Disorders of higher cerebral function Zhou Saijun周赛君周赛君, Department of Neurology, the First Affiliated Hospital of Wenzhou Medical Universitycognition functionour ability to perform complex intellectual behaviors such as speaking and writing navigating our way around our environment recognizing other people comprehending time Cerebral hemisphereCerebellumBrain stemdominant hemisphere The side of the brain that controls writing and speech is called the dominant hemisphere and the other side is the non-dominant hemisphere.The left hemisphere is dominant in over 90% of right-handed people and in about 60% of left-handed people . FRONTAL LOBE1.primary motor cortexthis is located in the percentral gyrus and is concerned with motor function of the opposite side of the body Supplementary motor and premotor corticesthese areas are concerned with coordinating and planning complex movements .Symptoms from lesions of the motor cortexcontralateral mono-or hemiparesis and facial weakness Supplementary motor and premotor cortices disorders of complex motor planning.2. Brocas area the motor or expressive centre for the productions of speech (dominant hemisphere only ).Symptoms from lesions of the Brocas area expressive dysphasia :This comprises non-fluent, hesitant speech with intact comprehension.The patient knows what he or she wants to say but has difficulty finding the correct words ,often producing the wrong word. The ability to repeat words is better than spontaneous speech. Handwriting is also often poor.3.Prefrontal cortexthe anterior and orbital parts of the frontal cortex govern personality ,emotion, initiative and the ability to plan.Symptoms from lesions of the Prefrontal cortex causes altered behaviors, including :social disinhibition loss of initiative and interestinability to solve problems with loss of abstract thought impaired concentration and attention without intellectual or memory decline 4.The cortical micturition centre this region lies in the paracentral lobule and is involved in the cortical inhibition of voiding of the bladder and bowel.Symptoms from lesions of the cortical micturition centre Incontinence of urine and/or faeces Milder symptoms are frequency and urgency of micturition5.Frontal eye fieldthis is involved in making eye movements to the contralateral side.Symptoms from lesions of the Frontal eye fieldgaze paresis impairment of eye movements to the contralateral side.This is most commonly seen in a large middle cerebral artery stroke and carries a worse prognosis.rightward gazePARIETAL LOBE1.Primary somatosensory cortex located in the postcentral gyrus concerned with perceiving complex somatosensory stimuli from the contralateral side of the face and bodySymptoms from lesions of the Primary somatosensory cortex Discriminative sensory impairment of the opposite side of the face and limbs 3. Use of numbers, e.g. calculation( dominant hemisphere)Gerstmanns syndromeinability to differentiate the right and left sides of the body, inability to distinguish the fingers of the hands(finger agnosia),impairment of calculation (dyscalculia) impairment of writing (dysgraphia).dominant hemisphere4.Integration of sensoryIntegration of somatosensory ,visual,and auditory information this allows awareness of the body and its surroundings appropriate movement of the body, and constructional ability. Symptoms from lesions of the parietal lobeApraxiathe dominant parietal lobe Bilateral ideomotor and ideational apraxia: the non-dominant parietal lobe Constructional apraxia Dressing apraxia Apraxia(the dominant parietal lobe )inability to carry out a sequence of tasks when there is normal comprehension and intact motor and sensory function Ideomotor apraxia occurs when a patient fails to copy an action, ideational or conceptual apraxia is more profound ,e.g.the patient fails to understand use of tools and objects at a basic level.Symptoms from lesions of the parietal lobeTopographical disorientationthe patient cannot find his or her way around normally familiar spaces e.g.home.Symptoms from lesions of the parietal lobeContralateral sensory inattention: neglect of the opposite side of the body For example ,a hemiplegic patient may ignore the paralysed side or there may be denial of the hemiplegia(anosognosia).TEMPORAL LOBE1. Wernickes areain the posterior part of the superior temporal gyrus, concerned with comprehension of written and spoken language.Symptoms from lesions of the Wernickes areareceptive dysphasia impaired comprehension of speech and written language . fluent but words are replaced with partly correct words and an incorrect word related to the word intended (paraphasia)or newly created meaningless words (neologisms)The speech does not make sense and the patient has poor insight into the problem.2. auditory cortices The dominant temporal lobe is important for the comprehension of spoken words the non-dominant for the appreciation of sounds and music. Symptoms from lesions of the auditory cortex Auditory agnosia: inability to recognize sounds e.g. ringing of a bell ,whistling of a kettle ,a melody (non-dominant hemisphere).Cortical deafness: bilateral lesions of the primary auditory cortices and is uncommon. Auditory hallucinations can occur in temporal lobe epilepsy.3.The limbic system the olfactory and gustatory cortices lie in the medial temporal lobe. The limbic system is important in memory. learning and emotion.Symptoms from lesions of the limbic systemOlfactory and gustatory hallucinations :arise from lesions within the medial temporal lobe ,particularly during seizures. Learning difficulties: difficulties with learning auditory information occur in dominant hemisphere lesions .difficulties with learning visual information occur in non-dominant hemisphere lesions.Symptoms from lesions of the limbic system Memory impairment: the hippocampus and parahippocampal gyrus. Bilateral damage results in marked impairment of retention of new information.50 First Dates Emotional disturbances: can include aggression rage, apathy hyper orality and hypersexuality.OCCIPITAL LOBE Visual cortexthe perception of vision recognition of whatever is visualized Symptoms from lesions of the occipital lobeContralateral homonymous hemianopic field defect Cortical blindness bilateral occipital lesions render the patient blindVisual agnosiaimpairment of recognition of faces and objects.Visual illusions :objects might appear larger (macropsia)or smaller (micropsia)disturbances of shape ,colour and number .Visual hallucinations seizures of the visual cortex unformed (flashes of light and geometric shapes) formed (objects,people)