Higher Cortical Functions Dr Charulata Sankhla MD DNB

Higher Cortical Functions Dr Charulata Sankhla MD DNB P D Hinduja National Hospital And Medical research Center

Higher cortical functions • Consciousness – awake, drowsy, stupor, coma • Orientation - time, person , place • Cognition – attention, language, praxis, judgment, reasoning, abstract thinking, insight, visuospatial orientation, gnosis, calculation • Affect – mood, behavior

Consciousness • Function of ARAS originating from brainstem, projecting to wide areas of bilateral cerebral networks. • Conscious – awake, aware • Drowsy – sleepy, arousable with verbal or mild physical stimulus but goes again into sleep once stimulus removed • Stupor – unconscious, responds to painful / vigorous mechanical stimulus • Coma – unconscious, not responding to painful stimulus.

Orientation • To time, place and person • Any disturbance which is diffuse, due to reversible or progressive process • Examples – encephalopathy, drugs, severe dementia with severe memory impairment

Attention • Preservation of attention and language is necessary to proceed further with other higher function examinations. • Function of ARAS and bilateral frontal lobe • Tests : • 1) digit span – forward - normal 5 -7 backward – normal 3 2) spell/ days/ months – backward 3) serial 7 s – subtract 7 consecutively 5 times from 100 – also checks calculation 4) vigilance – ask pt to tap when he hears a “A” when a series of letters presented to him

Language –Dominant Fronto temporal function • Perisylvian network in left dominant cortex • Aphasia is a acquired dysfunction of language • Spontaneous speech, comprehension, naming, repetition, reading, writing • Spontaneous speech : – Ask pt to describe his illness/ work – See fluency and grammar (motor speech area), prosody(non dominant motor speech area), articulation, paraphasia, neologism – normal fluency 100 -150 words/ min, sentence length >7 words – Reduced fluency in Brocas aphasia, transcortical motor, global aphasia, primary progressive aphasia

Comprehension • Comprehension : ability to understand spoken language • Posterior superior temporal gyrus (broadman area 22) 1) pointing commands – ask to point at 4 objects or room or body part 2) yes/ no questions – 7 questions 3) complex command – if lion was killed by tiger , then which animal is dead? • Classically impaired in Wernicks aphasia

Repetition • No if and or buts • Sarashwati sishu bal vidyamanadir • Impaired in all aphasias except transcortical motor and transcortical sensory, anomic • Classically severely and only parameter impaired in conduction aphasia

Naming • • Colors Body parts Objects Part of objects chain of wrist watch, shoe laces, buckle of belt Very sensitive for any kind of language dysfunction. anomia can be isolated as anomic aphasia or can be associated with other aphahsic syndroms

Reading • Alexia • Letters, numbers, words, paragraph – fluency, articulations and comprehension • Alexia without agraphia – posterior callosal / left deep occipital area involvement – classically in left PCA (P 2) infarct, disconnecting visual association from language area • Alexia with agraphia – angular gyrus – gerstmann syndrome

Writing • Agraphia • Writing on narration/ spontaneous • Write letters/ words/ sentence / paragraph

Brocas aphasia • Spontaneous speech –telegraphic mute nonfluent produces less words • Naming impaired • Comprehension- intact with mild difficulty • Reading impaired often • Repetition impaired • Writing impaired dysgrammatical • Posterior part of inferior frontal gyrus -upper division of left MCA

Wernickes aphasia • Spontaneous speech – fluent with paraphasia Logorrhoea • Naming impaired bizzarre • Comprehension impaired • Repetition impaired • Reading reading aloud but comprehension impaired • Writing well formed with paraphasia • Posterior part of superior temporal gyrus, inferior parietal lobule

Conduction aphasia Spontaneous speech- fluent with some hesitancy Naming - moderately impaired Comprehension –intact Repetition severely impaired Reading cannot read aloud some reading comprehension • Writing deficits • Arcuate fasciculus • • •

Differential of nonfluent speech/ condition mimicking nonfluent aphasia Speech apraxia - : disorder of programmimg of articulation , in a sequence of phonemes, especially consonants • Features 1) effortful 2) trial and error attempts – and self corrections 3) dysprosody 4) inconsistency in articulation errors- making one error at one time and different or no error next time with same word 5) difficulty in initiating utterance • Substrate : left insula, brocas area

