Selective Attention PDF

Selective attention - Selective attention is not global, instead, at any level of arousal, it is the allocation of attention among relevant inputs, thoughts, and actions while ignoring irrelevant things - ADHD is characterized by disturbances in neural processing that may result fro...

Selective attention - Selective attention is not global, instead, at any level of arousal, it is the allocation of attention among relevant inputs, thoughts, and actions while ignoring irrelevant things - ADHD is characterized by disturbances in neural processing that may result from anatomical variations of white matter through the attention network - People with ADHD have decrease white matter - Bottlenecks: stages through which only a limited amount of information can pass. Seem to occur at stages of perceptual analysis that have a limited capacity - In Broadbent’s model, the sensory inputs that can enter high levels of the brain for processing are screened early in the information-processing stream by a gating mechanism so that only the most important can pass - Early selection is the idea that a stimulus can be selected for further processing or be tossed out before perceptual analysis is complete - Late selection thinks that the perceptual system processes all inputs equally, and then selection takes place at higher stages of information processing - Tresiman proposed that information from an unattended channel was degraded or attenuated - Conjunction search is when something is being defined by two or more features - Feature integration theory of attention: Spatial attention must be directed to relevant stimuli in order to integrate the features into the perceived object, and it must be deployed in a sequential manner for each item in the array - The typical spatial attention effects in visual cortical processing seen with ERPs in cueing tasks are present during visual conjunction search - This study showed that conjunction search affects the P1 wae in much the same way that cued spatial attention does - Attention can be directed in advance to both spatial and nonspatial features of stimuli - Compared to divided attention, selective attention to one feature activated distinct, largely nonoverlapping regions of extrastriate cortex - The selective attention in modality-specific cortical areas alters the perceptual processing of inputs before the completion of features analysis - The feature based selective attention acts as relatively early stages of visual cortical processing with relatively short latencies after stimulus onset - Spatial attention still beats the clock and has an earlier effect than feature based ​ Agnosia ​ Neglect - Unilateral spatial neglect is when the brain's attention network is damaged in one hemisphere, mostly severe when in the right hemisphere - If there is two stimuli, one in each field, the patient cant see the contralesional stimulus, known as extinction - Result of unilateral lesions of the parietal, posterior temporal,, and frontal cortex - Can be due to damage in subcortical areas  - Know the characteristics of Balint’s syndrome (simultagnosia, ocular apraxia and optic ataxia) - They suffer from bilateral occipitoparietal lesions - With the cocktail effect, the only thing that they could report from the unattended ear was if they were male or female. In this case, voluntary attention affected what was processed - These findings led cherry to propose that attention to one ear results in better encoding of the inputs to the attended ear and loss or degradation of the unattended inputs to the other ear Attention Types - Spatial attention - Selective attention - In v1 through v4, increased activity occurred in uncued locations that were located on the same object as the cued location, compared to when the uncued location was not on the cued object - PPA is more activated by images of landscapes and scenery - Attention acts on object representations and shows that objects show interesting properties - Attention alters the effective connectivity between neurons by altering the pattern of rhythmic synchronization between areas, and that different brain regions can communicate through the coupling of their oscillation patterns - Top-down neuronal projections from attention control systems contact neurons in sensory specific areas to alter their excitability - The dorsal attention network is concert with voluntary attention based on spatial location, features, and properties - The dorsal frontoparietal network reflects the sources of attentional signals in the goal-directed control of attention - Goals - The ventral attention network is concerned with stimulus novelty and salience - Takes over when needed - Ventral right-hemisphere regions may reorient the focus of attention towards unexpected stimuli - Lateralized to right hemisphere, includes TPJ - In hopfinger’s study after the cue was presented but before the target display appeared, activations were observed not only in dorsal attention network but also visual cortical regions that would later process the incoming target - Patients with frontal cortex damaged has decreased visually evoked responses in ERP recordings over the visual cortex - Frontal cortex has a modulatory effect on visual cortex - Weak FEF stimulation enhanced attention task performance only if they were at the right spot - If the V4 neuron was not actuated by the visual stimulus, then stimulation of the FEF did not affect the activity of the V4  - When cued to discriminate motion, the TMS induced activity in V5 was increased, but when they were cued to discriminate the gender of the face, the same TMS was found to increase activity in FFA - Indicating dorsal system is involved in generation task specific, goal-directed attentional control signals - IFJ drives synchrony of FFA and PPA - PFC: top-down biasing - FEF: spatial attention - IFJ: feature attention - Stimuli in unexpected locations activated TPJ - The superior colliculus is a midbrain structure made up of many layers of neurons, receiving direct input from retina and other sensory systems, as well as basal ganglia and cerebral cortex - Have a role in preparing to make overt eye movements, but not covert for most of them - Patients with damage suffer progressive supranuclear palsy, difficulty shifting attention in response to a cue - The pulvinar is composed of several distinct nuclei with inputs and outputs - lesions= longer reaction time - Critical role in attentional control by coordinating synchronous activity of regions in ventral visual pathway - With GABA antagonist, monkeys direct attention covertly Posner spatial cuing task - Endogenous cuing is where the orienting of attention to the cue is voluntary - Exogenous is when attention of the cue is automatically captured - Reflexive or exogenous cueing is when attention is controlled by low-level features of external stimuli, not by internal voluntary processes - Responses are faster to targets that appear in the vicinity of the irrelevant light flash, but only for a short time after the flash - When more than 300 ms pass between the light and target, it is reversed: participants respond more slowly to stimuli that appear in the vicinity of the flash. This is called the inhibition of return (IOR) - Reposes to endogenous and exogenous cues result in attention shifts that enhance the processing of attended sensory stimuli and decrease the processing of unattended stimuli - A target item can be located more quickly among a field of distractor stimuli if it can be identified by a single stimulus feature, such as color - Conjunction search is when something is being defined by two or more features - Feature integration theory of attention: Spatial attention must be directed to relevant stimuli in order to integrate the features into the perceived object, and it must be deployed in a sequential manner for each item in the array - The typical spatial attention effects in visual cortical processing seen with ERPs in cueing tasks are present during visual conjunction search  - This study showed that conjunction search affects the P1 wae in much the same way that cued spatial attention does - In hopfinger’s study after the cue was presented but before the target display appeared, activations were observed not only in dorsal attention network but also visual cortical regions that would later process the incoming target - If the V4 neuron was not actuated by the visual stimulus, then stimulation of the FEF did not affect the activity of the V4 - When cued to discriminate motion, the TMS induced activity in V5 was increased, but when they were cued to discriminate the gender of the face, the same TMS was found to increase activity in FFA ​ Neurotransmitters: types ​ Apraxia - Apraxia is most commonly a result of left-side lesions, yet the problems may be evident in gestures produced by either limb - The motor cortex has direct access to spinal mechanisms via the corticospinal tract - Know the characteristics of Balint’s syndrome (simultagnosia, ocular apraxia and optic ataxia) Pyramidal motor tract - The extrapyramidal tracts are a primary source of indirect control over spinal activity modulating posture, muscle tone, and movement speed, receiving input from subcortical and cortical structures Extrapyramidal motor tract - The extrapyramidal tracts are a primary source of indirect control over spinal activity modulating posture, muscle tone, and movement speed, receiving input from subcortical and cortical structures Endpoint Control - Endpoint control reveals a fundamental capability of the motor control system - Motor control depends on several distributed anatomical structures that operate in a hierarchical fashion - The activity of the cells in the primary motor cortex correlates much better with movement direction than target location - The activity of each neuron can be described as a vector, oriented to the cells preferred direction with a strength equal to its firing rate. The population vector is the sum of all the individual vectors Motor planning - Mark churchland though that rather than viewing neurons as static representational devices, we can focus on the dynamic properties of neurons  - The traditional method defined the directional tuning of th neurons to create a population vector using simple linear summation - The dynamic model defined the trajectory of the neural activity in abstract, multidimensional space - This is a better prediction of movements - Damage to the supplementary motor area can lead to impaired performance on tasks that require integrated use of the two hands, even though the individual gestures performed by either hand alone are unaffected - Reference frame page 348 - The signal we are aware of when making a movement emerges not from the movement itself, but rather the prior conscious intention and predictions that we make about the movement in advance of action - Repetition suppression effect (RS) in the right inferior parietal cortex was related to the action goal, whereas RS in the left frontal cortex was related to the movement, providing a slide demonstration of goal-based processing in parietal cortex and movement based processing in frontal cortex - Our ability to understand the actions of others depends on the neural structures that would be engaged if we were to produce those actions ourselves - When basketball players, experts, and normal people are shown a shot, the experts and players both showed an increase in motor cortex excitability of their arm - Mice could learn if their brains can move the lever then they don’t have to move - Long-term neuroprosthetic control leads to the formation of a remarkably stable