Let’s Get to Know the Parietal Lobes!

A brief primer on parietal lobe function (as it relates to memory).

By Rebecca Emily Martin

Brodmann Areas associated with parietal lobes

BA 3, 1, 2, 5 - somatosensory

BA 7 - visuo-spatial imagery , self-processing

BA 23, 29, 31 - Retrosplenial cortex, posterior cingulate

BA 39 - reading, visuo-language processing

BA 40 - supramarginal gyrus

BA 43 - parietal operculum

1

2

The Parietal Lobes can be divided into 6 main regions

medial

lateral

The Parietal Lobes can be divided into 6 main regions

dorsal

ventral

3

4

The Parietal Lobes can be divided into 6 main regions

anterior

posterior

The Parietal Lobes can be divided into 6 main regions

posterior

(This presentation focuses on posterior parietal cortex, PPC)

5

6

Terminology

TerminologyLateral Posterior Parietal Cortex (PPC)

Includes two main regions separated by the intraparietal sulcus (IPS)

superior parietal lobule (SPL)

inferior parietal lobule (IPL)

7

8

Terminologysuperior parietal lobule

akadorsal posterior parietal cortex akaBA 7

(and sometimes BA 5 aka the association cortex)

akathe precuneus

Terminologyinferior parietal lobule akaventral posterior parietal cortex akaBA 39 and BA 40 akathe angular and supramarginal gyri which also include

the temporoparietal junctionWernicke’s area

9

10

TerminologyOther notable areas:

posterior cingulate cortex, BA 23, 31 (PPC)

retrosplenial cortex, BA 29 (Rsp, or RSC)

parietal operculum

(but we won’t talk about this part)

Function of Lateral Regions

somatosensorysensory integration

reading

language

comprehension

theory of mind

self-processing

11

12

Notable Networks

default network

frontoparietal control system

dual attentional processes hypothesis (Cabeza, 2008)dorsal parietal attention systemventral parietal attention system

Default NetworkKey Regions:

Posterior cingulate/Retrosplenial Cortex (considered a hub)

Inferior parietal lobule

Medial Prefrontal Cortex

hippocampus

lateral temporal cortex

Has inverse relationship with cognitive control networks.

Associated with autobiographical memory

Buckner et al., 2007Red = default networkBlue = cognitive control networks

13

14

Dual Attentional Processes Hypothesis of attention to Memory

Dorsal PPCincludes SPL and IPS top-down, preparatory, goal-driven allocation of attention

Ventral PPCincludes IPL and TPJbottom-up, reflexive reorienting of attention to behaviorally relevant information

Nature Reviews | Neuroscience

4040

39 39

7 7

Familiarity

Recollection High-confidencerecognition

Low-confidence recognition

c

a b

Familiarity Low-confidence recognitionRecollection High-confidence recognition

began as soon as the search instructions were given and continued throughout the search period, whereas VPC activity was greater than DPC activity when the target was detected66. Thus, DPC activity mediates preparatory top-down attention, whereas VPC activity is associated with the capture of bottom-up attention by behaviour-ally relevant stimuli. Activity that is associated with bot-tom-up attention can also be captured using unexpected (spatial and non-spatial) stimuli67–72. When a relevant stimulus that was out of the current attentional focus appears, the VPC sends a ‘circuit breaker’ signal to the DPC, which shifts attention to the previously unattended

stimulus73. The right VPC is also the most frequent loca-tion of lesions that cause neglect, which can be described as a deficit in bottom-up attention: patients with neglect can voluntarily direct attention to the contralesional side and can use cognitive cues to anchor attention to the left visual space, but they have a deficit in detecting stimuli that are outside the focus of ongoing processing23.

Parietal cortex, attention and episodic memoryCould the distribution of episodic-retrieval activations in FIG. 4c be associated with the allocation of top-down and bottom-up attention to memory by the DPC and the

