Copy of Test 2 Study Sheet PDF

Topic : Higher level perception (Visual agnosia & Prosopagnosia) What is visual agnosia ? - Condition where a person looks at an object but cannot say what the object is. - Trouble recognizing objects through vision....

Topic : Higher level perception (Visual agnosia & Prosopagnosia) What is visual agnosia ? - Condition where a person looks at an object but cannot say what the object is. - Trouble recognizing objects through vision. Our brain has two main pathways for seeing: 1. Vision for Perception ("what"): ○ This helps us recognize objects (like knowing something is a mug). ○ It uses the ventral pathway. If this is damaged, a person may see the object but not know what it is. 2. Vision for Action ("how"): ○ This helps us move and interact with objects (like reaching for a mug). ○ It uses the dorsal pathway. Even if the ventral pathway is damaged, this pathway can still guide actions correctly. Visual agnosia (3 types) 1. Apperceptive Agnosia: - Matching Task: The person see small details but can't combine them into a whole shape. For example, they might see lines and shapes but not recognize it as a picture of a dog. - Copying Task: They can draw an object by looking at it but won’t recognize their own drawing. They see shapes but can’t recognize them as a specific object. 2. Associative Agnosia: - Memory and Function: The person can draw objects from memory (like a pig) but won’t connect it to its meaning. - Recognition Failure: They may see the object and understand its shape but won’t link it to its name or use (they see the pig but don’t know it’s a pig). 3. Integrative Agnosia: - Combining Parts: The person can see individual parts but can’t combine them to understand the whole object. For example, they see a cylinder and a handle but don’t recognize it’s a mug because they can’t put the parts together. Modularity in visual cortex Lateral Occipital Complex (LOC): - The LOC is a part of the brain that helps us recognize the shapes of objects, no matter how they appear (like photos, line drawings, or shapes made with light and shadow). This region processes shape itself, ignoring specific visual details. Parahippocampal Place Area (PPA): - The PPA specializes in recognizing places and scenes, like rooms or outdoor spaces. This helps us identify and remember environments. Fusiform Face Area (FFA): - The FFA is critical for recognizing faces.It’s especially active when we see and differentiate individual faces.  Holistic Processing Holistic processing is how we recognize faces as a whole rather than by individual parts (like just the eyes or nose). - We see and process the entire face at once to understand who it is. - This type of processing only works well for upright faces—doesn’t work with face upside down, it’s harder to recognize because we can’t process it holistically. Exemples : - Study : Adapted from Farch,MJ., 1994. - They showed part of their faces & houses - good at identifying house, they did poorly when trying to identify Larry with only his nose, but did good with only his face. 1. The composite effect : - When you put two picture; look like a third person. 2. The Face-inversion effect : - We can’t use holistic processing - We are better at recognizing upright faces 3.1 Face cells in monkey IT: - Specialized cells in monkeys that only specialized faces. - Inferior temporal lobe. - Only responded to faces. - Looking directly and the other way, the cells were more excited in the study.. - Not tested enough to say that it shows that it is only face selective. 3.2 Face cells in monkey STS: - The redder (more response toward faces) - Blue (less response toward other object) - There was more control objects, clear answer for this study. Prosopagnosia (Face Blindness) Definition: A condition where a person cannot recognize familiar faces, including: ○ Family members ○ Famous personalities ○ Their own reflection in the mirror Emotion Recognition: The ability to recognize emotions in faces can still be intact. Auditory Recognition: People with prosopagnosia can often recognize voices, even if they can’t recognize faces. Impairment: Recognition is especially difficult when obvious clues (like hair, glasses, or mustaches) are missing.  Acquired Prosopagnosia: ○ Often caused by damage to the fusiform area of the brain, mainly in the right hemisphere. ○ It’s not an issue with matching images but involves a step-by-step identification process. ○ Individuals may have more trouble identifying faces from different points of view. ○ Prosopagnosia is not due to difficulty in discriminating between different categories of faces. Face vs object recognition :one system or two (Debate) - Prosopagnosia without object agnosia fits both possibilities, BUT what about agnosia without prosopagnosia. - Patient CK: agnosia w/out prosopagnosia (very rare),Patient CK cannot see objects but sees the face. Only exist if the two systems are separated. Reading : https://www.sciencedirect.com/science/article/pii/B9780123750006000124 Video: Face Blindness 1) Prosopagnosia (Face Blindness): Car Accident: Damage to a part of the brain led to Prosopagnosia (face blindness). Experience: The person finds it difficult to recognize faces, including his own. Symptoms (First Person): ○ Cannot recognize familiar faces, such as Marilyn Monroe. ○ Inability to Assemble Face Features: Can see individual facial features (eyes, nose, mouth) but cannot piece them together to identify the face. ○ Inability to Recognize His Own Face: Struggles to recognize his own face in the mirror. 