NSCI 160 - Lectures 15 & 16: Attention and the Frontal Lobes

Lamprey and attention studies

Spatial map of visual input to location objects in space and then do computations of when to engage. Simplified basal ganglia circuit.

Spotlight Metaphor

Focusing suggests that attention can be distributed but focusing sharpens details

Herman von Helmholtz Studies

Suggested that our perception is not a direct reflection of sensory input but is actively constructed by the brain based on prior experiences and expectations, which is closely related to the idea of how attention selects relevant information.

Mental Currency

Often say we "pay attention," implying attention is a finite resource. This leads to the idea of managing attention resources effectively to optimize cognitive processing

Attention vs. Consciousness

attention focuses on specific features of the world (what we attend to), consciousness gives us a gist of the world.

Attention and survival

Plays a role in sensory and motor activities that are essential for survival (finding food or a mate, avoiding predation)

Early selection (Broadbent)

Attention acts as a filter at the perceptual stage, allowing only certain stimuli to be processed deeply, while others are blocked early in the sensory input .

Treisman's Attenuation Model

While most stimuli are filtered out, highly salient stimuli (e.g., hearing your own name in a conversation) can still be processed, showing the filter is not absolute .

Late selection (Deutsch & Deutsch)

All stimuli are processed up to the perceptual level, but selection occurs later when responding. The bottleneck occurs at the decision-making or response stage .

Top-down Attention

Voluntary, goal-directed attention controlled by higher-order brain areas such as the prefrontal cortex. This type of attention is critical for tasks that require focus on specific sensory inputs .

Bottom-up Attention

Involuntary attention captured by salient external stimuli (e.g., a loud noise). This type of attention is driven by external factors and is often crucial for survival, as it helps detect unexpected threats or changes in the environment

Hillyard task

Subjects attend to one visual field while stimuli are flashed in both. ERP response is enhanced when subjects attends to target location.

Event-Related Potentials (ERPs)

Studies using tasks like the Hillyard task show that attention enhances neural responses as early as 100 milliseconds after stimulus onset. This demonstrates that attention influences sensory processing at early stages.

Attention fMRI studies

Reveals increased activity in sensory areas like V1 and V2 when attention is focused on stimuli, providing spatial evidence for how attention modulates neural processing

Receptive Fields and Attention

When attention is directed to a stimulus, the receptive fields of neurons in V1 can shrink, enhancing spatial resolution and allowing for finer detail discrimination. This shows that attention can change the way visual information is processed at the neural level

Posterior Parietal Cortex

Critical for directing attention to different parts of the visual field. Lesions in this area can result in hemispatial neglect

hemispatial neglect

Damage to the right parietal lobe can cause neglect of the left visual field. Patients are often unaware of objects in the left visual field and may even deny that part of their body exists

Frontal Eye Fields (FEF)

Involved in controlling voluntary shifts in attention, particularly in tasks requiring eye movements toward targets .

lateral geniculate nucleus (LGN)

plays a key role in filtering sensory input and is influenced by feedback from higher cortical areas like V1. Helps regulate what sensory information is passed forward for further processing

Feature Integration Theory

Proposed that basic features (e.g., color, orientation) are processed automatically, but attention is required to bind features together into a coherent object (e.g., green circle among red and green squares)

Illusory Conjunctions

In the absence of attention, features from different objects may be incorrectly combined (e.g., seeing a red square and a blue triangle but reporting a red triangle). This demonstrates that attention is essential for accurate feature binding .

somatoparaphrenia

A type of delusion where one denies ownership of a limb or an entire side of one's body. Often associated with hemispatial neglect.

Simultagnosia

This condition, often associated with bilateral parietal damage, impairs a person's ability to perceive multiple objects simultaneously. This is particularly evident in patients who have trouble integrating parts of a visual scene

Mismatch Negativity

A neural response to unexpected stimuli in a sequence of similar stimuli, often used to study automatic shifts in attention. The magnitude decreases when attention is focused on a difficult task, suggesting attentional resources can be shared between modalities (e.g., visual and auditory) .

