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Cognitive psychology Introduction to cognitive psychology Emma Mcnally SFU WS 2012 • • • • • • • • • • • • • • • • • • • • Mental processes involve interpretation and/or transformation of info that obey well-defined principles to produce specific output when given a specific input – Processes operate on representations – Serial processing – specific sequence of steps, where each step’s sequence depends on the previous step; i. Starting a car and driving to UH is sequential – Parallel – several operations occurring at the same time i. Keeping a conversation flowing: you are listening to your friend, generating your own response, watching your friend’s gestures etc. 4. Goal of cognitive psychology: establish general principles of the mind – General principles of the mind: processes and representations as they relate to attention, memory, perception, language comprehension and generation etc. in all people i. We may have very different memories about our childhoods but the process of remembering should be the same for all people – Age, gender, ethnicity, socio-economical status are not considered in “pure” cognitive psychology studies. Researchers typically study healthy normal adults (i.e. above 18 and under 50) – Studies with lesion patients, children or older adults are usually informative about general principles of the mind but these populations in and of themselves are not of predominant interest to cognitive scientists • 1. Cognitive psychology: study of the human mind and mental activity (i.e. how we reason, decide,produce and comprehend language etc.) • – Describes acquisition, storage, transformation and use of knowledge • – Interest in representations and processes • 2. Mental representation: physical state that conveys info, specifying an object, event, or category or its characteristics; serves to store info • – Form – means by which info is conveyed (e.g. visual, auditory) • – Content – meaning of what is being conveyed • – For example: receiving a phone call about a football game score • i. Form: phone call • ii. Content: football game score • • • • • • • • • • • • Cognitive science: An extension of information processing where many disciplines work together to understand how the human mind functions – Psychology: to understand human behavior – Computer Science: to understand computation – Neuroscience: to understand how the brain works – Philosophy: to understand the limits of our theories – Linguistics: to understand the structure of language – Anthropology: to help separate characteristics of the mind from characteristics of culture – Researchers often collaborate and/or work across these disciplines 6. Note that cognitive psychology refers to theories of information processing and involve experiments with behavioral data (i.e. how people perform on various tasks) while cognitive neuroscience takes cognitive psychology theories and looks at what the brain is doing while people are performing various tasks – In short, cognitive psychology = behavior, cognitive neuroscience = behavior and corresponding brain activity Functional Human Neuroanatomy • • • • • • • • • • • • • • Brain activity arises from activity in neurons a. There are different sizes and shapes of neurons but basic parts and functions are the same b. Dendrites and cell body receive input from other neurons c. Axon sends output to other neurons d. Neurons communicate with other neurons by releasing and accepting neurotransmitters which either activate or inhibit neurons e. If excitation of a neuron is higher than inhibition, neuron “fires” and sends a signal down its axon to another neuron Neurons and how they work • http://www.youtube.com/ watch?v=FR4S1BqdFG4&fea ture=player_embedded#! Central nervous system • • • • • Central nervous system a. Spinal cord i. Sensory info to brain from muscles ii. Motor commands from brain to muscles b. Brain: start from evolutionarily oldest to newest structure in brain. Cerebellum • • • • • • • • • • • Brainstem includes pons, medulla, reticular formation. Reticular formation is important for arousal, attention, sleep. Brainstem is involved in coordinating basic living functions 1. Balance, alertness, heart rate, blood pressure and temperature (less advanced functions than those controlled by hypothalamus) 2. Coordination center which keeps everything stable 3. Info relay station between brain and spinal cord 4. A person is considered dead when there is no response from the brainstem • • • • • • • • • Cerebellum, literally “little brain” 1. Contains as many (or even more) neurons than brain and spinal cord put together 2. Involved in indirect control of movements by influencing descending motor commands from brain to spinal cord 3. Damage results in symptoms of intoxication 4. We really know very little about the functions of the cerebellum iii. Midbrain. The textbook places midbrain together with the brainstem, whereas I teach it as a • separate structure by itself. Both approaches are correct but for ease of remembering, when you • think of midbrain, I want you to think of the superior and inferior