2) Object Agnosia (Second Person): Symptoms: ○ Visual Recognition Impairment: Sees visual details (e.g., green grass, soccer field) but cannot fully recognize objects without context or prior knowledge. ○ Top-Down Memory Usage: Relies on memory and prior knowledge to identify objects. For example: Recognizes grass by color and association, even without direct recognition of the visual features. ○ Holistic Processing: Cannot process objects holistically (e.g., seeing a brush and not recognizing it right away), but can eventually recognize it with the help of memory and context. ○ Visual Memory: Uses top-down processing by recalling previous knowledge to help identify objects, like a brush, once told what it is.  Topic: Attention -> What you see is not a faithful replication of the outside world; it is a creation of your brain Attention to Visual Objects or Features Attention Types: Reflexive (Exogenous): Automatic; drawn to noticeable things (e.g., yellow flower). Voluntary (Endogenous): Chosen focus; directed by goals (e.g., unopened flower). Overt: Eyes focus on what you're paying attention to Characteristic of Attention: Types: Reflexive (automatic) or Voluntary (chosen) Limited Capacity: Can only process some information at once Selective: Focuses on a subset of info Covert Attention: Works without eye or head movements Benefits: Speeds up and improves accuracy in processing Covert Visual Attention: Focusing on a location without moving the eyes. Helmholtz's Spotlight Theory: Attention acts like a spotlight, illuminating specific areas for focus. Posner Spatial Cueing Paradigm: VALID: Correctly cued (attended) location INVALID: Incorrectly cued (unattended) NEUTRAL: No specific cue + Both Ways Results: Attention : ‘’The Spotlight’’ Attention speeds up processing Exogenous vs Endogenous orienting (i.e., automatic vs voluntary) covert vs overt orienting (i.e., with vs without eye movements) Control of attention signals: Spatial shifts of attention (functional imaging) The ‘’fronto-parietal network’’ area 6 & area 7 area 7 & area 6 Attentional Control Network: Attention and Eye movements (covert vs overt orienting) - The fronto-parietal network = attentional control network - Extensive overlap of attention and eye movement Networks  Spatial attention in the brain : ERPs during spatial cueing task -Attentional effect found 70-100ms after stimulus - What happens in the occipital coretx ? There is 70-100milisecond when processing when we are paying attention (it happens faster) - FMRI : Usually happens in retinotopic cortex (even in V1 primary visual cortex) Results : Attentional modulation of motion (V5) processing in human MT+ (V5) - White dots (Activity Higher) - Black dots (Less Activity) - When theypay attention to the moving motion of the dots the activity in area V5 - The activity goes down in V5 when you don’t pay attention - When the part lights up depends when you pay attention - Attention is a big influence that happens in your brain Key Area: V5/MT+ (motion processing in the brain) Results: Attention on Motion: Higher activity in V5 (e.g., white dots). No Attention: Lower activity in V5 (e.g., black dots). Main Point: V5 activity changes based on attention; attention strongly influences brain activity. Attentional modulation of face processing in FFA: Attentional modulation occurs specifically in the area specialized for processing the attended objects (FFA activity increases when faces are attended) Summary : Attention Boosts Activity: Location-Based: Increases in V1 for attended locations. Feature/Object-Based: Increases in areas tied to attended features (e.g., MT for motion, FFA for faces). Sensory Modulation: Greater activity when a stimulus is  attended vs. ignored. Top-Down Signals: Can expectation alone (without stimulus) trigger activity? “Baseline shifts”: pure top-down signals (Monkey Data) - Spontaneous firing rates of V2 and V4 cells increase with attention to RF (receptive field) even in the absence of stimuli - Firing neurons (higher) Pure top- down signal (Human Data) - Neuron start to respond, same as the monkey - Human retinotopic area fire greatly when expecting - Expectation Effect: Retinotopic areas show increased activity even without a stimulus, purely from top-down signals. Summary : Attentional Control: Fronto-parietal network. Modulation Effects: Widespread in both early (V1) and higher-level visual areas (e.g., FFA, PPA). Attribute-Specific Modulation: Attention boosts activity in areas specialized for the attended attribute (e.g., MT for motion). Spatial Attention: Causes baseline shifts in retinotopic cortex. Different Metaphors of Attention: Attention as a Spotlight: Focuses on specific areas or objects. Attention as Glue: ○ Task Example: Finding an "X" among targets. ○ Results: Feature Search (Parallel Processing): Quick detection with one red "X" or multiple. Conjunction Search (Serial Processing): Slower when too many items are present; requires careful analysis of each. ○ Metaphor Meaning: Attention binds shape and color together. Spatial