Figure 4 | Ventral–dorsal dissociations in activity. a | In a functional MRI (fMRI) study of the remember–know paradigm60, the ventral parietal cortex (VPC) showed greater activity for remember than for know trials, whereas the dorsal parietal cortex (DPC) showed the opposite pattern. b | In an fMRI study of confidence during recognition memory63, the VPC showed greater activity for high- than for low-confidence hits, whereas the DPC showed the opposite pattern. c | A meta-analysis of parietal activity during episodic retrieval. The images plot the peaks of activations in two kinds of event-related fMRI studies (for a list of studies and coordinates, see Supplementary information S3 (table) and S4 (table)). A first group of peaks (red and dark blue dots) is from studies that identified activity related to recollection or familiarity by using the remember–know paradigm, by distinguishing successful from unsuccessful source-memory retrieval, or by comparing the retrieval of items encoded under deep versus shallow study tasks48,49,51,58,59,96,100–102,109–118. A second group of peaks (yellow and pale blue dots) is from studies that investigated recognition confidence61,62,81,119. In general, recollection and high-confidence recognition were associated with VPC activations, whereas familiarity and low-confidence recognition were associated with DPC activations. Part a modified, with permission, from REF. 60 (2006) American Physiological Society. Part b modified, with permission, from REF. 63 (2007) Pergamon Press.

REVIEWS

NATURE REVIEWS | NEUROSCIENCE VOLUME 9 | AUGUST 2008 | 619

red - familiarblue - remember

Cabeza, Nat Rev Neuro 2008

Fronto-parietal Control Network

Vincent et al., J. Neurophysiol 2008

Three key networks:dorsal attention system (similar to dorsal attn. network)

superior parietal lobule, intraparietal lobule, intraparietal sulcus, MT+, ventral premotor cortex and frontal eye fields

Hippocampal-cortical memory system (similar to ventral attn. network/ default network

declarative memory (e.g. autobiographical)inferior parietal lobule, retrosplenial cortex, posterior cingulate, ventromedial PFC, lateral temporal lobe

fronto-parietal control systemanatomically interposed between the two systems: anterior PFC, dorsolateral PFC, anterior cingulate, anterior insula, anterior inferior parietal cortexmediates the dorsal attn. and hippocampal-cortical memory systems

15

16

Memory and the Parietal LobesEncoding (Uncapher and Wagner, 2009)In a remember/know task:

successful remembering was associated with dorsal PPCi.e. the more you “pay attention” during a task, the more likely you are to remember something

forgetting associated with ventral PPCi.e. if you are “spacing out” your default network is probably more active, and you are less likely to remember...

Memory and the Parietal LobesRetrieval (Hutchinson, Uncapher, Wagner, 2009)

theories out there but no certainty...more research neededdoesn’t mirror the dual attention hypothesismain conclusion: attentional mechanisms more involved in encoding than in retrievalSuccessful remembering associated with ventral regions while less successful remembering associated with dorsal regionsdorsal system primarily left-lateralized

specialized role for IPS? (visual mapping)ventral system primarily right-lateralized (spatial reorienting)

default network also part of the ventral system

17

18

Don’t forget the medial parietal regions!

Retrosplenial Cortex (Rsp or RSC)considered an intermediate “translation” zoneinvolved in hippocampal-dependent function (many reciprocal connections with MTL regions) (Vann, Nat Rev Neuro, 2009)

Posterior Cingulate Cortex (PCC)considered hub of the default network“evaluative” region (as opposed to being an “executive” region like the ACC) (Vogt, Cerebral Cortex, 1992)

Precuneusactivated during source memory retrieval along with lateral PPC (Cavanna, Brain, 2006)

Nature Reviews | Neuroscience

Prefrontal cortexExecutive, scene manipulation

Retrosplenial cortexScene translation

Parietal cortexBody-oriented information

Occipital cortexVisual information

Allocentric framework

Egocentricframework

ATNHead direction, theta

Perirhinal cortexObject-based information

ParahippocampalScene-based information

HippocampusEvent within a scene,scene construction

key questions could be addressed by assessing patients with RSC damage on their ability to imagine ficti-tious and future experiences and on how they process scenes, and by using fMRI studies with task designs that specifically target the RSC. The RSC has too long

been the poor relation of cognitive neuroscience. It is our hope that the RSC will now become a major focus of dedicated research, and our belief that defining its role will prove pivotal in understanding a range of crucial cognitive functions.

Figure 3 | The key anatomical and functional relationships of the retrosplenial cortex. Effective episodic memory, navigation and future thinking all require the ability to integrate and manipulate different frameworks of information, for example egocentric (self-centred) and allocentric (world-centred) frameworks. By virtue of its principal connections, the retrosplenial cortex is uniquely placed to enable translation within these domains. ATN, anterior thalamic nuclei.

1. Brodmann, K. Vergleichende Lokalisationslehre der Grosshirnrinde inihren Prinzipien dargestellt auf Grund des Zellenbaues (Barth, Leipzig, 1909).

