10.1 Neural mechanisms of attention
3 min read•august 14, 2024
Attention is a complex cognitive process involving various brain regions and neurotransmitters. The prefrontal and parietal cortices, along with subcortical structures, work together to control and direct our focus. Neurotransmitters like and play crucial roles in modulating attention.
Three main attentional networks - alerting, orienting, and executive control - collaborate to efficiently allocate our mental resources. The neural basis of involves competitive interactions between stimuli, with top-down signals biasing processing towards relevant information. Understanding these mechanisms helps explain attention's limitations and phenomena.
Brain Regions for Attention
Prefrontal and Parietal Cortices
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- The (PFC) plays a crucial role in top-down attentional control, goal-directed behavior, and decision-making
- The , particularly the (PPC), is involved in the allocation of spatial attention and the integration of sensory information
Subcortical Structures
- The acts as a relay center for sensory information and plays a role in attentional gating and filtering of irrelevant stimuli
- The is involved in the control of eye movements and the orientation of attention towards salient stimuli (sudden movements, bright colors)
- The (ACC) is involved in conflict monitoring, error detection, and the allocation of attentional resources
Neurotransmitters and Attention
Monoamines
- Norepinephrine, released by the locus coeruleus, enhances arousal, alertness, and the signal-to-noise ratio of sensory processing, facilitating focused attention
- Dopamine, particularly in the mesocortical and mesolimbic pathways, is involved in reward-driven attention, motivation, and the allocation of attentional resources based on the salience of stimuli
- modulates mood, impulsivity, and the balance between focused and flexible attention
Other Neurotransmitters
- , released by the basal forebrain and the pontomesencephalic tegmental nuclei, enhances sensory processing, cortical activation, and attentional capacity
- and , the primary excitatory and inhibitory neurotransmitters, respectively, regulate the balance of neural activity and the formation of attentional networks
Attentional Networks and Functions
Alerting, Orienting, and Executive Control Networks
- The , which includes the locus coeruleus and the right frontal and parietal cortices, is responsible for maintaining vigilance and preparing the brain for incoming stimuli
- The , which includes the superior colliculus, the parietal cortex, and the frontal eye fields, is involved in the selection and spatial orientation of attention towards relevant stimuli
- The , which includes the prefrontal cortex and the anterior cingulate cortex, is responsible for the voluntary control of attention, conflict resolution, and the suppression of distracting information
Network Interactions
- These networks interact and collaborate to allocate attentional resources efficiently and adapt to changing environmental demands
- The alerting network modulates the orienting network by increasing its sensitivity to incoming stimuli
- The executive control network guides the orienting network to focus on task-relevant information and suppress irrelevant distractors
Neural Basis of Selective Attention
Biased Competition Model
- Selective attention involves the preferential processing of relevant stimuli while ignoring or suppressing irrelevant information
- The suggests that selective attention emerges from the competitive interactions between neural representations of different stimuli, with top-down signals from the prefrontal and parietal cortices biasing the competition in favor of task-relevant information
Limitations of Selective Attention
- The limited capacity of selective attention is attributed to the finite resources of the frontoparietal network and the inherent limitations of neural processing
- The phenomenon demonstrates the temporal limitations of selective attention, where the detection of a second target is impaired when it appears within a short time window (200-500 ms) after the first target
- The load theory of attention suggests that the efficiency of selective attention depends on the perceptual and cognitive load of the task, with high load leading to more focused attention and low load allowing for greater processing of irrelevant information
Key Terms to Review (19)
Acetylcholine: Acetylcholine is a neurotransmitter that plays a vital role in communication between neurons and is involved in various physiological functions such as muscle contraction, memory, and attention. It is found both in the central nervous system and the peripheral nervous system, influencing numerous neural pathways and processes.
Alerting network: The alerting network is a crucial component of the brain's attention system that prepares the individual to respond to stimuli in their environment. This network enhances sensitivity to incoming information and is essential for focusing attention and maintaining vigilance. It involves several brain regions, including the thalamus, parietal cortex, and frontal areas, working together to ensure that individuals can quickly notice and react to important cues in their surroundings.
Anterior cingulate cortex: The anterior cingulate cortex (ACC) is a region located in the frontal part of the cingulate cortex, playing a crucial role in emotion regulation, decision-making, and cognitive control. It connects emotional and cognitive processes, helping to manage responses to social situations and stress, thus linking it to various aspects of communication and attention.
Attentional blink: Attentional blink refers to a phenomenon where there is a brief period following the perception of a visual stimulus during which a second stimulus cannot be detected or identified, typically occurring within 200-500 milliseconds after the first stimulus. This effect highlights the limitations of visual attention, revealing how the brain processes information sequentially rather than simultaneously. It is a crucial concept for understanding both the neural mechanisms of attention and how top-down and bottom-up processes influence our ability to focus on multiple stimuli.
