COGS 172 VISION CONTINUED More on Face Processing Dorsal System, Vision for AcCon. Cogs 172 A.P. Saygin

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1 COGS 172 VISION CONTINUED More on Face Processing Dorsal System, Vision for AcCon Cogs 172 A.P. Saygin

2 Agnosia Videos AppercepCve

3 Are faces special? How to test?

4 Are faces special? How to test? How seleccve is the deficit? Are there face areas in healthy brain?

Are there pacents with selec%ve face processing impairments? Yes, there are pacents with relacvely seleccve face processing deﬁcits. Bruyer et al. (1983) Mr.

5 Are there pacents with selec%ve face processing impairments? Yes, there are pacents with relacvely seleccve face processing deﬁcits. Bruyer et al. (1983) Mr. W, farmer with prosopagnosia, could recognize his individual cows McNeil & Warrington (1993) WJ severe prosopagnosia Became sheep farmer and could learn to recognize sheep faces, but not human faces. à Dissociation

6 What about the reverse? Is there a double dissociacon? Would mean the systems could be separable. Assal, Faure, & Anderes (1984) Farmer MX: zooagnosia Able to recognize people, but not cows à Double Dissociation

7 But be aware Such seleccve deficits are the excepcon rather than the norm Most pacents have other deficits

8 Are faces inherently harder? Importance of comparison to general populacon Farah, Klein & Levinson, 1995 (see Farah reading) LH: Prosopagnosia since college Normal controls: 87% faces, 67% frames PaCent LH: 64% faces, 63% frames LH was disproporconately impaired at face recognicon relacve to non-face recognicon rela%ve to normal subjects

10 Face Inversion

11 Face Inversion Inverted faces are processed more like objects

12 Face Inversion and Prosopagnosia Farah s matching task (was it the same or different?) Controls Upright: 94% Inverted: 82% ProsopagnosCc pacent Upright: 58% Inverted: 72% PaCent does not benefit from upright face advantage Actually has an advantage for inverted faces

13 Face-selecCve regions in the human brain: What other evidence? fmri Fusiform Face Area (FFA) - Nancy Kanwisher and colleagues But Isabel Gauthier and colleagues showed that FFA responds to cars and birds and greebles in car/ bird/greeble experts

14 Faces may be special but There are mulcple areas important for face processing In addicon to FFA, other posterior corccal regions Occipital face area (OFA), Superior temporal sulcus (STSFA) Amygdala Hippocampus, parahippocampal gyrus Also note prosopagnoscc pacents can recognize that a face is a face (Compare to object/form agnosia)

15 Vision What/Where

16 Vision for AcCon What can pacents teach us? They have taught us a lot about the dorsal and ventral streams

17 What vs. Where IniCal evidence: Experiments with monkeys What pathway lesions Unable to discriminate objects Where pathway lesions Unable to locate objects

18 PercepCon/AcCon We don t just passively perceive or locate things ( where ). PercepCon guides accon. Posterior parietal neurons important for eye and hand movements to spacal locacons. But instead of monkey physiology, one of the most important lessons in this field came from brain disorders. Especially pacent DF David Milner and Mel Goodale

19 PaCent DF Anoxia from carbon monoxide poisoning Bilateral ventrolateral occipital lesion - spares V1 No blind spots Normal color vision, brightness discriminacon Normal smooth pursuit Cannot recogpy line drawings or pictures but can draw from memory

20 DF: Visual Agnosia Cannot recognize objects when presented visually. Especially hard Cme with drawings and leners Cannot copy line drawings or pictures but can draw from memory Cannot recognize objects when presented visually. Especially hard Cme with drawings and leners Cannot copy line drawings or pictures but can draw from memory

22 OrientaCon Matching Task

23 Reaching and PosCng Task

24 DF: Object Size DissociaCon between a Cannot escmate size of objects in front of her Can escmate size if she is to reach for the object Precision grip formed accurately from start of reach

25 What do you think would happen if DF delayed her reach?

26 What do you think would happen if DF delayed her reach? 2 sec and 30 sec delays At both delays, the precision grip was lost. (Eyes closed) Normal subjects can do well at 30 sec Means that accon must be natural Normals can probably visualize the object and pantomime the reach - but DF has impaired ventral stream so cannot visualize.

27 ImplicaCons on awareness Harder to fool the dorsal stream but you are usually not aware of it.

28 DF: Summary Cannot see when asked to do a perceptual task on the same visual scene Can see when asked to do an accve task on the exact same scene DF s vision for accon is intact -- dorsal stream Ventral stream damaged/disconnected.

29 Can pacents have other visual systems seleccvely damaged?

30 Cerebral Achromatopsia: Color blindness Deficit of color processing caused by acquired cerebral lesions Colors look dirty, washed out, lights are dim Inability to idencfy or discriminate color. Usually affects a porcon of visual field but can be full visual field How is it tested?