cortical map that is readily recalled and resistant to the storage of a second map - The afferent fibers to the basal ganglia terminate in the striatum, composed in primates of two nuclei, the caudate and putamen - There is the internal segment of the global pallidus GP and the pars reticularis of the substantia nigra SN - The SN axons project to and terminate primarily in the superior colliculus and provide a crucial signal for the eye movements - Excites direct pathway by acting on one type of dopamine receptor and inhibits indirect by acting on different dopamine receptor - D1 receptors are direct and produce excitatory - D2 are indirect and produce inhibitory - The CP axons terminate in thalamic nuclei, which projects to cerebral cortex BMI - BMI (brain-machine interfaces) use decoding algorithms to control prosthetic devices with neural signals - Using a BMI system to control a robotic arm, other researchers were able to not use this arm and regain control of the actual limb by using neural signals from the cortex to stimulate the peripheral muscles and nerves, bypassing the damaged spinal cord  - Performance was nearly as good for the virtual stimuli as for the real stimuli. This information could be included in a closed-loop BMI system Clinical disorders of motor system - Hemiplegia is the loss of the voluntary movements on the contralateral side of the body Hippocampus: structure and function - HM: had a medial temporal lobe resection - Found from him that the extent of memory deficit depends on how much of temporal lobe had been removed - After surgery, he retained all other knowledge about the world up to 2 years before his surgery - Also showed selective memory loss for personal life events as far back as a decade, but had normal short term and procedural memory - Could not form new long-term memories (anterograde amnesia) - Showed evidence for priming even when he could not remember seeing the word list or doing the fragment completion task before - His posterior parahippocampal gyrus was spared, but the anterior portion, the perirhinal and entorhinal cortices, were removed - The hippocampus is an infolding of a portion of the medial temporal lobe that is shaped like a seahorse - Only bilateral resection of this results in severe amnesia - Damage does not impair delay condition but does impair trace conditioning - The where in context memory - Rats with hippocampal lesions were not able to associate visual cues with location, unless they were able to practice that task - When a lesion to rats was made, they didn’t show fear in past fearful situations - Needed in the retrieval of short and long term memories - During retrieval, it was active only for words that were actually correctly recollected, thus indicating an episodic memory - Not activated for memories that did not contain awareness of the prior event in word memory tasks - Involved in encoding and retrieval of episodic memories - Correctly recollecting words activated regions of the hippocampus and the posterior parahippocampal cortex during encoding, as well as parts of the frontal cortex - Parts of the left anterior medial parahippocampal gyrus were activated during recognition based on familiarity, but the hippocampus itself was not activated - The amygdala can have influence on fear learning and memory, but is not involved with memory in general - Daa from amnesic patients indicate that it is not part of the brains episodic memory system, but it does play a role in emotion and emotional memories - Anterograde amnesia: the loss of memory for events that occur after a lesion or trauma. The inability to learn new things  - Retrograde amnesia: loss of memory for things that occurred before the lesion or trauma. Sometimes this is temporarily limited, only extending back a few hours - Known to be greatest for the most recent events - The severity of this amnesia was related to the extent of hippocampal damage - RB had a lesion restricted to the CAT1 pyramidal cells. The findings support the idea that the hippocampus is crucial for the formation of new long-term memories - Transient global amnesia is triggered by physical exertion of men over 50 or stress of women over 50. It results in a transient ischemia that later returns to normal - The disruption of blood flow results in a sudden transient anterograde amnesia, and retrograde amnesia spanning weeks, months, or years - MONKEY TESTS page 399 again cant be bothered - Lesions of the hippocampus and amygdala produced the most severe memory deficits only when the cortex surrounding those areas was also lesioned - This helped conclude that the amygdala is not part of the system that supports the acquisition of long term memory - Rat studies found that hippocampal regions did not disrupt stimulus-response learning - Declarative memory processes: assessing the items familiarity and recollecting the context of when the item was encountered - There is one medial temporal lobe mechanism involving the perirhinal cortex that supports familiarity based recognition, and a second system with the hippocampus and posterior parahippocampal cortex that supports recognition based on the recollection of source information - Information about what an object is passes through the perirhinal cortex - Where passes through the posterior parts of the parahippocampal cortex - Relational memory is the hippocampus being able to relate the various types of information about something that the individual encounters. It is the memory for relations among the elements of an experience - Relational memory theory proposes that the hippocampus supports emory for all manner of relations - Researchers have argued that medial temporal amnesia is a disorder of relational memory processing in the hippocampus - When evaluated on spatial, associative, and sequential tests, patients with just