Cross-modal attention

Studies have shown that when attention is consumed by a difficult visual task, responses to irrelevant auditory stimuli are diminished, further supporting the idea that attentional resources are fungible and can be deployed across modalities

Posner Cuing Task

Classic experiment showing that attention can enhance performance (faster reaction times) when a cue correctly predicts the target location (valid trial). However, when the cue incorrectly predicts the target location (invalid trial), reaction times are slower, reflecting the cost of having to disengage and reorient attention

Prefrontal Cortex

Responsible for executive functions—complex cognitive processes that include planning, decision-making, working memory, and attentional control, is defined by its connections to the dorsomedial thalamus

Dorsomedial thalamus

Serves as a gateway for information flow to the PFC, enabling prioritized cognitive processing

Frontal Lobes

Located at the front of the brain and are the largest region, making up roughly 41% of the cerebral cortex. They are critical for regulating behavior and integrating complex cognitive tasks.

Dorsolateral Prefrontal Cortex (dlPFC)

Involved in cognitive flexibility, working memory, and rule maintenance

Ventrolateral Prefrontal Cortex (vlPFC)

Critical for response inhibition and the ability to shift between tasks

Ventromedial Prefrontal Cortex (vmPFC) and Orbitofrontal Cortex

Essential for processing emotions, assessing risks, and managing social behavior

Dysexecutive Syndrome

Characterized by difficulties in planning, goal-setting, and maintaining complex activities, often linked to damage in the dlPFC. Patients show impaired working memory and struggle to adapt when conditions change

Disinhibition Syndrome

Marked by impulsive behavior and a lack of social restraint, associated with damage to the orbitofrontal cortex, leading to poor judgment and risk-taking.

Abulia

Involves a profound lack of motivation, reduced initiative, and difficulty in decision-making, related to damage in both the PFC and the basal ganglia, which play a role in voluntary actions

WR Case Study

notable case of bilateral frontal lobe damage, patient experienced a loss of goal-directed behavior, emotional flattening, and social withdrawal. These symptoms illustrate the impact of PFC damage on both cognitive and emotional domains

Inhibition

The ability to suppress automatic or inappropriate responses to maintain focus on relevant goals.

Task Switching

The capacity to adjust attention and behavior between different rules or conditions, requiring flexibility in problem-solving.

Working Memory

Considered a form of attention directed to internal percepts, working memory enables individuals to keep relevant information active without external cues, a function highly dependent on the dlPFC

thalamic reticular nucleus (TRN)

A thin layer of neurons surrounding the nuclei of the thalamus, which receives inputs from the cortex and acts as a filter to enhance or suppress sensory input based on relevance

Dorsal attention System

Responsible for focusing on goal-directed tasks

Ventral Attention System

Sensitive to unexpected changes and novel stimuli

Goldman-Rakic Studies

Show that the dlPFC maintains sustained neural activity during tasks that require holding information in mind, emphasizing its role in directing attention to internal goals rather than immediate sensory input

Wisconsin Card Sorting Task

A test of cognitive flexibility that involves changing rules based on feedback. Patients with dlPFC damage often exhibit perseveration, indicating difficulties in adapting to new rules.

Oddball Task

A task requiring detection of infrequent or unexpected stimuli, emphasizing the role of the dlPFC in shifting attention and updating rules based on context.

Filtering Tasks

These tasks require focusing on relevant information while ignoring distractions. Performance is closely tied to dlPFC function, highlighting its role in filtering and decision-making

Thalamus and sensory modulation

Especially the mediodorsal nucleus, serves as a gateway for information flow to the PFC, enabling prioritized cognitive processing

Working Memory Deficits

Inability to retain and manipulate information, commonly observed in patients with dlPFC damage

Source and Recency Memory

Difficulties in recalling the context or sequence of information, indicative of compromised PFC function, which integrates temporal and contextual details.

Utilization Behavior

A phenomenon where patients reflexively respond to objects in their environment, disregarding context due to impaired PFC function. Illustrates the role of the PFC in regulating context-appropriate behavior.

Cognitive Reappraisal

The ability to reinterpret emotional situations to reduce distress is heavily reliant on the PFC. Damage to this region results in rigidity and inappropriate emotional responses, underscoring its importance in emotional regulation.

Covert voluntary attention

shift attention to location of interest while keeping our gaze somewhere else (face)

Overt voluntary attention

attention at gaze direction (in charge of this)

Covert involuntary attention

gaze straight ahead, an external event (falling coffee cup) causes an involuntary shift of attention to the location of the event

Simultaneous extinction

inability to recognize stimuli presented to both sides

Temporoparietal Junction (TPJ)

The point in the brain where the temporal and parietal lobes meet. It plays a role in shifting attention to a new location after target onset. Can be referred to as a 'circuit breaker'