Scientific Understanding of Consciousness
Consciousness as an Emergent Property of Thalamocortical Activity

Attention

Attention allows us to engage with the environment by selecting information relevant for behavior. Research activity is currently intensive on the brain mechanisms of attention.

 Attention focuses the functionality of working memory with the functionality of other cortical areas.

 Attention is strongly influenced by functions in the limbic system: (fear -- pleasure)

 Motivation is driven by a conflagration of executive decisions produced by working memory along with (fear -- pleasure) mechanisms of the limbic system.

The coordinated activity within the thalamus, anterior cingulate cortex (ACC), the ventral lateral prefrontal cortex (VLPFC), posterior parietal cortex (PPC), and the brain stem probably regulate the content of consciousness through mechanisms of executive attention. (Vogt; Cingulate Neurobiology, 384)

Attention is broadly of two types -- (1) bottom-up, caused by the sensory input, and (2) top-down, produced by the planning parts of the brain. (Crick & Koch; Consciousness and Neuroscience, 39)

 

The reticular activating system also helps mediate transitions from relaxed wakefulness to periods of high attention. There is increased regional blood flow (presumably indicating an increased measure of neuronal activity) in the midbrain reticular formation (MRF) and thalamic intralaminar nuclei during tasks requiring increased alertness and attention. (Wikipedia, Reticular activating system)

 

Link to Topics for Attention functionality

Link to Attention Model by Cowan (Cowan, Attention and Memory, 31)

 

Research Study Thalamic Control of Sensory Selection and Divided Attention

Research Study Attention Modulated Top-Down, Selectively Processes Information

Research Study Attention Neural Mechanisms

Research Study Strength of Gamma Rhythm Depends on Normalization

Mechanisms of Attention discussion of neural mechanisms

Two types of attention: (1) automatic engagement of the senses that occurs when your eye is caught by a flash of movement, (2) deliberate turning of the mind to a subject. (Carter; Mapping the Mind, 192)

Attention has two complementary components -- an intensive, selective component, and an exclusionary one. (Fuster; Prefrontal Cortex, 347)

Selective component of attention seems based primarily in dorsolateral frontal cortex. (Fuster; Prefrontal Cortex, 347)

Exclusionary component of attention, the inhibitory control of interference, seems primarily based in ventral frontal cortex. (Fuster; Prefrontal Cortex, 347)

An attention event is a necessary but not sufficient condition for and awareness event, so that there can be attention without awareness, but no awareness without attention. (LaBerge; Attention, the Triangular Circuit, 314)

 

Selective attention is perhaps the closest we will come to finding one system in the brain that determines the current content of our conscious experience. (Calvin; Neil's Brain, 81)

Before we can be conscious of something, we have to pay attention. (Ratey; User's Guide to Brain, 114)

Difficult to distinguish clearly between attention and consciousness. We can know and remember things even when we are not paying attention to them, or are not even "conscious" of them. (Ratey; User's Guide to Brain, 133)

 

Research Study Attention Enhances Synaptic Efficacy and Signal-to-Noise Ratio

Research Study Context-dependent computation by recurrent dynamics in prefrontal cortex

 

Varieties of Attention

High-frequency, low-amplitude, asynchronous cortical EEG, associated with the alert, waking state, appears to reflect an increase in subcortical noradrenergic activity with an efficient relay of subcortical afferent inputs to the cortex. (Parasuraman; Varieties of Attention, 228)

Low-frequency, high-amplitude, synchronous EEG, accompanying states of drowsiness and sleep, is associated with decreased noradrenergic activity and a blockade of sensory-afferent thalamic input to the cortex. (Parasuraman; Varieties of Attention, 228)

Alert attentiveness is associated with fast EEG beta (14-30 Hz) activity. (Parasuraman; Varieties of Attention, 229)

Relaxed wakefulness in which attentiveness per se is not necessary is characterized by slower alpha (8-13 Hz) activity. (Parasuraman; Varieties of Attention, 229)

Drowsiness leads to even slower theta (4-7 Hz) and delta (1-3 Hz) activity. (Parasuraman; Varieties of Attention, 229)

 

 

Suppression of non-relevant stimuli

In the real world, multiple streams of information reach our awareness, some of it relevant, some not for the task at hand. With the inherent capacity limitations of working memory, it is essential that only representations of task-relevant information are generated and maintained. An important aspect of goal-directed behavior is understanding the neural mechanisms underlying how task-relevant versus task-irrelevant information is differentially processed. (Gazzaley; Top-down WM, 197)

Human interaction with our environment involves a fluid integration of externally driven perceptual information that demands attention based on stimulus salience or novelty (bottom-up processes) and internally driven, goal-directed decisions concerning external stimuli or stored representations (top-down modulation). (Gazzaley; Top-down WM, 197)

In the biased competition model, with reciprocal suppression of activity in visual regions that encode non-relevant stimuli, suppression occurs due to competition of multiple stimuli for limited visual processing resources. (Gazzaley; Top-down WM, 198)

Three components of attention

Three components of attention: (1) selection, (2) vigilance, (3) control. All three aspects maintain goal-directed behavior in a context of multiple, competing distractions. (Parasuraman; Attentive Brain, 3)

Attention serves the goals of (1) accurate and speedy perception and action, (2) maintenance of processing over time. (Parasuraman; Attentive Brain, 6)

An organism's goals are determined not only by the environment but by the organism's internal dispositions, both temporary and enduring. This is presumably what links attention to motivation and emotion. (Parasuraman; Attentive Brain, 6)

Selection

A critically important component of attention is selection, which is perhaps the most widely studied area. Selectivity of processing is required because of the computational limitations imposed by fully parallel processing of all sources. The large receptive field of neurons in higher perceptual processing areas results in a computational limitation. The primate brain presumably evolved mechanisms of selective attention to cope with that limitation. (Parasuraman; Attentive Brain, 6)

Selective attention is widely recognized as a powerful factor in perception, action, and memory -- and the unity of conscious experience. (Kandel; Search of Memory, 311)

Vigilance

Vigilance or sustained attention ensures that goals are maintained over time. (Parasuraman; Attentive Brain, 7)

Control

Attentional control -- information-processing activity may need to be temporarily stopped (to respond to some other important activity) and then resumed; there may be other concurrent activities; and the future course of all such activities must be coordinated. (Parasuraman; Attentive Brain, 7)

Attention a cause or an effect? Whether there exist (1) attentional systems that are separate from other sensory and motor systems in the brain, or whether (2) attention represents an emergent property of other processing activities. Functional brain-imaging studies have provided clear evidence for attentional effects in many parts of the brain. Anterior cingulate gyrus of the frontal lobe plays a key role in attentional control and is therefore one of the brain areas that act as the causal source. (Posner, 1995) (Parasuraman; Attentive Brain, 12)

 

 

Attention and Consciousness (Koch; Quest for Consciousness, 153, 266, 173)

Consciousness requires attention? (Koch; Quest for Consciousness, 153, 163)

 

 

Link to Dynamic Core

Link to Working Memory

Further discussion -- Covington Theory of Consciousness