colliculi, which are involved • in sensory processing. • 1. Superior colliculus: Important for vision; eye movements • 2. Inferior colliculus: Important for • audition • • • • • • • • • • • • • • • • • Hypothalamus 1. Regulates body functions necessary for survival (more advanced than brainstem but also involved in same functions as brainstem by regulating those functions via hormones) a. Salivation, feeding, sex, circadian rythms v. Thalamus 1. Relay signals from one cortex area to another 2. A lot of sensory processing/relay a. Thalamus consists of numerous nuclei, several of which are devoted to sensory processing only; lateral geniculate nucleus (LGN is for vision, medial geniculate nucleus is for audition • Basal ganglia: Group of structures and nuclei involved in complex movement planning and • habit formation • vii. Limbic system is involved in forming memories, experiencing pleasure, motivational and • emotional activities and contains: • 1. Reticular formation (from brainstem) • 2. Hypothalamus • 3. Thalamus: sensory inputs • 4. Nucleus accumbens: rewards • 5. Amygdala • 6. Hippocampus: memory Limbic system • Cortex: evolutionarily newest “structure” • 1. Thin grey outermost layer of the brain • 2. Gyrus – bulge on the cortex • 3. Sulcus/fissure – groove between gyri • 4. Cortex is divided into four major lobes 4 major lobes • • • • • • • • • • • • • • • • • • • • • • • a. Occipital lobes are at the back of the brain i. Processing of visual input ii. 60% of monkey’s cortex is devoted to visual processing b. Temporal lobes are behind our ears i. Higher order visual processing (i.e. face recognition) ii. Memory consolidation and storage (this function also includes subcortical structures, such as hippocampus) iii. Auditory processing iv. Language comprehension (Wernicke’s area) c. Parietal lobes: top back of our heads i. Representation of space ii. Attention iii. Contain somatosensory cortex d. Frontal lobes: right above the eyes i. Plan sequences of behaviors ii. Reasoning, decision making iii. Speech production (Broca’s area) iv. Emotion, personality v. Contains primary motor cortex • • • • • • • • Brain: 2 cerebral hemispheres (halves of brain) are connected via corpus callosum. The left hemisphere is (almost) a mirror image of the right hemisphere ii. Some structures are bigger/smaller iii. Some functions are more expressed in one hemisphere than others (i.e. language processing in the left hemisphere for over 90% of humans; spatial information processing in right hemisphere) iv. Key point: there are two amygdalas, two LGNs etc. Directional terminology: finding your way around the brain • • • • • • • • • • • • • • Anterior/Rostral: toward the nose end • Posterior/Caudal: toward the tail end • Dorsal: toward surface of the back (spine) or top of the head • Ventral: toward surface of chest/stomach or bottom of the head • Lateral: toward the sides of brain, left or right • Medial: toward the middle of brain • Superior: toward the dorsal surface of head (humans) • Inferior: toward the ventral surface of the head Terms in action: • • • • Frontal lobe is anterior to the occipital lobe • Occipital lobe is posterior to the frontal lobe • Parietal lobe is dorsal to the temporal lobe • Temporal lobe is ventral to the parietal lobe • • • • • • • • • More terms: • Bilateral: both sides of brain • Contralateral: opposite side of brain from a given reference point – I.e. inputs from the left visual field are processed in the right hemisphere; inputs from the right visual field are processed in the left hemisphere • Ipsilateral: same side of brain as a given reference point – Left eye is ipsilateral to left LGN • How we study cognition: Methodology • • • • • • • • • • • • • • • • Converging evidence: Different methods are often combined to establish dissociations, double dissociations, associations about the processes, properties of processes and brain areas involved in the processes of a specific mental activity a. Different methods are combined to establish dissociations, double dissociations, and associations i. Dissociation: establish that an activity or a variable affects the performance of one task (or aspect of one task) but not of another 1. Hypothesis: Occipital cortex is crucial for visual perception 2. Test: Lesion occipital cortex, give visual and auditory perception test 3. Result: visual perception is impaired but auditory perception is not ii. Double dissociation: an activity or variable affects one process but not another and a second activity or variable has the reverse properties. 