Temporal lobe ppt

TEMPORAL LOBETEMPORAL LOBE

PRESENTOR:-PRESENTOR:- DR VIRINCHI DR VIRINCHI SHARMASHARMA

MODERATOR:-MODERATOR:- Dr. V S RAJDr. V S RAJ

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0VERVIEW 0VERVIEW • ANATOMY(parts)ANATOMY(parts)

• FUNCTIONAL AREASFUNCTIONAL AREAS

• LOOPS & PATHWAYSLOOPS & PATHWAYS

• FUNCTIONSFUNCTIONS

• DISORDERSDISORDERS2

• The Temporal lobes are one of the most The Temporal lobes are one of the most heterogeneous regions of the Neocortex.  heterogeneous regions of the Neocortex.  

• Input for the Limbic and Para-Limbic Input for the Limbic and Para-Limbic cortex.   cortex.  

• This is the lobe that is credited with being This is the lobe that is credited with being the seat of human para-Psychological and the seat of human para-Psychological and Psychic abilities!   Psychic abilities!  

• The temporal lobe, Is considered in its The temporal lobe, Is considered in its broadest context, links the present sensory broadest context, links the present sensory and emotional experience of our world and emotional experience of our world

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ANATOMY

ANATOMY

OF OF

TEMPORAL

TEMPORAL

LOBELOBE

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• The temporal lobes, are the part of the cerebral cortex The temporal lobes, are the part of the cerebral cortex in the left and right hemispheres of the brain lying in the left and right hemispheres of the brain lying inside the temples. inside the temples.

• Directionally, the temporal lobes are anterior to the occipital lobes, inferior to the frontal lobes and parietal lobes, and lateral to the Fissure of Sylvius, also known the lateral sulcus

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• SUPERIOR AND INFERIOR SUPERIOR AND INFERIOR TEMPORAL SULCI DIVIDE TEMPORAL SULCI DIVIDE TEMPORAL LOBE INTO 3 LOBESTEMPORAL LOBE INTO 3 LOBES

• SUPERIOR TEMPORAL LOBESUPERIOR TEMPORAL LOBE

• MIDDLE TEMPORAL LOBEMIDDLE TEMPORAL LOBE

• INFERIOR TEMPORAL LOBEINFERIOR TEMPORAL LOBE

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SUPERIOR TEMPORAL SUPERIOR TEMPORAL LOBELOBE

• involves areas 41,42,22• Primary auditory area (area 41)• On the left side of the brain this area

helps with generation and understanding of individual words.

• On the right side of the brain it helps tell the difference between melody, pitch, and sound intensity

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MIDDLE TEMPORAL LOBEMIDDLE TEMPORAL LOBE

The region encompasses most of the lateral temporal cortex, a region believed to play a part in auditory processing and language.

• Language function is left lateralized in most individuals.

• Brodmann area 21.

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INFERIOR TEMPORAL LOBEINFERIOR TEMPORAL LOBE

• It refers to a subdivision of the cytoarchitecturally defined temporal region of cerebral cortex. In the human it corresponds approximately to the inferior temporal gyrus.

• Brodmann area 20. • The region encompasses most of the

ventral temporal cortex, a region believed to play a part in high-level visual processing and recognition memory.

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MEDIAL PART OF MEDIAL PART OF TEMPORAL LOBETEMPORAL LOBE

• The medial temporal lobe comprises the hippocampus and amygdala, as well as the entorhinal, perirhinal and parahippocampal neocortical regions.

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Amygdala

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Amygdala• The fear & flight response • Inputs: The association areas of visual,

auditory, and somato sensory cortices are the main inputs to the amygdala.

• Outputs: The main outputs of the amygdala are to the hypothalamus and brainstem autonomic centers, including the vagal nuclei and the sympathetic neurons.

• The amygdala is also involved with mood and the conscious emotional response to an event

• The amygdala is also extensively interconnected with frontal cortex, medio dorsal thalamus, and the medial striatum. 13

• The deep group, which The deep group, which includes the lateral, includes the lateral, basal, accessory basal basal, accessory basal nucleicnucleic

• Func: collects input from Func: collects input from sensory cortex. sensory cortex.