Memory – A temporal lobe function • Digit span 7 numbers • Recent memory – recall hippocampus (limbic system) parahippocampus Medial temporal lobe learning and recalling of events/ experiences Give 4 words , ask after 5, 10, 15 minutes. Recalling less than 3 words after 10 minutes is abnormal – Check visual memory in pts with motor aphasia – hide 5 objects and ask location and name of objects after 5 minutes – less than 4 is abnormal – Classically impaired early in Alzheimer's disease, also in bilateral MTS – – • Immediate memory – registration – Frontal lobe – attention – online holding of information – To be checked similarly as described in attention

• Remote memory – personal information- name of grand parents, firstgrade school teacher – Stored in broad networks in bilateral cerebral hemisphere, gets affected in late stages of dementia • Semantic memory – concepts / word meanings – anterior temporal lobe – checked by categorical word fluency – name of animals /flowers in 1 minute – less than 13 is impaired – Classically impaired in Alzheimer's disease and semantic dementia

• Implicit memory / procedural memory – basal ganglia, cerebellum • Driving from work to home • cycling

Parietal lobe • Visuospatial (non dominant hemisphere) ---– geographic orientation (neglect) ---- construction (construction apraxia) ---- dressing (dressing apraxia) • Praxis (dominant hemisphere) – ability to perform learned skilled movement correctly • Calculation • Cortical sensations –tactile localisation, 2 point discrimination, sensory extinction, stereognosis, graphesthesia

neglect • 1) simultaneous bilateral stimulation – visual, tactile, auditory – patient will neglect stimuli presented on left hemispace – Anosognosia – denial of deficit – left hemiplegia , in case of rt hemispheric stroke – different from true agnosia - essentially a form of neglect of left hemifield due to rt parietal involvement. • 2) visual target cancellation – line bisection (ask pt to divide line in 2 ) – letter cancellation ( tick all letter A from randomly written letters)

construction • Copy cubes/ triangles/ complex structure • Draw clock – it also tests for visuospatial orientation, planning, sequencing calculation Verbal simple, verbal complex, written complex Rt left orientation

Apraxia Acquired inability to correctly perform learned skilled movements in absence of motor, sensory or cerebellar dysfunction. Action semantics and concepts – posterior parietal movement formulas and gesture knowledge - Left inferior parietal lobule Motor programs - Left supplementary motor area Ask to pantomime use brush, comb, lock n key Imitate the gesture – bye, come, good luck etc Gesture knowledge - which gesture is it Tool knowledge – which tool is it n what its used for Use of real tool – give pt brush, comb, lock n key , hammer and use it Causes – left parietal SOL, dementias – AD, corticobasal syndrome

Other traditional apraxias , not fitting into definition of true apraxia and have different localizing value • Dressing and construction apraxia – more related to visuospatial and self orientatation – rt parietal area • Oculomotor apraxia • Gait apraxia – bilateral frontal lobe • Speech apraxia • Oral/ buccolingual apraxia

Occipital Hemianopia Cortical blindness in case of B/L involvement – pupillary (always) and macular (mostly) sparing. Extension of pathology into adjacent parietal lobes § color agnosia § anton syndrome – denial of blindness in a patient with cortical blindness § balint syndrome – optic ataxia – inability to trace an object with visual guidance. optic apraxia – inability to voluntarily shift the gaze +/_ asimultagnosia - inability to notify gross picture , though able to pick up fine detail – misses forest for trees. – ask patient to circle A , from random letters of varying size, patient might encircle small sized A and will miss very large sized A

Extension of pathology into adjacent temporal lobes Agnosia – inability to recognize object Visual , tactile, auditory (sensory input specific ) Prosopognosia – inability to recognize familiar face - show pictures of familiar and popular personality, animals Object agnosia – show various objects and ask to identify

MMSE • • • Screening test 30 points 5 - orientation to time 5 - orientation to space 5 - attention serial 7 or spell world backwards 3 registration of the 3 items 3 recall 2 naming 3 three stage command 1 for reading 1 for writing 1 1 copying a diagram