Functional Topography

Primary sensory cortex general function

•discriminate qualities of sensory information (basic processing)

Sensory association cortex general function

•complex analysis of sensation from thalamus and primary sensory areas (higher level processing & identifying)

Primary motor cortex general function

selective motor control

Motor planning areas general function

organizes movements

Association cortex general function

controls behavior, interprets sensation, processes emotions and memory

Primary Sensory Areas include

primary somatosensory

primary auditory

primary visual

primary vestibular

Secondary Sensory Areas include

secondary somatosensory

secondary auditory

secondary visual

Motor planning areas include

premotor, supplementary motor, Brocas, Area corresponding to Broca's in the opposite hemisphere

Association cortex includes

Prefrontal

Parietotemporal

Limbic

Primary somatosensory area function

discriminates shape, texture, size of object

Primary somatosensory area lesion

loss of tactile localization and conscious proprioception

(impairs ability to discriminate intensity or assess quality)

Primary somatosensory area lesion -not affected significantly

Crude awareness and thermal stimuli (because it occurs in the thalamus)

Nociception (Pain): information is also processed in sensory association cortex

Primary somatosensory area receives

•Receives tactile, proprioceptive, and pain/temperature

Primary auditory area function

conscious discrimination of loudness and pitch of sounds

Primary auditory area lesion

loss of localization of sounds

Primary auditory cortex location

-lateral fissure on adjacent superior temporal gyrus

Primary auditory cortex receives info from

the cochlea of both ears

Primary auditory cortex

•Low frequency:

•High frequency:

•Low frequency: anterolateral

•High frequency: posteromedial

Primary visual area function

distinguishes intensity of light, shape, size, and location of objects

Primary visual area receives information from

•Receives information from lateral geniculate body (geniculocalcarine tract)

Primary visual area location

-within calcarine sulcus and adjacent gyri

•Upper field of vision: _____ wall of the sulcus

•Lower field of vision: _____ wall of the sulcus

•Upper field of vision: lower wall of the sulcus

•Lower field of vision: upper wall of the sulcus

Primary visual area lesion

homonymous hemianopsia

•blindness of the opposite visual field

Primary vestibular area function

discriminates among head positions and head movements, contributes to perception of vertical

Primary vestibular area location

-posterior to primary somatosensory cortex

Primary vestibular area lesion

change in awareness of head position and movement and perception of vertical (= lateropulsion)

Secondary somatosensory area function

stereognosis (identification of object) and memory of the tactile and spatial environment

Secondary somatosensory area location

-superior aspect of parietal lobe posterior to SI

Secondary somatosensory area lesion

Astereognosis-

inability to discriminate shape and size by touch and the inability to recognize objects by touch

(& cortical neglect)

Secondary visual area function

analysis of motion, color; recognition of visual objects; understanding of visual spatial relationships; control of visual fixation

(& recognition of faces)

Secondary visual area location

surrounds primary visual area

Secondary visual area lesion

–Visual agnosia: inability to recognize objects in the contralateral visual field

–Prosopagnosia: inability to recognize people’s faces – usually associated with bilateral damage to the inferior visual association areas

Secondary auditory area function

classification of sounds (as language, music, or noise)

Secondary auditory area lesion

auditory agnosia (cannot recognize/ differentiate between sounds)

-Destruction of left auditory association cortex: unable to understand speech

-Destruction of right auditory assoc. cortex: unable to interpret noises

primary motor cortex function (generalized)

selective motor control

primary motor cortex function (detailed)

-source of many UMN (CorticoBulbar) & controls contralateral movement (CorticoSpinal)

-Fine movements

-Bilateral projections: upper face and back muscles

motor homunculus

largest area:

smaller:

largest area for hands and face (fine movements) - smaller representation for trunk and proximal limbs (gross motor)

primary motor cortex lesion (general)

paresis, loss of fine motor control, spastic dysarthria (harsh/awkward speech)

primary motor cortex lesion (detailed)

•Contralateral paresis and loss of fractionation of movement

•Complete destruction: cannot voluntarily move contralateral hand, lower face, and/or foot

•Spastic Dysarthria: speech disorder resulting from spasticity of the muscles used for speaking

(damage to UMN> Harsh, awkward speech)

premotor cortex function

control of trunk and girdle muscles, anticipatory postural adjustments

pre motor cortex lesion

apraxia

pre motor cortex location

-anterior to the upper body representation in M1

supplementary motor cortex function

initiation of movement, orientation planning, control of bimanual and sequential movements

supplementary motor cortex lesion

apraxia

supplementary motor cortex location

anterior to the lower body represent in M1

broca's area function

motor programming of speech (usually in the left hemisphere only)

brocas area lesion

Broca's aphasia

Area corresponding to Broca's in the opposite hemisphere function

planning nonverbal communication (& gestures; adjusts tone of voice)

