Psyc4130 1nd Edition Lecture 14 Outline of Last Lecture II. Opponent Process TheoryIII. Sensory RelayIV. Visual RelayV. dLGNVI. Contralateral RepresentationVII. Primary Visual Cortexa. Contralateral representationVIII. Retinopic OrganizationIX. V1 Lesions and Cortical BlindnessX. Characteristics of V1: Feature Detectorsa. Simple Cellsb. Complex Cellsc. Hypercomplex CellsXI. Characteristics of V1a. Spatial Frequency Detectionb. The Highs and Lows of Spatial Resolution XII. Characteristics of V1a. Color Elements of V1 and V2XIII. SummaryOutline of Current Lecture I. Extrastriate Cortexa. V2b. Dorsal Stream/Pathwayc. Ventral streami. V4ii. V8iii. LOCiv. FFAv. Prosopagnosia vi. EBAvii. PPACurrent Lecture Extrastriate Cortex (aka Visual Association cortex and “Hierarchical” processingThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- The response patterns of V1 are used as building blocks for creating a more complex visual analysis. - Humans > Pretty Much Everybody Else- “Higher” visual centers in the occipital and temporal lobes. - Humans have at least 30 different areas of the brain concerned with visual processing.- The functions of these regions tends to be highly specialized (“modular”- aka specificity),more so than with most other perceptual functions.- Focal damage to specific/discrete areas of extrastriate cortex can produce some very selective (and fascinating) changes in visual perception. o V2 Receives signals from V1 Receptive fields are several times larger than in V1, because each neuron in V2 receives input from several V1 cells.  V2 gives rise to the dorsal and ventral visual pathways/streams. o Dorsal Stream/Pathway Mostly M cell input (**know magnocellular- big receptive cells/fields, lotsof input form rods, big areas of light/dark contrast) Important for skilled movements directed toward objects and for object localization. Targeted/focal damage within the “dorsal stream” can disrupt awareness of movement. From V2 (relays signals) toward and into Posterior Parietal V5 (ability to perceive constant and fluid streams of motion; where and how pathway) and Akinetopsia (conscious awareness of fluid motion is gone. Meanwhile, the brains recognition pathway is uncompromised; “glass is half full, wait no half empty… oh crap…” When pouring water into a cup, don’t perceive glass filling up literally, only see flashes and before they know it the cup has overflowed)o Ventral Stream Important for detailed analysis of size, shape, color, texture. M and P cells contribute equally to the ventral visual stream.  From V2 toward and into Inferior Temporal V4- Color Constancy V8- Color perception; fusiform gyrus- Focal damage to V8—a posterior region of the inferior temporal cortex—can cause cerebral achromatopsia (cortical blindness) (“vision without color”)- Neurons in the more anterior regions of the inferior temporal cortex have HUGE receptive fields—sometimes corresponding to nearly half of the contralateral visual field!- These cells continue to respond when objects move, change size, are placed against different background or are partially occluded. Brain recognizes objects holistically (i.e. can’t see legs, but know that they are there; concerned with perception of the whole event/object) LO/LOC (Lateral Occipital Complex)- Object Recognition (general); visual agnosia (inability to recognize something/object, i.e. can’t tell you what mountain bike is, can us it but can’t describe it or say name, can’t recognize object)- Still within the occipital lobe headed down to temporal, serves general role in object recognition - The LOC responds to a wide variety of objects and shapes.- Damage to the LOC is likely to elicit visual agnosia—deficits in visual perception in the absence of blindness. - Chapter 6 opening vignette FFA - Aka fusiform face area- Face recognition- ability to recognize people by face- People who have this can describe the face (hair color, eyes, nose size) but they can’t pull it all together to say this is President Obamas face (gestalt/whole)- A functional imaging (i.e. fMRI) study by Golby and colleagues (2001) revealed that people’s FFAs become more active when viewing faces of members of their own race than when viewing members of a different race.- Is FFA specific for face recognition? As participants gained experience differentiating greebles, they shift from part-based to holistic processing. At the same time, fMRI studies revealed that participants come to engage the FFA while identifying greebles.  Prosopagnosia- Patient can read, can see color, can describe objects, can track object movement normally, et cetera. FACE BLINDNESS- can’t recognize who person is, subconsciously break face down into geometric shape- Patient cannot recognize people by face, can’t see larger picture only see geometric parts and face features- “Gestalt”(holistic processing) fail!- brain sees triangle- Prosopagnosia offers some of the best evidence to date of a domain-specific/modularity brain regions (i.e. brain regions performing highly specific functions). - Recall the localization/antilocalization debate in the history of neuroscience. - Of Greebles and FFA: Data from the “Greebles” studies (Gauthier and colleagues, late 90’s) were interpreted by many cognitive scientists to suggest that facial recognition wasn’t as domain-specific as suggested by the case study data. Object familiarity.-EBA- The EBA (Extrastriate Body Area) is found immediately posterior tothe FFA, with neuron fields partly overlapping. It is so named because it responds more robustly to bodies or body parts than it does to faces (feet, legs, arms, overall body parts)- Also responds to faces- Targeted/focal damage within the “ventral stream” can disrupt recognition awareness.PPA- Recognizing places- natural/manmade - The Parahippocampal Place Area (PPA) is a region of limbic cortex specializing in the ability to recognize natural and (hu)manmade locations by their context.- D.F.—a patient with profound damage to the LOC showed visual agnosia for objects, but an intact recognition for scenes (e.g. beaches, forests, markets, cities, et cetera)- Although she could recognize and name these locations when