Cerebral Cortex and Diencephalon

Association

connect with different parts of the brain in the same hemisphere

Commissural

Ru between hemispheres

Ex: corpus callosum

Projection fibers

connect cortex with different parts of the CNS

ex: internal capsule

Brodmann’s Area

DO NOT MEMORIZE NUMBER FOR TESTING PURPOSES

What is the 2 main functions of the Frontal lobe?

Controlling voluntary movement and thinking/problem solving

Brocas area

Primary cortex (4) of the frontal lobe

located on precentral gyrus

control voluntary movements on the contralateral side

related tracts: corticospinal and corticobulbar

lesion: paralysis of the contralateral side of the body and muscles of facial expression on the bottom portion of the face

Motor Homunculus “little man”

Premotor cortex (6) of frontal lobe

Located just anterior to primary motor cortex

control action of trunk and limb muscles

“Body part ownership”

related tracts: reticulospinal and vestibulospinal

lesion: unilateral neglect

Supplementary motor area (8) of frontal lobe

located medial to the premotor cortex

stores motor memories, directs activity of primary motor cortex

lesion: apraxia, motor planning deficit

Broca’s Area (44)

Ataxia

uncoordinated movement that manifests when voluntary movements are attempted; may influence gait, posture and patterns of movemetn

often related to cerebellar lesion

Apraxia

Orbitofrontal cortex frontal lobe(11, 47)

contains area for impulse control, inhabitation in appropriate behaviors and carrying out plans

lesion: pt can’t make realistic plans, or carry out plans they make. tend to have trouble with focus, organization and inhibition of impulses (prefrontal syndrome)

Ventromedial Frontal Cortex (11, 12, 25) of frontal

part of limbic system

connects emotions with thought, attaches emotional meaning to life experiences

lesion: flat emotional affect

underactive in people with depression and overactive in people with mania

Anterior cingulate gyrus (24, 32) of frontal lobe

part of limbic system

helps integrate thought, motivation, attention and behavior

allows a person to “tune” into their own thoughts

What is the function of the parietal lobe

perception and processing of sensation

Somatosensory cortex (3,1,2)

located on the postcentral gyrus

perceives sensations such as pain, temperature, pressure, touch, vibration and proprioception

sensory homunculus

Somatosensory Association (5,7)

responsible for interpretation of somatosensory information

stereognosis: the ability of someone to recognize an object by touching it

disorders of body image, such as anorexia nervosa and unilateral neglect, are linked to dysfunction in this area

Parietotemporal association cortex (40)

Abstract thought, reasoning, reading and writing, mathematics and spatial perception

Angular gyrus (39)

understanding written language

Function of the occipital lobe

visual perception

Primary visual cortex (17)

visual perception

lesion: loss of vision in the opposite visual field (hemianopsia)

visual association cortex (18,19)

located anterior to primary visual cortex

interpreting visual stimuli

lesion: pt can see objects or faces but not recognize (visual agnosia)

Functions of the temporal lobe

contains portions of the limbic system (emotion, memory), auditory system, olfactory system, area for recognizing faces

Primary auditory cortex (41)

sound is perceived

auditory cortex on each side get input from both ears

Auditory association cortex (42)

located posterior to the primary auditory cortex

responsible for interpretation and understanding of sounds

Wernicke’s area (22)

understanding language (verbal, sign and written)

usually located only on left side

lesion: receptive aphasia

Receptive aphasia

unable to understand any form of language

can’t speak fluidly, but what they say doesn’t make sense

Global aphasia

expressive aphasia + receptive aphasia

inferotemporal lobe (21)

recognition of faces, objects, colors

lesion: pt’s can’t recognize faces of people they know (prosopagnosia)

• it is an early sign of Alzheimer’s disease

olfactory cortex

on the medial part of the temporal lobe

responsible for perceiving odor

lesion: loss of sense of smell (anosmia)

Amygdala

medial side of temporal lobe

involved in strong negative emotion

connections to the hypothalamus

hippocampus

medial side of temporal lobe

involved in creation of new long-term memories

lesion: if lesion is (B) pt will not be able to create new long-term memories and have anterograde amnesia

can generate new neurons throughout life

Think about 50 first dates (movie)

Diencephalon

located just above the brainstem

4 components:

thalamus, hypothalamus, epithalamus, and subthalamus

Thalamus

right and left thalami are located on either side of the 3rd ventricle

almost all information that reaches the cortex passes through thalamus first

• pain, temperature, pressure, touch, auditory, visual taste and vestibular sensations synapse in thalamus before cortex

Relay nuclei

6 relay nuclei receive info from a specific area of the nervous system and send the info to the cerebral cortex

• 2 generals sensory (receive from contralateral side of the body)

• 2 special sensory (visual and auditory)

• 2 motor

association nuclei

receive action potentials from CNS

send projections to limbic regions of the cortex where they connect sensory input to emotional response

ex: fear aroused with a particular touch or smell

intralaminar nuclei

have reciprocal connections with the basal ganglia and the limbic system

send projections to area of the cortex. many interconnections

involved in maintaining conscious awareness

lesions may cause coma

reticular nucleus of thalamus

narrow band of cells anterior and lateral to the thalamus

function is to determine which signals will be conveyed to the cerebral cortex

controls the activity of relay nuclei

CLINICAL REFERENCE

thalamic syndrome

Hypothalamus

*Central autonomic fibers

basic life function

pituitary gland (hypophysis)

has widespread effects of pituitary hormones all over the body

epithalamus

subthalamus

contains subthalamic nucleus

part of basal ganglia circuitry