Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
Chapter 2 A Framework
“It seems that the human mind has first to construct forms independently before we can find
them in things … Knowledge cannot spring from experience alone, but only from a
comparison of the inventions of the intellect with observed fact.”
Albert Einstein (1949)
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
Chapter Outline
1.0 Introduction
2.0 Classical working memory
3.0 Limited and large-capacity functions
4.0 The inner and outer senses
5.0 The central executive
6.0 Action
7.0 Consolidation of short-term events into long-term memory
8.0 Summary
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
1.0 Introduction
We use a functional framework to organize a good deal of cognitive neuroscience.
While not all of the details are settled, it combines a large body of brain and
psychological evidence into a single diagram.
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
1.0 Introduction
Sensory information enters the system (left side of diagram), integrating with executive
and memory systems on the way to output -- Action -- systems (right side of diagram).
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
1.0 Introduction
A central goal of mind-brain science is to determine where the functions depicted on
the framework diagram are processed in the brain.
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
1.0 Introduction
Some major functions of the human cortex,
color coded to show brain areas that support
their processes.
Top: a lateral view of the brain
Bottom: a medial view at the midline
Sensory information is processed in the
posterior (back) half of the cortex
Executive and motor functions occupy the
frontal half.
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
2.0 Classical Working Memory
Located in the center of the functional framework diagram, working memory systems
interact with sensory input, executive function, long-term memories, and action systems
The ‘inner senses’: below the working
memory, two of the ‘inner senses’ are shown:
verbal rehearsal and visuospatial sketchpad.
These inner senses interact constantly with
the long-term stores, shown in gray boxes on
the bottom of the diagram.
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
2.0 Classical Working Memory
Output functions include the central executive, action planning, and motor
output, shown on the right side of the diagram.
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
2.0 Classical Working Memory
Only a fleeting moment … the story of Clive Wearing, a rising young musician in
Britain who was suddenly struck with a rare type of brain damage.
In 1985, a viral infection destroyed regions of Clive
Wearing’s brain, including both of his hippocampi. He
was still able play the piano and conduct musical
pieces that he knew before the injury, but could no
longer learn new episodic (conscious) events.
Wearing retains conscious events for only 10-20
seconds, living in an eternal present.
His case has illuminated the role of the hippocampi in
memory consolidation.
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
2.0 Classical Working Memory
Only a fleeting moment … the hippocampi are critical to memory consolidation
The two hippocampi, one in each cerebral hemisphere
The red bulbs at the tips of the hippocampi are the
amygdala, which play a fundamental role in emotion
processing and emotional memory.
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
2.0 Classical Working Memory
The case of HM -- bilateral surgical removal of the hippocampi
The most studied memory patient is HM, who had both
hippocampi removed in a surgery to relieve his epilepsy
when he was a young man.
The epilepsy symptoms ended, but HM had severe
amnesia: he was unable to store new memories of his
conscious life experiences (autobiographical memory),
however he could learn new skills showing that his
procedural memory formation was intact.
A bottom view of the brain shows the
regions removed by surgery for HM.
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
2.0 Classical Working Memory
Understanding Clive Wearing in the functional framework diagram
The case of Clive Wearing has
provided evidence for the role of
the hippocampi -- and the medial
temporal lobe where they are
located -- in cognition. Most
functions are spared, however he
has lost the ability to encode and
retrieve conscious experiences.
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
2.0 Classical Working Memory
The importance of immediate memory: immediate memory is needed for even the
simplest of activities, like reading this sentence. You must be able to hold information
during the few seconds it takes to read the entire sentence in order to understand its
meaning.
A similar storage process is required in
visual processing: immediate memory is
needed in order to integrate the small
fixations that occur in vision. Long eye
movements (saccades) jump from one
point to another in the visual scene. The
visual system must be able to hold this
information in order to integrate and
encode the visual image.
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
3.0 Limited and Large-Capacity Functions
Even though the human brain has tens of billions of neurons, in some ways it has
very narrow capacity limits …
Limited capacity tasks
Very large-capacity functions
Dual input tasks
Long-term memory
Immediate memory limits
Language vocabulary (+100,000
words)
Ambiguous stimuli and meanings
(necker cube, ambiguous words)
Complex sensory and motor
processes
Competition between various
features in a stimulus (Stroop
task)
Vast number of neurons,
connections, and networks in the
bran
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
3.0 Limited and Large-Capacity Functions
Limited capacity tasks: dual task limits, Donald Broadbent, and his research
on selective attention
Can you pay attention to someone speaking into your
right ear while another person is speaking into your left
ear? What happens to your comprehension when your
attention is divided?
