THE OCCIPITAL LOBE

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THE OCCIPITAL LOBE
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OL
Function Vision perception of form, movement
and color.

• Separated from parietal lobe by
• Parieto-occipital sulcus.
• Within the OL 3 landmarks
• Calcrine fissure Div. The upper
• and lower halves of the visual
• world.
• Lingual Gyrus V2 VP
• Fusiform Gyrus V4

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Subdivisions of the OL (6 Areas)
OL

• V1
• V2
• V3
• V3A
• V4
• V5

Primary Visual Cortex
Secondary Visual Cortex
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Connections
OL
V1 Largest area, called striate cortex.
Receives the largest input from the LGN and
projects to ALL other occipital regions.
1st processing level.
V2 Also projects to all other occipital areas.
Segregates info from V1.
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2 Pathways into the visual brain
OL
Connections cont

• Geniculo-striate system
• Tecto-pulvinar system

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Dorsal (ParL) How or Where Visual Guidence of
mov.
LGN V1V2
Eye
Ventral (TempL) What Obj. perception recog.
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Beyond the Occ. L
OL
Visual processing in humans does NOT culminate
in the Secondary visual ares (V3, V4, V5) but
continues within multiple visual regions in the
parietal, temporal and frontal lobes.
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Theory of O.L Function
OL
V1 V2 function like mailboxes segregating info
to other areas involved in the perception of
Color/Form/Motion V3 Dynamic form
(dancing) V3A Just form
V4 Color Shape V5 Perception of motion
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Theory of O.L Function Cont
OL
5 Types of visual functions

• Vision for action Visual processing
• required to direct specific
• movements.
• Action for vision Active search of
• the target object. Selective attention.
• Visual Recognition Ventral stream info
• to the temporal lobe specialized in
• recognition of faces
• Grandmother cells

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Theory of O.L Function Cont
OL
5 Types of visual functions

• Visual Space Visual info comes form specific
  location in space.
• Objects have a location relative to an
  individual (egocentric),
• or to one another (allocentric).
• Visual Attention Process of features of the
  visual world (otherwise
• it would be too much!).

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Dorsal Ventral stream functions
OL
Milner Goodale studies Patient DF Blind
but dorsal stream intact, so patient shaped her
hand Appropriately while reaching. Unconsciously
see location size and shape. Patient VK
Ventral stream intact, Can see objects but cant
reach Accurately or shape the hand.
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Symptoms of OL Damage
OL

• Object Agnosia
• a) Apperceptive
• b) Associative

1. Agnosias 2. Monocular Blindness 3. Bitemporal
Blindness
4. Nasal Hemianopia 5. Homonymous Hemianopia
2. Other visual Agnosias Alexia Visual-spatial
agnosia
6. Quadrantanopia 7. Scotoma
Prosopagnosia
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Symptoms of OL Damage Cont
OL

• Object Agnosia
• a) Apperceptive agnosia Cant recognize an
  object although basic
• visual functions (color, motion etc.) are
  preserved. Cant copy or
• match simple objects. Can see one thing at a
  time Simultagnosia.
• Diffuse bilateral lesion in the ventral stream
  in OL.
• b) Associative agnosia Cant recognize objects
  in spite of being
• to perceive them. Subjects can describe the
  object, know what it
• is for, copy it, but cant identify it. Lesion
  in ventral stream in TL.

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OL
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THE PARIETAL LOBE
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v
PL
Function Processes and integrates somatosensory
and visual info with regard to the control of
movement.
Separated from the frontal lobe By the central
fissure, from the Temporal lobe by the
Sylvian Fissure and from the occipital Lobe by
the parieto-occipital Sulcus.
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Subdivisions of the PL
PL

• Within the PL
• Postcentral gyrus (B.A. 1,2,3)
• Par Operculum (B.A. 43)
• Superior Par Lobule (B.A. 5,7)
• Supramarginal gyrus (B.A. 40)
• Angular gyrus (B.A. 39)

Anterior Zone Includes Postcentral gyrus and
Par Operculum Called Somatosensory cortex.
Processes Somatic sensation and
perception. Posterior Zone Includes Superior
Par Lobule, supramarginal angular areas.
Called Posterior Parietal Cortex. Processes
control of movement with somatic and visual info.
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Connections
PL
1. The somatosensory cortex projects to PE,
primary motor cortex, Supplementary and premotor
areas. For tactile recognition, sensory info
about limb position in the control of movement.
von Economos maps 3 PP areas PE, PF, PG
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Connections cont
PL
2. PE output to M1 to guide movement with tactile
information, input from S1 (1,2,3). 3. PF output
to M1 to guide movement with tactile and visual
info input from S1 through PE. 4. PG output to
FL. Main dorsal stream, vision for action control
of spatially guided behavior. Input from
visual, somesthetic, proprioceptive, auditory,
vestibular, oculomotor and cingulate.
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Connections cont
PL
5. PG output to paralimbic for memory of
movements 6. PG PF output to PFC for STM of
visual guided movements. 7. PG output to temporal
for processing the shape of objects
So, the APC processes somatic sensation and
perception and the PPC integrates sensory input
from the somatic and visual regions for the
control of movement.
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Theory of P.L Function
PL
There must be a spatial (internal) representation
of things. There is a map or several maps that