Attention and Feature Integration: Key Areas: Superior Parietal Cortex (SPL/IPS) and Superior Frontal Cortex. Nonspatial Attention: ○ Attentional Blink: Condition 1: Is there an "X"? Condition 2: What is the red letter, and is there an "X"? Result: Target detection takes time (attentional dwell time). Selection and Unattended Information: Inattentional Blindness: Failure to notice salient events (e.g., invisible gorilla demo). Change Blindness: Missing important changes in visual scenes (e.g., color card trick demo). Early vs. Late Selection: Limited Capacity: Cannot process everything; must select relevant info from distractions. Historical Context: ○ Broadbent's Filtering (1958): Proposed that filtering occurs early. ○ Dichotic Listening Experiments (Cherry, 1950s): Initial findings suggested little processing from the unattended ear. Unattended Stimuli: - Evidence shows minimal processing (e.g., RED shapes rated for pleasantness; good recognition for attended shapes but chance for unattended GREEN shapes).  Visuospatial neglect Contralateral Neglect: Patients fail to detect or respond to information on the side opposite to their brain damage. Common Lesion Location: Right temporal/parietal lobe. Resulting Deficit: Failure to attend to the contralesional space (the space opposite the lesion). Article: - When people are unaware, they don’t detect or respond. They fail to pay attention to the opposite side of the lesion hemisphere. - You fail to detect things in your head - The woman had to imagine herself in the square and they asked her to say what she saw. She knows everything, she only detects the right side. When she turns the other way she also neglects the other part. Neglect can happen also in the real world and in her mind. - Picture with… inferio parietal, superior temporal brain: - Different numbers, clock, asking to write something - Line bisection - Sudo neglect : Happens in healthy people, they have more attention to the left side than right → they saw in the study with the line dissection. - - Neglect patient - Healthy patient - Excite the right hemisphere which the left side pay attention Video: Visual Neglect - Peggy visual neglect, 10y stroke -> parietal lobe -> 3D visual - Draw daisies from memory - Left side not working well - When someone notice it and she pay attention to it, she notice it, she neglect the left side - She says 2 attention system, 1 of them not working - She tried to fit all the petal in one side  Plasticity Plasticity: The nervous system's ability to change, involved in: Development, Learning, Recovery from Injury Greatest during early life. Critical Period: A specific window early in life when experience has the greatest impact on the organization and function of the nervous system. Postnatal Development: Neuronal Connectivity: Increases after birth; myelination starts in primary sensory and motor areas, later in association cortex. Synaptogenesis: ○ Starts before birth, peaks around 15 months. ○ Followed by synaptic pruning (eliminating nonfunctional or redundant connections). Neurogenesis After Birth: New Neurons: Form after birth, notably in the hippocampus, prefrontal, and temporal cortices (macaques) and humans (hippocampus, caudate nucleus). ○ Related to enriched environments and exercise. ○ May improve learning and reduce anxiety. Effect of Cognitive and Sensory Experience: Enriched Environments: Rats raised in enriched environments: ○ Perform better in maze learning. ○ Have thicker neocortex regions and greater dendritic branching. Sensory Experience Alters Brain Development: ○ Example: Removing mouse whiskers alters brain cell development. ○ Monocular Deprivation: Blocking one eye in infants leads to neurons responding only to the non-deprived eye. Plasticity in the Adult Brain: Somatosensory Map Reorganization: ○ Example: Sewing two digits together leads to less clear cortical representation boundaries. ○ Amputation: After finger amputation, the cortical region initially stops responding, later responds to adjacent fingers. Auditory Cortex: ○ Training on sound discrimination enlarges cortical representation of trained frequencies. Motor Skill Learning: ○ Finger tapping: Greater activity in the primary motor cortex for trained sequences. Phantom Limb: ○ Amputees experience sensations in the "phantom limb"; stimulation of adjacent body areas can trigger sensation in the phantom. Cross-modal Plasticity: Sensory Loss/Deprivation: ○ Blind humans show improved hearing and sound localization. ○ Deaf humans have better peripheral vision. Cross-modal Reorganization: ○ Sensory cortex responds to a different modality when a primary sensory input is disrupted (e.g., vision shifts to touch in the blind). ○ Echolocation in Blind Subjects: Activates the occipital cortex, including primary visual areas. Specialized Brain Regions: Spatial Navigation: Larger parahippocampus/posterior hippocampus in experienced London cab drivers. Echollocation (visual cortex-> auditory stimuli) Plasticity in Blind People: Echolocation: Blind individuals can use sound to navigate and discriminate shapes. ○ Activation: Echolocation activates the occipital cortex, including the calcarine sulcus (primary visual cortex). Sound Processing: ○ Lateral Occipital Cortex: Even when the primary visual cortex processes sound, this area adapts to enhance auditory processing.  