Attention and Consciousness

These flashcards cover key terms and concepts related to attention and consciousness as discussed in the lecture notes.

Visual Processing Streams

Two major pathways in the brain that process visual information, originating from the primary visual cortex (V1): the ventral stream (the 'what' pathway) responsible for object identification and recognition, projecting to the temporal lobe; and the dorsal stream (the 'where/how' pathway) responsible for spatial location, motion, and guiding actions, projecting to the parietal lobe.

Ventral Stream

Known as the 'what' pathway, this occipitotemporal pathway processes information related to object identity, form, color, and recognition. It progresses from V1 through V2, V4, and ultimately to the inferotemporal (IT) cortex, playing a crucial role in forming stable object representations for memory and recognition.

Dorsal Stream

Referred to as the 'where/how' pathway, this occipitoparietal pathway is critical for spatial awareness, perception of motion, and visuomotor control (guiding actions with visual input). It originates from V1 and projects through V2, V3, and into the posterior parietal cortex, contributing to tasks like reaching and grasping.

Fusiform Face Area

A specialized region within the fusiform gyrus of the inferior temporal cortex, primarily located in the right hemisphere. It exhibits selective activation when processing faces, supporting the 'domain-specific' hypothesis, but also shows responses to highly familiar non-face objects for which an individual has expert recognition (the 'expertise' hypothesis). Damage to this area can lead to prosopagnosia (face blindness).

Parahippocampal Place Area

A region in the parahippocampal gyrus that is selectively activated by visual scenes and backgrounds (e.g., landscapes, rooms) rather than individual objects or faces. It plays a significant role in spatial memory, navigation, and the processing of contextual spatial information.

Balint's Syndrome

A rare neurological disorder resulting from bilateral lesions to the posterior parietal cortex, typically following strokes or trauma. It is characterized by a triad of symptoms:

1. Simultagnosia: The inability to perceive more than one object at a time, even if multiple objects are present.

2. Optic Ataxia: Difficulty in accurately reaching for objects under visual guidance, despite intact motor control and visual acuity.

3. Oculomotor Apraxia: Difficulty in voluntarily directing eye movements (saccades) to new visual stimuli.

Hemispatial Neglect

An attentional disorder, not a sensory deficit, most commonly caused by damage to the right posterior parietal cortex. Patients fail to attend to or respond to stimuli presented on the contralesional side of space (typically the left). Neglect can manifest as egocentric (relative to the observer's body) or allocentric (relative to the object itself), and often co-occurs with anosognosia (unawareness of the deficit) and extinction (failure to detect a contralesional stimulus when presented with a simultaneous ipsilesional stimulus).

Change Blindness

The striking failure to notice often-obvious changes in a visual scene when those changes occur during a brief disruption (e.g., a flicker, a saccade, or an occlusion). It highlights the limited capacity of visual attention and working memory, suggesting that we only process a small fraction of the visual information in our environment in detail.

Inattentional Blindness

The failure to notice a fully visible, but unexpected, object or event when attention is engaged in another task. A classic example is the 'gorilla experiment.' This phenomenon demonstrates that conscious perception requires attention, meaning unattended stimuli, even if vivid, may not be consciously experienced.

Top-Down Attention

Also known as endogenous or voluntary attention, this form of attention is goal-directed and driven by an individual's internal plans, expectations, or prior knowledge. Neurologically, it involves activity in regions such as the prefrontal cortex and the dorsal attention network (e.g., intraparietal sulcus, frontal eye fields), allowing for sustained and deliberate focus on relevant stimuli.

Bottom-Up Attention

Also known as exogenous or reflexive attention, this type of attention is stimulus-driven and automatically captured by salient or novel external events (e.g., a sudden flash, a loud noise). Its neural correlates involve areas like the temporoparietal junction (TPJ) and the ventral frontal cortex, comprising the ventral attention network, which acts as a 'circuit breaker' to reorient attention to unexpected but important stimuli.

Posner Orienting Paradigm

An experimental task designed to study the mechanisms of spatial attention by measuring reaction times (RTs) to targets presented after cues. Participants fixate on a central point while a cue (e.g., an arrow or a peripheral flash) indicates a potential target location. Valid cues (target appears at cued location) lead to faster RTs (benefits), while invalid cues (target appears at uncued location) lead to slower RTs (costs), demonstrating the time and effort involved in shifting and reorienting spatial attention.

Pulvinar

The largest nucleus of the human thalamus, playing a critical role in attentional control, visual processing, and sensory gating. It has extensive reciprocal connections with numerous cortical areas, particularly those in the parietal, temporal, and frontal lobes. The pulvinar is involved in filtering irrelevant information, enhancing processing of attended stimuli, and coordinating communication between different cortical regions to facilitate the selection and processing of relevant sensory input.

Neural Correlates of Attention

The specific patterns of brain activity and the brain regions whose activity systematically changes with the allocation and type of attention. This includes enhanced neural firing rates in sensory cortices for attended stimuli, synchronization of neural oscillations (e.g., gamma band) between distant brain regions within attention networks (e.g., dorsal and ventral attention networks), and modulation of sensory processing at early stages (e.g., increased amplitude of evoked potentials).

EEG Waves

Distinct patterns of electrical activity recorded from the brain's surface (electroencephalography), characterized by specific frequency ranges (Hz) and associated with different states of consciousness and cognitive processes:

• \textbf{Delta (0.5-4 Hz)}: Deep sleep, unconsciousness.

• \textbf{Theta (4-8 Hz)}: Light sleep, drowsiness, meditative states, memory encoding.

• \textbf{Alpha (8-13 Hz)}: Relaxed wakefulness, eyes closed, calm mental states.

• \textbf{Beta (13-30 Hz)}: Alertness, active thinking, problem-solving, focused concentration.

• \textbf{Gamma (30-100+ Hz)}: High-level cognitive processing, attention, perception, consciousness, binding of sensory features.

General Anesthesia

A pharmacologically induced, reversible state characterized by a triad of unconsciousness (loss of awareness and recall), analgesia (loss of pain sensation), and amnesia (inability to form new memories). It is achieved by drugs that typically modulate neurotransmitter systems, such as enhancing GABAergic inhibition or blocking NMDA receptors, leading to widespread suppression of brain activity vital for consciousness and sensory processing, distinct from natural sleep due to global changes in brain connectivity and oscillatory patterns.