• The more dorsal group, The more dorsal group, which includes the which includes the central & medial nucleicentral & medial nuclei

• Func: receives Func: receives projections from the projections from the deep group and sends deep group and sends the signal out to the signal out to autonomic centers. autonomic centers.

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• The amygdala is the heart of the emotional system. It processes and interprets all sensory data.

• It modulates the flow of emotional information between the cerebral cortex and the hypothalamus, and in doing that, it modulates autonomic, endocrine, and affective responses.

• Lesions in amygdala lead to-- agitation, irritability, anxiety, mood disorders, paranoia, and psychosis.

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The Hippocampus

• The hippocampus is a scrolled structure The hippocampus is a scrolled structure located in the medial temporal lobe. located in the medial temporal lobe.

• The hippocampus can be divided into at The hippocampus can be divided into at least five different areas.least five different areas.

• The dentate gyrus is the dense dark layer The dentate gyrus is the dense dark layer of cells at the "tip" of the hippocampus. of cells at the "tip" of the hippocampus. Areas CA3 and CA1 are more diffuse; the Areas CA3 and CA1 are more diffuse; the small CA2 is hard to distinguish between small CA2 is hard to distinguish between them. (CA stands for cornu ammonis, from them. (CA stands for cornu ammonis, from its ram's horn shape.) its ram's horn shape.)

• The subiculum sits at the base of the The subiculum sits at the base of the hippocampus, and is continuous with hippocampus, and is continuous with entorhinal cortex, which is part of the entorhinal cortex, which is part of the parahippocampal gyrus. parahippocampal gyrus.

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FUNCTIONAL AREAS OFFUNCTIONAL AREAS OF TEMPORAL LOBE TEMPORAL LOBE

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• AUDITORY – primary & Association

• OLFACTORY - primary & Association

• VISUAL (Recognition & association)

• MEMORY

• EMOTIONAL & SOCIAL

• Link past and present sensory and emotional experiences into a continuous self 20

LANGUAGE & COMPREHENSION

• LANGUAGE AREAS • A specialized integration area called Wernicke's area is

found in the posterior temporal lobe of one hemisphere (usually the left). Commonly called the "speech area, " Wernicke's area surrounds and encompasses part of the auditory association area.

• AFFECTIVE LANGUAGE AREAS • Affective language areas involved in the nonverbal

emotional components of language - appear to be present in the hemisphere opposite Brocas's and Wernickes's areas.

• These "mirror images" allow the lilt of tone of our voice and our gestures to express our emotions when we speak, and permit us to comprehend the emotional content of what we hear.

• Lesions to this area result in aprosodia, a condition in which speech is flat and emotionsess, lacking the intonations that modify the meaning of our spoken words.21

AUDITORY SENSESAUDITORY SENSES• PRIMARY AUDITORY AREA (area 41) Essential to detect changes in

frequency , & to know the direction from which sounds originate.

• AUDITORY ASSOCIATION AREA (area 42)

• HIGHER AUDITORY ASSOCIATION AREA (area 22) 22

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VISUAL SENSESVISUAL SENSES• Processing of our

recognition of objects occurs in a path on the lower, dorsal stream in the temporal lobe; here you find areas sensitive to faces vs. objects,

• Area MT (right) performs processing on motion. Subjects without an area MT describe seeing motion as discontinuous pictures – eg.having to rely on sound before crossing a street.

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OLFACTORY SENSESOLFACTORY SENSES

The rightmost green spots are the location in cortex where smell is processed.

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GUSTATORY SENSESGUSTATORY SENSES• The sensation of

taste is processed in insular cortex

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connections of the Temporal Lobes

• Five main types:• Hierarchical sensory pathway• Dorsal auditory pathway• Polymodal pathway• Medial (mesial) temporal pathway• Frontal lobe projection

