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Biological Basis of Behaviour II > Neuroscientific Facial Recognition > Flashcards

Neuroscientific Facial Recognition Flashcards

1
Q

COGNITIVE NEUROSCIENCE TECHNIQUES

A

FUNCTIONAL MAGNETIC RESONANCE IMAGING (fMRI)
ELECTROENCEPHALOGRAPHY (EEG)
BRIAN STIMULATION

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2
Q

THE ACCOUNT DEBATE

A
  • increased w/cognitive neuroscience
  • lots of evidence used face inversion + brain activation investigation in Face Fusiform Area (FFA) via fMRI/event-related potential (ERP) measurement aka. N170 via EEG
  • brain stimulation application (ie. tDCS) helped expand investigation into face recognition mechanisms
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3
Q

FMRI

A
  • non-invasive imaging technique; detects brain activity via finding changes in blood oxygen lvls (blood-oxygen-level-dependent aka. BOLD)
  • relies on cerebral blood flow & neuronal activation; when brain area = used -> ^ regional blood flow; ^ active brain area = neurons send ^ electrical signals than before (ie. raise leg -> active area => that area controls movement)
  • MRI = checks everything is right size/place (ie. damage); fMRI = takes brain activity images while performing function -> functional map
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4
Q

FMRI: EVALUATION

A

+
- readily available to clinical/academic researchers
- non-invasive
- provides high resolution anatomic scans in same session for localisation
-
- poor temporal resolution

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5
Q

KANWISHER ET AL. (1997): PART I

A
  • search for occipitotemporal areas specialised for face perception via looking in pps for ventral (occi) pathway regions that responded statsig ^ strongly during passive facial photo viewing > common object photos
  • comparison allowed anatomical localisation of candidate “facial areas” in pps & determine which areas activate consistently across pps
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6
Q

KANWISHER ET AL. (1997): PART I RESULTS

A
  • only fusiform gyrus activated consistently across subjects for face VS object
  • fusiform gyrus region produced statsig ^ signal intensity for faces > objects
  • hypothesis = region specialised for face perception aspect; tested alternatives w/several dif stimuli (aka. Part II/III)
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7
Q

KANWISHER ET AL. (1997): PART II

A
  • comparison 1 = intact faces VS scrambled faces (rearranged component black regions; preserved mean luminance & low-level features avoiding “cut-n-paste” marks affecting previous studies)
  • aka. tested if “face areas” responded to low-level visual features in faces but NOT non-face stimuli
  • comparison 2 = intact faces VS houses
  • aka. tested if face areas not involved in face perception but distinguishing between dif objects
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8
Q

KANWISHER ET AL. (1997): PART II RESULTS

A
  • higher activation pattern for face VS non-face stimuli clearly visible in each test raw data
  • quantitative testing = averaged mean MR signal intensity across each subject/all images in given stimulus epoch; 3-way ANOVA
  • main effect of ^ signal intensity in face trials > controls (p < .01); no other main effects/interactions = statsig
  • separate pairwise comparisons (face VS control) for all 3 tests; each reached statsig independently (p < .001 = face/objects; p = < .05 = intact/scrambled; p = .01 = face/houses)
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9
Q

KANWISHER ET AL. (1997): PART III

A
  • pps passively viewed face photos of people w/hair tucked in black ski hat VS human hands to test:
    1. would response of candidate face area generalise to dif POVs?
    2. is area involved in recognising faces on hair/external feature basis OR internal features? (ski hat covers external features)
    3. if face area responds to any animate/human body part (hands = controls)
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10
Q

KANWISHER ET AL. (1997): PART III RESULTS

A
  • confirmed statsig ^ brain activation for faces VS hands (p < .005)
  • aka. all part results support SPECIFICITY account
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11
Q

THE FACE FUSIFORM AREA (FFA)

A

KANWISHER ET AL. (1997)
- cortical region in fusiform gyrus
- more highly activated when pps presented w/faces > non-face stimuli

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12
Q

GAUTHIER ET AL. (1999): METHOD

A
  • pps trained w/Greebles til equally fast at categorising stimuli at individual lvl as familial lvl
  • performance assessed in name-verification trials; pps judged if label (fam/individual) shown for 1000ms matched Greeble 200ms later
  • performance change = expertise diagnostic
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13
Q

