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SUMMARY PART 2: Fundamentals of human Neuropsychology
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Kolb & Whishaw (2015). Fundamentals of human Neuropsychology (7th edition). PART 2: Chapters 15, 16, 18, 19, 20, 21, 23, 24, 25, 26, 27, 28.
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Kolb & Whishaw (2015). Fundamentals of human Neuropsychology (7th edition).PART 2: Chapters 15, 16, 18, 19, 20, 21, 23, 24, 25, 26, 27, 28
Chapter 15: The temporal lobes
15.1 Anatomy of the Temporal Lobe
The temporal lobe comprises all the tissue that lies below the lateral (Sylvian) fissure and anterior to the
occipital cortex. Subcortical temporal- lobe structures include the limbic cortex, the amygdala, and the
hippocampal formation. Connections to and from the temporal lobe extend throughout the brain.
Subdivisions of the Temporal Cortex
We can divide the temporal regions on the lateral surface into those that are auditory (Brodmann’s areas
41, 42, and 22 in Figure 15.1B) and those that form the ventral visual stream on the lateral temporal lobe.
The visual regions are often referred to as inferotemporal cortex. The superior temporal sulcus (STS)
separates the superior and middle temporal gyri and contains a significant amount of neocortex as well.
The medial temporal region (limbic cortex) includes the amygdala and adjacent cortex (uncus), the
hippocampus and surrounding cortex (subiculum, entorhinal cortex, perirhinal cortex), and the fusiform
gyrus Cortical areas TH and TF at the posterior end of the temporal lobe are often referred to as the
parahippocampal cortex. The fusiform- and inferior temporal gyrus are part of the lateral temporal cortex
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,Connections of the Temporal Cortex
The temporal lobes are rich in internal connections, afferent projections from the sensory systems, and
efferent projections to the parietal and frontal association regions, limbic system, and basal ganglia. The
neocortex of the left and right temporal lobes is connected by the corpus callosum, whereas the medial
temporal cortex and amygdala are connected by the anterior commissure. Here, we list the different
functions that each projection pathway presumably subserves:
1. A hierarchical sensory pathway. This pathway subserves stimulus recognition. The hierarchical
progression of connections emanates from the primary and secondary auditory and visual areas,
ending in the temporal pole
2. Adorsal auditory pathway. Projecting from the auditory areas to the posterior parietal cortex
3. A polymodal pathway. This pathway is a series of parallel projections from the visual and auditory
association areas into the polymodal regions of the superior temporal sulcus.
4. A medial temporal projection. Crucial to long-term memory, the projection from the auditory and
visual association areas into the medial temporal, or limbic, regions goes first to the perirhinal cortex,
then to the entorhinal cortex, and finally into the hippocampal formation or the amygdala or both. The
hippocampal projection forms the perforant pathway. A disturbance of this projection results in a
major dysfunction in hippocampal activity.
5. A frontal-lobe projection. This series of parallel projections, necessary for various aspects of
movement control, short-term memory, and affect, reaches from the temporal association areas to
the frontal lobe.
15.2 A Theory of Temporal-Lobe Function
On the basis of the cortical anatomy, we can identify three basic sensory functions of the temporal cortex:
1. Processing auditory input
2. Visual object recognition
3. Long-term storage of sensory input—that is, memory
Sensory Processes
Object recognition is the function of the ventral visual pathway in the temporal lobe. Developing object
categories is crucial to both perception and memory and depends on the inferortemporal cortex.
Categorization may require a form of directed attention, because certain characteristics of stimuli likely
play a more important role in classification than do others. The process of matching visual and auditory
information is called cross-modal matching. It likely depends on the cortex of the superior temporal
sulcus. Damage to the temporal cortex leads to deficits in identifying and categorizing stimuli.
Affective Responses
Your affective response is a function of the amygdala. Associating sensory input and emotion is crucial for
learning, be- cause stimuli become associated with their positive, negative, or neutral consequences, and
behavior is modified accordingly. In the absence of this affective system, all stimuli would be treated
equivalently.
Spatial Navigation
When you change routes and go elsewhere, you use the hippocampus, which contains cells that code
places in space. Together, these cells allow you to navigate in space and to remember where you are. As
we consider these general functions of the temporal lobes—sensory, affective, and navigational—we can
see that losing them has devastating consequences for behavior: an inability to perceive or to remember
events, including language and a loss of affect.
The Superior Temporal Sulcus and Biological Motion
As already mentioned, the STS receives multimodal inputs that play a role in categorizing stimuli. A major
category is social perception, which includes the analysis of actual or implied bodily movements that
provide socially relevant in- formation. This information plays an important role in social cognition, or
“theory of mind,” that allows us to develop hypotheses about other people’s intentions.