1. Hypothesis: Occipital cortex is crucial for visual perception 2. Test: Lesion occipital cortex, lesion auditory cortex, give visual and auditory perception test 3. Result: visual perception is impaired with occipital lesion but auditory perception is not; auditory perception is impaired with auditory cortex lesion but visual perception is not • iii. Association: the effects of an activity or variable on one task are accompanied by effects • on another task • 1. Dual task: counting backwards by threes and reading words is slower than either task done alone • 2. Some of the processes and/or representations between these two tasks overlap. Behavioral methods: what we typically measure • a. Reaction time (RT) data – speed of response; used very often • b. Number of correct items – used very often, also in conjunction with RT • c. Judgments/protocol Neuroimaging - Correlates behavior to a pattern of brain activity; does not mean cause and effect • • • • a. What functions are performed? i. Is this a language comprehension or language generation task? b. Where are they performed? i. Issue of spatial resolution – how well can brain activity be localized? Poor spatial • resolution means poor ability of a tool to locate where activity is originating from. I.e.compare ability to detect activity in frontal or occipital lobes versus ability to detect activity in the superior colliculus (a much smaller structure than lobes) • c. When does the activity occur? • i. Issue of temporal resolution – how well can changes in brain activity be detected? How fast can those changes be detected? Neuroimaging approaches • a. EEG: electroencephalogram(recording of brain waveselectrical activity of brain) • b.MEG: magnetoencephalography (measures magnetic fields from neuronal activity • c. PET: positron emission tomography (3D picture of functional processes in the body) • d. MRI: Magnetic resonance imaging • i. MRI gives a nice clear picture of brain structure • ii. fMRI (functional magnetic resonance imaging)gives an activation map for the brain • 1. MRI and fMRI images are overlaid and reported together in all scientific papers DOT (diffuse optical imaging) • • • • • • • • • • • • PET/fMRI and DOT are all built on the idea that an active brain site will require more glucose and oxygen to supply energy to the neurons in that site. Therefore, an active brain area will attract more blood and thus it will attract more of the radioactive substance (used in PET), more oxygen (detected by fMRI) or more hemoglobin (as measured by DOT). Although these different techniques measure a different component present in the blood, the temporal resolution of these three approaches is almost equivalent because again, they all rely on the blood flow. Because it takes several seconds for the blood to flow to an active site in the brain, the temporal resolution, therefore, is fairly poor when compared to the EEG temporal resolution (which is excellent). Notice that the table in the book indicates that the temporal resolution of optical imaging can be as bad as several minutes – for the purposes of the quiz/exams think of DOT resolution as that of PET/fMRI, which, again, is poor. • Most studies generate brain images to indicate where activity occurred. Each brain can be viewed from three different planes that are taken directly from anatomy: sagittal, coronal and horizontal planes. These planes tell us from what position we’re looking at the brain: • i. Sagittal: looking from the side • 1. Brain “sliced” between the two eyes • 2. Mid-sagittal cut divides the brain in two equal halves (hemispheres) • ii. Horizontal: looking either directly from top or bottom; such cuts are parallel to the ground • 1. Think of taking off the scalp • iii. Coronal: looking either directly from front or back; such cuts are perpendicular to the ground • 1. “Slice” separates the two eyes from the two ears • • • • • • • • • • • • • • • • Apply the planes on the left to the brain (rather than the body). MRI images are examples of these cuts in human subjects. • Sagittal (mid-sagittal here) cut • Frontal lobe • Corpus callosum • Thalamus • Occipital lobe • Cerebellum • Pons By looking at the slide with structures that are visible in the cut you can determine where the brain was cut: right between the eyes or between the eye and the ear. We need to cut the brain in different places because the brain is 3-D and we can’t see all brain structures if we always cut right between the eyes or right above the ears (compare how different the frontal and occipital lobes, thalamus and corpus callosum look in these cuts below). Research papers often report several horizontal/coronal/sagittal cuts to indicate where activity is originating from. The type of a cut, its thickness and frequency is chosen by researchers. Ways to infer what brain does without directly measuring brain activity • • • • • • • • • • • a. Lesion studies i. Usually . with human patients suffering brain damage or lab experiments using animals ii. If an area has a lesion and the person shows a specific deficit, then that area probably has something to do with that function. iii. Could be hard to interpret data since locations of lesions across humans vary greatly and patients that suffer brain damage typically suffer brain damage to more than one area b. TMS (Transcranial magnetic stimulation) c. “Freeze” a given area with special chemical and test performance on a behavioral task; compare to the performance in “non-freeze” condition; reversible, invasive & done with animals only d. Give drugs that target a given brain region and test performance on a behavioral task; invasive, used with humans and animals The end • Congratulations you survived the introduction.