Groundbreaking studies were conducted by Donald
Broadbent and others on the capacity limits of selective
attention processes.
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
3.0 Limited and Large-Capacity Functions
Limited capacity theory of Donald Broadbent
Broadbent used a selective listening task, in which two
messages are sent simultaneously to the two ears, to
study the capacity limits of selective attention.
Broadbent proposed a ‘funnel’ image of limited capacity
functions that dramatizes the fact that our large brains
have narrow limits for selective attention, conscious
perception, and voluntary control.
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
3.0 Limited and Large-Capacity Functions
Why are there such narrow capacity limits?
Limited capacity tasks are associated with
conscious experience while large-capacity
functions are generally unconscious.
Some scientists argue that capacity limits
are due to the role of consciousness in
combining numerous components of a very
large brain into an integrated whole.
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
3.0 Limited and Large-Capacity Functions
Measuring working memory: verbal and spatial memory tasks
One way that visual working memory is assessed is by presenting visual shapes
one at a time over specific time periods. Any stimulus may be presented and retested some seconds later to see if the subjects recalls the previous presentation.
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
3.0 Limited and Large-Capacity Functions
Measuring working memory: ‘n-back’ tasks
Another way that visual working memory is
assessed is by presenting visual shapes one
at a time over specific time periods and asking
the subject to recall the item presented one,
two, or three slides before. This is called an ‘nback’ task and is very demanding.
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
3.0 Limited and Large-Capacity Functions
Measuring working memory: ‘n-back’ tasks
Brain activity increases with working memory
‘load’, which is higher in 2- and 3-back tasks than
in 0- and 1-back tasks
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
4.0 The Inner and Outer Senses
What we see, hear, touch, taste, and smell (the outer senses) initially activate
differing brain regions that then become integrated with the motor (action)
system and other brain systems and processes
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
4.0 The Inner and Outer Senses
What we see, hear, touch, taste, and smell (the outer senses) initially activate
differing brain regions that then become integrated with the motor (action)
system and other brain systems and processes
The functional framework diagram,
showing the sensory inputs to the brain
Sensory systems tend to be located in
posterior brain regions
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
4.0 The Inner and Outer Senses
The mind’s eye, ear and voice: inner senses (for example, imagery) activate
sensory regions in the brain
a
b
c
d
Here is an example of a brain study where activation for perceived visual
items (a) and imagined visual items (b) are quite similar. In fact, if you
subtract brain areas activated for perceived stimuli from the imagined stimuli
(c), almost no brain areas are active. The brain images are from the posterior
portion of the brain (d) in visual cortex.
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
4.0 The Inner and Outer Senses
Further evidence that the inner senses (for example, ‘talking’ to yourself) use
brain processes that are very similar to those used for outer senses (such as
speaking) is provided by experiments by Gary Dell and others who found that
errors made in repeating tongue twisters were similar for inner (internally
generated) vs. outer (spoken) speech.
Try it yourself: repeat “Peter Piper picked a a peck of pickled peppers”
silently to yourself as quickly as you can. Did you notice any errors? Was it
difficult to do, despite the fact that your actual tongue was not involved in
repeating this tongue twister (or was it?)
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
4.0 The Inner and Outer Senses
Is there only one working memory?
Investigators are researching whether
there are working memory systems
that are specific to a sensory system
(such as vision), if there are systems
that are non-specific/executive (a
general temporary storage), or a
combination of the two.
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
4.0 The Inner and Outer Senses
Recent neuroimaging studies show evidence that there are differing brain areas
that are activated during tasks that require differing types of working memory
•The executive part of Working Memory
involves the prefrontal lobe.
•The verbal part -- such as rehearsing words
silently --- involves speech areas (especially
in the dominant hemisphere), e.g., Broca’s
and Wernicke's areas.
•The visual part --- such as visual imagery to
think about how to walk from one place to
another --- seems to involve visual regions,
including the occipital lobe.
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
5.0 The Central Executive
The prefrontal lobes play an important executive role in the brain. They are needed for
voluntary control over actions. Prefrontal regions also support emotional processes
and seem to be necessary to control one’s own unwanted impulses.
