cerebral cortex - physiology

KSMU – KURSK MEDICAL UNIVERSITY

CEREBRAL CORTEX

Physiology – MedicineGuilherme Paschoalini

PHYSIOLOGIC ANATOMY OF THE CEREBRAL CORTEX

• The functional part of the cerebral cortex is a thin layer of neurons covering the surface of all the convolutions of the cerebrum

• Types of cells:

Granular; Fusiforme;

Pyramidal

RELATIONS OF THE CERERAL CORTEX TO THE THALAMUS

Cortex operates in close association with the Thalamus (Thalamocortical System) and when the thalamic connections are cut, the functions of the corresponding cortical area become almost entirely lost.

FUNCTIONS OF SPECIFIC CORTICAL AREAS

Motor Areas•Primary motor areas: Have direct connections with specific muscles for causing discrete muscle movements

Sensory Areas•Primary sensory areas: Detect specific sensations (visual, auditory, or somatic)

Secondary areas make sense out of the signals in the P. areas

ASSOCIATION AREAS Association areas because they receive and analyze signals from

multiple regions of the cortex. The most importat association areas are:

Parieto-occipitotemporal association area Prefrontal association area

Limbic association area

PARIETO-OCCIPITOTEMPORAL ASSOCIATION AREA

Provides a high level of interpretative meaning for signals from all the surrounding sensory areas

o Analysis of the Spatial Coordinates of the BodyProvides continuous analysis of the spatial coordinates of all parts of the body as well as of the surroundings of this body

o Area for Language ComprehensionThe most important region for higher intelectual function because almost all such intellectual functions are language based.

o Area for Initial Processing of Visual Language – ReadingMake meaning out of the visually perceived words

o Area for Naming Objects

PREFRONTAL ASSOCIATION AREA Important for elaboration of thoughts and is also essential to carrying out

thoughts processes in the mind

• Broca’s Area: Provides the neural circuity for word formation and work witth close association with Wernicke’s area

Limbic Association AreaIt is concerned primarily with behavior, emotions, and motivations

WERNICKE’S AREA – GENERAL INTERPRETATIVE AREA

Highly developed in the dominant side It plays the greatest single role in comprehension levels of brain functions that

we call intelligence After demage in Wernicke’s area the person turn be unable to arrange words

into a coherent thought

Angular GyrusLying behind Wernicke’s areaAnd fusing posteriorly into visualAreas of the occipital lobe Dyslexia

CONCEPT OF THE DOMINANT HEMISPHERE

The general interpretative functions of Wernicke’s area and the angular gyrus, as well as the functions of the speech and motor control areas, are usually much more highly developed in one cerebral hemisphere – Dominant Hemisphere

95% of all people – left dominant hemisphere

Corpus Callosum – Communication between the two hemispheres

FUNCTIONS OF THE PARIETO-OCCIPITOTEMPORAL CORTEX IN THE

NONCOMINANT HEMISPHERE Nondominant hemisphere may be especially important for

understanding and interpreting music, nonverbal visual experiences, the significance of body language, and intonation of the people’s voice

EMOTION LOGIC

FUNCTION OF THE BRAIN IN COMMUNICATION

Two aspects to communication: 1 Sensory Aspect (Language input) - Ears and eyes

2 Motor Aspect (Language output) - Vocalization

o Sensoryo Destruction of portions of the auditory or visual association areas can result in

inability to understand the spoken word or the writen word – Auditory receptive aphasia and visual receptive aphasia (dyslexia)

o Understand either the spoken or writen word but are unable to interpret the thought that is expressed – Wernicke’s Aphasia

o Motoro Word’s formation in the mind Motor control of vocalizationo Loss of Boca’s Area – Motor Aphasia – Able of deciding what to say but

cannot make the vocal system emit words

Cortical Interpretation

1 - Speak a word written

2 – Speak a word read

THOUGHTS, CONSCIOUSNESS, AND

MEMORY

• ThoughtsA thought results from a ‘pattern’ of stimulation of many parts of the nervous system at the same time, probably involving most importantly the cerebral cortex, thalamus, limbic system, and upper reticular formation of the brain stem

• ConsciousnessCan be describe as our continuing stream of awareness of either our surroundings or our sequencial thoughts

• Memory• Changing the basic sensitivity of synaptic transmission• The greater share of our memories are negative • Negative memory: Our brain is inundated with sensory information

from all our senses – The brain has the cability to ignore information – Result from inhibition of the synaptic pathways – Effect called habituation

• Positive memory – Storing memory – Facilitation of the synaptic pathways = MEMORY SENSITIZATION

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