GAUTHIER ET AL. (1999): STIMULI & FMRI TASKS

A
  • 8 sequential matching runs p/fMRI session; 4 Greeble; 4 facial in alteration
  • 5 stimulus sets each w/8 grayscale faces & 8 Greebles of same fam (not used in training) used in sequential matching tasks (order counterbalanced across pps); faces cropped in same oval shape
  • pics repeated x12 p/session
  • pps performed same/dif identity judgements by pressing 1/2 buttons
  • faces/Greebles shown inverted/upright (4 conditions)
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14
Q

GAUTHIER ET AL. (1999): RESULTS

A
  • ^ upright-specific activation = faces > Greebles in FFA in first 2 sessions
  • specific prediction = upright Greeble expertise training -> ^ inverted Greeble activation in face-specific brain areas BUT no face change; result confirms this
  • p < = .01; paired t-tests for faces VS Greebles
  • important implications for interpreting fusiform role in visual object recognition
  • indicate inversion effect can be obtained for face-specific area faces & similarly in novel objects post expertise training
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15
Q

FFA: MAIN FINDINGS

A

KANWISHER ET AL. (1997)
- higher activation for faces > other stimuli sets on cortical region (FFA); supports specificity account for face recognition mechanisms
GAUTHIER ET AL. (1999)
- similar FFA activation for faces/Greebles for Greeble experts; supported expertise account for face recognition mechanisms

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16
Q

ELECTROENCEPHALOGRAPHY (EEG)

A
  • measures electrical activity generated by synchronised neuron activity (in volts)
  • provides excellent time resolution; allows detection of activity within cortical areas at sub-second timescales
17
Q

EVENT-RELATED POTENTIALS (ERPs)

A
  • small voltages generated in brain structures in response to specific stimuli
  • EEG changes time-locked to sensory/motor/cognitive events
  • reliable ERP = obtained via averaging EEG fragments in multiple trials
  • provide non-invasive approach to studying psychophysiological correlates of mental processes w/high temporal resolution
18
Q

EVENT-RELATED POTENTIALS (ERPs)

A
  • small voltages generated in brain structures in response to specific stimuli
  • EEG changes time-locked to sensory/motor/cognitive events
  • reliable ERP = obtained via averaging EEG fragments in multiple trials
  • provide non-invasive approach to studying psychophysiological correlates of mental processes w/high temporal resolution
19
Q

FACE INVERSION EFFECT ON N170: SPECIFICITY

A
  • first ERP face recognition studies reported larger positive potential at vertex (VPP) following face stimulus presentation > other visual objects
  • VPP also presented negative counterpart component at occipitotemporal sites suggesting origin sites in temporal cortex areas
  • VPP emphasised as few electrodes usually placed on posterior regions; ref oft located in electrode site vicinity (ie. mastoid) picking up occipitotemporal activity
20
Q

FACE INVERSION EFFECT ON N170: SPECIFICITY

A
  • first ERP face recognition studies reported larger positive potential at vertex (VPP) following face stimulus presentation > other visual objects
  • VPP also presented negative counterpart component at occipitotemporal sites suggesting origin sites in temporal cortex areas
  • VPP emphasised as few electrodes usually placed on posterior regions; ref oft located in electrode site vicinity (ie. mastoid) picking up occipitotemporal activity
  • result = occipitotemporal negativity amplitude attenuated; VPP increased
21
Q

FACE INVERSION EFFECT ON N170: SPECIFICITY (LATER STUDIES)

A
  • using dif refs (ie. common average) to analyse ERPs & availability of EEG systems w/larger electrode numbers favoured occipitotemporal negative counterpart of VPP investigation aka. N170 peak component
  • key advantage of focusing on N170 = electrodes recording on scalp = closer to neural generators of component
22
Q