• Hierarchical sensory pathway• connections from• primary(sensory neuron) and secondary auditory

and visual cortical

• through the lateral temporal cortex

• terminate in the temporal pole

• visual travels inferior temporal gyrus• • auditory travels e suprior temporal gyrus• Major destinations:• amygdala and hippocampus• This results in the integration of information into:

memory, retrieval of stored information, emotional tone

• Ultimate effect stimulus recognition• The familiar conscious experience of knowing,

assimilating, and feeling

• Dorsal auditory pathway

• Forms important functional connections with the posterior parietal cortex

• Enables location of sounds in space• Promotes orienting and initiation of

movements relative to sound location

Polymodal Pathway• connections emerging from the auditory and

visual hierarchical pathways• Directed towards the neurons enfolded within

the superior temporal sulcus• Polymodal nature of neurons• Assigns stimuli to specific category of classes,

linked to and can be retrieved by memory

• Medial Temporal Projection• Projections from auditory and visual areas into the

limbic regions• E.g., amygdala and hippocampus• Directions of projectionsPeripheral cortex entorhinalcortex

amygdala/hippocampus• Perforant pathway• forms the main projection to thehippocampus• Damage in this region severely affects memory

formation

• Frontal-lobe Projection

• Neurons from the temporal lobe have strong connections with the frontal lobe

• Posterior temporal cortex• Projects to the dorsolateral prefrontal cortex • anterior temporal cortex• Projects to the orbital frontal cortex• Damage leads to terrible life decisions

DISORDERS OFTEMPORAL LOBE

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8 principal symptoms of 8 principal symptoms of temporal lobe damage:temporal lobe damage:

• Disturbance of auditory sensation and perception

• Disturbance of selective attention of auditory and visual input

• Disorders of visual perception• Impaired organization and categorization

of verbal material• Disturbance of language comprehension• Impaired long-term memory• Altered personality and affective behaviour• Altered sexual behaviour

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Manifestations of temporal Manifestations of temporal lobe lesionslobe lesions• Disorders of auditory perception:

– Lesions of the left superior temporal gyrus produce problems of speech perception with difficulty in discriminating speech and the temporal order of sounds is impaired.

• Lesions of the right superior temporal gyrus can produce disorders of perception of music with inability to discriminate melodies and produce prosody

• The inferior temporal cortex is responsible for visual perception and lesions produce inability to recognise faces, called prosopagnosia.

• There may be disturbance of visual and auditory input selection. This presents as impairment of short term memory, also called working memory and judgement about the recency of events. 41

disorders of memory• The medial and inferior temporal cortex and

hippocampus are responsible for memory.• There is complete anterograde amnesia following

bilateral removal of medial temporal lobes, including hippocampus & amygdala.

• There is difficulty recalling information. • The left side is responsible for verbal material and the

right for non-verbal memory such as faces, tunes and drawings.

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• temporal lobe personality. There is egocentricity, pedantic speech, perseveration of speech, paranoia, religious preoccupations and a tendency to aggressive outbursts, especially after right temporal lobectomy.

• temporal lobe lesions can present with visual field defects in the form of superior quadrant loss, sometimes called the "pie in the sky defect."

• Stroke normally reduces libido but temporal lobe lesions can increase it.

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APHASIAAPHASIA• Any disturbance in the comprehension or

expression of language caused by a brain lesion.

• NONFLUENT APHASIA, i.e. in lesion to Broca's area results in slow speech, difficulty in choosing words, or use of words that only approximate the correct word.e.g., a person may say "tssair" when asked to identify a picture of a chair.

• A lesion to Wernicke's area may result in FLUENT APHASIA, in which a person speaks normally, and sometimes excessively, but uses jargon and invented words, that make little sense (e.g., "choss" for chair). The person also fails to comprehend written and spoken words.

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Kluver-Bucy syndrome Kluver-Bucy syndrome results due to a

bilateral destruction of the amygdaloid body and inferior temporal cortex.

It is characterized by Visual agnosia, Placidity,

Hypermetamorphosis, Hyperorality

Hypersexuality. causes: cerebral trauma; infections including

herpes and other encephalitides; Alzheimer's disease and other dementias; Niemann-Pick disease and cerebrovascular disease. 45

Diseases of the Diseases of the HippocampusHippocampus

• The hippocampus is particularly vulnerable to several disease processes, including ischemia, which is any obstruction of blood flow or oxygen deprivation, Alzheimer's disease, and epilepsy.

• These diseases selectively attack CA1, which effectively cuts through the hippocampal circuit. 46

TEMPORAL LOBE EPILEPSY (TLE) WAS DEFINED IN 1985 BY THE INTERNATIONAL LEAGUE AGAINST EPILEPSY (ILAE) AS A CONDITION CHARACTERIZED BY RECURRENT UNPROVOKED SEIZURES ORIGINATING FROM THE MEDIAL OR LATERAL TEMPORAL LOBE.