• Make movements to different objects
• Discriminate similar objects
• Make movements relative to body position
• Order the movements
• Attend to some objects and ignore others

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Somatosensory symptoms(anterior zone, areas
1,2,3,43)
PL

• Somatosensory thresholds

2. Perceptual Disorders

• 3. Blind touch
• Somatosensory agnosias

2. Simultaneous Extinction objects can only be
perceived if presented one at a time RgtL
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PL
Posterior Parietal Symptoms(PE, PF, PG)
7. Recall deficits 8. Acopia 9. Spatial
Attention 10. Spatial Cognition 11. Attentional
shift for action

• Balints syndrome
• Contralateral neglect

3. Object recognition
4. Gerstmann syndrome 5. Language deficits
12. Mental imaging
6. Apraxia a. Ideomotor b. Constructional
Neglect follows a RPPLx because the
integration of the spatial properties of stimuli
becomes disturbed. Although stimuli are
perceived, their location is uncertain to the
CNS ignore it.
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PL
Neuropsychological Assessment
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THE TEMPORAL LOBE
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TL
Function Processes visual and auditory
information, and integrates them for emotion,
spatial navigation and spatial and
object recognition.
Includes all the tissue that lies below the
Sylvian sulcus and anterior to the OL. Includes
subcortical structures limbic cortex, amygdala,
and hippocampus.
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Subdivisions of the TL
TL

• Within the TL
• Superior Temporal Gyrus multimodal
• receiving inputs from auditory, visual
• and somatic regions as well as from
• the FC, PC and paralimbic cortex.

• Middle Temporal Gyrus (Limbic
• cortex). Includes the amygdala, uncus,
• hippocampus, subiculum, entorhinal
• and perirhinal cortices and the
• fusiform gyrus.

• Inferior Temporal Gyrus (Visual
• regions). Includes the fusiform
• gyrus, called TE.

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Connections
TL
The TL receives afferents from the sensory
systems, and sends efferents to parietal,
frontal, limbic system and basal ganglia. 5
distinct types of cortico-cortical connections
1. Hierarchical sensory pathway From primary and
secondary visual and auditory areas. Ventral
stream. For stimulus recognition.
2. Dorsal auditory pathway From auditory areas
to PPC. For detecting spatial localization of
auditory inputs.
3. Polymodal Pathway parallel projections from
the visual and auditory association areas
into the STS. For stimulus categorization.
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TL
Connections cont
4. Medial Temporal projection from the visual
and auditory association areas into the
medial temporal or limbic. Called perforant
pathway. For long term memory.
AA perirhinal entorhinal hippocampus
amygdala
5. Frontal lobe projection from the visual and
auditory association areas into the FL. For
movement control and short term memory.
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Theory of TL Function
TL

• On the basis of cortical anatomy 3 basic sensory
  functions
• Processing of auditory input
• Visual object recognition
• Long term storage of sensory input (memory)

• The TL is a WHAT system for auditory and visual
  info that is going to
• Identify
• Categorize
• Store
• Give affect

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Theory of TL Function cont
TL
The STS and biological motions species typical
movements, necessary for social perception. E.g.
dogs sniffing each others butt
The STS analyzes these type of movements.
Necessary for social Cognition the development
of hypotheses about the intentions of other Ss.
Theory of Mind
Ss with RTL cant do theory of Mind and their
personalities are sticky egocentric
and negative.
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Symptoms of TL Damage
TL

• Disturbance of auditory sensation and perception
• Disorders of music perception
• Disorders of visual perception
• Disorders in the selection of visual and auditory
  input
• Impaired organization and categorization of
  sensory input
• Inability to use contextual information
• Impaired LTM
• Altered personality and affective behavior
• Altered sexual behavior

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Symptoms of TL Damage cont
TL
1. Disturbance of auditory sensation and
perception
Formants Frequency or sound waves specific
to each vowel sound. Ba Ga Da Context
Duck and deer we perceive it as the same
although the formant is different. Speed
Language is fast, we categorize the sounds
A. Language
Left TLLx more affected
2. Disorders of music perception
The brain has neural networks dedicated to the
processing of language and music both are
biological processes. Proof neanderthal flute,
infants have preferences for music, congenital
amusia (tone deafness). RTLLx more affected, RTL
is necessary to distinguish melodies.
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TL
Neuropsychological Assessment