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,An important correlate of mouth movements is vocalization, and so we might predict that regions of the
STS are also implicated in perceiving species- typical sounds. We could predict activation in some part of
the superior temporal sulcus in response to the combination of the visual stimulus (mouth movements)
and talking or singing. We could predict that, if people have temporal-lobe injuries that lead to impairments
in analyzing biological motion, there is likely to be a correlated deficit in social awareness.
Visual Processing in the Temporal Lobe
The ventral stream of visual processing is performed by several discrete visual regions including
specialized facial and object-recognition zones. Investigators allowed subjects to freely view a 30-minute
segment of a feature film, The Good, The Bad, and The Ugly, while cortical activity was monitored by
fMRI. Research found the following results:
1. Extensive activity throughout the entire temporal lobe was highly correlated across subjects.
2. Although there was a general activation of the temporal cortex during the film clip, there were
selective activations related to the precise moment-to-moment film content.
3. Regions of the parietal and frontal lobes showed no intersubject coherence
The selective activation of FFA and PPA related to categories of visual stimulation that include very
different exemplars of the specific categories leads us to wonder how such dissimilar objects are treated
equivalently by specialized cortical regions. Not only are different views of the same object linked together
as being the same, but different objects appear to be linked together as being part of the same category
as well.
Are Faces Special?
The importance of faces as visual stimuli has led
to the idea that a special pathway exists in the
visual system for the analysis of faces.
The face-perception system is surprisingly
extensive and includes regions in the occipital lobe
as well as several different regions of the temporal
lobe.
The model also includes other cortical regions as
an “extended system” that includes the analysis of
other facial characteristics such as emotion and lip
reading. The key point here is that the analysis of
faces is unlike that of other visual stimuli.
A clear asymmetry exists in the role of the
temporal lobes in the analysis of faces. Right
temporal lesions have a greater effect on facial
processing than do similar left temporal lesions.
Even in normal subjects, researchers can see an
asymmetry in face perception.
Auditory Processing in the Temporal Lobe
Many cells in the auditory cortex respond to
specific frequencies, often referred to as sound
pitches or to multiples of those frequencies. Two
of the most interesting sound types for humans are language and music.
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,Speech Perception
Speech differs from other auditory input in three fundamental ways:
1. Speech sounds come largely from three restricted ranges of frequencies, which are known as
formants.
2. The same speech sounds vary from one context in which they are heard to another, yet all are
perceived as being the same.
3. Speech sounds change very rapidly in relation to one another, and the sequential order of the sounds
is critical to understanding.
Music Perception
Music is fundamentally different from language because music relies on the relations between auditory
elements rather than on individual elements. Musical sounds may differ from one another in three aspects:
1. Loudness refers to the magnitude of a sensation as judged by a given person. Loudness, although
related to the intensity of a sound.
2. Timbre refers to the distinctive character of a sound, the quality that distinguishes it from all other
sounds of similar pitch and loudness.
3. Pitch refers to the position of a sound in a musical scale, as judged by the listener. Pitch is clearly
related to frequency, the vibration rate of a sound wave.
Frequence and pitch. The ability to determine pitch from the overtones alone is probably due to the fact
that the difference between the frequencies of the various harmonics is equal to the fundamental
frequency. An important aspect of pitch perception is that, although we can generate (and perceive) the
fundamental frequency, we still perceive the complex tones of the harmonics. This pitch is referred to as
spectral pitch. The primary auditory cortex of the right temporal lobe appears to make this periodicity-pitch
discrimination.
Rhythm.Timing is a critical component of music, and two types of time relations are fundamental to the
rhythm of musical sequences: the segmentation of sequences of pitches into groups based on the
duration of the sounds and the identification of temporal regularity, or beat, which is also called meter.
Music memory. Music is more than the perception of pitch, rhythm, timbre, and loudness, however. Peretz
and Zatorre reviewed the many other features of music and the brain, including music memory, emotion,
performance (both singing and playing), music reading, and the effect of musical training. The contribution
of memory to music processing is crucial because music unfolds over time for us to perceive a tune.
Although injury to either temporal lobe impairs the learning of melodies, the retention of melodies is more
affected by right temporal injury. Although both hemispheres take part in the production of music, the role
of the right temporal lobe appears to be generally greater in producing melody and that of the left temporal
lobe appears to be generally greater in rhythm
Music and brain morphology. The gray-matter differences are positively correlated with musical aptitude:
the greater the aptitude, the larger the gray-matter volume.
Asymmetry of Temporal-Lobe Function
The temporal lobes are sensitive to epileptiform abnormalities, and surgical removal of the abnormal
temporal lobe is often of benefit in treating epilepsy. Although the left and right temporal lobes are
relatively specialized in their functions, do not be overly impressed by the apparent functional asymmetry.