2. Vogt, B. A., Absher, J. R. & Bush, G. Human retrosplenial cortex: where is it and is it involved in emotion? Trends Neurosci. 23, 195–197 (2000).

3. Papez, J. W. A proposed mechanism of emotion. Arch. Neurol. Psychiatry 38, 725–743 (1937).

4. MacLean, P. Psychosomatic disease and the visceral brain; recent developments bearing on the Papez theory of emotion. Psychosom. Med. 11, 338–353 (1949).

5. Vogt, B. A., Nimchinsky, E. A., Vogt, L. J. & Hof, P. R. Human cingulate cortex: surface features, flat maps, and cytoarchitecture. J. Comp. Neurol. 359, 490–506 (1995).

6. Cavanna, A. E. & Trimble, M. R. The precuneus: a review of its functional anatomy and behavioural correlates. Brain 129, 564–583 (2006).

7. Kobayashi, Y. & Amaral, D. G. Macaque monkey retrosplenial cortex: II. Cortical afferents. J. Comp. Neurol. 466, 48–79 (2003).

8. Kobayashi, Y. & Amaral, D. G. Macaque monkey retrosplenial cortex: I. Three-dimensional and cytoarchitectonic organization. J. Comp. Neurol. 426, 339–365 (2000).

9. Vogt, B. A., Vogt, L., Farber, N. B. & Bush, G. Architecture and neurocytology of monkey cingulate gyrus. J. Comp. Neurol. 485, 218–239 (2005).

10. Morris, R., Petrides, M. & Pandya, D. N. Architecture and connections of retrosplenial area 30 in the rhesus monkey (Macaca mulatta). Eur. J. Neurosci. 11, 2506–2518 (1999).

11. Vogt, B. A. in Cingulate Neurobiology and Disease (ed. Vogt, B. A.) 65–93 (Oxford Univ. Press, London, 2009).A chapter from a recent book devoted to the entire cingulate cortex, of which the RSC is a component area. This is the first book devoted to the neurobiology of this region since 1993.

12. Vogt, B. A. & Peters, A. Form and distribution of neurons in rat cingulate cortex: areas 32, 24, and 29. J. Comp. Neurol. 195, 603–625 (1981).

13. Van Groen, T. & Wyss, J. M. Connections of the retrosplenial granular a cortex in the rat. J. Comp. Neurol. 300, 593–606 (1990).

14. Van Groen, T. & Wyss, J. M. Connections of the retrosplenial granular b cortex in the rat. J. Comp. Neurol. 463, 249–263 (2003).

15. Van Groen, T. & Wyss, J. M. Connections of the retrosplenial dysgranular cortex in the rat. J. Comp. Neurol. 315, 200–216 (1992).

16. Kobayashi, Y. & Amaral, D. G. Macaque monkey retrosplenial cortex: III. Cortical efferents. J. Comp. Neurol. 502, 810–833 (2007).The final paper in a series of three that provide the most detailed descriptions to date of the inputs to the RSC in an Old World monkey brain.

17. Mufson, E. J. & Pandya, D. N. Some observations on the course and composition of the cingulum bundle in the rhesus monkey. J. Comp. Neurol. 225, 31–43 (1984).

18. Morris, R., Pandya, D. N. & Petrides, M. Fiber system linking the mid-dorsolateral frontal cortex with the retrosplenial/presubicular region in the rhesus monkey. J. Comp. Neurol. 407, 183–192 (1999).

19. Jones, B. F., Groenewegen, H. J. & Witter, M. P. Intrinsic connections of the cingulate cortex in the rat suggest the existence of multiple functionally segregated networks. Neuroscience 133, 193–207 (2005).

20. Vogt, B. A. & Miller, M. W. Cortical connections between rat cingulate cortex and visual, motor, and postsubicular cortices. J. Comp. Neurol. 216, 192–210 (1983).

21. Vogt, B. A. in Cerebral Cortex: Association and Auditory Cortices Vol. 4 (eds Peters, A. & Jones, E.) 89–149 (Plenum, New York, 1985).

22. Sutherland, R. J. & Hoesing, J. M. in Neurobiology of Cingulate Cortex and Limbic Thalamus: A

REVIEWS

800 | NOVEMBER 2009 | VOLUME 10 www.nature.com/reviews/neuro

19

20