31 Achromatopsia Must make sure problem is not in color naming or color categorization Ishihara plates Farnsworth-Munsell 100 Hue Test

32 Achromatopsia Usually V4 damage - anatomically lingual gyrus, fusiform gyrus, or white maner between the regions Lingual gyrus seems more strongly implicated than fusiform gyrus Form and mocon percepcon is usually intact Concurrent alexia and object agnosia is fairly common Color knowledge is intact (they can answer semancc quescons) But color imagery is oqen also affected

33 Cerebral Akinetopsia: MoCon blindness Deficit of mocon processing caused by acquired cerebral lesions Because mocon cues serve many purposes, a range of deficits can result E.g., Difficulty using mocon to find objects Pursuit eye movements are oqen impaired

34 MoCon blindness PaCent MP: When I m looking at the car first, it seems far away. But then when I want to cross the road, suddenly the car is very near. Strobe-like, stacc images Usually Good stacc visual acuity PercepCon of taccle and acouscc mocon intact Accurate localizacon of visual targets by saccadic eye movements RelaCve preservacon of face and object recognicon, reading, and color vision

35 Patient LM: The patient had great difficulty pouring coffee into a cup. She could clearly see the cup's shape, color, and position on the table, she told her doctor. She was able to pour the coffee from the pot. But the column of fluid flowing from the spout appeared frozen, like a waterfall turned to ice. She could not see its motion. So the coffee would rise in the cup and spill over the sides. More dangerous problems arose when she went outdoors. She could not cross a street, for instance, because the motion of cars was invisible to her: a car was up the street and then upon her, without ever seeming to occupy the intervening space. Was diagnosed with agoraphobia Lesions: Bilateral dorsolateral visual association cortex, spares area V1, covers V5/MT. Could see/catch very slowly moving objects.

36 MoCon Blindness: Lesion Sites Bilateral MT/V5 lesions Human monkey mocon area analogies - not completely clear Temporoparietal, near angular gyrus Parieto-occipital As part of another disease (Balint's syndrome or Alzheimer's disease) Deficits of mocon percepcon (not as severe) can also occur with lesions in parietal insula and midline cerebellum Transient cases of mocon blindness have been reported as side effects of ancdepressant medicacon (SSRI)

38 Space and Attention

39 Dorsal System Attention and space Simultanagnosia and Balint s syndrome Neglect

40 What is attention? William James 1890: Everyone knows what anencon is. It is the taking possession of the mind, in clear and vivid form, of one out of what seems several simultaneously possible objects or trains of thought. FocalizaCon, concentracon, of consciousness are of its essence.

41 AnenCon One name for many processes SelecCon of informacon Awareness OrienCng ConcentraCon Conscious Monitoring ex. Driving Capacity to perform mulcple tasks

42 SelecCve AnenCon SelecCon of sensory informacon for further processing - irrelevant informacon discarded - e.g., spotlight metaphor

43 Many aspects of attention to focus on Everyone knows what anencon is. It is the taking possession of the mind, in clear and vivid form, of one out of what seems several simultaneously possible objects or trains of thought. AnenCon is potencally relevant to everything we study in cognicve neuroscience. A. Treisman AnenCon need not be a unitary process simply because a single word is used in everyday language

44 Space and AnenCon

45 Space and AnenCon Spa$al A(en$on: The neural mechanisms have been studied using a variety of methods: single-cell recordings, event-related brain potencals (ERPs), neuroimaging, and neuropsychological pacents. We will focus on data obtained from studies using neuropsychological pacents Today - we will not talk about execucve systems, somecmes called the anterior anencon system because of the importance of frontal lobes.

46 Space-based and Object-based anencon are oqen confounded Certain experimental paradigms can get at one or the other --- evidence for shared neural substrates

47 MulCple parietal areas are important for spacal processes LIP: Lateral intraparietal: SelecCng targets for eye movements. DirecCng anencon to spacal locacons. Contains eye-centered recno. map AIP: Anterior intraparietal: Hand manipulacon, grasping (connects to premotor cortex hand areas) Visual, motor, visuomotor responses MIP/VIP: Medial/Ventral intraparietal: MIP: Reaching; both taccle, visual VIP head/mouth centered maps, space around face; both taccle, visual Intraparietal sulcus opened up for viewing CIP: Caudal intraparietal. 3D shape. 7a: Primarily visual

48 In the human brain, analogues of these areas exist but are close together in the posterior parietal cortex - lesions oqen affect mulcple areas

49 Consequences of dorsal stream/ parietal damage

50 Right Hemisphere

51 ConCnued next Cme

Topic 11 - Parietal Association Cortex. 1. Sensory-to-motor transformations. 2. Activity in parietal association cortex and the effects of damage

Topic 11 - Parietal Association Cortex 1. Sensory-to-motor transformations 2. Activity in parietal association cortex and the effects of damage Sensory to Motor Transformation Sensory information (visual,