Substantial functional overlap is revealed in the relatively minor effects of unilateral temporal lobectomy, a
striking result considering that such a large zone of the cerebral hemispheres is removed.
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,15.3 Symptoms of Temporal-Lobe Lesions
Nine principal symptoms are associated with disease of the temporal lobes: (1) disturbance of auditory
sensation and perception, (2) disorders of music perception, (3) disorders of visual perception, (4)
disturbance in the selection of visual and auditory input, (5) impaired organization and categorization of
sensory input, (6), inability to use contextual information, (7) impaired long- term memory, (8) altered
personality and affective behavior, and (9) altered sexual behavior.
Disorders of Auditory and Speech Perception
Damage to the primary visual or somatic cortex leads to a loss of conscious sensation; so it is reasonable
to predict that bilateral damage to the auditory cortex will produce cortical deafness, an absence of neural
activity in the auditory regions.
The auditory cortex plays a role in discriminating two forms of auditory processing—namely, rapidly
presented stimuli and complex patterns of stimuli. Impaired auditory processing reveals the difficulty that
temporal-lobe patients have in discriminating speech sounds. The problem is not just in discriminating the
speech sounds, however, but also in judging the temporal order in sounds heard.
The fact that left-temporal-lobe lesions alter the perception of speech sounds ought not to be surprising:
since the time of Wernicke, lesions of the left temporal association cortex (primarily area 22) have been
known to pro- duce aphasia
Disorders of Music Perception
Although it is tempting to compartmentalize music and language on opposite sides of the brain, in fact,
only certain characteristics of musical and language input are analyzed selectively by the two
hemispheres. Zatorre emphasized the key difference: the left hemisphere is concerned more with speed
and the right hemisphere with distinguishing frequency differences, a process called spectral sensitivity.
That the brain appears to have neural networks dedicated to processing language and music leads to the
conclusion that both language and music have biological roots. Although this conclusion seems obvious
for language, it is less obvious for music, which has often been perceived as an artifact of culture. But
considerable evidence suggests that humans are born with a predisposition for processing music.
Disorders of Visual Perception
Although persons with temporal lobectomies do not normally have large defects in their visual fields, they
do have deficits in visual perception. Although patients with right temporal lesions can describe the
contents of the cartoon accurately, they are impaired at recognizing the anomalous aspects of this picture
and others.
One of the most interesting visual perceptual deficits is in facial perception and recognition. They found
that those with right-temporal-lobe resections fail to show a bias for that part of the face falling in the
left visual field, suggesting that these patients perceive faces abnormally.
Disturbance of Selection of Visual and Auditory Input
We must select which inputs to process from the wealth of information in our environment. This selectivity
is generally not conscious, because the nervous system automatically scans input and selectively
perceives the environment. In regard to visual input, however, it is noteworthy that right temporal lesions
produce bilateral deficits, whereas left temporal lesions produce unilateral ones. This difference implies
that the right temporal lobe may have a greater role than the left in selective attention to visual input.
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,Impaired Organization and Categorization
The ability to organize material is especially important for language and memory. Organization of sensory
input appears to be a function of the temporal lobes. Patients with left temporal lobectomies are impaired
in their ability to categorize even single words or pictures of familiar objects. Patients with posterior
temporal lesions may show dysphasic symptoms in which they can recognize the broader categorization
but have difficulty with the more specific ones.
Inability to Use Contextual Information
The meaning of identical stimuli can vary, depending on context. The interpretation of events, and indeed
our role in events, depends on the social context. Thus, stimuli may be interpreted in one way when we
are with our parents and in a different way when we are with our peers.
Memory impairments
Damage to the inferotemporal cortex specifically interferes with conscious recall of information, the extent
of the memory disturbance increasing in direct proportion to the amount of temporal-lobe damage. Lesions
of the left temporal lobe result in impaired recall of verbal material, such as short stories and word lists,
whether presented visually or aurally; lesions of the right temporal lobe result in impaired recall of
nonverbal material, such as geometric drawings, faces, and tunes.
Altered Affect and Personality
Temporal-lobe epilepsy has traditionally been associated with personality characteristics that
overemphasize trivia and the petty details of daily life. Symptoms of this personality include pedantic
speech, egocentricity, perseveration in discussions of personal problems (sometimes referred to as
“stickiness,” because one is stuck talking to the person), paranoia, preoccupation with religion, and
proneness to aggressive outbursts (Pincus and Tucker, 1974). This constellation of behaviors produces
what is described as temporal-lobe personality, although very few people combine all these traits.
Similar personality traits arise after temporal lobectomy. There appears to be a relative asymmetry in the
symptoms, with right temporal lobectomy more likely to be associated with these personality traits than left
temporal lobectomy.