"The frontal lobes are the latest achievements of
the nervous system; it is only in human beings
(and great apes, to some extent) that they reach
so great a development. ... they lack the simple
and easily identifiable functions of the more
primitive parts of the cerebral cortex, the
sensory and motor areas ... but they are
overwhelmingly important.”
-- Oliver Sacks, in Goldberg 2001
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
The prefrontal lobes play an important executive role in the brain. They are needed for
voluntary control over actions. Prefrontal regions also support emotional processes
and seem to be necessary to control one’s own unwanted impulses.
"Thus in the famous case of Phineas Gage --- a railway
foreman who while setting an explosive charge in 1848 had a
two-foot tamping iron blown through his frontal lobes when the
charge backfired --- while there was preservation of Gage's
intelligence as well as his ability to move and talk and see,
there were other, profound changes in him. He became
reckless and improvident, impulsive, profane; he could no
longer plan or think of the future; and for those who had
known him before, "he was no longer Gage." He had lost
himself, the most central part of his being, and (as is the case
with all patients with severe damage to the frontal lobes), he
did not know it".
-- Oliver Sacks, in Goldberg 2001
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
5.0 The Central Executive
Are there different brain areas involved for voluntary vs. automatic movements? The
evidence supports the notion that movements that are automatic engage different
regions than those that require executive effort.
On the left, this brain damaged patient cannot produce a voluntary smile. On the right,
this patient can smile when presented with a funny image. Frontal lobe damage
impaired her executive control of smiling movements but not the automatic response
of a natural, spontaneous smile.
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
5.0 The Central Executive
Executive attention networks in the cortex
What brain areas are active during selective attention? Posner proposed that an
executive attention network includes regions in parietal and prefrontal cortex.
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
5.0 The Central Executive
The task in ‘a’ and ‘b’ is to search for a horizontal green bar. In a, the green bar
appears to ‘pop-out’ spontaneously, while in b, finding the green bar requires effortful
search. This type of task is used to investigate brain regions involved in voluntary
attention under executive control vs. spontaneous attentional capture.
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
5.0 The Central Executive
The functional diagram shows a hypothesized relationship between selective attention
and conscious events. A number of scientists believe that selective attention may be
needed for conscious sensory experiences.
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
6.0 Action
The last elements of the functional diagram involve output: control of voluntary
actions. On the output side, the motor system is proposed to be structured with a
processing hierarchy beginning with general goals, influenced by emotional and
motivational input, proceeding to more specific motor plans and maps.
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
7.0 Consolidation of short-term events into long-term memory
Long-term stores are shown in the functional framework diagram along the bottom,
ranging from perceptual memory to highly practiced habits
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
7.0 Consolidation of short-term events into long-term memory
If information is retained over a period of
seconds to hours, it may become permanent or
‘consolidated’. A good night’s sleep is now
known to facilitate memory consolidation.
In this way, transient, short-term memories
become consolidated into stable, long-term
memories over time.
Short term memories are subject to interference,
probably because they involve active neuronal
circuits in the brain.
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
7.0 Consolidation of short-term events into long-term memory
Long-term memory functions are widely
distributed throughout the brain. According to
the consolidation hypothesis put forward by
Fuster, memories are stored in many different
regions of the brain.
For example, perceptual memory involves
perceptual regions, while executive memory,
such as plans for future actions, engage frontal
regions .
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
Chapter Summary
A broad functional framework for cognitive neuroscience is presented, based
on widely accepted ideas from cognitive psychology
•Immediate memory seems to depend on the medial temporal lobe, including
the two hippocampi. Damage to these regions impairs the ability to transfer
information from the present moment to long-term storage.
•The posterior half of the cortex is involved in sensory processes and probably
also in sensory-perceptual memory.
•The front half of the cortex is involved with motor and executive functions, and
probably also with long-term memory needed for those processes.
Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience
Edited by Bernard J. Baars and Nicole M. Gage
2007 Academic Press
Chapter Summary
•Selective attention has been studied for some fifty years and, in the past 15 years,
the traditional question of conscious experience has again come to the fore
•There is an ongoing debate about the meaning of terms like ‘working memory’,
‘attention’ and ‘conscious experiences’. Such debates are common in science.
•There has been a wealth of new knowledge learned about human cognition and
the brain. It is an intricate business to tease apart these aspects of human thought
and action experimentally.
While the field has made progress in understanding how these areas of cognition
interact, we have far to go before we will have a clear understanding of the dynamic
integrative and interactive processes that underlie the human condition.