FACE INVERSION EFFECT ON N170: EXPERTISE

A

ROSSION ET AL. (2002)
- ERPs recorded pre-training phase revealed larger inversion effect on N170 component for faces > Greebles; NOT case for results post-training phase w/Greeble categories where inversion effect on N170 = comparable for 2 stimuli’s types
BUSEY & VANDERKOLK (2005)
- fingerprint experts exhibited delayed (NOT larger) N170 for inverted fingerprints similar to exhibited w/inverted faces

23
Q

CIVILE, ZHAO ET AL. (2014)

A
  • checkerboard inversion effect on N170
  • categorisation phase = to categorise checkerboard set from 2 dif categories (A & C)
  • study phase = to memorise set of checkerboards presented upright/inverted
  • old/new recognition task = to press “.” if checkerboard = familiar OR “x” if not; timed out within 4000ms
24
Q

CIVILE, ZHAO ET AL. (2014): RESULTS (LATENCY ANALYSIS ON PO8)

A
  • ANOVA = trend for orientation via familiarity interaction (p = .06)
  • STATSIG delay in N170 for familiar inverted checkerboards; peaked 6ms later > familiar upright stimuli (p = .016)
  • no statsig dif in latency for novel stimuli (p = .46)
25
Q

CIVILE, ZHAO ET AL. (2014): RESULTS (PEAK AMPLITUTUDE ANALYSIS FOR PO8)

A
  • ANOVA = statsig orientation via familarity interaction
  • inversion effect = reliable for familiar categories w/^ negative amplitudes for inverted > upright checkerboards
  • not statsig in novel categories
  • highly STATSIF dif between novel inverted stimuli & familiar inverted stimuli w/^ negative amplitudes for familiar inverted > novel inverted
26
Q

TRANSCRACIAL DIRECT CURRENT STIMULATION (tDCS)

A
  • modern brain stimulation
  • apparatus = target channel electrode & ref channel electrode placed on scalp delivering continuous low electro-current stimulation between 1-2mA
  • active anodal stimulation delivered -> current induces depolarisation of resting membrane potential -> ^ neural excitability; allows ^ spontaneous cell firing
  • 9-13min stimulation generates 1h after effects
27
Q

NEUROSTIMULATION

A
  • new research line based on using particular transcranial direct current stimulation (tDCS) procedure
  • gave evidence that inversion effect for checkerboards & faces share at least some causal mechanisms
28
Q

CIVILE ET AL. (2016; 2018): SET-UP

A
  • tDCS on inversion effect
  • stimulation delivered via battery driven constant current stimulator (neuroConn DC-Stimulator Plus) via surface sponge electrodes soaked in saline allied to scale at target areas
  • adopt bilateral bipolar-non-balanced montage w/1 electrode placed over target area (Fp3/rIFG) & cathode over ref area
  • pps Cz identified -> measure 7cam anterior relative to Cz/9cm to left
29
Q

CIVILE ET AL. (2016; 2018): PROCEDURE

A
  • double-blind procedure reliant on neuroConn study mode; experimenter inputs numerical codes that switch stimulation mode between normal (ie. anodal)/sham stimulation
  • anodal = direct current 1.5mA stimulation w/fade-out for 10m start as soon as pps start beh task
  • sham = identical stimulation mode displayed on stimulator; same fade-out BUT w/1.5mA for 30s
  • small current pulse (3ms peak) delivered every 550ms (0.1mA/15ms) for remainder of 10m to check impedance lvls
30
Q

CIVILE ET AL. (2016)

A

-

31
Q

CIVILE ET AL. (2018)

A

-

32
Q

CIVILE ET AL. (2021)

A

-

33
Q

CIVILE ET AL. (2021): MATERIALS

A

-

34
Q

CIVILE ET AL. (2021): PROCEDURE

A

-

35
Q

CIVILE ET AL. (2021): RESULTS

A

-

36
Q

SUMMARY

A
  • specific tDCS procedure used for evidence for causal link between robust inversion effect for faces & non-face stimuli
  • the tDCS eliminates checkerboard inversion effect index of expertise; similarly statsig reduces face inversion effect indicating that component = expertise based
  • importantly, the fact that the tDCS doesn’t entirely reduce face inversion effect suggests that remaining effect could be due to specificity
  • aka. faces are both special and not

Biological Basis of Behaviour II (25 decks)

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