 73: dots in light against dark that move in a way that simulates movement, means not evs as in isolation (point light figures of bio motion figures), can also use dots moving in common fate/grouping that changes when alone e.g. one hinge says nothing but 3 looks like leg walking. Can also change dots to look more fem/masc walk. Can get actions, hand, face, speech, gender, emotion, body weight, identity (motion gen form info)
Bio motion bio evidence
Processed in the posterior STS- grossman: did movements w dots compared to same dots just jumbled, mst provides direct input. Similar to other complex stim as can’t id if upside down, adding sounds can improve perception. Pervasive as infants preference for bio motion at 3m, asd dont. Can create social interactions between figures, get emotions from faces and some animals can discrimate thier species-innate. Get sts activity to faces, processing motion of animate being, natur of moving human stim. Rigid/non articulated in posterior middle temp gyrus. More anterioir sts more articulated
Implied motion
No motion but see it happening e.g, still image of a person running to the right. Zeki-v5- responds more things things moving than stationary bandw squares, also to illusion of movements leg. Visual illusion more bold response than stationary. Implied motion- 50% more bold to implied than similar figures that don’t, also in imaginary mental rotation
Integrating form and motion in sts
Dorsal has motion, ventral has form. Cells in ventral respond to body parts, combined motion and form to rep actions, gets info from v5 motion and AIT for features. E.g. right side of body and walking to the right, but need both, all you need to rec actions. Get cells that respond to static things, not implied motion. Some cells for implied motion and walking direction from static pictures
Single cell responses to action processing
Monkey cells in sts respond to spec actions like picking, tearing, rotating and body ones like bending at knee, face like grasping w lips, lip smacking, eye movements, coo-pant-threat, face and hand combos. Bigger response of cell, more likely action is happening, not grandmother as mor broad (population coding) respond irrespective of light, size, position, some egocentric some allocentric. Cells get lower level input, view dependent, respond excitatory input to view independent, big cells only needs input from one- org to dev independent reps. For detailed properties, low level says who is completing action e.g. hand position
Evidence for action processing systems in humans
Downing: extrastriate body area, area responds more to bodies than anything else, hierarchical e.g. more to whole bodies, then parts, the pace parts, than other objects and parts. Fusiform body area, also both respond to bio motion but less so. Pitcher tms: disrupted occipital face area, lateral occipital area (objects) and extrastriate body area. Shown 3D object stim, then mask, then probe, asked same or diff (mask makes it harder to id change), got tms during probe. Found inhibiting area inhibited the function but not the other functions- triple dissociation
STS studies
If record from humans brain, also see activity during observation of actions-pet in sts and inferior frontal gyrus. Sts has subregions and related like STG,TPJ, respond to bio motions, hands, faces, eye. Allison: sts responds to eye gaze, mouth, hands, action and movement, body movement. Eba and fba are static bodies and parts, sts is dynamic action
Social info
For our bodies, we integrate multimodal info from senses, bodies only way we influence world,central tool of our minds and real tools are extensions. Lang gives intention to own and others action. Fist person always conc of goal but others are speculation that action is functional and has phenomenal state (mind that decides).
Intentions and TOM
Intentions imply ends: need to have the want to do something , also means to take measures. One isn’t enough to make an intentional. Perception of intention is ascribe intention to others actions, info beyond stim. Infants attend humans bodies, toddlers understand foal directed actions and pre schoolers have tom. TOM: tell diff between objects of mental state and content which differs from reality- in theTPJ.
Mouth movements
Eating, drinking, emotive utterances, speech. Cells in monkey sts respond to mouth moves. In humans-Allison: erp from sts r, ps watched mouth moves and images of faces, sts responses more to mouth moves. Important for perception of speech and face movements- cocktail party effect-blur turns clearer, deaf ppl use it to get info. Calvert: vision and sound give diff responses but have common activation in sts to integrate but so does auditory cortex A1
Hand gestures
Ppl use gesture during speech to make clear semantic relationships, get better understanding of speech. Blind use hand gestures w other blind children-innate. Neville 98: fmri of deaf fluent n aslm tested asl and nonsense hand gestures. Stst more active to asl
Emotional body lang
Make inferences about emotions from actions, posture as well as face Processed by sts, amygdala, body processing network (eba, fba, stst), emotional network (amyg, anterioir cingulate). Sts and amygdala highly connectioned, emotinal body lang increases activity in sts
Motor cortex structure
Mirror neurones are motor neurones, in the frontal lobe- anything before the central sulcus, has primary motor cortex m1, premotor cortex and supplementary motor cortex. Topographical map of the Bod, diff neurones craft diff muscles. More neurones for tongue and mouth compared to knees. Contractural control. Neighbouring neurones activate neruboring muscles e.g. food and far away cortex- m1 neurones operate single muscles
Pre motor cortex part 1
Give input to m1, activity in single pre motor neurone can cause activity in a number of m1 to create coordinated contraction. First mirror neurones found here in f5. Respond to execution of goal directed action but also the sight of others performing them (visual and motor) rizzollatti 96: live actions performed by monkey or experimenter, cells respond to both, very spec as only respond to hand grasp not pliar grasp,only anti-clockwise twisting of rubber peanut some more broad
Pmc part 2
Some respond to movement and observation of faces- ferrari 2003: some like teeth graspin but also communicative like lip smack in, teeth chattering. Also respond when the late part of the action can’t actually be seen- umilta 2001: occluded in front of someone picking up block. Doesn’t fire when someone miming the actions. Monkey must know object being occluded and must see hand before going behind . Not just visual- knowledge of an action taking place
Mirror neurones in the sts and the mns background
Respondselectively to actions but also the sight and sound of an action but no evidence they have mn. Keysers: inferior parietal respond to sight sound and motor so may occur here. Mn in f5 inferior frontal gyrus also respond to sight and sound. o keys so far, get input from sts to inferior parietal
Mns in humans - tms studies
Should be in the pmc, evidence that maybe: fadiga 95: tms of motor cortex m1 causes motor evoked potential mep in muscles. If coil in m1 for for hand, get twitch in opposite side hand, bigger tms bigger twitch so mep metric of motor activity. Motor system gets info from premotor, increased input from visual to motor means more activity I motor as premotor. Whe looking at actions of pthers during tms activated of m1 increases the likelihood of mep- raises threshold of rm1 stim
Sound and mep and nuero imaging studies
Mep enhanced during action observation e.g. only increase when viewing hand action in hand map- action spec. Fadiga 95: listening to words that use tongue enhances mep of tongue. Areas of activity in parietal and frontal lobes when person performing pt observing vids of someone moving face, also seen for hand and foot actions
Weaknesses of ideas of mns in humans
Some argue only indirect evidence, not recording from spec neurones, getting inferences from imaging, relied of correlation of blood flow. Mukamel 2010: used depth electrodes on supp motor area and hippocampus (used to map regions for epilepsy surgery), found neurones that respond to observation and performing actions for hands and face- mirror neurones may be more distributed in humans
Why we have mn
Some think for loads of things: action perception, understanding, touch, smell, imitation, mind reading, motor learning, autism, schizo but unlikely. Do play role in action perception: hamilton 2004: if you do action, changes the way you see someone else doing action as when picking up heavy items- rated another persons item as lighter and vice versa. Jacob and shiffrar 2005: when walking on treadmill, worse as guessing speed of bio motion when compared to standing still and cycling
Understanding actions of others
We understand the intent of our own actions so as mns activates when someone else doing action, implies if we understand own, then should in
Understand others actions- simulation theory: to understand others action we must simulate them or theory theory which is we use common sense tom to understand others- causal laws