Consciousness (First part) Consciousness and Awareness: Definition: Consciousness involves awareness and mental representation of information, but also includes implicit processes and subliminal perception (processing without awareness). Subjective Experience: The personal feeling of being, like the sensation of pain (e.g., "I have a headache"). Others can understand but can’t feel it themselves. Intentionality/Volition: The ability to act voluntarily; crucial for determining consciousness in patients in a vegetative state (e.g., whether they perform actions voluntarily). Info-Processing and Subliminal Perception: Subliminal Perception: Perception without conscious awareness (e.g., seeing "boy" or "cake" too quickly to consciously register). Brain Processing: Much of our brain’s activity happens below the level of conscious awareness. Consciousness (second part) Philosophical Perspectives on Consciousness 1. Dualism ○ Key Idea: Mind and brain are distinct; mind/conscious experience is nonphysical and beyond the scope of science. ○ Current View: Generally dismissed by science. 2. Materialism ○ Key Idea: Mind is the brain, a physical entity. ○ Implication: Mental states are physical states, so conscious experience can be studied with normal scientific methods. 3. Functionalism ○ Key Idea: Materialism with a twist—anything that acts, feels, or thinks appropriately is functionally equivalent to the human brain. ○ Implication: In principle, robots could possess consciousness.  Different Aspects of Consciousness (Steve Pinker) 1. Sentience ○ Definition: Subjective experience; what it feels like to be you (e.g., pain). ○ Challenge: This is the "hard problem" of consciousness (David Chalmers) and difficult to address scientifically. 2. Access ○ Definition: The content of mental experience, which allows for reasoning, reporting, and controlling action. ○ Research Focus: Differences between conscious and nonconscious representations. 3. Self-Knowledge ○ Relation to Access: Part of the "easy problem" of consciousness, which can be studied scientifically. Purpose of Consciousness 1. In Visual Awareness ○ Role: To produce the best interpretation of the visual scene and make it available to parts of the brain for planning and voluntary movement (Crick & Koch). 2. Global Workspace Theory ○ Concept: Consciousness serves as a "global workspace," sharing information between different systems (Baars; Dehaene). Anatomy of Consciousness (Damasio) 1. Core Consciousness ○ Description: Being awake, alert, and aware of the present moment. ○ Brain Areas: Brainstem + Thalamus. 2. Extended Consciousness ○ Description: Sense of self and thoughts about the past or future. ○ Brain Area: Cortex. Cognitive Neuroscience of Consciousness 1. Focus on Visual Awareness ○ Vision is the best-understood system and allows for detailed monkey neurophysiology studies. 2. Essential Elements for Consciousness (Crick & Koch) ○ Visual Short-Term/Working Memory: Critical for consciousness; involves the prefrontal cortex and sometimes the parietal and inferior temporal (IT) cortex. ○ Visual Attention: Essential; involves the parietal and prefrontal cortex. 3. Perception without Awareness  ○ Observed in neglect patients (attention deficits), who may process visual information without conscious awareness. Neural Correlates of Consciousness (NCC) 1. Is V1 Necessary? ○ Blindsight: Patients with V1 lesions can show primitive vision without awareness, suggesting that an intact V1 is necessary for visual awareness but not sufficient. ○ Visual Extinction: V1 activates equally to “seen” and “extinguished” stimuli, reinforcing that V1 is necessary but insufficient for awareness. 2. Binocular Rivalry ○ Concept: When each eye sees a different image (e.g., apple vs. mug), perception alternates between images. ○ Brain Areas: Activity in the FFA (for faces) and PPA (for places) reflects what the person is consciously aware of, but FFA may activate without awareness in some cases (e.g., in extinction patients). ○ Superior Parietal Lobule (SPL) and Prefrontal Cortex: Active during perception changes, indicating their role in conscious awareness transitions. 3. Summary of NCC ○ Key Point: Awareness of specific stimuli is associated with activity in areas that represent those stimuli (e.g., FFA for faces, PPA for places), but this activity alone is insufficient. ○ Additional Areas: Parietal and frontal regions contribute critically to conscious awareness, beyond ventral pathway activation. Meditation and Consciousness 1. Types of Meditation ○ Focused Attention: Focusing on a single object to block out distractions. ○ Open Monitoring: Observing one’s mental state moment by moment. 2. Effects of Meditation ○ Arousal Reduction: Meditation lowers arousal, reduces stress, and can decrease pain (e.g., "relaxation response," Herbert Benson). ○ Emotional Well-Being: Increases emotional balance, reduces anxiety (Mindfulness-Based Stress Reduction). 3. Enhanced Attention and Concentration ○ Improvement: Meditators show better sustained, selective, and executive visual attention. ○ Brain Waves: Increased gamma waves and effortless concentration during meditation (Lutz, Davidson et al.). ○ Attention Network Activity: Higher activity in the fronto-parietal attention network.