Biased competition model: The biased competition model proposes that attention is allocated based on competitive interactions between stimuli, where certain items are favored over others depending on their relevance or salience. This model suggests that stimuli competing for cognitive resources are processed unequally, leading to enhanced perception and response for prioritized items, which plays a crucial role in understanding how attention is guided in neural mechanisms.
Dopamine: Dopamine is a neurotransmitter that plays several important roles in the brain, influencing mood, motivation, reward, and motor control. It is critical in many neural pathways, connecting various brain regions and affecting behavior and cognitive functions.
Executive Control Network: The executive control network refers to a group of brain regions that work together to manage higher-order cognitive processes, such as attention, decision-making, and problem-solving. This network is essential for regulating and coordinating various mental activities, enabling individuals to focus on relevant information while ignoring distractions. It plays a key role in maintaining goal-directed behavior and adapting responses based on changing circumstances.
GABA: GABA, or gamma-aminobutyric acid, is the primary inhibitory neurotransmitter in the brain that plays a crucial role in reducing neuronal excitability throughout the nervous system. It helps maintain a balance between excitatory and inhibitory signals, influencing various functions such as mood, motor control, and cognitive processes.
Glutamate: Glutamate is the main excitatory neurotransmitter in the brain, playing a crucial role in sending signals between nerve cells. It's involved in various essential functions including synaptic transmission, plasticity, and learning processes, highlighting its significance across multiple neural pathways and mechanisms.
Norepinephrine: Norepinephrine is a neurotransmitter and hormone that plays a critical role in the body's response to stress and in regulating mood, attention, and arousal. It acts primarily in the brain and the peripheral nervous system, influencing various physiological functions, such as heart rate and blood pressure, while also impacting cognitive processes like focus and emotional responses.
Orienting network: The orienting network is a collection of neural mechanisms in the brain responsible for directing attention to specific stimuli or locations in the environment. This network is crucial for prioritizing sensory information and enhancing awareness of relevant stimuli while filtering out distractions. It plays a key role in visual attention and spatial awareness, enabling individuals to respond effectively to their surroundings.
Parietal Cortex: The parietal cortex is a region located in the upper back part of the brain, primarily responsible for processing sensory information and integrating it with spatial awareness. It plays a crucial role in attention, perception, and the manipulation of objects, connecting sensory input with motor functions and cognitive processes. Its functions are vital in forming a comprehensive understanding of the environment and coordinating actions based on that understanding.
Perceptual Load: Perceptual load refers to the amount of cognitive resources required to process visual information in a given environment. It influences how well an individual can focus on a specific task while ignoring distractions, as higher perceptual load tends to consume more attentional resources, leaving less available for processing irrelevant stimuli. Understanding perceptual load is crucial for examining how attention is allocated and the neural mechanisms that support selective focus amidst competing demands.
Posterior parietal cortex: The posterior parietal cortex (PPC) is a region of the brain located in the parietal lobe, playing a crucial role in integrating sensory information and coordinating spatial awareness. It connects visual and sensory input to help guide attention and motor responses, making it essential for tasks that involve perception and action.
Prefrontal cortex: The prefrontal cortex is the front part of the frontal lobes of the brain, crucial for higher-level cognitive functions such as decision-making, planning, and social behavior. Its role in integrating information from various brain regions makes it essential for tasks involving learning, memory, attention, and emotional regulation.
Selective Attention: Selective attention is the cognitive process of focusing on specific stimuli while ignoring others, allowing individuals to concentrate on relevant information. This mechanism plays a critical role in learning and memory, helping to filter out distractions and prioritize information that is important for task completion and memory formation. It also involves neural mechanisms that support this focus and can operate through both top-down and bottom-up processes.
Serotonin: Serotonin is a neurotransmitter that plays a key role in regulating mood, emotions, and various physiological processes in the body. It's involved in functions like sleep, appetite, and digestion, and is often linked to feelings of well-being and happiness.
Superior colliculus: The superior colliculus is a paired structure located in the midbrain that plays a crucial role in visual processing and the coordination of eye movements. It integrates sensory information from the eyes and other sensory modalities to guide attention and orientate towards stimuli in the environment, thereby influencing the neural mechanisms of attention.
Thalamus: The thalamus is a small, egg-shaped structure located near the center of the brain, serving as a critical relay station for sensory and motor signals. It plays a vital role in processing and transmitting information between various parts of the brain, and it's involved in regulating consciousness, sleep, and alertness.