Changes in Sexual Behavior
A classic symptom of bilateral temporal-lobe damage that includes the amyg- dala is a release of sexual
behavior.
15.4 Clinical Neuropsychological Assessment of Temporal-Lobe Damage
A number of standardized assessment tools have
proved sensitive and valid predictors of temporal-
lobe injury:
Auditory- and visual-processing capacity can
be assessed by using dichotic listening and
the McGill Picture-Anomalies Test.
The best test of general verbal-memory ability
is the revised Wechsler Memory Scale.
The Rey Complex-Figure Test has proved one of the best for evaluating nonverbal memory function
of the right temporal lobe.
A deficit in language comprehension could be the result of a lesion in any of the language zones of
the left hemisphere (that is, in the parietal, temporal, or frontal lobes). No current neuropsychological
assessment tool can localize the area of damage within the left hemisphere. For this reason, we once
again recommend the Token Test as the test of choice for language comprehension.
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,Chapter 16: The frontal lobes
16.1 Frontal-lobe Anatomy
Controlling our behavior in response to the social or
environmental situation requires considerable skill. The
frontal lobe can perform such a function only if it is
provided with all the relevant sensory and mnemonic (that
is, memory) information.
Subdivisions of the Frontal Cortex
In the human brain, the frontal lobes include all the tissue
anterior to the central sulcus. This vast area, constituting
20% of the neocortex, is made up of several functionally
distinct regions that we group into four general categories:
primary motor, premotor and anterior cingulate.
Primary Motor cortex
Primary Motor Cortex (MI): specifies elementary movements,
such as those of the mouth and limbs, movement force and
direction. It cells project to subcortical motor structures such as
the basal ganglia and the red nucleus as well as to the spinal
cord.
Premotor cortex
Premotor cortex (PM): includes a dorsal region called the
supplementary motor cortex and, lying below it, three major
premotor sectors: the dorsal and ventral premotor cortex and
inferior frontal gyrus (Broca’s area). The premotor regions are
connected to areas concerned with the execution of limb
movements. The premotor areas can influence movement
directly through corticospinal projections or indirectly through
projections to the motor cortex.
Prefrontal cortex
Prefrontal cortex (PFC): receives significant input from the
mesolimbic dopamine cells in the tegmentum. This input plays
an important role in regulating how prefrontal neurons react to
stimuli, including stressful stimuli. The prefrontal cortex can be
divided into three regions (refer to Figures 16.1 and 16.2): (1)
dorsolateral prefrontal cortex (areas 9 and 46); (2) inferior
(ventral) prefrontal cortex (areas 11, 12, 13, and 14); and (3)
medial frontal cortex (areas 25 and 32).
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, The connectome and the frontal cortex
Frontal lobe regions are
central to many cortical
networks. Most studied is
de brain’s default network,
which links a set of far-flung
brain regions active in
participants who are resting
rather than engaging in
specific cognitive tasks.
The prefrontal cortex is also
a major participant in many
cortical networks involved in
emotional behaviors. The
ventromedial region plays a
active role in these network,
and mood disorders result
in abnormal activity in these
regions.
16.2 A Theory of Frontal-Lobe Function
You are working under a time constraint because you must return home be- fore your guests arrive and
you need time to prepare. Because the items that you need are not all at the same store, you must make
an efficient plan of travel. You also must not be distracted by stores selling items (such as shoes) that you
do not need or by extended chats with store clerks or friends whom you might encounter.
The task that you have set yourself is a bit rushed but, for most people, it offers little challenge. People
with frontal-lobe injury, however, cannot manage it. The fundamental requirements of the task that
challenge frontal-lobe patients are:
Planning in advance and selecting from many options
Ignoring extraneous stimuli and persisting in the task at hand
Keeping track of the stores to which they have gone and the items that they have already
purchased
The premotor and prefrontal regions contribute in different ways to this control function, and so we will
consider them separately.
Functions of the Premotor Cortex
Whereas the motor cortex provides a mechanism for executing individual movements, the premotor cortex
selects the movements to be executed. The premotor region functions primarily choose behavior in
response to external cues and the supplementary motor region makes a greater internal contribution when
no such cues are available. Not only are motor acts paced by cues, but they also can become associated
with cues. For example, to drive safely, we must learn that red means stop and green means go. When
subjects are trained on such arbitrary associations in an fMRI paradigm, there is an increase in functional
activity in the premotor cortex
Functions of the Prefrontal Cortex
The motor cortex is responsible for making movements. The premotor cortex selects movements. The
prefrontal cortex controls cognitive processes so that appropriate movements are selected at the correct
time and place. This se- lection may be controlled by internalized information or by external cues or it may
be made in response to context or self-knowledge
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