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Matters of the Mind: the Neuron and Beyond Notes Week 6 Ventral Stream  Most of the 30 visual areas are in this stream  Hasson and colleagues o fMRI: viewing a film  Event related action potentials  Findings: selective activation to precise movement- to-movement film content in temporal lobe areas o Fusiform face area  Lights up when you see faces o Parahippocampal place area  Lights up when you see places  Tanaka and colleagues o Hyper-complex cells  Cells in area of TL require complex features for activation (diff faces) o Vertical columns  Similar selectivity  Minimize the effect of small changes to allow categorization o Experience-dependent specificity  Specificity of neurons is altered by experience  Gauthier and coworkers (1999) o Everyone has different facial features o We focus on faces because they are of importance to us D.F.’s damage to LO area  Blind to certain objects but could shape her hands to pick up objects  Dorsal stream intact o Can understand things to orient body to correct movements o “Unconsciously see location, shape, and size”  Visual agnosia o Different lesions create bewildering variety of symptoms o Lack of agreement on how different patterns of varying symptoms should be classified (taxonomy) o Object agnosia  1. Apperceptive  Intact basic visual functions  Deficit in the ability to develop a perceptive of the structure of an object or objects (like DF)  Perceptual problems  Regions sending output to ventral stream  Carbon monoxide poisoning in “water-shed” regions  2. Associative  Can perceive objects (copy and draw) but cannot identify them  Memory not perception  Results from lesions to the anterior and medial temporal lobes (objects have no meaning)  Double blood supply helps fight strokes in the watershed regions Medial temporal lobe: limbic system  Amygdala and septum o Emotion and species typical behaviors  Hippocampus o Memory and spatial navigation The dorsal  Dorsal stream damage causes hands to not be able to use an object A theory of parietal lobe function  Anterior zones (1,2,3) o Somatosensory strip o Processes somatic sensations and perceptions  Posterior zones (the rest) o Integrates vision to motor cortex to plan movement o Integrate everything together o Integrate info from vision with somatosensory info for control of movement Case V.K.: parietal damage and visuomotor guidance  Bilateral hemorrhages in occipito-parietal regions  Could not form appropriate hand postures  Initially blind ut after 1 month had Balint’s syndrome o Disorder control of gaze, impairment in visual attention (simulatognosia: only one object) and optic ataxia o Ataxia: lack of voluntary coordination of muscle movement o Optic ataxia: deficit in visually guided hand movements An ‘older’ pathway  Geniculostriate pathway o Goes through V1  Damage (functionally blind)  Tectopulvinar o Goes through this pathway with blindsight  Info sent to parietal lobe but wasn’t sent to V1 so he wasn’t conscious that he could see V1 and Blindsight  Blindsight or cortical blindness o Evidence of vision processing without conscious awareness o You have no conscious vision but can process info without being conscious  B.K. o Could perceive location in hindsight o Couldn’t see images but could point to them  D.B. o Can report movement orientation and location of objects o Provides evidence that not all info has to go through V1 G.Y.: Emotion and blindsight  44 year old male  Emotional faces presented in both (damaged/undamaged fields)  Areas activated in undamaged fields o Facial recognition o Emotion  Amygdala (emotion regulator)  R hemianopia o Damage to left V1  Possible explanations o Dorsal pathway spared o Tectopulvinar pathway used  Zombie in the brain  Movements that you don’t consciously think about Superior Temporal sulcus (STS)  Imaging reveals activation in the STS during perception of biological motion  Biological motion o Movements relevant to a species o Social cognition or “theory of mind”  Understanding others intentions from their body movements  David Perrett and colleagues o STS cells are maximally responsive to particular types of biological motion  Eye gaze, mouth and eye movement, facial expression, hand movements