LATERAL TEMPORAL LOBE EPILEPSY : ARISES IN THE NEOCORTEX MESIAL TEMPORAL LOBE EPILEPSY:HIPPOCAMPUS, PARAHIPPOCAMPAL GYRUS AMYGDALA

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TEMPORAL LOBE EPILEPSYTEMPORAL LOBE EPILEPSY

• Hereditary• Febrile sezuires• Brain tumors• spinal meningitis,• encephalitis,• head injury or blood vessel malformations• Trauma• congenital brain malformations• Alcohol withdrawl• Sleep deprivation

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causescauses

• Seizures usually simple partial but can be complex partial seizures also

• Duration is one to two minutes• Auras• Motionless staring• Anxiety• Emergent past memories• Spiritual religious experience

• Most common type comprising 70percent of seizures with 1.5%of population world wide

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symptosymptomsms

treatmenttreatment• Antiepilectic drugs

• Surgical procedures

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CVA---TEMPORAL LOBECVA---TEMPORAL LOBE• Middle cerebral artery in farct:Middle cerebral artery in farct:

– Aphasia or non-dominant hemisphere findings depending on Aphasia or non-dominant hemisphere findings depending on the side.the side.

– ““Partial” middle cerebral artery syndromes, almost always of Partial” middle cerebral artery syndromes, almost always of embolic origin, may include a) sensorimotor paresis with little embolic origin, may include a) sensorimotor paresis with little aphasia b) conduction aphasia c) Wernicke’s aphasia without aphasia b) conduction aphasia c) Wernicke’s aphasia without hemiparesis.hemiparesis.

– Wernicke's aphasia, caused most often by occlusion of the Wernicke's aphasia, caused most often by occlusion of the lower division of the MCA bifurcation or one of its branches. lower division of the MCA bifurcation or one of its branches. Patients with Wernicke's aphasia vocalize smoothly and with Patients with Wernicke's aphasia vocalize smoothly and with expression, but they demonstrate paraphasias or speech with expression, but they demonstrate paraphasias or speech with distorted phonetic structure, word substitution, and additional distorted phonetic structure, word substitution, and additional prefixes and suffixes. prefixes and suffixes.

– The infarct responsible for a classic Wernicke's aphasia The infarct responsible for a classic Wernicke's aphasia includes the dominant posterior temporal, inferior parietal, and includes the dominant posterior temporal, inferior parietal, and lateral temporo-occipital regions.lateral temporo-occipital regions.

• Posterior cerebral artery syndrome:Posterior cerebral artery syndrome:

Recent memory loss may be present (involvement of Recent memory loss may be present (involvement of hippocampus).hippocampus). 51

Temporal lobe abscess Temporal lobe abscess • Brain abscess is a

newly formed cavity in brain tissue, filled with pus.

• Mastoiditis causes temporal lobe abscess.

• Hematogenous abscesses are often multiple.

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TEMPORAL LOBE TEMPORAL LOBE TUMORSTUMORS

• As many as 50 to 55 percent of patients with temporal lobe tumors experience psychiatric, behavioral, or personality changes

• Psychopathology related to temporal lobe tumors can be ictal, that is, seizure associated, or interictal, completely unrelated to seizure activity.

• Patients with tumors of the temporal lobe who have temporal lobe seizures often have seizure-associated schizophrenia-like psychotic symptoms

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SYMPTOMS INCLUDE SYMPTOMS INCLUDE

• Auditory hallucinations and atypical Auditory hallucinations and atypical dream-like episodes, depersonalization, dream-like episodes, depersonalization, blanking-out spells, and dazed feelingsblanking-out spells, and dazed feelings

• Patients with temporal lobe seizures Patients with temporal lobe seizures may present with depression and may present with depression and frontal lobe–like apathy and irritability,frontal lobe–like apathy and irritability,

• Or with features suggesting hypomania Or with features suggesting hypomania or mania,or mania,

• Personality changes commonly occur Personality changes commonly occur and may be one of the earliest and may be one of the earliest indications of an undiagnosed temporal indications of an undiagnosed temporal lobe tumorlobe tumor

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