hippocampal damage were impaired on the relation tasks but not recollection. More temporal lobe damage had issues with both tests Types of memory - Modal model: At each stage, information can be lost by decay, interference, or both. - Short term memory may not be required to form long term memory. This contrasts to the modal model - Working memory is using memory for limited moments such as addition - The phonological loop has two parts: a short-lived acoustic store for sound inputs, and an articulatory component that plays a part in the subvocal rehearsal of visually presented items to be remembered over the short term - The visuospatial sketchpad is a short term memory store that parallels the phonological loop and permits information storage of either purely visual or visuospatial codes - Patients with lesions of the left supramarginal gyrus have deficits in phonological working memory: they cannot hold strings of words in working memory - Patients with lesions in the right parieto-occipital region have difficulty with nonverbal visuospatial working memory tasks like retaining and repeating the sequence of blocks touched by another person - The activation for spatial working memory is not just right sided, but rather more bilateral in the brain - Episodic memory is comprised of memories that a person has experienced - Semantic memory is memory of life facts - Procedural memory is memory of how to complete a task - In the serial recognition task, participants do not seem to know that the pattern existed, yet they learned the skill - Relational memory is the hippocampus being able to relate the various types of information about something that the individual encounters. It is the memory for relations among the elements of an experience - Relational memory theory proposes that the hippocampus supports emory for all manner of relations - Researchers have argued that medial temporal amnesia is a disorder of relational memory processing in the hippocampus - The working memory maintenance hypothesis proposes that activation of the parietal cortex is related to maintenance of information in working memory - Semantic dementia patients have extensive damage to the anterior temporal lobes - The attention to memory model argues that the dorsal regions of the superior parietal lobule are necessary for top-down search of episodic memory for specific content, and the ventral regions of the inferior parietal lobe are critical to capturing attention once the salient content is identified - Changing a decision criteria seems to turn off SRE activity in said region - ECT electroconvulsive therapy, passes electrical currents through the brain by electrodes on scalp, used to treat disorders - Consolidation occurs after repeated reactivation of the memory creates direct connections within the cortex itself between various representations so that it no longer requires the hippocampus as the middleman - Multiple trace theory: episodic memories degrade over time and are slowly converted into semantic memory - Two mechanisms are involved in replaying an activity: the reverse-order awake replay of neural activity, and the sleep-related replay in which activity is replayed in the same temporal order as it was experienced - Cortisol can enhance initial encoding and consolidation of information perceived around the time of the stressor - Cushings and depression can be correlated with impaired memory - remember new long term memories  - Declarative memory: our conscious memory for both facts that we have learned (semantic), and events that we have experienced (episodic) - Nondeclarative memory: nonconscious memory that cannot be verbally reported, often expressed through the performing of procedures (procedural memory) - Learning and memory - Encoding: - Acquisition: first step of encoding. During this period the stimuli are available for processing, known as the sensory buffer. Only some of these stimuli are sustained and acquired by short term memory - Consolidation: changes in the brain stabilize a memory over time, resulting in long term memory - Storage: the retention of memory trances, the result of acquisition and consolidation - Retrieval: accessing stored memories NMDA - Mice without NMDA in hippocampal CA1 and dentate gyrus granule cells cant produce LTP at these regions - LTP exists at the cellular level - NMDA plays a crucial role in LTP induction in many pathways of the brain Amygdala: structure and function - The amygdala can have influence on fear learning and memory, but is not involved with memory in general - Daa from amnesic patients indicate that it is not part of the brains episodic memory system, but it does play a role in emotion and emotional memories - MONKEY TESTS page 399 again cant be bothered - Lesions of the hippocampus and amygdala produced the most severe memory deficits only when the cortex surrounding those areas was also lesioned - This helped conclude that the amygdala is not part of the system that supports the acquisition of long term memory Aphasia: types and symptomes ​ Stop Signal Task Paradigm ​ Top-Down vs Bottom-Up: Attention & Emotion - Top-down neuronal projections from attention control systems contact neurons in sensory specific areas to alter their excitability - The attention to memory model argues that the dorsal regions of the superior parietal lobule are necessary for top-down search of episodic memory for specific content, and the ventral regions of the inferior parietal lobe are critical to capturing attention once the salient content is identified - In the biased competition model, the idea is that when different stimuli in a visual scene fall within the receptive field of a visual neuron, the bottom-up signals compete to control the neurons firing. This model suggests that attention can help resolve competition by favoring one stimulus