Area corresponding to Broca's in the opposite hemisphere lesion

difficulty producing nonverbal communication

Apraxia

Premotor or supplementary motor damage> inability to perform movement or sequence of movements

Prefrontal location

anterior part of the frontal lobe

Prefrontal functions

self-awareness and executive functions (deciding on a goal, planning how to accomplish, executing the plan, and monitoring execution)

Prefrontal impairments

-Loss of executive functions and divergent thinking

-Apathy, lack of initiative, lack of goal-directed behavior

-Difficulty choosing goals, planning, executing plans, and monitoring plans

-Difficulty conceiving of many possibilities [(uses of a stick)]

-Little effect on intelligence

Parietotemporal functions

•intelligence, problem solving, comprehension of communication, and spatial relationships

Parietotemporal impairments

-Problems with communication, understanding, and directing attention

-Wernicke's aphasia (receptive aphasia): inability to understand written and spoken language

(same place on right hemisphere= deficits in directing attention, comprehension of space, and understanding nonverbal commands)

Limbic functions

•regulates mood (subj. feelings), affect (observable demeanor), and processing memory

Limbic impairments

-Personality and emotional changes

-Damage to orbitofrontal cortex: inappropriate or risky behavior, poor judgement but intact intellect; saying or doing things that are socially unacceptable

Limbic location

-anterior temporal and orbitofrontal/inferior frontal cortex

damage to cortex --> what type of symptoms

"A" words

•Thalamic Injury

-Relay nuclei involvement:

-Relay nuclei involvement: loss of sensation and proprioception

•Thalamic Injury

-Thalamic pain:

-Thalamic pain: involving severe contralateral pain with/without provoking stimulus

•Internal capsule(IC) common injury results from

occlusion or hemorrhage of lenticulostriate vessels supplying IC are common - even small lesion may have severe consequences

Injury to posterior limb of internal capsule results in

-Contralateral loss of voluntary movement

-Contralateral decreased automatic movement control

-Contralateral loss of conscious somatosensation

-Visual & auditory radiations

Basal Ganglia Disorders:

Lenticular dysfunction

-hypokinetic (Parkinson's) to hyperkinetic (Huntington's ds)

Basal Ganglia Disorders:

caudate lesions

•rarely causes motor disorders but does cause behavioral disturbances (e.g. apathy, loss of initiative, loss of spontaneous thought, and loss of emotional response)

•Acute cerebellar infarction:

-dizziness and /or vertigo, lack of balance, nausea, vomiting, dysarthria, HA, Ataxia, Hypotonia

primary somatosensory cortex = # area

3, 1, 2

primary auditory cortex= # area

41

primary vestibular cortex= # area

40

primary visual cortex= # area

17

primary motor cortex = # area

4

supplementary and pre -motor cortex = # area

6

Vascular insufficiency of the cerebral arteries: Anterior Cerebral Artery (ACA)

1. frontal lobe: Change personality / confusion

2. Medial S1 and M1: Contralateral strength and sensory deficits (LE>UE)(result in difficult with bimanual task) + urinary incontinence

3. Deep: putamen (basal ganglia) and anterior limb of IC: Motor dysfunction

4. secondary motor cortex: apraxia

Vascular insufficiency of the cerebral arteries: Middle Cerebral Artery (MCA) deep

striatum and IC (posterior limb):

Hemiparesis / hemisensory -Contralateral strength and sensory deficits

Optic radiation- loss of contralateral field of vision (homonymous hemianopia)

Vascular insufficiency of the cerebral arteries: Middle Cerebral Artery (MCA) superficial

1. ?: sterotyped posture

2. Lateral S1 and M1: Hemiparesis / hemisensory -Contralateral strength and sensory deficits (UE/face>LE)

3. a) Brocas/wernike's (if dominant hemisphere): Aphasia

OR b) alternative (if non dominant): Difficulty with nonverbal communication /spatial relationships

Vascular insufficiency of the cerebral arteries: Posterior Cerebral Artery (PCA)

1. Cerebral peduncle: Contralateral hemiparesis

2. ?= Eye movement

3. Calcarine branches: Blindness affecting contralateral visual field

Deep:

4. hippocampus: declarative memory

5. diencephalon (thalamus): thalamic syndrome

Vascular insufficiency of the cerebral arteries: Watershed area

(where distal cerebral arteries anastomose is vulnerable to ischemia)

· Impairments: upper limb paresis and paresthesias

Vascular insufficiency of the cerebral arteries: Vertebral and Basilar Arteries

· Complete vs partial occlusion:

· Complete occlusion: death (vital functions of the brainstem)

· Partial occlusion: tetraplegia, loss of sensation, cranial nerves signs, and/or coma